JP2007005279A - Laminate including active material layer and solid electrolyte layer, and all solid lithium secondary battery using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate with a solid electrolyte layer and an active material layer both densified or crystallized by thermal processing having an active material/solid electrolyte interface which is active electrochemically, and to provide an all solid lithium secondary battery having low internal resistance and large capacity. <P>SOLUTION: The laminate includes: the active material layer; and the solid electrolyte layer which is joined to the active material layer by sintering. The active material layer includes a first crystalline material which can emit and occlude lithium ions, and the solid electrolyte layer includes a second crystalline material which has lithium ion conductivity. When the laminate is analyzed by the X-ray diffractometry, any component is not detected except constituents of the active material layer and the solid electrolyte layer. The all solid lithium secondary battery includes a laminate and a negative electrode active material layer like these. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laminate including a positive electrode active material layer and a solid electrolyte layer, and an all solid lithium secondary battery using the same.

  With downsizing of electronic devices, a battery having high energy density is demanded as its main power source or backup power source. Among these, lithium ion secondary batteries are attracting attention because they have higher voltage and higher energy density than conventional aqueous batteries.

In lithium ion secondary batteries, oxides such as LiCoO ₂ , LiMn ₂ O ₄ and LiNiO ₂ are used as positive electrode active materials, alloys such as carbon and Si, and oxides such as Li ₄ Ti ₅ O ₁₂ are used as negative electrode active materials. It is used as. Moreover, what melt | dissolved Li salt in carbonate ester or an ether type organic solvent is used for electrolyte solution.

However, since the above electrolyte is a liquid, there is a possibility of leakage. Furthermore, since a combustible material is used for the electrolytic solution, it is necessary to improve the safety of the battery when misused. In order to increase the safety and reliability of lithium ion secondary batteries, research on all-solid lithium secondary batteries using a solid electrolyte instead of an electrolytic solution has been actively conducted.
However, the solid electrolyte has a problem that the electrical conductivity is low and the output density is low as compared with the electrolytic solution which is a liquid.

On the other hand, in order to achieve high energy density, a multilayer battery including a laminate in which at least one set of a positive electrode, a solid electrolyte or a separator including an electrolyte, and a negative electrode are stacked and integrated has been proposed ( Patent Document 1). Terminal electrodes connected to the positive electrode and the negative electrode are provided on at least one of the side surfaces and the upper and lower end surfaces of the laminate.
In order to increase the conductivity, it is also conceivable to place a gel electrolyte containing a liquid electrolyte between the positive electrode active material layer and the negative electrode active material layer.

  In Patent Document 1, a set of a positive electrode, a solid electrolyte, and a negative electrode is connected in parallel or in series by a terminal electrode. The terminal electrode is formed by plating, baking, vapor deposition, sputtering, or the like. However, for example, it is difficult to use the above method in a stacked battery including a gel electrolyte containing a liquid electrolyte. In the case of plating, since the water contained in the plating solution is mixed into the battery, it cannot be applied to a system containing a non-aqueous electrolyte. In the case of baking, the electrolyte solution boils and evaporates, so that it is difficult to apply. In the case of vapor deposition or sputtering, these methods need to be performed under a reduced pressure atmosphere. Also in this case, it is difficult to apply since the electrolytic solution boils and evaporates.

Perovskite-type Li _0.33 La _0.56 TiO ₃ and NASICON-type LiTi ₂ (PO ₄ ) ₃ are Li ion conductors capable of conducting Li ions at high speed. In recent years, all solid state batteries using such a solid electrolyte have been studied.
A solid battery using an inorganic solid electrolyte, a positive electrode active material, and a negative electrode active material is formed by sequentially laminating a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer, and is sintered by heat treatment. It is produced by. In this method, the interface between the positive electrode active material layer and the solid electrolyte layer and the interface between the solid electrolyte layer and the negative electrode active material layer can be joined. However, using this method has been disadvantageous for various reasons.

For example, in Non-Patent Document 1, when sintering is performed using LiCoO ₂ which is a positive electrode active material and LiTi ₂ (PO ₄ ) ₃ which is a solid electrolyte, both react in the sintering process, and charge / discharge reaction occurs. It has been reported that compounds such as CoTiO ₃ , Co ₂ TiO ₄ , and LiCoPO ₄ that do not contribute to the formation of Nb are formed.
In this case, there may be a problem that a sintered interface between the active material and the solid electrolyte is generated at the sintered interface between the active material and the solid electrolyte, so that the sintered interface is electrochemically inactivated.

In order to solve such problems, for example, the following manufacturing methods have been proposed. First, after forming a three-layer pellet having a structure of LiMn ₂ O ₄ / Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ / Li ₄ Ti ₅ O ₁₂ , the pellet was sintered at 750 ° C. for 12 hours to obtain an electrode. Get. Next, the electrode is polished to a thickness of 10 to 100 μm to make an all-solid battery (see Non-Patent Document 2). Here, each of the above layers contains 0.44 LiBO ₂ -0.56 LiF as a sintering aid by 15 wt%.

However, in the manufacturing method of Non-Patent Document 2, sintering does not proceed sufficiently at a low temperature of 750 ° C., and the interface bonding between the solid electrolyte and the active material becomes insufficient. For this reason, the charge / discharge curve shown in Non-Patent Document 2 has a very small current value of 10 μA / cm ² . That is, it is estimated that the internal resistance of the solid state battery disclosed in Non-Patent Document 2 is very large.
In this case, in order to reduce the internal resistance of the solid state battery, it is conceivable that the sintering temperature is increased to promote the sintering. Therefore, there is a problem that charging / discharging becomes difficult.

  It has also been proposed to produce a solid battery by laminating a molded body of a positive electrode material, a solid electrolyte material, and a negative electrode material containing a binder, and sintering them by microwave heating (Patent Document 2). reference). In Patent Document 2, a molded body is produced by sheet molding or screen printing of a raw material paste on a substrate and then drying to remove the substrate.

  According to the production method of Patent Document 2, it is possible to improve the filling rate while suppressing the reaction between the electrodes and each particle in the solid electrolyte layer. However, in the active material / solid electrolyte combination as described in the example of Patent Document 2, the active material and the solid electrolyte react essentially at high temperature, and there is no Li ion conductivity at the interface. A phase develops. For this reason, it is difficult to completely suppress the expression of the inactive phase at the interface between the active material and the solid electrolyte, no matter how short the firing time is by microwave heating. That is, with the manufacturing method of Patent Document 2, it is difficult to suppress an increase in resistance at the sintered interface of the active material / solid electrolyte and a decrease in capacity due to the modification of the active material.

  Furthermore, when a battery is produced by laminating a positive electrode comprising a positive electrode active material and a positive electrode current collector, a solid electrolyte, and a negative electrode comprising a negative electrode active material and a negative electrode current collector, the expansion and contraction of the active material during charge / discharge As a result, delamination may occur at the active material / electrolyte interface and the active material / current collector interface, and cracks may occur in the battery. In particular, when an inorganic oxide is used as the solid electrolyte, since there is no layer that relieves stress, the tendency increases.

By the way, when LiTi ₂ (PO ₄ ) ₃ is used alone, the sinterability is poor, and even when sintered at 1200 ° C., the lithium ion conductivity is only about 10 ⁻⁶ S / cm. Therefore, the LiTi ₂ (PO _{4) 3,} by adding Li ₃ PO ₄ and Li ₃ BO ₃ is a sintering aid, an LiTi ₂ (PO _{4) 3} can be sintered at 800 to 900 ° C. It has been reported that lithium ion conductivity is improved (see Non-Patent Document 3).

On the other hand, a thin film battery using lithium phosphorous oxynitride (Li _X PO _Y N _Z , where X = 2.8 and 3Z + 2Y = 7.8) as a solid electrolyte has also been proposed. (See Patent Document 3).

When a battery is manufactured by forming a thin film of an active material and a solid electrolyte on a substrate by a technique such as sputtering, the thin film is formed in an amorphous state. Generally used active materials such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ and Li ₄ Ti ₅ O ₁₂ cannot be charged / discharged in an amorphous state. It is necessary to crystallize.

However, since lithium phosphorous oxynitride used in Patent Document 3 is decomposed at about 300 ° C., the positive electrode, the solid electrolyte, and the negative electrode are successively laminated, and then heat treatment is performed to crystallize the active material. It is impossible.
In addition, when a solid electrolyte such as heat-resistant Perovskite type Li _0.33 La _0.56 TiO ₃ or NASICON type LiTi ₂ (PO ₄ ) ₃ is used, when heat treatment is performed together with a general active material, the active material / solid Since impurities are generated at the electrolyte interface, it is difficult to charge and discharge.

  As described above, a side reaction that generates a substance that does not contribute to charge / discharge proceeds at the interface between the active material and the solid electrolyte, so that the active material layer and the solid electrolyte layer are well densified or crystallized by heat treatment. It is conventionally difficult to form a simple active material / solid electrolyte interface.

In addition, it has been proposed to use LiCoPO ₄ that charges / discharges lithium metal at 4.8 V as the positive electrode active material (see Non-Patent Document 4).

However, the electrolytic solution is decomposed due to a high operating potential of 4.8 V, and a battery using such an active material has a problem that the life characteristics are shortened.
Conventionally, it has been difficult to stably operate an active material having a high operating voltage such as LiCoPO ₄ .
Japanese Patent Application Laid-Open No. 6-231796 Japanese Patent Laid-Open No. 2001-210360 US Pat. No. 5,597,660 J. et al. Power Sources, 81-82, (1999), 853. Solid State Ionics 118 (1999), 149 Solid State Ionics, 47 (1991), 257-264 Electrochemical and Solid-State Letters, 3 (4), 178 (2000)

  Therefore, the present invention provides a laminate having an electrochemically active active material / solid electrolyte interface while the solid electrolyte layer and the active material layer are densified or crystallized by heat treatment, and a low internal resistance and large capacity. An object is to provide an all-solid lithium secondary battery. Another object of the present invention is to provide an all-solid lithium secondary battery in which warpage and embrittlement due to sintering are suppressed and the bonding strength at the interface between the active material layer and the solid electrolyte layer is improved. It is another object of the present invention to provide a highly reliable all-solid lithium secondary battery by suppressing demillation and cracks.

  The present invention relates to a laminate including an active material layer and a solid electrolyte layer bonded to the active material layer. Here, the active material layer includes a crystalline first material capable of releasing and occluding lithium ions, and the solid electrolyte layer includes a crystalline second material having lithium ion conductivity. When the laminate is analyzed by the X-ray diffraction method, no components other than the constituent components of the active material layer and the solid electrolyte layer are detected.

  In the laminate, the first substance includes a crystalline first phosphate compound capable of releasing and occluding lithium ions, and the second substance includes a crystalline second phosphate compound having lithium ion conductivity. It is preferable.

  It is preferable that at least the solid electrolyte layer has a filling factor of more than 70% in the laminate. Here, the filling rate represents the ratio of the apparent density of each layer to the true density of the substance constituting each layer as a percentage value. Alternatively, the filling rate of each layer can be defined as (100-X)%, where the porosity of the layer is X%.

  In the laminate, at least one layer selected from the group consisting of an active material layer and a solid electrolyte layer preferably contains an amorphous oxide. In the layer containing the amorphous oxide, the amorphous oxide preferably occupies 0.1 to 10% by weight of each layer. The softening point of the amorphous oxide is preferably 700 ° C. or higher and 950 ° C. or lower.

In the laminate, the first phosphate compound has the following general formula:
LiMPO ₄
(M is at least one selected from the group consisting of Mn, Fe, Co and Ni)
It is preferable to be represented by The diphosphate compound has the following general formula:
Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃
(M ^III is at least one metal ion selected from the group consisting of Al, Y, Ga, In and La, and 0 ≦ X ≦ 0.6)
It is preferable to be represented by

  The present invention also relates to an all solid lithium secondary battery including a laminate including at least one set including a positive electrode active material layer and a solid electrolyte layer bonded to the positive electrode active material layer. The positive electrode active material layer includes a crystalline first material capable of releasing and occluding lithium ions, and the solid electrolyte layer includes a crystalline second material having lithium ion conductivity. When the laminate is analyzed by an X-ray diffraction method, components other than the constituent components of the active material layer and the constituent components of the solid electrolyte layer are not detected. The first substance is preferably a crystalline first phosphate compound that can release and occlude lithium ions. The second substance is preferably a crystalline second phosphate compound having lithium ion conductivity.

  In the all-solid lithium secondary battery, the set includes a negative electrode active material layer facing the positive electrode active material layer with the solid electrolyte layer interposed therebetween, and the solid electrolyte layer and the negative electrode active material layer are bonded to each other. The active material layer preferably contains a crystalline tertiary phosphate compound capable of releasing and occluding lithium ions or an oxide containing Ti.

  In the all-solid lithium secondary battery, it is preferable that at least the solid electrolyte layer has a filling rate exceeding 70%.

In the all solid lithium secondary battery, the first phosphate compound has the following general formula:
LiMPO ₄
(M is at least one selected from the group consisting of Mn, Fe, Co and Ni)
It is preferable to be represented by The diphosphate compound has the following general formula:
Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃
(M ^III is at least one metal ion selected from the group consisting of Al, Y, Ga, In and La, and 0 ≦ X ≦ 0.6)
It is preferable to be represented by

In the all solid lithium secondary battery, the third phosphate compound is at least one selected from the group consisting of FePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , and LiFeP ₂ O ₇ , and at least a solid electrolyte layer. It is more preferable that the filling rate exceeds 70%.

In the all solid lithium secondary battery, the solid electrolyte is Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃ (M ^III is at least selected from the group consisting of Al, Y, Ga, In, and La). It is preferable that the solid electrolyte layer also serves as the negative electrode active material layer.

In the all solid lithium secondary battery, it is preferable that at least one layer selected from the group consisting of an active material layer and a solid electrolyte layer contains an amorphous oxide. In the layer containing the amorphous oxide, the amorphous oxide preferably occupies 0.1 to 10% by weight of each layer. The softening point of the amorphous oxide is preferably 700 ° C. or higher and 950 ° C. or lower.
In another aspect of the present invention, it is preferable that at least one layer selected from the group consisting of an active material layer and a solid electrolyte layer contains Li ₄ P ₂ O ₇ .

  In the all solid lithium secondary battery, the surface of the solid electrolyte layer that is not joined to the positive electrode active material layer may be joined to metallic lithium or a current collector through a layer made of an electrolyte having reduction resistance. Good.

  In the all solid lithium secondary battery, the set is preferably sandwiched between a positive electrode current collector and a negative electrode current collector.

  In the all solid lithium secondary battery, the positive electrode active material layer preferably includes a positive electrode current collector, and the negative electrode active material layer preferably includes a negative electrode current collector. In another aspect of the present invention, it is preferable that a thin-film current collector is provided in at least one of the positive electrode and negative electrode active material layers.

In the all solid lithium secondary battery, the porosity of at least one current collector selected from the group consisting of a positive electrode current collector and a negative electrode current collector is preferably 20% or more and 60% or less.
In addition, it is preferable that at least one of the thin film-shaped positive electrode current collector and the thin film-shaped negative electrode current collector is disposed at a central portion in the thickness direction of the active material layer.

  In another aspect of the present invention, at least one of the positive electrode active material layer and the negative electrode active material is preferably arranged in a three-dimensional network throughout the current collector.

  The all solid lithium secondary battery has a positive electrode active material layer on a surface opposite to the surface in contact with the solid electrolyte layer and a negative electrode active material layer on the surface opposite to the surface in contact with the solid electrolyte. It is preferable that at least one has a current collector.

  In the all solid lithium secondary battery, the number of the sets is two or more, and the positive electrode current collector and the negative electrode current collector are connected in parallel by the positive electrode external current collector and the negative electrode external current collector, respectively. Is preferred. The positive electrode external current collector and the negative electrode external current collector are more preferably made of a mixture of a metal and glass frit.

  In the all solid lithium secondary battery, the positive electrode current collector and the negative electrode current collector are preferably made of a conductive material. More preferably, the conductive material includes at least one selected from the group consisting of stainless steel, silver, copper, nickel, cobalt, palladium, gold, and platinum.

  In the all solid lithium secondary battery, it is preferable that the laminate is housed in a metal case, and the metal case is sealed.

  The all solid lithium secondary battery is preferably covered with a resin. In another aspect of the present invention, the surface of the all solid lithium secondary battery is preferably subjected to water repellent treatment. In still another aspect of the present invention, the all solid lithium secondary battery is preferably covered with a resin after being subjected to a water repellent treatment.

  In still another aspect of the present invention, the all solid lithium secondary battery is preferably covered with low-melting glass.

The present invention also includes a step of obtaining an active material layer forming slurry 1 by dispersing an active material in a solvent containing a binder and a plasticizer,
A step of dispersing the solid electrolyte in a solvent containing a binder and a plasticizer to obtain a solid electrolyte layer forming slurry 2;
Using the slurry 1 to obtain an active material green sheet;
Using the slurry 2 to obtain a solid electrolyte green sheet;
Including a step of laminating the active material green sheet and the solid electrolyte green sheet and heat-treating at a predetermined temperature to obtain a laminate;
The active material includes a first phosphate compound that can release and occlude lithium ions,
The said solid electrolyte is related with the manufacturing method of the laminated body which consists of an active material layer and a solid electrolyte layer containing the 2nd phosphate compound which has lithium ion conductivity.

  In the method for manufacturing a laminate, the amorphous oxide is included in at least one slurry selected from the group consisting of the slurry 1 and the slurry 2, and a predetermined temperature when the heat treatment is performed is 700 ° C. or more and 1000 ° C. or less. It is preferable that In the at least one slurry, the ratio of the amorphous oxide to the total of the amorphous oxide and the active material or the solid electrolyte is more preferably 0.1 wt% to 10 wt%. The softening point of the amorphous oxide is preferably 700 ° C. or higher and 950 ° C. or lower.

The present invention also provides:
Depositing an active material on a substrate to form an active material layer;
Including a step of depositing a solid electrolyte on the active material layer to form a solid electrolyte layer, and a step of crystallizing the active material layer and the solid electrolyte layer by heat treatment at a predetermined temperature, The active material includes a crystalline first phosphate compound capable of releasing and occluding lithium ions, and the solid electrolyte includes an active material layer including a crystalline second phosphate compound having lithium ion conductivity; The present invention relates to a method for manufacturing a laminate including a solid electrolyte layer. Here, it is preferable that the active material and the solid electrolyte are deposited on the substrate by a sputtering method.

The present invention also provides:
(A) A step of dispersing the positive electrode active material in a solvent containing a binder and a plasticizer to obtain a positive electrode active material layer forming slurry 1;
(B) Dispersing the solid electrolyte in a solvent containing a binder and a plasticizer to obtain a solid electrolyte layer forming slurry 2;
(C) Dispersing the negative electrode active material in a solvent containing a binder and a plasticizer to obtain a negative electrode active material layer forming slurry 3;
(D) a step of obtaining a positive electrode active material green sheet using the slurry 1;
(E) A step of obtaining a solid electrolyte green sheet using the slurry 2;
(F) Step of obtaining a negative electrode active material green sheet using the slurry 3;
(G) forming a first green sheet group including at least one solid electrolyte green sheet and a set including a positive electrode active material green sheet and a negative electrode active material green sheet disposed so as to sandwich the solid electrolyte green sheet; And (h) a step of obtaining a laminate including at least one set in which the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are integrated by heat-treating the first green sheet group at a predetermined temperature. The present invention relates to a method for producing an all-solid lithium secondary battery. Here, the positive electrode active material includes a crystalline first phosphate compound capable of releasing and occluding lithium ions, the solid electrolyte includes a second phosphate compound having lithium ion conductivity, and the negative electrode active material is A tertiary phosphate compound capable of releasing and occluding lithium ions or an oxide containing Ti is included.

In the method for producing an all solid lithium secondary battery, it is preferable that at least one slurry selected from the group consisting of slurry 1, slurry 2 and slurry 3 contains an amorphous oxide. In the at least one slurry, the ratio of the amorphous oxide to the total of the amorphous oxide and the active material or the solid electrolyte is more preferably 0.1 wt% to 10 wt%. The softening point of the amorphous oxide is preferably 700 ° C. or higher and 950 ° C. or lower.
In this case, it is preferable that the predetermined temperature when performing the heat treatment be 700 ° C. or higher and 1000 ° C. or lower.

In another aspect of the present invention, Li ₄ P ₂ O ₇ is added to at least one slurry selected from the group consisting of Slurry 1, Slurry 2 and Slurry 3 and heat treatment is performed at 700 ° C. or higher and 1000 ° C. or lower. Is preferred.

  In the step (g) of the method for producing an all solid lithium secondary battery, when the set is produced, at least one selected from the group consisting of the positive electrode active material green sheet and the negative electrode active material green sheet is collected. It is preferable to be integrated with the electric body.

  In another aspect of the present invention, in the step (g), the set is configured using at least two positive electrode active material green sheets, at least two negative electrode active material green sheets, and a solid electrolyte green sheet. To do. At this time, one positive electrode current collector is provided between at least two positive electrode active material green sheets, and one negative electrode current collector is provided between at least two negative electrode active material green sheets. It is preferable that one end of the positive electrode current collector and one end of the negative electrode current collector are exposed in different regions on the surface of the body.

  In still another aspect of the present invention, in the steps (a) and (c), the material constituting the positive electrode current collector and the material constituting the negative electrode current collector are further added to the slurry 1 and the slurry 3, respectively. It is preferable that one end of the positive electrode active material layer and one end of the negative electrode active material layer are exposed to different regions on the surface of the laminated body.

The present invention also provides:
(A) obtaining a first group comprising a positive electrode active material layer, a negative electrode active material layer, and a set including a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer; And a step of heat-treating the first group at a predetermined temperature so that the positive electrode active material layer, the solid electrolyte layer and the negative electrode active material layer are integrated and crystallized.
The step (A)
(I) depositing a positive electrode active material or a negative electrode active material on a predetermined substrate to form a first active material layer;
(Ii) a step of depositing a solid electrolyte on the first active material layer to form a solid electrolyte layer; and (iii) a step different from the first active material layer on the solid electrolyte layer. Including a step of stacking two active material layers to obtain a first group including a set of the first active material layer, the solid electrolyte layer, and the second active material layer. A crystalline first phosphoric acid compound that can release and occlude, a solid electrolyte containing a second phosphoric acid compound having lithium ion conductivity, and a negative electrode active material that releases and occludes lithium ions. The present invention relates to a method for manufacturing an all-solid lithium secondary battery including a phosphate compound or an oxide containing Ti. It is preferable that the active material and the solid electrolyte are deposited on the substrate by sputtering or thermal evaporation.

  In the method for producing an all-solid lithium secondary battery, step (iii) is performed by stacking at least two of the above-mentioned groups via a solid electrolyte layer before step (B) to obtain a laminate. It is preferable to further include a step.

The present invention also provides:
(A) A step of dispersing the positive electrode active material in a solvent containing a binder and a plasticizer to obtain a positive electrode active material layer forming slurry 1;
(B) Dispersing the solid electrolyte in a solvent containing a binder and a plasticizer to obtain a solid electrolyte layer forming slurry 2;
(C) using the slurry 1 to obtain a positive electrode active material green sheet;
(D) a step of obtaining a solid electrolyte green sheet using the slurry 2;
(E) forming a second green sheet group including at least one set including the positive electrode active material green sheet and the solid electrolyte green sheet; and (f) heat-treating the second green sheet group at a predetermined temperature. A step of obtaining a laminate including at least one set in which the positive electrode active material layer and the solid electrolyte layer are integrated, and in step (e), the set is divided into at least two positive electrode active materials. A green sheet is formed using at least two solid electrolyte green sheets, and one positive electrode current collector is provided between the at least two positive electrode active material green sheets, and the at least two solid electrolyte greens are provided. One negative electrode current collector is provided between the sheets, the positive electrode active material includes a first phosphoric acid compound capable of releasing and occluding lithium ions, and the solid electrolyte is A second phosphate compound having lithium ion conductivity, wherein the solid electrolyte also serves as a negative electrode active material, and at least one of the positive electrode current collector and the negative electrode current collector is selected from the group consisting of silver, copper, and nickel; The present invention relates to a method for manufacturing an all-solid lithium secondary battery in which heat treatment is performed in an atmospheric gas containing water vapor and a low oxygen partial pressure gas.

In the method for producing an all-solid lithium secondary battery, the second phosphate compound and the third phosphate compound are Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃ (M ^III is Al, Y , Ga, In, and La, at least one metal ion selected from the group consisting of 0 ≦ X ≦ 0.6), and the heat treatment is in an atmospheric gas containing water vapor and a low oxygen partial pressure gas More preferably, the water vapor accounts for 5 to 90% by volume of the atmospheric gas, and the maximum temperature of the heat treatment is 700 ° C. or higher and 1000 ° C. or lower.

In the method for manufacturing the laminate and the all-solid-state secondary battery, the first phosphoric acid compound has the following general formula:
LiMPO ₄
(M is at least one selected from the group consisting of Mn, Fe, Co and Ni)
The first phosphoric acid compound contains Fe, and the heat treatment is performed in an atmospheric gas containing water vapor and a low oxygen partial pressure gas, and the water vapor contains 5 to 90% by volume of the atmospheric gas. The maximum temperature of the heat treatment is more preferably 700 ° C. or higher and 1000 ° C. or lower.

In the manufacturing method of the laminate and the all-solid-state secondary battery, when the equilibrium partial pressure PO ₂ (atmospheric pressure) of the oxygen gas contained in the atmospheric gas is T ° C. as the constant maintenance temperature of the heat treatment, the following formula:
−0.0310T + 33.5 ≦ −log ₁₀ PO ₂ ≦ −0.0300T + 38.1
It is further preferable to satisfy Here, in the heat treatment (sintering), the green chip is heated at a predetermined rate of temperature rise, and during the predetermined time, the green chip is maintained at a predetermined constant temperature for sintering. Before the binder is removed. In the present invention, the predetermined constant temperature is referred to as a constant maintenance temperature.

  In the method for manufacturing the laminate and the all-solid lithium secondary battery, it is more preferable that the low oxygen partial pressure gas includes a mixture of a gas capable of releasing oxygen and a gas that reacts with oxygen.

  In the method for producing an all solid lithium secondary battery, at least one of the positive electrode current collector and the negative electrode current collector is made of one selected from the group consisting of silver, copper, and nickel, and the heat treatment is performed on the electrode. More preferably, the heat treatment is performed in an atmospheric gas having an oxygen partial pressure lower than the redox equilibrium oxygen partial pressure, and the maximum temperature of the heat treatment is 700 ° C. or higher and 1000 ° C. or lower. At this time, the atmospheric gas contains carbon dioxide gas and hydrogen gas, and the oxygen partial pressure of the atmospheric gas is adjusted by changing the mixing ratio of the carbon dioxide gas and the hydrogen gas.

  In the method for producing an all-solid-state lithium secondary battery, at least one of the positive electrode current collector and the negative electrode current collector contains at least one selected from the group consisting of silver, copper, and nickel, It is preferably carried out in an atmospheric gas containing a low oxygen partial pressure gas, and the water vapor accounts for 5 to 90% by volume of the atmospheric gas, and the maximum temperature of the heat treatment is preferably 700 ° C. or higher and 1000 ° C. or lower.

  According to the present invention, it is possible to form an electrochemically active active material / solid electrolyte interface while densifying the solid electrolyte layer and the active material layer by heat treatment. It is also possible to improve the life characteristics of an active material having a high operating voltage. Moreover, by using at least one set of the laminate and the negative electrode, an all-solid lithium secondary battery having a low internal resistance and a high capacity can be provided. Furthermore, by performing the water repellent treatment, a highly reliable all-solid lithium secondary battery can be provided even when stored in a high temperature and high humidity atmosphere.

The laminate of the present invention (hereinafter also referred to as a first laminate) includes an active material layer and a solid electrolyte layer bonded to the active material layer.
The active material layer includes a crystalline first material capable of releasing and occluding lithium ions, and the solid electrolyte layer includes a crystalline second material having lithium ion conductivity. Here, in the laminate, no component other than the constituent components of the active material layer and the solid electrolyte layer is detected by the X-ray diffraction method.
The active material layer and the solid electrolyte are preferably crystalline.
Note that in the battery manufactured using the stacked body, the positive electrode includes an active material layer.

As the first substance contained in the active material layer, for example, a crystalline first phosphate compound capable of releasing and occluding lithium ions can be used. As the first phosphoric acid compound, the following general formula:
LiMPO ₄
It is preferable to use a material represented by (M is at least one selected from the group consisting of Mn, Fe, Co, and Ni).

As the second substance contained in the solid electrolyte layer, a crystalline second phosphoric acid compound having lithium ion conductivity can be used. As the second phosphoric acid compound, the following general formula:
Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃
(M ^III is, Al, Y, Ga, at least one metal ion selected from the group consisting of In and La, 0 ≦ X ≦ 0.6) is preferably used a material represented by.

  By using the active material layer containing the active material as described above and the solid electrolyte layer containing the solid electrolyte as described above, even when the heat treatment is performed when the laminate is manufactured, the first material and the second material are used. At the junction interface with the substance (that is, the junction interface between the active material and the solid electrolyte), neither the active material nor the solid electrolyte, and the occurrence of an impurity phase that does not contribute to the charge / discharge reaction can be suppressed.

  In order for an all solid state battery to be chargeable / dischargeable, lithium ion conductivity is maintained at the bonding interface between the active material layer and the solid electrolyte layer, and the active material layer and the solid electrolyte layer are firmly bonded in a wide area. It is necessary to be. According to the combination of the active material layer and the solid electrolyte layer according to the present invention, such interface bonding is possible.

  Both the active material layer and the solid electrolyte layer preferably have lithium ion conductivity. Moreover, it is preferable that the filling rate of the solid electrolyte in at least the solid electrolyte layer exceeds 70%. Similarly, it is preferable that the filling rate of the active material in the active material layer exceeds 70%. When the filling rate is smaller than 70%, for example, the high rate charge / discharge characteristics of a battery manufactured using the laminate of the present invention may be deteriorated.

  Since electronic conductivity and ion conductivity in the active material layer and the solid electrolyte layer are hindered, it is preferable that the active material layer and the solid electrolyte layer do not contain an organic substance such as an organic binder. That is, a deposited film or a sintered body is preferable.

In the first laminated body, the thickness x ₁ of the active material layer is preferably 0.1 to ₁₀ μm. If the thickness x ₁ of the active material layer is smaller than 0.1 μm, a battery having a sufficient capacity cannot be obtained. When the thickness x ₁ of the active material layer is larger than 10 μm, it becomes difficult to charge and discharge the battery.

  Further, the thickness y of the solid electrolyte layer can take a relatively wide range. Especially, it is preferable that the thickness y of a solid electrolyte layer is about 1 micrometer-1 cm, and it is further more preferable that it is 10-500 micrometers. This is because, from the viewpoint of energy density, the thickness of the solid electrolyte layer is preferably thin, but the mechanical strength of the solid electrolyte layer is also necessary.

In the laminate of the present invention, it is preferable that at least one layer selected from the group consisting of an active material layer and a solid electrolyte layer contains an amorphous oxide.
In general, different ceramic materials (eg, the first phosphate compound and the second phosphate compound) have different sintering temperatures. For this reason, when the laminated body formed by laminating a plurality of different ceramic materials is heat-treated and sintered at a time, the temperature at which the sintering starts, the sintering speed, and the like differ for each material. Thus, if the temperature at which each layer starts to be sintered, the sintering speed, and the like are different, warping may occur during sintering, or thermal strain may remain in the laminate and become brittle. Furthermore, the interface between the active material layer and the solid electrolyte layer may peel off. Therefore, an amorphous oxide as a sintering aid is added to the layer of which the sintering is to be promoted among the active material layer and the solid electrolyte layer. As a result, the temperature at which the sintering of each layer starts, the sintering speed, and the like can be made uniform. Therefore, it is possible to reduce warpage and embrittlement of the laminate when the laminate is sintered, and interfacial peeling between the active material layer and the solid electrolyte layer. The temperature at which sintering starts can be adjusted by the type (softening point) of the amorphous oxidizer, and the sintering rate can be adjusted by the amount added.
Furthermore, when an all-solid battery is produced using the above laminate, the impedance of the all-solid battery can be lowered by including an amorphous oxide in at least one of the active material layer and the solid electrolyte layer. . Such a battery with reduced impedance has excellent high-rate characteristics.

Examples of the amorphous oxide include those containing SiO ₂ , Al ₂ O ₃ , Na ₂ O, MgO and CaO, 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% Na ₂ O-3 wt. % MgO-4 wt% CaO, 72 wt% SiO ₂ -1 wt% Al ₂ O ₃ -14 wt% Na ₂ O-3 wt% MgO-10 wt% CaO, 62 wt% SiO ₂ -15 wt% Al ₂ O ₃ -8 wt% CaO-15 wt % BaO and the like.
Note that the softening temperature of the amorphous oxide is changed by adding an alkali metal, an alkaline earth metal, or a rare earth oxide to the amorphous oxide or changing the content thereof. be able to.

  In the layer to which the amorphous oxide is added, the amount of the amorphous oxide is preferably 0.1% by weight or more and 10% by weight or less of the layer. If the amount of the amorphous oxide is less than 0.1% by weight, the sintering promotion effect of the amorphous oxide may not be obtained. When the amount of the amorphous oxide exceeds 10% by weight, the amount of the amorphous oxide in the layer is too large, and the electrochemical characteristics of the battery may be deteriorated.

Next, the all solid lithium secondary battery of the present invention will be described.
The all solid lithium secondary battery of the present invention includes a laminate including at least one set including a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer. A body (hereinafter also referred to as a second laminate). In the all solid lithium secondary battery of the present invention, at least the positive electrode active material layer and the solid electrolyte layer are joined (integrated). That is, in the second stacked body, the first stacked body functions as a positive electrode active material layer and a solid electrolyte layer.

  Also in this case, it is preferable that at least the filling rate of each solid electrolyte layer exceeds 70%. Similarly, the filling rate of the positive electrode active material layer is preferably more than 70%.

Similarly to the first laminate, the positive electrode active material layer includes a first material such as the first phosphate compound, and the solid electrolyte layer includes a second material such as the second phosphate compound. including. As the negative electrode active material, for example, a material made of a material that can be used in a plate shape can be used. Examples of such a material include metallic lithium, Al, Sn, In, and the like.
The thickness of the negative electrode active material layer is preferably 500 μm or less.

Among the first phosphoric acid compounds, compounds represented by the above general formula: LiMPO ₄ (M is at least one selected from the group consisting of Mn, Fe, Co and Ni) generally have an operating potential. high. For this reason, for example, a battery having a high operating voltage can be obtained by using the first phosphoric acid compound represented by the above general formula as the positive electrode active material and metal lithium as the negative electrode active material.

Among the diphosphate compounds used as the solid electrolyte, Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃ (M ^III is a group consisting of Al, Y, Ga, In, and La). It is known that the compound represented by the formula (1) is a metal ion selected from the group consisting of 0 ≦ X ≦ 0.6) is subjected to reduction at about 2.5 V with respect to the Li / Li ⁺ electrode. Yes. Therefore, when an active material having an operating voltage of 2.5 V or less with respect to the Li / Li ⁺ electrode is used, in order to prevent such reduction, a layer made of an electrolyte having reduction resistance is referred to as a solid electrolyte layer. It is preferable to arrange it between the negative electrode. Thereby, a solid battery excellent in reversibility can be obtained.

As the electrolyte having reduction resistance, a polymer electrolyte common in this field can be used. Examples of such polymer electrolytes include gel electrolytes in which a polymer host such as polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, and polyether is impregnated and swollen, and polyethers having polyethylene oxide as a basic skeleton. , A siloxane, an acrylic acid compound, a polymer obtained by copolymerization with a branched polyhydric alcohol, and the like, in which a Li salt such as LiPF ₆ , LiClO ₄ , LiBF ₄ , LiN (SO ₂ CF ₃ ) ₂ is dissolved Examples thereof include polymers.
Examples of the electrolytic solution used in the gel electrolyte include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiN (SO ₂ Examples include those in which a Li salt such as CF ₃ ) ₂ is dissolved.

The layer made of the gel electrolyte can be formed on the surface of the solid electrolyte layer as follows, for example.
In advance, the polymer host alone is dissolved in an organic solvent such as acetonitrile, 2-methylpyrrolidinone, 1,2-dimethoxyethane, dimethylformamide. This solution is applied to the surface of the solid electrolyte layer by a method such as casting or spin coating, and dried to form a thin film. Thereafter, an electrolytic solution containing the above-described Li salt is added to the thin film, and the film is gelled, whereby a layer made of a gel electrolyte can be formed on the surface of the solid electrolyte layer.

  Moreover, the layer which consists of dry polymers can also be formed similarly to a gel electrolyte. That is, it is dissolved in an organic solvent such as acetonitrile, 2-methylpyrrolidinone, 1,2-dimethoxyethane, dimethylformamide, etc. in a state where Li salt is dissolved in the copolymer containing the polyether. By applying this solution to the surface of the solid electrolyte layer by a method such as casting or spin coating and drying, a layer made of a dry polymer can be formed on the surface of the solid electrolyte layer.

  In the battery of the present invention, a negative electrode current collector is directly provided on a layer made of an electrolyte having reduction resistance without providing a negative electrode between the layer made of the electrolyte having reduction resistance and the negative electrode current collector. It may be provided. This is because when the battery is charged, lithium ions contained in the positive electrode active material are deposited on the negative electrode current collector as metallic lithium, and the metallic lithium can act as the negative electrode.

In the all solid lithium secondary battery of the present invention, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are preferably integrated. When the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are integrated, the negative electrode active material preferably contains a tertiary phosphate compound that can release and occlude lithium ions. The third phosphoric acid compound is preferably at least one selected from the group consisting of FePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , and LiFeP ₂ O ₇ .

Moreover, the negative electrode active material layer may contain, for example, Li ₄ Ti ₅ O ₁₂ as an active material. In this case, for example, Li _0.33 La _0.56 TiO ₃ can be used as the solid electrolyte.

  The positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are each preferably crystalline.

By using such a negative electrode active material, not only at the interface between the positive electrode active material and the solid electrolyte, but also at the interface between the negative electrode electrolyte and the solid electrolyte, the occurrence of an impurity phase that does not contribute to the charge / discharge reaction is suppressed. Is possible. In addition, lithium ion conductivity is maintained at the interface, and the active material layer and the solid electrolyte layer can be firmly bonded in a wide area. That is, the internal resistance of the all-solid lithium secondary battery can be reduced and the reliability can be improved.
In this case, the thickness x ₃ of the negative electrode active material layer is preferably 0.1 to 10 μm. If the thickness x ₃ of the active material layer is smaller than 0.1 μm, a battery having a sufficient capacity cannot be obtained. When the thickness x ₃ of the active material layer is larger than 10 μm, it becomes difficult to charge and discharge the battery.
The thickness x ₁ of the positive electrode active material is preferably 0.1 to 10 μm, and the thickness y of the solid electrolyte layer is preferably about ₁ μm to ₁ cm, and preferably 10 to 500 μm. This is for the same reason as described above.

  In the second laminate including one or more of the above-mentioned sets, it is preferable that each set is also joined. Since one or more sets are included, the battery capacity can be increased, and the internal resistance of the all-solid lithium secondary battery can be reduced because the sets are integrated.

  Also in this case, it is preferable that the filling rate of each of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer exceeds 70%.

  The all solid lithium secondary battery of the present invention may include a positive electrode current collector and a negative electrode current collector.

For example, a positive electrode current collector is provided on the surface of the positive electrode active material layer opposite to the surface in contact with the solid electrolyte layer, and a negative electrode current collector is provided on the surface of the negative electrode active material layer opposite to the surface in contact with the solid electrolyte layer. A body may be provided. In this case, for example, after the production of the stacked body is completed, the positive electrode current collector and the negative electrode current collector are provided.
In addition, when the positive electrode current collector and the negative electrode current collector are formed after forming the above set, the positive electrode current collector and / or the negative electrode current collector are made of a conductive material known in the art ( For example, a predetermined metal thin film or the like can be used.

  Further, in the all solid lithium secondary battery of the present invention, when two or more of the above groups are laminated, each positive electrode active material layer and each negative electrode active material layer included in the all solid lithium secondary battery are respectively positive electrodes. The current collector and the negative electrode current collector may be included therein. At this time, the positive electrode current collector may be in the form of a thin film or may have a three-dimensional network structure.

When two or more sets are laminated as described above, the positive electrode current collector provided in each positive electrode active material layer and the negative electrode current collector provided in each negative electrode active material layer are respectively It can be connected in parallel by the electric current collector and the negative electrode external current collector. At this time, it is preferable that one end of the positive electrode current collector and one end of the negative electrode current collector are exposed on different surfaces of the laminate in which two or more sets are laminated. For example, when the second stacked body in which two or more sets are stacked is a hexahedron, one end of the positive electrode current collector is exposed on a predetermined surface of the stacked body, and one end of the positive electrode current collector is exposed. One end of the negative electrode current collector can be exposed on the surface opposite to the surface.
In addition, it is preferable that the surface of the said 2nd laminated body is covered with the solid electrolyte layer except the part covered with the positive electrode external electrical power collector and the negative electrode external electrical power collector. In this case, the positive electrode external current collector, the negative electrode external current collector, and the solid electrolyte layer function as an exterior.

  As the positive electrode external current collector and the negative electrode external current collector, those made of a mixture containing a metal material having electron conductivity and a glass frit having heat fusion properties can be used. As the metal material, copper is generally used, but other metals can also be used. As the glass frit, a glass frit having a low melting point of about 400 to 700 ° C. is used.

When a positive electrode current collector or a negative electrode current collector is provided during the production of the above set, the positive electrode current collector or the negative electrode current collector is placed in the same atmosphere as the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer. It is preferable that the heat treatment can be performed, and the positive electrode active material and the negative electrode active material do not react with each other.
The material of such a positive electrode current collector and a negative electrode current collector is preferably at least one selected from the group consisting of silver, copper, nickel, palladium, gold and platinum. In the case where the heat treatment is performed in the air atmosphere (in air), among these, palladium, gold, and platinum are more preferable. This is because silver, copper, and nickel may show reactivity with the active material.

  In addition, when there are two or more sets, the active material layers of the same type are stacked through a current collector to form a positive electrode current collector and a negative electrode current collector in an all-solid lithium secondary battery. A body can be provided. For example, when there are three sets of the first set, the second set, and the third set, the positive electrode active material layer of the first set and the positive electrode active material layer of the second set of the positive electrode current collector The second set of negative electrode active material layers and the third set of negative electrode active material layers are stacked so as to be supported on both sides of the negative electrode current collector. In this manner, the all-solid-state lithium secondary battery can be provided with the positive electrode current collector and the negative electrode current collector.

Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃ (M ^III is at least one metal ion selected from Al, Y, Ga, In and La, and 0 ≦ X ≦ 0. When the solid electrolyte layer containing 6) is used, this solid electrolyte can also serve as the negative electrode active material. This is because this solid electrolyte can occlude and release Li at about 2.5 V with respect to the Li / Li ⁺ electrode.

Further, in an all-solid lithium secondary battery, particularly an all-solid lithium secondary battery in which a plurality of the above groups are stacked, the porosity of at least one of the positive electrode current collector and the negative electrode current collector is 20% or more and 60 % Or less is preferable.
In general, the volume of an active material expands and contracts as lithium is inserted and extracted during charge and discharge. Even when the volume of the active material is changed, the current collector has holes, and the holes serve as a buffer layer. For this reason, it can suppress that the delamination of the interface of a collector and an active material, the crack of an all-solid-state battery, etc. arise.

  If the porosity of the current collector is smaller than 20%, the volume change of the active material cannot be relaxed, and the battery may be easily damaged. If the porosity of the current collector is greater than 60%, the current collecting property of the current collector is reduced, and the battery capacity may be reduced.

  Furthermore, it is preferable that the positive electrode current collector does not react with the positive electrode active material, and the negative electrode current collector does not react with the negative electrode active material. Further, it is desirable that the positive electrode current collector and the negative electrode current collector can be simultaneously heat-treated in the same atmosphere as the positive electrode active material, the solid electrolyte, and the negative electrode active material.

As a material constituting such a positive electrode current collector and a negative electrode current collector, for example, platinum, gold, palladium, silver, copper, nickel, cobalt, and stainless steel can be used.
However, since silver, copper, nickel, cobalt, and stainless steel have high reactivity with the active material, atmosphere control is essential in the firing process of the laminate. Therefore, it is more preferable to use a current collector made of platinum, gold, or palladium.
Further, it is preferable that the positive electrode current collector is inserted into the central portion of the positive electrode active material layer, and the negative electrode current collector is inserted into the central portion of the negative electrode active material layer.

Similar to the first laminate, in the all solid lithium secondary battery of the present invention, at least one layer selected from the group consisting of a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer is amorphous. An oxide may be included. In the layer containing the amorphous oxide, the amount of the amorphous oxide is preferably 0.1% by weight or more and 10% by weight of the layer. This is for the same reason as described above.
As described above, when at least one layer selected from the group consisting of a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer contains an amorphous oxide, the impedance of the all-solid battery is reduced. Therefore, high rate characteristics can be improved.

Li ₄ P ₂ O ₇ can be sintered with the first phosphate compound, the second phosphate compound, or the third phosphate compound. Therefore, at least one layer selected from the group consisting of a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer may contain Li ₄ P ₂ O ₇ . The melting point of Li ₄ P ₂ O ₇ is a 876 ° C., to act as a sintering aid at 700 ° C. or higher, Li ₄ P ₂ O ₇ is the positive electrode active material layer, the negative electrode active material layer and the solid electrolyte layer By being contained in at least one selected from the group consisting of, the sinterability of the layer can be improved. Thus, Li ₄ P ₂ O ₇ has the same effect as an amorphous oxide and can be handled in the same way as an amorphous oxide.

Next, the manufacturing method of a 1st laminated body is demonstrated.
The first stacked body can be produced, for example, as follows.
First, the active material is dispersed in a solvent containing a binder and a plasticizer to obtain the active material layer forming slurry 1. Similarly, the solid electrolyte is dispersed in a solvent containing a binder and a plasticizer to obtain a solid electrolyte layer forming slurry 2 (step (1)). Here, the active material includes, for example, the first phosphoric acid compound, and the solid electrolyte includes, for example, the second phosphoric acid compound.

  Here, the binder and the plasticizer may be dispersed in a solvent or may be dissolved.

  Next, the obtained slurry 1 is applied, for example, on a predetermined substrate (for example, a sheet, a film, etc.) provided with a release agent layer and dried to obtain an active material green sheet. Similarly, the slurry 2 is applied onto a predetermined substrate and dried to obtain a solid electrolyte green sheet (step (2)).

Next, the obtained active material green sheet and solid electrolyte green sheet are laminated and heat-treated (sintered) to obtain a first laminate comprising an active material layer and a solid electrolyte layer (step (3)).
Since organic substances such as binders and plasticizers contained in the active material green sheet and solid electrolyte green sheet are decomposed during sintering, the active material layer and solid electrolyte layer of the obtained laminate do not contain organic substances. .
Moreover, the filling rate of the active material layer and the solid electrolyte layer can be adjusted by adjusting the maximum value of the sintering temperature, the heating rate, and the like. Here, the maximum value of the sintering temperature is preferably in the range of 700 ° C to 1000 ° C. If the maximum sintering temperature is less than 700 ° C., sintering may not proceed. When the maximum sintering temperature is higher than 1000 ° C., Li is volatilized from the Li-containing compound and the composition of the Li-containing composition changes, or mutual diffusion between the active material and the solid electrolyte occurs, and charge / discharge is possible. It may disappear. Moreover, it is preferable that a temperature increase rate is 400 degreeC / hour or more. If the rate of temperature increase is slower than 400 ° C./hour, mutual diffusion between the active material and the solid electrolyte may occur, and charging / discharging may not be possible.

In the step (1), the amorphous oxide may be added to at least one selected from the group consisting of the slurry 1 and the slurry 2.
It is desirable that the softening point of the amorphous oxide to be added is matched to the sintering start temperature of the layer in which the sintering is most likely to proceed among the active material layer and the solid electrolyte layer. For example, when the active material layer contains LiCoPO ₄ , the positive electrode active material layer is most easily sintered. Therefore, the softening point of the amorphous oxide is preferably matched with the sintering start temperature of the active material layer. Further, the softening point of the amorphous oxide oxide may be appropriately adjusted according to the maximum temperature of sintering.
In the present invention, the softening point of the amorphous oxide is desirably 700 ° C. or higher and 950 ° C. or lower.

The first laminate can also be produced as follows.
First, an active material is deposited on a predetermined substrate to form an active material layer, and then a solid electrolyte is deposited on the active material layer to form a solid electrolyte layer (step (1 ′)). ). The active material and the solid electrolyte can be deposited by sputtering.

Next, the active material layer and the solid electrolyte layer are heat-treated at a predetermined temperature and crystallized to obtain the first laminate (step (2 ′)).
Here, in the step (2 ′), the temperature at which the active material layer and the solid electrolyte layer are crystallized by heat treatment is preferably 500 ° C. to 900 ° C. When this temperature is lower than 500 ° C., crystallization may be difficult. When the temperature is higher than 900 ° C., mutual diffusion between the active material and the solid electrolyte may become intense.

  In the laminated body thus obtained, the third layer that prevents the movement of lithium ions is not formed between the active material layer and the solid electrolyte layer.

  In the method for manufacturing the laminate, as the active material, for example, a first material such as the first phosphate compound can be used. As the solid electrolyte, a second substance such as the second phosphoric acid compound can be used.

Next, a method for producing the all solid lithium secondary battery of the present invention will be described.
An all-solid lithium secondary battery including a second stacked body including at least one set including the first stacked body and the negative electrode active material layer is provided on the first stacked body obtained as described above via a solid electrolyte layer. Thus, the negative electrode active material layer can be provided so as to face the positive electrode active material layer. When there are a plurality of sets, an all solid lithium secondary battery can be manufactured by stacking each set via, for example, a solid electrolyte layer.

  Further, as described above, when a layer made of an electrolyte having reduction resistance is provided between the solid electrolyte layer and the negative electrode active material layer, the negative electrode active material layer is formed on the solid electrolyte layer. Before being provided, a layer made of an electrolyte having reduction resistance is provided. The method for forming this layer is not particularly limited, and various methods can be used.

Next, a method for manufacturing an all-solid lithium secondary battery in which the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are integrated in the second laminate will be described. Such an all-solid lithium secondary battery is produced, for example, as follows.
First, the positive electrode active material is dispersed in a solvent containing a binder and a plasticizer to obtain the positive electrode active material layer forming slurry 1. Similarly, the solid electrolyte is dispersed in a solvent containing a binder and a plasticizer to obtain a slurry 2 for forming a solid electrolyte layer, and the negative electrode active material is dispersed in a solvent containing a binder and a plasticizer to obtain a negative electrode active material. A layer forming slurry 3 is obtained (step (a)). Here, the positive electrode active material includes, for example, the first phosphate compound, the solid electrolyte includes, for example, the second phosphate compound, and the negative electrode active material includes, for example, the third phosphate compound or Ti. Containing oxides.

  Next, the obtained slurry 1 is applied, for example, on a predetermined substrate (for example, a sheet, a film, etc.) provided with a release agent layer, and dried to obtain a positive electrode active material green sheet. Similarly, a negative electrode active material green sheet and a solid electrolyte green sheet are obtained (step (b)).

  Next, a first green sheet group including at least one set including a solid electrolyte green sheet and a positive electrode active material green sheet and a negative electrode active material green sheet arranged so as to sandwich the solid electrolyte green sheet is formed (step ( c)). When there are a plurality of the above sets, the sets are stacked, for example, via a solid electrolyte green sheet.

  Next, the first green sheet group is sintered at a predetermined temperature to obtain a second laminate including at least one set including a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer (step (d) )). In addition, the said 1st phosphate compound, the 2nd phosphate compound, and the 3rd phosphate compound are crystalline things, and each layer becomes crystalline by sintering these.

  Since organic substances such as binders and plasticizers contained in the active material green sheet and the solid electrolyte green sheet are decomposed during sintering, the active material layer and solid electrolyte layer of the obtained laminate include organic substances. I can't.

  Further, the filling rate of the active material layer and the solid electrolyte layer can be adjusted by adjusting the maximum value of the sintering temperature, the heating rate, etc., as described above. Here, the maximum value of the sintering temperature is preferably in the range of 700 ° C. to 1000 ° C., and the heating rate is preferably 400 ° C./hour or more. This is for the same reason as described above.

  In the step (a), the amorphous oxide may be added to at least one slurry selected from the group consisting of the slurry 1, the slurry 2, and the slurry 3. For example, when the positive electrode active material green sheet, the negative electrode active material green sheet and the solid electrolyte green sheet have different sintering rates, an amorphous oxide is added to the slurry for forming two green sheets having a low sintering rate. It may be added. In addition, when the difference in sintering speed between the green sheets is small, an amorphous oxide may be added to the slurry for forming the green sheet having the slowest sintering speed.

  In addition, if the positive electrode active material, the solid electrolyte, and the negative electrode active material are the phosphoric acid compounds as described above and their particle sizes are almost the same, the positive electrode active material green sheet and the negative electrode active material green sheet In comparison, the solid electrolyte green sheet tends to have a higher sintering start temperature. Therefore, in this case, it is preferable to add an amorphous oxide to the slurry for forming the solid electrolyte layer.

  In the slurry to which the amorphous oxide is added, the amount of the amorphous oxide is preferably 0.1 to 10% by weight of the slurry. This is for the same reason as described above.

  In the step (d), in the state where the positive electrode active material green sheet, the solid electrolyte green sheet, and the negative electrode active material green sheet are sequentially laminated, the laminate is heat-treated, and the positive electrode active material layer and the solid electrolyte layer are heat treated. It is preferable to obtain a laminate composed of a negative electrode active material layer. For example, a laminate obtained by laminating a positive electrode active material green sheet and a solid electrolyte green sheet is heat-treated, and then the negative electrode active material green sheet is opposite to the surface of the solid electrolyte layer that is in contact with the positive electrode active material layer. It is formed on the surface, and it is further heat-treated and joined. In this case, although the solid electrolyte layer is sufficiently sintered, the negative electrode active material green sheet shrinks due to sintering, so the interface between the solid electrolyte layer and the negative electrode active material layer peels off without being bonded. It is because it may end up.

  The positive electrode current collector and the negative electrode current collector may be disposed so as to sandwich the second laminate, and each positive electrode active material layer and / or each negative electrode active material layer each have a current collector. May be.

When the positive electrode current collector and the negative electrode current collector are arranged so as to sandwich the second stacked body, the positive electrode current collector and the negative electrode current collector are respectively disposed on both end surfaces in the stacking direction of the second stacked body, Be placed.
In this case, the current collector can be formed as follows.
For example, a conductive layer can be formed by applying a paste containing a conductive material as described above onto an active material layer and drying the layer, and this layer can be used as a current collector. Alternatively, a metal layer made of a conductive material as described above can be formed on the active material layer using a sputtering method, a vapor deposition method, or the like, and used as a current collector.
By providing such a conductive layer or metal layer, current collection from the active material layer can be performed efficiently.

  As described above, in the obtained laminate, the porosity of the positive electrode current collector and the negative electrode current collector is preferably 20 to 60%, respectively. The porosity of the current collector can be controlled, for example, by appropriately adjusting the amount of the conductive material contained in the paste containing the conductive material, the maximum sintering temperature, and / or the heating rate of the sintering. it can. Here, it is preferable that the maximum temperature of sintering and the heating rate of sintering are 700 to 1000 ° C. as described above. It is preferable that the heating rate of sintering is 400 ° C./hour or more.

Next, the case where each positive electrode active material layer and / or each negative electrode active material layer has a current collector will be described.
For example, when a thin film current collector is provided in the positive electrode active material layer, two green sheets are used, for example, a metal thin film is disposed as a current collector between the two green sheets, Alternatively, a layer made of a conductive material is provided. After the sintering, two green sheets each having a current collector therebetween become one positive electrode active material layer in the above set. In this way, a positive electrode active material layer including a thin film current collector can be obtained. In the above description, two green sheets are used, but three or more green sheets may be used.
When a thin film current collector is provided in the negative electrode active material layer, the same method as in the case of providing a thin film current collector in the positive electrode active material layer can be performed.

  When a metal thin film is used as the current collector, gold, platinum, palladium, silver, copper, nickel, cobalt, and stainless steel can be used as the material constituting the current collector as described above. Similarly, when a layer made of a conductive material is used as the current collector, the above-described metal material can be used as the conductive material.

When the three-dimensional network current collector is provided by dispersing the particles of the material constituting the current collector in the entire inside of the positive electrode active material layer and / or the negative electrode active material layer, first, for forming the positive electrode active material layer When producing the slurry and / or the slurry for forming the negative electrode active material layer, the material constituting the positive electrode current collector or the material constituting the negative electrode current collector is mixed.
Using such a slurry, a positive electrode active material green sheet and a negative electrode active material green sheet are produced. In the obtained positive electrode active material green sheet and negative electrode active material green sheet, the current collector forms a three-dimensional network structure.

  Similarly, gold, platinum, palladium, silver, copper, nickel, cobalt, and stainless steel can be used as the material constituting the current collector contained in the slurry. Moreover, it is preferable that the quantity of the material particle which comprises the electrical power collector contained in a slurry is 50-300 weight part per 100 weight part of active materials.

Using the positive electrode active material green sheet and the negative electrode active material green sheet provided with the thin film current collector or the three-dimensional network current collector and the solid electrolyte green sheet obtained as described above, the second lamination is performed. Create a body. At this time, it is preferable that one end of the positive electrode active material layer and one end of the negative electrode active material layer are exposed in different surface regions of the second laminate.
Such exposure to the different area | region of the surface of a 2nd laminated body can be performed as follows, for example.
At the stage where the positive electrode active material green sheet, the solid electrolyte green sheet and the negative electrode active material green sheet are laminated, one end of the positive electrode active material green sheet and one of the negative electrode active material green sheet are formed in different regions of the surface of the laminate. Expose the edges. Such a laminate may be sintered to expose one end of the positive electrode active material layer and one end of the negative electrode active material layer in different regions on the surface of the second laminate.

  In addition, a laminate in which a positive electrode active material green sheet, a solid electrolyte green sheet, and a negative electrode active material green sheet are laminated and / or arranged in a predetermined pattern is appropriately cut and sintered. Thereby, one edge part of a positive electrode active material layer and one edge part of a negative electrode active material layer can be exposed to the area | region where the surface of a 2nd laminated body differs.

  Thus, even when two or more positive electrode active material layers and / or negative electrode active material layers are provided, by exposing the current collector of each active material layer to a different region on the surface of the second laminate, For example, it is easy to form an external current collector that connects the current collectors of each positive electrode active material layer in parallel.

  The positive electrode external current collector and the negative electrode external current collector are, for example, a paste containing a metal material having electronic conductivity and a glass frit having heat fusion properties, and an exposed region of the positive electrode current collector and the negative electrode current collector. It can form by apply | coating to an exposed area | region and heat-processing.

  Moreover, it is preferable that the surface of the second laminated body is covered with a solid electrolyte layer except for a region covered with the positive electrode external current collector and the negative electrode external current collector. For example, before the second laminate is produced by sintering the laminate, the region other than the portion that would be covered with the external current collector of the laminate is covered with a solid electrolyte green sheet. Can be achieved.

Moreover, the 2nd laminated body which comprises the all-solid-state lithium secondary battery of this invention can also be produced as follows.
A first group including a set including a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer is obtained (step (A)). Next, the first group is heat-treated at a predetermined temperature so that the positive electrode active material layer, the solid electrolyte layer and the negative electrode active material layer are integrated and crystallized to obtain a laminate (step) (B)).

In the step (A), the first group can be produced as follows.
First, a positive electrode active material or a negative electrode active material is deposited on a predetermined substrate to form a first active material layer. Next, a solid electrolyte is deposited on the first active material layer to form a solid electrolyte layer. Next, on this solid electrolyte layer, a second active material layer different from the first active material layer (that is, if the first active material layer is a positive electrode active material layer, the second active material layer is a negative electrode active material layer). ). In this way, a first group including a set of the first active material layer, the solid electrolyte layer, and the second active material layer is formed. At this time, it is preferable that the first group is formed of one set or two or more sets are stacked. In addition, when there are two or more sets, it is preferable that the sets are stacked, for example, via a solid electrolyte layer.
Here, the deposition of the active material and the solid electrolyte can be performed using a sputtering method.

  In the said process (B), it is preferable that the temperature when heat-processing and crystallizing a solid electrolyte layer and both active material layers is 500 to 900 degreeC. When this temperature is lower than 500 ° C., crystallization may be difficult. When the temperature is higher than 900 ° C., mutual diffusion between the active material and the solid electrolyte may become intense.

  The all solid lithium secondary battery of the present invention may be housed in a metal case that can be sealed. In this case, the metal case can be sealed using, for example, a sealing plate and a gasket at the opening.

  Moreover, the all-solid-state lithium secondary battery of this invention may be covered with resin. In addition, the whole battery can be covered with resin by performing resin molding.

Furthermore, the surface of the all solid lithium secondary battery of the present invention may be subjected to water repellent treatment. This water-repellent treatment can be performed, for example, by immersing the laminate in a dispersion in which a water-repellent agent made of silanes, fluororesin or the like is dispersed.
Before covering the all solid lithium secondary battery of the present invention with a resin, the surface thereof may be subjected to water repellent treatment.

  Moreover, you may form glass layers, such as a glaze, on the surface of the all-solid-state lithium secondary battery of this invention. For example, the all-solid lithium secondary battery of the present invention can be sealed with a glass layer by applying a slurry containing a low-melting glass and performing a heat treatment at a predetermined temperature.

  Thus, by preventing the all-solid-state lithium secondary battery from coming into contact with the outside air, it is possible to prevent the influence of moisture contained in the outside air, for example, an internal short circuit caused by a reaction between the current collector metal and water. It becomes possible.

  In the method for producing an all solid lithium secondary battery, for example, in heat treatment (sintering) in air (oxidizing atmosphere), the binder and the plasticizer are easily removed by oxidative decomposition. However, at this time, materials that can be used as the current collector are only expensive noble metals such as palladium, gold, and platinum.

In the present invention, at least one of the positive electrode current collector contained in the positive electrode and the negative electrode current collector contained in the negative electrode can be composed of a relatively inexpensive metal material such as silver, copper, or nickel. In this case, the second phosphate compound constituting the solid electrolyte layer is Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃ (M ^III is a group consisting of Al, Y, Ga, In, and La). It is preferable that the second phosphoric acid compound also serves as the negative electrode active material. The phosphoric acid compound is preferably at least one metal ion selected from the group consisting of 0 ≦ X ≦ 0.6.

When a metal material that is easily oxidized, such as silver, copper, or nickel, is used, the heat treatment (sintering) needs to be performed in an atmosphere having a low oxygen partial pressure. On the other hand, the third phosphoric acid compound (negative electrode active material) such as FePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , and LiFeP ₂ O ₇ contains Fe (III). In order to sinter stably, a relatively high oxygen partial pressure (for example, 10 ⁻¹¹ atm (700 ° C.)) is required. That is, when a metal material such as copper, silver, or nickel is used as the current collector material, a negative electrode active material containing Fe (III) may not be used. In this case, a current collector made of a metal material such as silver, copper, or nickel can be used by using a phosphoric acid compound not containing Fe (III), for example, a solid electrolyte as the negative electrode active material.

  However, under the low oxygen partial pressure condition, carbonization (carbonization) of the binder and the plasticizer usually proceeds, and sintering and densification of the active material, the solid electrolyte, and the current collector material are hindered. Furthermore, when the carbons to be generated have electrical conductivity, the self-discharge characteristics of the constituted battery may be deteriorated. An internal short circuit may occur.

Further, when at least Fe is contained in the first phosphoric acid compound represented by the above formula LiMPO ₄ constituting the positive electrode active material layer, Li _{3 in the} positive electrode active material layer is obtained by firing in an oxidizing atmosphere such as air. Since Fe (III) compounds such as Fe ₂ (PO ₄ ) ₃ are formed, the charge / discharge capacity and the internal resistance of the battery may increase. When firing in a non-oxidizing atmosphere such as Ar or N ₂ in order to prevent the formation of Fe (III), carbonization (carbonization) of the binder and the plasticizer proceeds as described above. The battery may have various adverse effects.

When the current collector is made of a metal material such as copper, silver, or nickel, it is preferable to perform sintering in an atmospheric gas containing water vapor and a low oxygen partial pressure gas in order to avoid carbonization as described above. Under such an atmosphere, the thermal decomposition of organic substances is promoted, so that it is possible to remove binders and deplasticizers while suppressing the formation of carbons, and the positive electrode active material, the negative electrode active material and the solid electrolyte are sintered densely. Can conclude. For this reason, it becomes possible to improve the charging / discharging characteristic and reliability of a battery.
In addition, in the positive electrode active material containing Fe, it is possible to remove the binder and deplasticizer while suppressing the formation of Fe (III) and the formation of carbons.

  An example of a method for manufacturing such an all-solid lithium secondary battery is shown below. In this manufacturing method, a positive electrode active material green sheet is obtained using the slurry 1, and a solid electrolyte green sheet is obtained using the slurry 2. Next, a second green sheet group including at least one set including the positive electrode active material green sheet and the solid electrolyte green sheet is formed. Next, the second green sheet group is heat-treated to obtain a laminate including at least one set in which the positive electrode active material layer and the solid electrolyte layer are integrated. Here, when the second green sheet group is manufactured, the set is configured by using at least two positive electrode active material green sheets and at least two solid electrolyte green sheets, and at least two positive electrode active material greens. One positive electrode current collector is provided between the sheets, and one negative electrode current collector is provided between at least two solid electrolyte green sheets. Here, the solid electrolyte also serves as a negative electrode active material, and at least one of the positive electrode current collector and the negative electrode current collector is selected from the group consisting of silver, copper, and nickel. The heat treatment is performed in an atmospheric gas containing water vapor and a low oxygen partial pressure gas.

Furthermore, when LiMPO ₄ containing at least Fe (for example, LiFePO ₄ ) is used as the positive electrode active material, the oxidation number of Fe contained in the positive electrode active material is divalent. At this time, it is preferable to perform sintering in a region where the divalent Fe is stable. Therefore, the equilibrium oxygen partial pressure PO ₂ contained in the atmosphere in which sintering (heat treatment) is performed is expressed by the following equation (1):
It is desirable to be within the range of −0.0310T + 33.5 ≦ −log ₁₀ PO ₂ ≦ −0.0300T + 38.1 (1). When the oxygen partial pressure is larger than the range defined by the above formula (1), Fe may be oxidized or the current collector may be oxidized. On the other hand, if the oxygen partial pressure is smaller than the range defined by the above formula (1), it may be difficult to suppress the generation of carbons.

  In order to stably adjust the oxygen partial pressure within the above range, the atmosphere in which sintering is performed includes at least a mixed gas composed of a gas capable of releasing oxygen gas and a gas that reacts with oxygen gas. Is preferred. Examples of such a mixed gas include a mixed gas composed of carbon dioxide gas, hydrogen gas, and nitrogen gas. Here, for example, carbon dioxide gas can be used as a gas capable of releasing oxygen gas, and hydrogen gas can be used as a gas that reacts with oxygen gas. When the mixed gas contains hydrogen gas, the volume content of the hydrogen gas is preferably 4% or less, which is below the explosion limit of hydrogen, for safety.

  A gas composed of these gases can stably maintain a constant oxygen partial pressure in an atmosphere in which sintering is performed during sintering (heat treatment) by an equilibrium reaction.

  Also in the production of the first laminate, when the active material contains Fe or the like, it is preferable to adjust the oxygen partial pressure in the atmospheric gas as described above.

Also, for example, when sintering a laminate including a current collector made of a metal material such as silver, copper, nickel, and cobalt, or when sintering a laminate including an active material containing Fe or the like, the atmospheric gas is It is preferable to have an oxygen partial pressure lower than the redox equilibrium oxygen partial pressure of these materials. As such an atmospheric gas, a mixed gas containing carbon dioxide (CO ₂ ) and hydrogen gas (H ₂ ) can also be used. Even in such a mixed gas containing CO ₂ and H ₂ , the oxygen partial pressure contained in the mixed gas can be kept low.

The mixing ratio of CO ₂ and H ₂ contained in the mixed gas is appropriately changed depending on the metal material constituting the current collector. For example, the volume ratio of CO ₂ and H ₂ in the mixed gas is preferably 10 to 8 × 10 ³ : 1. If the volume ratio of carbon dioxide gas to hydrogen gas is less than 10, decomposition of the binder may be difficult. When the volume ratio of carbon gas to hydrogen gas is larger than 8 × 10 ³ , the current collector may be oxidized.
When using a current collector made of copper, the volume ratio of CO ₂ and H ₂ contained in the atmospheric gas, for example, 10 ^3: can be 1.
When a current collector made of cobalt is used, the volume ratio of CO ₂ and H ₂ contained in the atmospheric gas can be set to 10: 1, for example.
When the current collector made of nickel is used, the volume ratio of CO ₂ and H ₂ contained in the atmospheric gas can be set to 40: 1, for example. In the case of using a current collector made of nickel, the volume ratio of CO ₂ and H ₂ is 10 to 50: it is preferably 1.

  The volume content of hydrogen gas contained in the mixed gas is preferably 4% or less. This is for the same reason as described above.

As described above, for example, when the positive electrode active material layer is composed of the first phosphate compound represented by the formula LiMPO ₄ and the first phosphate compound contains at least Fe, CO ₂ and H It is preferable to use a mixed gas containing ₂ as a firing atmosphere gas. At this time, the volume ratio between CO ₂ and H ₂ is preferably 10 to 10 ⁴ : 1. When the ratio of carbon dioxide gas to hydrogen gas is less than 10, decomposition of the binder may be difficult. When the ratio of carbon dioxide gas to hydrogen gas is larger than 10 ⁴ , the positive electrode active material may be decomposed.

<< Example 1-1 >>
When the first laminated body and the second laminated body are produced using a sintering process, in order to make the interface between the active material and the solid electrolyte electrochemically active, the active material and the solid electrolyte are It is necessary that no side reaction other than sintering occurs at the sintering interface. Therefore, the reactivity between the active material and the solid electrolyte when heated at 800 ° C. was examined.

First, the reactivity between the positive electrode active material and the solid electrolyte will be described below.
(Sintered body 1)
LiCoPO ₄ was used as the positive electrode active material, and Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ was used as the solid electrolyte. Each of the positive electrode active material and the solid electrolyte was pulverized by a ball mill to have a particle size of about 1 μm. These powders were mixed at a weight ratio of 1: 1 using a ball mill, and formed into pellets having a diameter of 18 mm by powder molding. The pellets were sintered in air at 800 ° C. for 5 hours. The sintered body after sintering was pulverized using an agate mortar. The sintered body after pulverization was designated as sintered body 1.

(Sintered body 2)
A sintered body 2 was obtained in the same manner as the method for producing the sintered body 1 except that LiNiPO ₄ was used as the positive electrode active material.

(Comparative sintered body 1)
A comparative sintered body 1 was obtained in the same manner as the method for producing the sintered body 1 except that LiCoO ₂ was used as the positive electrode active material.

(Comparative sintered body 2)
A comparative sintered body 2 was obtained in the same manner as the method for producing the sintered body 1 except that LiMn ₂ O ₄ was used as the positive electrode active material.

(Comparative sintered body 3)
A comparative sintered body 3 was obtained in the same manner as the method for producing the sintered body 1 except that Li _0.33 La _0.56 TiO ₃ was used as the solid electrolyte.

(Comparative sintered body 4)
A comparative sintered body 4 was obtained in the same manner as the method for producing the sintered body 1 except that LiNiPO ₄ was used as the positive electrode active material and Li _0.33 La _0.56 TiO ₃ was used as the solid electrolyte.

(Comparative sintered body 5)
A comparative sintered body 5 was obtained in the same manner as the method for producing the sintered body 1 except that LiCoO ₂ was used as the positive electrode active material and Li _0.33 La _0.56 TiO ₃ was used as the solid electrolyte.

(Comparative sintered body 6)
A comparative sintered body 6 was obtained in the same manner as the method for producing the sintered body 1 except that LiMn ₂ O ₄ was used as the positive electrode active material and Li _0.33 La _0.56 TiO ₃ was used as the solid electrolyte.

(Sintered body 3)
A sintered body 3 was obtained in the same manner as the method for producing the sintered body 1 except that LiCo _0.5 Ni _0.5 PO ₄ was used as the positive electrode active material.

  Using the sintered bodies 1 to 3 and the comparative sintered bodies 1 to 6, X-ray diffraction patterns before and after sintering were examined by an X-ray diffraction method using Cu α-rays. The X-ray diffraction patterns of the respective sintered bodies are shown in FIGS. 1 to 9, the X-ray diffraction pattern after sintering is represented by A, and the X-ray diffraction pattern before sintering is represented by B.

In FIG. 1 (sintered body 1), FIG. 2 (sintered body 2), and FIG. 9 (sintered body 3), the position and pattern of each peak were well maintained before and after the heat treatment. On the other hand, in FIGS. 3 to 8 (comparative sintered bodies 1 to 6), a new peak was observed after the heat treatment.
From the above results, in the sintered bodies 1 to 3, the sintered phase between the positive electrode active material and the solid electrolyte does not exhibit the third phase due to the solid phase reaction, whereas in the comparative sintered bodies 1 to 6, It was revealed that a third phase that is neither a positive electrode active material nor a solid electrolyte was developed.

  Therefore, by using the first phosphoric acid compound (positive electrode active material) and the second phosphoric acid compound (solid electrolyte) as described above, at the interface between the positive electrode active material and the solid electrolyte, The positive electrode active material and the solid electrolyte can be sintered and bonded without developing a third phase that is neither a positive electrode active material nor a solid electrolyte.

Next, the reactivity between the negative electrode active material and the solid electrolyte will be described.
(Sintered body 4)
Trigonal FePO ₄ was used as the negative electrode active material, and Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ was used as the solid electrolyte. Each of the negative electrode active material and the solid electrolyte was pulverized with a ball mill to have a particle size of about 1 μm. These powders were mixed at a weight ratio of 1: 1 using a ball mill, and formed into pellets having a diameter of 18 mm by powder molding. The pellets were sintered in air at 800 ° C. for 5 hours. The sintered body after sintering was pulverized using an agate mortar. The sintered body after pulverization was designated as sintered body 4.

(Sintered body 5)
A sintered body 5 was obtained in the same manner as the method for producing the sintered body 4 except that Li ₃ Fe ₂ (PO ₄ ) ₃ was used as the negative electrode active material.

(Sintered body 6)
A sintered body 6 was obtained in the same manner as the method for producing the sintered body 4 except that LiFeP ₂ O ₇ was used as the negative electrode active material.

(Comparative sintered body 7)
A comparative sintered body 7 was obtained in the same manner as the method for producing the sintered body 4 except that Li ₄ Ti ₅ O ₁₂ was used as the negative electrode active material.

(Comparative sintered body 8)
A comparative sintered body 8 was obtained in the same manner as the method for producing the sintered body 4 except that Nb ₂ O ₅ was used as the negative electrode active material.

(Comparative sintered body 9)
A comparative sintered body 9 was obtained in the same manner as the method for producing the sintered body 4 except that Li _0.33 La _0.56 TiO ₃ was used as the solid electrolyte.

(Comparative sintered body 10)
Comparative firing was performed in the same manner as the method for producing the sintered body 4 except that trigonal Li ₃ Fe ₂ (PO ₄ ) ₃ was used as the negative electrode active material and Li _0.33 La _0.56 TiO ₃ was used as the solid electrolyte. A knot 10 was obtained.

(Comparative sintered body 11)
Comparative sintered body 11 was obtained in the same manner as the method for producing sintered body 4 except that LiFeP ₂ O ₇ was used as the negative electrode active material and Li _0.33 La _0.56 TiO ₃ was used as the solid electrolyte.

(Sintered body 12)
Sintered body 12 was obtained in the same manner as for the sintered body 4 except that Li ₄ Ti ₅ O ₁₂ was used as the negative electrode active material and Li _0.33 La _0.56 TiO ₃ was used as the solid electrolyte.

(Comparative sintered body 13)
A comparative sintered body 13 was obtained in the same manner as the method for producing the sintered body 4 except that Nb ₂ O ₅ was used as the negative electrode active material and Li _0.33 La _0.56 TiO ₃ was used as the solid electrolyte.

  In the same manner as described above, the X-ray diffraction patterns before and after sintering of the sintered bodies 4 to 6 and 12 and the comparative sintered bodies 7 to 11 and 13 were examined. X-ray diffraction patterns of the respective sintered bodies are shown in FIGS. 10-19, the X-ray diffraction pattern after sintering is represented by A, and the X-ray diffraction pattern before sintering is represented by B.

  In FIG. 10 (sintered body 4), FIG. 11 (sintered body 5), FIG. 12 (sintered body 6), and FIG. 18 (sintered body 12), the position and pattern of each peak are well maintained before and after heat treatment. It was. On the other hand, in FIGS. 13 to 17 (Comparative sintered bodies 7 to 11) and FIG. 19 (Comparative sintered body 13), the intensity of the peak was drastically decreased by heat treatment, and the appearance of a new peak was observed. That is, in the sintered bodies 4 to 6 and the sintered body 12, the third phase due to the solid phase reaction does not appear at the sintered interface between the negative electrode active material and the solid electrolyte, whereas the comparative sintered bodies 7 to 11. And in the comparative sintered body 13, it became clear that the 3rd phase which is neither an active material nor a solid electrolyte expresses.

Therefore, the second phosphoric acid compound (solid electrolyte) and the third phosphoric acid compound (negative electrode active material) as described above, and an oxide (negative electrode active material) containing titanium such as Li ₄ Ti ₅ O ₁₂ and Li _0.33 When an oxide (solid electrolyte) containing titanium such as La _0.56 TiO ₃ is used, a _third layer that is neither a negative electrode active material nor a solid electrolyte is formed at the interface between the negative electrode active material and the solid electrolyte when a laminate is produced. It is possible to sinter and bond the negative electrode active material and the solid electrolyte without developing a phase.

  Therefore, according to the results of the sintered bodies 1 to 3, the positive electrode active material layer containing the first phosphorus compound and the solid electrolyte layer containing the second phosphorylated compound are connected to the battery at the interface between the positive electrode active material layer and the solid electrolyte layer. It can be seen that bonding can be performed without generating an impurity phase that is not involved in the charge / discharge. Further, from the results of the sintered bodies 4 to 6 and 12, the solid electrolyte layer comprising the solid electrolyte layer containing the second phosphorylated compound, the negative electrode active material layer containing the third phosphoric acid compound, and the oxide containing titanium. It can be seen that a negative electrode active material layer made of an oxide containing titanium and titanium can be bonded without causing an impurity phase not involved in charge / discharge of the battery at the interface between the negative electrode active material layer and the solid electrolyte layer.

<< Example 1-2 >>
The following batteries and comparative batteries were prepared and charged / discharged under predetermined conditions to determine the discharge capacity.

(Battery 1)
First, a solid electrolyte powder represented by Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ and a positive electrode active material powder represented by LiCoPO ₄ were prepared. To the solid electrolyte powder, polyvinyl butyral resin as a binder, n-butyl acetate as a solvent, and dibutyl phthalate as a plasticizer are added and mixed with a zirconia ball in a ball mill for 24 hours to obtain a slurry for forming a solid electrolyte layer. Prepared.
The positive electrode active material layer forming slurry was also prepared in the same manner as when the solid electrolyte layer forming slurry was prepared.

  Next, the slurry for solid electrolyte layer formation was apply | coated using the doctor blade on the carrier film 1 which has a polyester resin as a main component. Thereafter, the applied slurry was dried to obtain a solid electrolyte green sheet 2 (thickness: 25 μm) as shown in FIG. Note that a release agent layer containing Si as a main component is formed on the surface of the carrier film 1.

  Further, as shown in FIG. 21, a positive electrode active material green sheet 4 (thickness: 4 μm) was produced on the carrier film 3 by the same method as that for producing the solid electrolyte green sheet.

  Next, a polyester film 6 having an adhesive on both sides thereof was pasted on the support base 5. Next, as shown in FIG. 22, the surface of the solid electrolyte green sheet 2 on the side not in contact with the carrier film 1 was placed on the polyester film 6.

Next, a temperature of 70 ° C. was applied from above the carrier film 1 while applying a pressure of 80 kg / cm ² , and the carrier film was peeled from the carrier film 1 and the solid electrolyte green sheet 2 as shown in FIG.

On this solid electrolyte green sheet 2, the solid electrolyte green sheet 2 ′ formed on another carrier film 1 ′ produced as described above was placed. Next, by applying pressure and temperature from above the carrier film 1 ′, the carrier film 1 ′ was peeled from the green sheet 2 ′ while bonding the green sheets 2 and 2 ′.
This operation was repeated 20 times to produce a solid electrolyte green sheet group 7 (thickness: 500 μm).

Next, the positive electrode active material green sheet 4 formed on the carrier film 3 produced as described above was placed on the produced green sheet group 7. Next, the carrier film 3 was peeled from the green sheet 4 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from above the carrier film 3. In this way, as shown in FIG. 24, a laminate (thickness: about 500 μm) composed of the green sheet group 7 and the positive electrode active material green sheet 4 was produced. This laminate was peeled from the polyester film 6 and cut into a size of 7 mm (width) × 7 mm (length) × about 500 μm (thickness) to obtain a green chip 8.

  Next, as shown in FIG. 25, two sets of the obtained green chips 8 were made. At this time, the solid electrolyte surfaces 9 on the side opposite to the side where the positive electrode active material green sheet 4 of the green chip 8 is placed are overlapped so that the active material green sheet 4 comes to the outside.

Next, two alumina ceramic plates 10 that have been sufficiently baked in a Li atmosphere in advance to absorb Li are used so that each ceramic plate is in contact with the active material green sheet 4. I sandwiched a pair of green chips.
Since Li is easily volatilized, Li may volatilize from the green chip during sintering. As described above, by using a ceramic plate that has sufficiently absorbed Li, volatilization of Li from the green chip during sintering is suppressed, and generation of an impurity layer is suppressed.

  Next, these were heated to 400 ° C. at a temperature rising rate of 400 ° C./h in the air and held at 400 ° C. for 5 hours to sufficiently thermally decompose organic substances such as binder and plasticizer. Then, it heated up to 900 degreeC with the temperature increase rate of 400 degreeC / h, and then cooled to room temperature rapidly with the cooling rate of 400 degreeC / h. In this way, the green chip was sintered.

Here, the filling rate of the green chip after sintering can be measured, for example, as follows.
First, the weight of the solid electrolyte contained in the solid electrolyte layer and the weight of the active material contained in the active material layer are determined. Specifically, for example, the amount of Ti contained per unit area of the solid electrolyte layer green sheet having a predetermined thickness, or the amount of Co contained per unit area of the active material green sheet having a predetermined thickness, Determined by ICP analysis. Using the obtained amounts of Ti and Co, the weight of Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ per unit area of the solid electrolyte green sheet and the weight of LiCoPO ₄ per active material green sheet can be obtained. .

  Next, the volume of the solid electrolyte layer and the active material layer of the chip after sintering is determined. Since the sintered chip has a prismatic shape as shown in FIG. 24, for example, the volume of each layer can be obtained if the bottom area and the thickness of each layer are known. Here, as for the thickness of each layer, the cross-section of the chip is measured, for example, at a plurality of locations, for example, 5 predetermined locations with a scanning electron microscope (SEM) or the like, and the average value is used as the thickness of each layer be able to.

  From the weight of the active material contained in the active material layer and the volume of the active material layer obtained as described above, the apparent density of the active material layer ((weight of active material contained in the active material layer) / (active material layer) The volume after sintering))) can be determined. This also applies to the solid electrolyte layer.

As described above, in the case of the active material layer, the filling rate is a value expressed as a percentage value of the ratio of the apparent density of the active material layer to the true density of the active material. When the X-ray density of the substance is used, the filling factor is given by the following formula:
{[(Weight of active material contained in active material layer) / (Volume after sintering of active material layer)] / (X-ray density of active material)} × 100
Can be obtained using
Further, the filling rate of the solid electrolyte layer can be obtained in the same manner as described above.

  Also, each of the active material layer containing a predetermined amount of active material or the solid electrolyte layer containing a predetermined amount of solid electrolyte is sintered under the same conditions as the sintering conditions for producing the laminate, and the active material layer or A solid electrolyte layer is prepared separately. The filling rate of each obtained layer can be obtained using the above formula, and the value can be regarded as the filling rate of each layer in the laminate.

In this example, since the active material layer is sufficiently thin as compared with the solid electrolyte layer, it is assumed that all the chips after sintering are Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) _3. The rate was determined. As a result, the filling rate was about 83%. Here, the filling rate of the chip was determined by [{(chip weight) / (chip volume)} / (X-ray density of solid electrolyte)] × 100.

  From the SEM image or the like, it can be assumed that the filling rate of the active material layer is almost 100%.

  In addition, regarding the positive electrode active material layer, the polished cross section of the green chip after sintering was observed with an SEM. It was confirmed that it was densely sintered.

  Although two green chips are paired and sintered, the two green chips are not joined by sintering.

  Next, one set of green chips is divided into two, and as shown in FIG. 26, gold is sputtered on the surface of the active material layer 11a of the first laminate 11 composed of the positive electrode active material layer 11a and the solid electrolyte layer 11b. Then, a gold thin film 12 (thickness: several nm to several tens of nm) serving as a positive electrode current collector was formed. Then, the gold | metal | money adhering to each side surface 13 of the 1st laminated body 11 was grind | polished and removed using the paper file.

Next, a layer made of an electrolyte having reduction resistance and a negative electrode active material layer were formed on the first laminate in dry air having a dew point of −50 ° C. or less as follows.
First, a 150 μm-thick metal lithium foil 14 was punched to a diameter of 10 mm, and affixed to the center of the SUS plate 15 punched to a thickness of 0.5 mm and a diameter of 20 mm. The SUS plate functions as a negative electrode current collector.

Polyethylene oxide having an average molecular weight of 1,000,000 (hereinafter also referred to as PEO) and LiN (SO ₂ CF ₃ ) ₂ (hereinafter also referred to as LiTFSI), oxygen atoms of PEO and lithium of LiTFSI are [O] / [Li ] Was dissolved in dehydrated acetonitrile so as to be 20/1. In this solution, the concentration of Li was set to 0.1M.
Next, this solution was spin-coated on metallic lithium at 2000 rpm, and vacuum-dried to form a PEO-LiTFSI layer 16 on the metallic lithium foil 14. When the thickness of the PEO-LiTFSI layer was confirmed by SEM after vacuum drying, it was about 50 μm.

  The PEO-LiTFSI layer 16 and the solid electrolyte surface 17 on the side opposite to the positive electrode active material layer of the first laminate 11 were bonded together to produce an all solid lithium secondary battery as shown in FIG. The obtained battery was designated as battery 1.

(Battery 2)
A battery 2 was produced in the same manner as the battery 1 except that LiMnPO ₄ was used instead of LiCoPO ₄ .

(Comparative battery 1)
A comparative battery 1 was produced in the same manner as the battery 1 except that LiCoO ₂ was used instead of LiCoPO ₄ .

(Comparison battery 2)
A comparative battery 2 was produced in the same manner as the battery 1 except that LiMn ₂ O ₄ was used instead of LiCoPO ₄ .

(Battery 3)
With reference to FIG. 28, an all-solid lithium secondary battery manufactured by sputtering will be described.
A titanium thin film 23 having a thickness of 0.05 μm is formed by RF magnetron sputtering on a 30 mm × 30 mm single crystal silicon substrate 22 whose surface is covered with a layer 21 made of silicon nitride. Then, a gold thin film 24 having a thickness of 0.5 μm as a positive electrode current collector was formed. At this time, a metal mask having an opening of 20 mm × 12 mm was used. The titanium thin film 23 has a function of bonding the layer 21 made of silicon nitride and the gold thin film 24.

Next, a LiCoPO ₄ thin film 25 having a thickness of 0.5 μm was formed on the gold thin film 24 by RF magnetron sputtering using a LiCoPO ₄ target. At this time, a metal mask having an opening of 10 mm × 10 mm was used. As the sputtering gas, a gas composed of 25% oxygen and 75% argon was used.

Next, a metal mask having an opening of 15 mm × 15 mm was disposed so that the LiCoPO ₄ thin film 25 was positioned at the center of the opening. A ₂ μm thick LiTi ₂ (PO ₄ ) ₃ thin film 26 was formed so as to cover the LiCoPO ₄ thin film 25 by RF magnetron sputtering using a LiTi ₂ (PO ₄ ) ₃ target. Here, as the sputtering gas, a gas composed of 25% oxygen and 75% argon was used.

The obtained laminate was annealed in air at 600 ° C. for 2 hours to crystallize a positive electrode active material made of LiCoPO ₄ and a solid electrolyte made of LiTi ₂ (PO ₄ ) ₃ , respectively. Formed body.

Next, a reduction-resistant electrolyte layer and a metal lithium layer as a negative electrode were formed on the LiTi ₂ (PO ₄ ) ₃ thin film 26 as a solid electrolyte layer. These formations were performed in dry air having a dew point of −50 ° C. or lower.

  Specifically, first, PEO (average molecular weight 1,000,000) and LiTFSI are mixed with dehydrated acetonitrile so that the oxygen atom of PEO and the lithium of LiTFSI are [O] / [Li] = 20/1. Dissolved. In this solution, the concentration of Li was 0.05M.

Next, the above solution was spin-coated at 2000 rpm on the LiTi ₂ (PO ₄ ) ₃ thin film 26 and vacuum-dried to form a PEO-LiTFSI layer 27 as a reduction-resistant electrolyte layer. When the thickness of the PEO-LiTFSI layer was confirmed by SEM after vacuum drying, it was about 5 μm.

  Next, a metal lithium thin film 28 having a thickness of 0.5 μm constituting the negative electrode was formed on the PEO-LiTFSI layer 27 by resistance heating vapor deposition. At this time, a metal mask having an opening of 10 mm × 10 mm was used.

Thereafter, a copper thin film 29 having a thickness of 0.5 μm as a negative electrode current collector is formed by RF magnetron sputtering so as not to contact the gold thin film 24 as the positive electrode current collector and completely cover the metal lithium thin film 28. And an all-solid lithium secondary battery as shown in FIG. 28 was obtained. At this time, a metal mask having an opening of 20 mm × 12 mm was used.
The all solid lithium secondary battery thus obtained was designated as battery 3. Here, the filling rate of each layer of the positive electrode layer and the solid electrolyte layer is approximately 100%.

(Battery 4)
A battery 4 was produced in the same manner as the battery 3 except that LiMnPO ₄ was used instead of LiCoPO ₄ .

(Comparative battery 3)
A comparative battery 3 was produced in the same manner as the battery 3 except that LiCoO ₂ was used instead of LiCoPO ₄ .

(Comparison battery 4)
A comparative battery 4 was produced in the same manner as the battery 3 except that LiMn ₂ O ₄ was used instead of LiCoPO ₄ .

  The batteries 1 to 4 and the comparative batteries 1 to 4 immediately after production were charged and discharged once at a current value of 10 μA in an atmosphere with a dew point of −50 ° C. and an environmental temperature of 60 ° C. The discharge capacity at that time is shown as the initial discharge capacity. Table 1 also shows the upper limit cut voltage and the lower limit cut voltage.

As shown in Table 1, Comparative batteries 1 to 4 could not be discharged. This is presumably because an impurity phase that is neither an active material nor a solid electrolyte was generated at the interface between the positive electrode active material and the solid electrolyte by the heat treatment, and the interface was electrochemically inactive.
On the other hand, in the batteries 1 to 4, charging / discharging was possible. In the present invention, this is because a positive electrode active material composed of a crystalline first phosphate compound capable of releasing and occluding lithium ions, and a solid electrolyte composed of a crystalline second phosphate compound having lithium ion conductivity, This is probably because an impurity phase that does not participate in the charge / discharge reaction is not generated at the interface, and the interface is electrochemically active.
As described above, according to the present invention, it was shown that no impurity phase was formed at the interface between the positive electrode active material and the solid electrolysis, and that the interface was electrochemically active and charge / discharge was possible. .

  Next, for batteries 1 to 4, a charge / discharge cycle was repeated in the range of 3.5 to 5.0 V at a current value of 10 μA in an atmosphere with a dew point of −50 ° C. and an environmental temperature of 60 ° C. The number of charge / discharge cycles when the capacity reached 60% was examined. The obtained results are shown in Table 2.

The batteries 1 and 2 could be charged and discharged about 100 times, and the batteries 3 and 4 could be charged and discharged about 180 times.
On the other hand, a positive electrode made of 70 parts by weight of LiCoPO ₄ , 25 parts by weight of acetylene black, and 5 parts by weight of polytetrafluoroethylene, a negative electrode made of metallic lithium, ethylene carbonate (EC) and dimethyl carbonate (DMC) A conventional liquid battery using an electrolytic solution in which LiPF ₄ was dissolved at a concentration of 1 M in a mixed solvent (EC: DMC = 1: 1 (volume ratio)) was prepared, and its cycle life was measured in the same manner as described above. However, it was about 10 times.

  Thus, when the cycle life of the battery of the present invention was compared with the cycle life of the conventional liquid battery, it was revealed that the cycle life of the battery of the present invention was greatly improved.

<< Example 1-3 >>
Next, the filling rate of the laminate was examined.

(Battery 5)
A battery 1 was produced in the same manner as the battery 1 except that the temperature was raised to 850 ° C. at a rate of 400 ° C./h during sintering.

(Reference battery 6)
A reference battery 6 was produced in the same manner as the battery 1 except that the temperature was raised to 800 ° C. at a rate of 400 ° C./h during sintering.

  For these battery 1, battery 5, and reference battery 6, the impedance at 1 kHz was measured.

Table 3 shows the filling rate of the laminate used for the battery 1, the battery 5, and the reference battery 6, and the impedance of these batteries. Regarding the filling rate, as in Example 1-2, Table 3 shows the filling rate when it is assumed that all of the laminates are Li _1.3 Al _0.3 Ti (PO ₄ ) ₃ .

As shown in Table 3, when the filling factor of the laminate was less than 70%, the impedance was extremely increased. This is considered to be because the path for conducting lithium ions becomes thin unless the positive electrode active material powder and the solid electrolyte powder are sintered.
In addition, a battery having a large impedance is not preferable because high-rate charge / discharge performance is degraded.

  From the above results, it is preferable that the filling rate of each of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer constituting the laminate exceeds 70%.

<< Example 1-4 >>
A battery in which the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer were integrated was produced.
(Battery 7)
First, a solid electrolyte powder represented by Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , a positive electrode active material powder represented by LiCoPO ₄ , and a negative electrode represented by Li ₃ Fe ₂ (PO ₄ ) ₃ An active material powder was prepared.
A solid electrolyte layer slurry is prepared by adding polyvinyl butyral resin as a binder, n-butyl acetate as a solvent, and dibutyl phthalate as a plasticizer, and mixing with a zirconia ball in a ball mill for 24 hours. did.
The positive electrode active material layer forming slurry and the negative electrode active material layer forming slurry were also prepared in the same manner as when the solid electrolyte layer forming slurry was prepared.

  Next, the slurry for solid electrolyte layer formation was apply | coated using the doctor blade on the carrier film 30 which has a polyester resin as a main component. Thereafter, the applied slurry was dried to obtain a solid electrolyte green sheet 31 (thickness: 25 μm) as shown in FIG. Note that a release agent layer containing Si as a main component is formed on the surface of the carrier film 30.

  As shown in FIG. 30, a positive electrode active material green sheet 32 (thickness: 4 μm) was produced on another carrier film 30 by the same method as the production of the solid electrolyte green sheet. In the same manner as described above, a negative electrode active material green sheet 33 (thickness: 7 μm) was produced on another carrier film 30 as shown in FIG.

  Next, a polyester film 35 having an adhesive on both sides thereof was pasted on the support base 34. Next, as shown in FIG. 32, the surface of the negative electrode active material green sheet 33 on the side not in contact with the carrier film 30 was placed on the polyester film 35.

Next, a temperature of 70 ° C. was applied from above the carrier film 30 while applying a pressure of 80 kg / cm ² , and the carrier film 30 was peeled from the negative electrode active material green sheet 33 as shown in FIG.

  Next, the surface of the solid electrolyte green sheet 31 that is not in contact with the carrier film is placed on the negative electrode active material green sheet 33, and the solid electrolyte green sheet is placed under the same pressure and temperature conditions as described above. The carrier film was peeled from the solid electrolyte green sheet while being bonded to the green sheet.

Next, on this solid electrolyte green sheet 31, the solid electrolyte green sheet 31 'formed on another carrier film 30' produced as described above was placed. Next, by applying pressure and temperature from above the carrier film 30 ′, the carrier film 30 ′ was peeled from the green sheet 31 ′ while bonding the green sheets 31 and 31 ′.
This operation was repeated 20 times to produce a solid electrolyte green sheet group 36 (thickness: about 500 μm).

Next, the positive electrode active material green sheet 32 formed on the carrier film 30 produced as described above was placed on the produced solid electrolyte green sheet group 36. Next, the carrier film 30 was peeled from the positive electrode active material green sheet 32 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from above the carrier film 30. In this way, as shown in FIG. 34, a laminate (thickness: about 500 μm) composed of the negative electrode active material green sheet 33, the solid electrolyte green sheet group 36, and the positive electrode active material green sheet 32 was produced. The laminate was peeled from the polyester film 35 and cut into a size of 7 mm (width) × 7 mm (length) × about 500 μm (thickness) to obtain a green chip (first green sheet group) 37.

  Next, as shown in FIG. 35, the obtained green chips 37 were made into a set of two. At this time, the surfaces of the green chip 37 on the side where the negative electrode active material green sheet 33 is provided are overlapped so that the surface on the side where the positive electrode active material green sheet 32 is present comes to the outside.

  Next, by using two alumina ceramic plates 38 that have sufficiently absorbed Li by firing in advance in an Li atmosphere, each ceramic plate is in contact with the positive electrode active material green sheet 32, respectively. I sandwiched a pair of green chips.

  Next, these were heated to 400 ° C. at a temperature rising rate of 400 ° C./h in the air and held at 400 ° C. for 5 hours to sufficiently thermally decompose organic substances such as binder and plasticizer. Then, it heated up to 900 degreeC with the temperature increase rate of 400 degreeC / h, and then cooled to room temperature rapidly with the cooling rate of 400 degreeC / h. In this way, the green chip was sintered.

  Here, the filling rate of the green chip after sintering was determined in the same manner as in Example 1-2. As a result, the green chip filling rate after sintering was about 83%.

  Further, regarding the positive electrode active material layer and the negative electrode active material layer, the polished cross section of the green chip after sintering was observed with an SEM. The positive electrode active material layer had a thickness of about 1 μm, and the negative electrode active material layer had a thickness of The positive electrode active material layer and the negative electrode active material layer were confirmed to have almost no voids and were sintered densely.

  Although two green chips are paired and sintered, the two green chips are not joined by sintering.

  Next, one set of green chips is divided into two, and as shown in FIG. 36, a second laminate 39 including one set of a positive electrode active material layer 39a, a solid electrolyte layer 39b, and a negative electrode active material layer 39c is provided. Obtained. Gold was sputtered on the surface of the positive electrode active material layer 39a of the second laminate to form a gold thin film 40 (thickness: several nm to several tens of nm) serving as a positive electrode current collector. In addition, a gold thin film 41 (thickness: several nm to several tens of nm) serving as a negative electrode current collector was formed on the surface of the negative electrode active material layer 39c of the laminate 39 in the same manner as described above. Thereafter, the gold adhering to each side surface 42 of the prismatic laminate 39 was polished and removed with a paper file to produce an all-solid lithium secondary battery. This battery was designated as battery 7.

(Battery 8)
A battery 8 was produced in the same manner as the battery 7 except that LiMnPO ₄ was used as the positive electrode active material instead of LiCoPO ₄ . The filling rate of the green chips after sintering was 80% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 9)
A battery 9 was produced in the same manner as the battery 7 except that FePO ₄ was used as the negative electrode active material instead of Li ₃ Fe ₂ (PO ₄ ) ₃ . The filling rate of the green chips after sintering was 85% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 10)
A battery 10 was produced in the same manner as the battery 7 except that LiFeP ₂ O ₇ was used as the negative electrode active material instead of Li ₃ Fe ₂ (PO ₄ ) ₃ . The filling rate of the green chips after sintering was 75% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Comparison battery 5)
A comparison was made in the same manner as the battery 7 except that LiCoO ₂ was used as the positive electrode active material instead of LiCoPO ₄ and Li ₄ Ti ₅ O ₁₂ was used instead of Li ₃ Fe ₂ (PO ₄ ) _3. Battery 5 was produced. The filling rate of the green chips after sintering was 71% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 11)
Using the sputtering method, an all solid lithium secondary battery as shown in FIG. 37 was produced as follows.
A titanium thin film 45 having a thickness of 0.05 μm is formed by RF magnetron sputtering on a 30 mm × 30 mm single crystal silicon substrate 44 whose surface is covered with a layer 43 made of silicon nitride. Then, a gold thin film 46 having a thickness of 0.5 μm as a positive electrode current collector was formed. At this time, a metal mask having an opening of 20 mm × 12 mm was used. The titanium thin film 45 has a function of bonding the layer 43 made of silicon nitride and the gold thin film 46.

Next, a LiCoPO ₄ thin film 47 having a thickness of 0.5 μm was formed on the gold thin film 46 by RF magnetron sputtering using a LiCoPO ₄ target. At this time, a metal mask having an opening of 10 mm × 10 mm was used, and a sputtering gas composed of 25% oxygen and 75% argon was used.

Next, a metal mask having an opening of 15 mm × 15 mm was arranged so that the LiCoPO ₄ thin film 47 was positioned at the center of the opening. A ₂ μm thick LiTi ₂ (PO ₄ ) ₃ thin film 48 was formed so as to cover the LiCoPO ₄ thin film 47 by RF magnetron sputtering using a LiTi ₂ (PO ₄ ) ₃ target. In the sputtering, a sputtering gas composed of 25% oxygen and 75% argon was used.

Next, a Li ₃ Fe ₂ (PO ₄ ) ₃ thin film 49 having a thickness of 1 μm is formed on the LiTi ₂ (PO ₄ ) ₃ thin film 48 by RF magnetron sputtering using a Li ₃ Fe ₂ (PO ₄ ) ₃ target. Formed. At this time, a metal mask having an opening of 10 mm × 10 mm was used, and a sputtering gas composed of 25% oxygen and 75% argon was used.

The obtained laminated body (first group) was annealed at 600 ° C. for 2 hours, whereby a positive electrode active material layer made of LiCoPO ₄ , a solid electrolyte layer made of LiTi ₂ (PO ₄ ) ₃ , and Li ₃ Fe _2. A negative electrode active material layer made of (PO ₄ ) ₃ was integrated and crystallized.

Thereafter, the thickness of the negative electrode current collector is determined by RF magnetron sputtering so as not to contact the gold thin film 46 as the positive electrode current collector and completely cover the Li ₃ Fe ₂ (PO ₄ ) ₃ thin film 49. A copper thin film 50 having a thickness of 0.5 μm was formed, and an all solid lithium secondary battery as shown in FIG. 37 was obtained. At this time, a metal mask having an opening of 20 mm × 12 mm was used.
The all solid lithium secondary battery thus obtained was designated as battery 11. The filling rate of each layer of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer is approximately 100%.

(Battery 12)
A battery 12 was produced in the same manner as the battery 11 except that LiMnPO ₄ was used as the positive electrode active material instead of LiCoPO ₄ .

(Battery 13)
A battery 13 was produced in the same manner as the battery 11 except that FePO ₄ was used as the negative electrode active material instead of Li ₃ Fe ₂ (PO ₄ ) ₃ .

(Battery 14)
A battery 14 was produced in the same manner as the battery 11 except that LiFeP ₂ O ₇ was used as the negative electrode active material instead of Li ₃ Fe ₂ (PO ₄ ) ₃ .

(Comparison battery 6)
Similar to the production method of the battery 11 except that LiCoO ₂ was used as the positive electrode active material instead of LiCoPO ₄ and Li ₄ Ti ₅ O ₁₂ was used as the negative electrode active material instead of Li ₃ Fe ₂ (PO ₄ ) _3. Thus, a comparative battery 6 was produced.

(Comparative battery 7)
When producing an all-solid lithium secondary battery, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer contained in the laminate produced by the sputtering method were not annealed and crystallized. Except for this, the comparative battery 7 was produced in the same manner as the production method of the battery 11.

  Using the batteries 7 to 14 and the comparative batteries 5 to 7 produced as described above, charging and discharging were performed once at a current value of 10 μA in an atmosphere with a dew point of −50 ° C. and an environmental temperature of 25 ° C. The discharge capacity at that time is shown as the initial discharge capacity. Table 4 also shows the upper limit cut voltage and the lower limit cut voltage.

As shown in Table 4, the comparative batteries 5 to 7 could not be discharged. On the other hand, the batteries 7 to 14 could be charged and discharged.
In comparative batteries 5 to 6, the heat treatment formed impurity phases that were neither active material nor solid electrolyte at the interface between the positive electrode active material and the solid electrolyte and / or the interface between the negative electrode active material and the solid electrolyte. It is thought that the interface of was electrochemically inactive. In the comparative battery 7, the annealing process for crystallizing the positive electrode active material, the negative electrode active material, and the solid electrolyte was not performed. For this reason, lithium ion conductivity is not expressed in the solid electrolyte, and sites for charging / discharging lithium ions are not formed in the positive electrode active material and the negative electrode active material, and charging / discharging is impossible.

  As described above, according to the present invention, the positive electrode active material and the solid electrolyte, the negative electrode active material and the solid electrolyte are joined to each other without forming an impurity phase, and the interface is electrochemically active. It was shown that the battery including the laminate was chargeable / dischargeable.

  Next, with respect to the batteries 7 to 14, a charge / discharge cycle was repeated at an electric current value of 10 μA in an atmosphere having a dew point of −50 ° C. and an environmental temperature of 25 ° C. with the cut voltage shown in Table 4 above, and the discharge capacity was initially set. The number of charge / discharge cycles when the discharge capacity was 60% was examined. The results obtained are shown in Table 5.

The batteries 7 to 10 can be charged and discharged about 300 times, and the batteries 11 to 14 can be charged and discharged about 500 times.
From the above, it has been clarified that an all-solid lithium secondary battery excellent in cycle life characteristics can be produced by the present invention.

<< Example 1-5 >>
Next, the sintered density of the second laminate was examined.
(Battery 15)
A battery 15 was produced in the same manner as the battery 7 except that the temperature was raised to 850 ° C. at a rate of 400 ° C./h during sintering.

(Reference battery 16)
A reference battery 16 was produced in the same manner as the battery 7 except that the temperature was raised to 800 ° C. at a temperature raising temperature of 400 ° C./h when sintering.

  Using the battery 15, the reference battery 16, and the battery 7, the impedance at 1 kHz was measured.

Table 6 shows the filling rate of the second laminate used for the battery 7, the battery 15, and the reference battery 16, and the impedance of these batteries. As for the filling rate, Table 6 shows the filling rate when it is assumed that all of the second stacked body is Li _1.3 Al _0.3 Ti (PO ₄ ) ₃ .

As shown in Table 6, when the filling rate of the second laminate was less than 70%, the impedance was extremely increased. This is considered to be because the path for conducting lithium ions becomes thin unless the positive electrode active material powder and the solid electrolyte powder and / or the negative electrode active material powder and the solid electrolyte powder are sintered. .
In addition, a battery having a large impedance is not preferable because high-rate charge / discharge performance is deteriorated.

  Therefore, in each layer of the second laminate in which the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are integrated, it is preferable that the filling rate exceeds 70%.

<< Example 1-6 >>
Next, the effect of moisture on the battery was examined.
(Battery 17)
The battery 17 was formed in the same manner as the battery 7 except that a current collector made of a silver thin film was formed on each of the positive electrode active material layer surface and the negative electrode active material layer surface of the laminate by sputtering. Produced.

(Battery 18)
As shown in FIG. 38, the battery 17 is housed in a metal case 51 in which a nylon gasket 53 is disposed, and the opening of the metal case 51 is caulked to the metal sealing plate 52 via the gasket 53. A button-type sealed battery having a diameter of 9 mm and a height of 2.1 mm was produced. The battery thus obtained was designated as battery 18. At this time, the battery 17 was accommodated in the metal case so that the metal case 51 became a positive electrode terminal and the metal sealing plate 52 became a negative electrode terminal. Further, a sponge metal piece 54 made of nickel was inserted between the metal case 51 and the battery 17 so that the battery 17 and the metal case and the metal sealing plate were in close contact with each other.
38, the battery 17 includes a silver thin film 55, a positive electrode active material layer 39a, a solid electrolyte layer 39b, a negative electrode active material layer 39c, and a silver thin film 56.

(Battery 19)
A lead 57 made of copper having a diameter of 0.5 mm was connected to each of the silver thin film on the positive electrode active material layer side and the silver thin film on the negative electrode active material side of the battery 17 by solder 58 to form a positive electrode terminal and a negative electrode terminal, respectively. As shown in FIG. 39, a resin mold was applied with epoxy resin 59 so that battery 17 including a silver thin film, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a silver thin film was enclosed. The battery thus obtained was designated as battery 19.

(Battery 20)
A battery 17 provided with copper leads as a positive electrode terminal and a negative electrode terminal is immersed in a dispersion in which a water repellent made of a fluororesin is dispersed in n-heptane, and the surface of the battery 17 is subjected to a water repellent treatment. A battery 20 was produced in the same manner as the battery 19 was produced.

With respect to the batteries 17 to 20 obtained as described above, the discharge capacities before and after storage were measured as follows.
Using batteries 17 to 20, charging and discharging were performed in the range of 1.0 to 2.6 V at a current value of 10 μA in an atmosphere with a dew point of −50 ° C. and an environmental temperature of 25 ° C., and the initial discharge capacity was determined. Thereafter, these batteries were charged to 2.6 V, and then stored for 30 days in an atmosphere having a temperature of 60 ° C. and a relative humidity of 90%. Next, these batteries were discharged at a current value of 10 μA in an atmosphere having a dew point of −50 ° C. and an environmental temperature of 25 ° C. Table 7 shows the initial discharge capacities of these batteries and the discharge capacities after 30 days storage.

  The initial discharge capacities of the batteries 17 to 20 were almost equal at about 20 μAh in any of the batteries. After storage for 30 days in a high humidity state, the battery 17 could not be discharged, and the battery 19 had a reduced capacity. In the batteries 18 and 20, the discharge capacity after storage was almost the same as the initial discharge capacity.

When the battery 17 is exposed to a humid atmosphere during storage, a liquid film of water is generated on the battery surface (that is, the surface of the laminate). The formation of this liquid film of water causes ionization of Ag, which is a current collector, and migration of Ag ions, causing a short circuit, which is considered impossible to discharge after 30 days of storage.
In the battery 19, as described above, although not as much as the battery 17, the capacity was reduced. Since the resin mold alone has poor sealing performance, moist air enters the resin. As a result, the ionization of Ag as the current collector and the migration of Ag ions occur, causing a short circuit, which is considered to have reduced the capacity.

  On the other hand, in the battery 18 and the battery 20, the discharge capacity was maintained even after being stored for 30 days in a humid state. From this, in the battery 18, it is possible to block wet air by using a container having a good hermeticity, and in the battery 20, by applying a water repellent to the surface of the battery (laminate), the battery surface It was confirmed that the formation of a liquid film was suppressed.

  As described above, by storing the battery (laminate) in a highly sealed container or by performing water-repellent treatment on the surface of the battery (laminate), the handling of the battery is improved and the humidity of the outside air is reduced. The influence can be reduced.

<< Example 1-7 >>
In this example, an all-solid lithium secondary battery including a second laminate including two or more pairs including a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer was produced.
(Battery 21)
First, a solid electrolyte powder represented by Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , a positive electrode active material powder represented by LiCo _0.5 Ni _0.5 PO ₄ , and Li ₃ Fe ₂ (PO ₄ ) ₃ The negative electrode active material powder represented was prepared.
A solid electrolyte layer slurry is prepared by adding polyvinyl butyral resin as a binder, n-butyl acetate as a solvent, and dibutyl phthalate as a plasticizer, and mixing with a zirconia ball in a ball mill for 24 hours. did.
The positive electrode active material layer forming slurry and the negative electrode active material layer forming slurry were also prepared in the same manner as when the solid electrolyte layer forming slurry was prepared.

  Next, the slurry for solid electrolyte layer formation was apply | coated using the doctor blade on the carrier film 60 which has a polyester resin as a main component. Thereafter, the applied slurry was dried to obtain a solid electrolyte green sheet 61 (thickness: 10 μm) as shown in FIG. Note that a release agent layer containing Si as a main component is formed on the surface of the carrier film 60.

On another carrier film 60, a row 63 in which five positive electrode active material green sheets 62 are linearly arranged as shown in FIG. 41 is arranged in a zigzag pattern by screen printing the positive electrode active material layer forming slurry. The coated pattern was applied and dried to obtain a plurality of positive green sheets arranged in a predetermined pattern. Here, the thickness of the positive electrode active material green sheet was 3 μm. The width X ₁ of the positive electrode active material green sheet was 1.5 mm, and the length X ₂ of the positive electrode active material green sheet was 6.8 mm. The spacing Y ₁ between the positive electrode active material green sheets in each row was 0.4 mm, and the spacing Y ₂ between each row was 0.3 mm.

  Next, when a gold paste using a commercially available polyvinyl butyral resin as a binder is produced, and this gold paste is screen-printed on the carrier film 60 to produce a positive electrode active material green sheet as shown in FIG. The positive electrode current collector green sheet 64 (thickness: 1 μm) was produced by applying and drying in the same pattern as in FIG.

A negative electrode active material layer forming slurry is formed on the carrier film 60 by screen printing, and a row of five negative electrode active material green sheets 65 arranged in a straight line as shown in FIG. In the case, it was applied in a pattern in which the zigzag bulge direction was reversed. Here, the thickness of the negative electrode active material green sheet was 5 μm. Further, the width X _{1 of} the negative electrode active material green sheet, the length X ₂ of the negative electrode active material green sheet, the interval Y ₁ between the negative electrode active material green sheets in each row, and the interval Y ₂ between each row are expressed as positive electrode active material green Same as sheet.

  Next, the gold paste is applied onto the carrier film 60 by screen printing, as shown in FIG. 44, and applied in the same pattern as when the negative electrode active material green sheet was prepared, dried, and negative electrode current collector A body green sheet 66 (thickness: 1 μm) was produced.

  Next, a polyester film 68 with an adhesive on both sides thereof was pasted on the support base 67. Next, as shown in FIG. 45, the surface of the solid electrolyte green sheet 61 that is not in contact with the carrier film 60 was placed on the polyester film 68.

Next, a temperature of 70 ° C. was applied from above the carrier film 60 while applying a pressure of 80 kg / cm ² , and the carrier film 60 was peeled from the solid electrolyte green sheet 61 as shown in FIG.

Next, on the solid electrolyte green sheet 61, the solid electrolyte green sheet 61 ′ formed on another carrier film 60 ′ produced as described above was placed. Next, by applying pressure and temperature from above the carrier film 60 ′, the carrier film 60 ′ was peeled from the green sheet 61 ′ while bonding the green sheets 61 and 61 ′.
This operation was repeated 20 times to produce a solid electrolyte green sheet group 69 (thickness: about 200 μm) as shown in FIG.

Next, as shown in FIG. 48, on the solid electrolyte green sheet 61 formed on the carrier sheet 60, a plurality of negative electrode active material green sheets 65 formed on the carrier film 60 manufactured as described above are provided. The negative electrode active material green sheet 65 was placed in contact with the solid electrolyte green sheet 61. Next, the carrier film 60 was peeled from the negative electrode active material green sheet 65 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from the carrier film 60 carrying a plurality of negative electrode active material green sheets.

Next, a plurality of negative electrode current collector green sheets 66 supported on the carrier sheet 60 were laminated on the negative electrode active material green sheets so as to overlap the negative electrode active material green sheets 65. The carrier film 60 was peeled from the negative electrode current collector green sheet 66 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from the carrier film 60 carrying the plurality of negative electrode current collector green sheets 66. Furthermore, the negative electrode active material green sheet 65 was laminated on the negative electrode current collector green sheet 66 in the same manner as described above to obtain a laminate as shown in FIG. Here, a laminate including a solid electrolyte green sheet 61 and a plurality of two negative electrode active material green sheets carried thereon and a negative electrode current collector green sheet sandwiched between the two green sheets. Was used as a negative electrode laminate 70.

Next, as shown in FIG. 50, on the solid electrolyte green sheet 61 formed on the carrier sheet 60, a plurality of positive electrode active material green sheets 62 formed on the carrier film 60 manufactured as described above are provided. The positive electrode active material green sheet 62 was placed in contact with the solid electrolyte green sheet 61. Next, the carrier film 60 was peeled from the positive electrode active material green sheet 62 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from the carrier film 60 carrying a plurality of positive electrode active material green sheets.

Next, a plurality of positive electrode current collector green sheets 64 supported on the carrier sheet 60 were laminated on the positive electrode active material green sheet 62 so as to overlap the positive electrode active material green sheet. The carrier film 60 was peeled from the positive electrode current collector green sheet 64 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from the carrier film 60 carrying the positive electrode current collector green sheet 64 group. Furthermore, the positive electrode active material green sheet 62 was laminated on the positive electrode current collector green sheet 64 in the same manner as described above to obtain a laminate as shown in FIG. Here, a laminate including a solid electrolyte green sheet 61 and a plurality of two positive electrode active material green sheets carried thereon and a positive electrode current collector green sheet sandwiched between the two green sheets. Was used as the positive electrode laminate 71.

Next, as shown in FIG. 52, the negative electrode laminate 70 was placed on the solid electrolyte green sheet group 69 installed on the support base 67. The carrier film 60 was peeled from the negative electrode laminate 70 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from above the carrier film 60. In this way, the negative electrode laminate 70 was laminated on the solid electrolyte green sheet group 69 so that the negative electrode active material green sheet was in contact therewith.

Similarly, the positive electrode laminate 71 was placed on the negative electrode laminate 70 so that the positive electrode active material green sheet of the positive electrode laminate 71 was in contact with the solid electrolyte green sheet of the negative electrode laminate 70. The carrier film 60 was peeled from the positive electrode laminate 71 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from above the carrier film 60. In this way, the positive electrode laminate 71 was laminated on the negative electrode laminate 70. When the negative electrode laminate and the positive electrode laminate are laminated, the zigzag pattern is opposite between the line in which the negative electrode active material green sheets are arranged in a straight line and the line in which the positive electrode active material green sheets are arranged in a straight line I made it.

  The above operation was repeated to obtain a laminate 72 composed of a solid electrolyte green sheet group, a five-layer negative electrode laminate, and a four-layer positive electrode laminate as shown in FIG. In the stacking direction of the stack 72, a negative electrode stack is disposed at the end opposite to the solid electrolyte green sheet group side.

  Finally, 20 layers of the solid electrolyte green sheets were laminated on the negative electrode laminate on the opposite side of the solid electrolyte green sheet group side of the laminate 72 to obtain a laminate sheet. Thereafter, the laminated sheet was peeled from the support base 67 provided with the polyester film 68.

The obtained laminated sheet was cut to obtain a green chip 73. The obtained green chip is shown in FIGS. Here, FIG. 54 is a top view of the green chip 73. FIG. 55 is a longitudinal sectional view taken along line XX. FIG. 56 is a longitudinal sectional view taken along line YY.
As shown in FIG. 56, in the obtained green chip 73, a plurality of sets including a positive electrode active material green sheet 74, a solid electrolyte green sheet 75, and a negative electrode active material green sheet 76 are stacked. By sintering such a green chip, a laminate including at least one set in which the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are integrated can be obtained. Note that the number of integrated sets can be adjusted by changing the number of stacked positive electrode laminates, solid electrolyte green sheets, and negative electrode laminates.

Further, the green chip obtained in this example has a hexahedron shape, and as shown in FIG. 55, a negative electrode active material green sheet 76 and a negative electrode current collector green sheet are formed on one surface of the hexahedron. One end of 78 is exposed. One surface of the positive electrode active material green sheet 74 and the positive electrode current collector green sheet 77 is exposed on the surface opposite to this surface. That is, by using the manufacturing method as described above, the positive electrode current collector and the negative electrode current collector can be exposed to different regions on the surface of the laminate. Further, the positive electrode current collector and the negative electrode current collector may be exposed to different regions on the surface of the laminate using a method other than the above.
In the present embodiment, the surfaces other than these two are covered with a solid electrolyte layer.

  Next, the obtained green chip is heated to 400 ° C. at a temperature increase rate of 400 ° C./h in the air and held at 400 ° C. for 5 hours to sufficiently thermally decompose the organic substances such as the binder and the plasticizer. I let you. Then, it heated up to 900 degreeC with the temperature increase rate of 400 degreeC / h, and then cooled to room temperature rapidly with the cooling rate of 400 degreeC / h. In this way, the green chip was sintered to obtain a sintered body (second laminate). The dimensions of the obtained sintered body were about 3.2 mm in width, about 1.6 mm in depth, and about 0.45 mm in height.

Here, the filling rate of the sintered body was determined in the same manner as in Example 1-2, assuming that all of the sintered body was Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ . As a result, the filling factor of the sintered body was about 83%.

  Further, when the polished cross section of the sintered body was observed by SEM, the thicknesses of the positive electrode current collector and the negative electrode current collector were each about 0.3 μm. The thickness of the positive electrode active material layer supported on one side of the positive electrode current collector was about 1 μm, and the thickness of the negative electrode active material layer supported on one side of the negative electrode current collector was about 2 μm. . Further, it was confirmed that the sintered body was densely sintered with almost no pores.

  An external current collector paste containing copper and glass frit was applied to each of the positive electrode current collector exposed surface 80 and the negative electrode current collector exposed surface 81 of the obtained sintered body 79. Thereafter, the sintered body coated with the external current collector paste is heat-treated at 600 ° C. for 1 hour in a nitrogen atmosphere, so that the positive electrode external current collector 82 and the negative electrode external current collector as shown in FIG. A body 83 was formed. In this way, an all-solid lithium secondary battery was produced. The obtained battery was designated as battery 21.

(Battery 22)
A battery 22 was produced in the same manner as the battery 21 except that LiMnPO ₄ was used instead of LiCo _0.5 Ni _0.5 PO ₄ .

(Battery 23)
A battery 23 was produced in the same manner as the battery 21 except that FePO ₄ was used instead of Li ₃ Fe ₂ (PO ₄ ) ₃ .

(Battery 24)
A battery 24 was produced in the same manner as the battery 21 except that LiFeP ₂ O ₇ was used instead of Li ₃ Fe ₂ (PO ₄ ) ₃ .

(Comparative battery 8)
Except that LiCoO ₂ was used instead of LiCo _0.5 Ni _0.5 PO ₄ and Li ₄ Ti ₅ O ₁₂ was used instead of Li ₃ Fe ₂ (PO ₄ ) ₃ , the same method as that for producing the battery 21 was used. Thus, a comparative battery 8 was produced.

(Battery 25)
A battery 25 was produced in the same manner as the battery 21 except that Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ was used instead of Li ₃ Fe ₂ (PO ₄ ) ₃ .

(Battery 26)
Solid electrolyte powder represented by Li _1.3 Al _0.3 Ti _0.7 (PO ₄ ) ₃ , positive electrode active material powder represented by LiCo _0.5 Ni _0.5 PO ₄ , negative electrode active represented by Li ₃ Fe ₂ (PO ₄ ) ₃ Material powder was prepared.
To the solid electrolyte powder, a polyvinyl butyral resin as a binder, n-butyl acetate as a solvent, and dibutyl phthalate as a plasticizer are added and mixed with a zirconia ball in a ball mill for 24 hours to obtain a slurry for forming a solid electrolyte layer. Produced.

Polyvinyl butyral resin, n-butyl acetate, dibutyl phthalate, and palladium powder were added to the positive electrode active material powder, and mixed with a zirconia ball in a ball mill for 24 hours to prepare a slurry for forming a positive electrode active material layer. . Note that the palladium powder functions as a three-dimensional network current collector in the formed positive electrode active material layer.
The negative electrode active material layer forming slurry was prepared in the same manner as in the case of the positive electrode active material layer forming slurry using the above negative electrode active material.

  Using the solid electrolyte layer forming slurry, a solid electrolyte green sheet (thickness: 10 μm) was formed on the carrier film in the same manner as in the case of the battery 21.

  Using the positive electrode active material layer forming slurry, a current collector is included on the solid electrolyte green sheet 61 on the carrier film 60 in a pattern as shown in FIG. A plurality of positive electrode active material green sheets 84 were formed, and a positive electrode sheet 85 including a solid electrolyte green sheet and a positive electrode active material green sheet was produced. The thickness of each positive electrode active material green sheet was 4 μm.

Using the slurry for forming the negative electrode active material layer, as in the case of the battery 21, a current collector is included on the solid electrolyte green sheet 61 on the carrier film 60 in a pattern as shown in FIG. 59. A plurality of negative electrode active material green sheets 86 were formed, and a negative electrode sheet 87 including a solid electrolyte green sheet and a negative electrode active material green sheet was produced. The thickness of each negative electrode active material green sheet was 7 μm.
The width X _{1 of} the positive electrode active material green sheet, the length X ₂ of the positive electrode active material green sheet, the interval Y ₁ between the positive electrode active material green sheets in each column, and the interval Y ₂ between each column are as follows. Same as the case. The same applies to the negative electrode active material green sheet.

  Next, 20 layers of solid electrolyte green sheets are stacked on a support base including a polyester film with an adhesive on both sides in the same manner as in the case of the battery 21, and a group of solid electrolyte green sheets (thickness: about 200 μm).

Next, as shown in FIG. 60, a sheet 87 was placed on the solid electrolyte green sheet group 69 in the same manner as in the case of the battery 21. The carrier film 60 was peeled from the solid electrolyte green sheet 61 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from above the carrier film 60. Thus, the negative electrode sheet 87 was laminated | stacked on the solid electrolyte green sheet group. Similarly, the positive electrode sheet 85 was laminated on the solid electrolyte green sheet of the negative electrode sheet 87 so that the positive electrode active material green sheet of the positive electrode sheet 85 was in contact therewith. Thereafter, the carrier film was peeled from the solid electrolyte green sheet in the same manner as described above.

  By repeating these operations, as shown in FIG. 61, a laminate 88 including five layers of negative electrode sheets 87 and four layers of positive electrode sheets 85 was formed. 20 layers of solid electrolyte green sheets were laminated on the negative electrode sheet 87 on the opposite side of the solid electrolyte green sheet group of the laminate 88 to produce a laminate sheet.

The obtained laminated sheet was cut to obtain a green chip. The obtained green chip is shown in FIGS. Here, FIG. 62 is a top view of the green chip 89. 63 is a longitudinal sectional view of the green chip 89 of FIG. 62 taken along the line XX. 64 is a longitudinal sectional view of the green chip 89 of FIG. 62 taken along line YY.
The green chip 89 is almost the same as the green chip 73 (FIGS. 54 to 56) manufactured by the battery 21 except that the current collector is arranged in a three-dimensional network shape in the active material green sheet. That is, in the green chip 89, a plurality of sets including the positive electrode active material green sheet 90, the solid electrolyte green sheet 91, and the negative electrode active material green sea 92 are stacked. Also, one end of the positive electrode active material green sheet and one end of the negative electrode active material green sheet are exposed in different regions of the surface of the green chip.

  Next, the obtained lean chip is heated up to 400 ° C. at a temperature increase rate of 400 ° C./h in the air and kept at 400 ° C. for 5 hours to sufficiently thermally decompose the organic substances such as the binder and the plasticizer. I let you. Then, it heated up to 900 degreeC with the temperature increase rate of 400 degreeC / h, and then cooled to room temperature rapidly with the cooling rate of 400 degreeC / h. In this way, the green chip was sintered. The dimensions of the obtained sintered body were about 3.2 mm in width, about 1.6 mm in depth, and about 0.45 mm in height.

Here, the filling rate of the sintered body was determined in the same manner as in Example 1-2, assuming that all of the sintered body was Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ . As a result, the filling factor of the sintered body was about 83%.

  Further, when the polished cross section of the sintered body was observed by SEM, the thickness of the positive electrode active material layer was about 2 μm, and the thickness of the negative electrode active material layer was about 4 μm. Further, it was confirmed that the sintered body was densely sintered with almost no pores.

  An external current collector paste containing copper and glass frit was applied to each of the positive electrode current collector exposed surface 94 and the negative electrode current collector exposed surface 95 of the obtained sintered body 93. Thereafter, the sintered body coated with the external current collector paste is heat-treated at 600 ° C. for 1 hour in a nitrogen atmosphere, so that the positive electrode external current collector 96 and the negative electrode external current collector as shown in FIG. Body 97 was formed. In this way, an all-solid lithium secondary battery was produced. The obtained battery was designated as battery 26.

  Using the obtained batteries 21 to 26 and the comparative battery 8, charging and discharging were performed once at a current value of 10 μA in an atmosphere having a dew point of −50 ° C. and an environmental temperature of 25 ° C. Table 8 shows the discharge capacity at that time as the initial discharge capacity. Table 8 also shows the upper limit cut voltage and the lower limit cut voltage.

  The batteries 21 to 26 could be discharged. However, in the comparative battery 8, neither charge nor discharge was possible. From the above results, it can be seen that according to the present invention, an all-solid lithium secondary battery capable of charging and discharging can be produced. Further, the battery capacity can be increased by increasing the number of positive electrode active material layers, solid electrolyte layers, and negative electrode active material layers. For this reason, it is possible to increase the battery capacity by increasing the number of stacked layers.

Next, the surface-treated battery was evaluated.
(Battery 27)
A water-repellent treatment was performed by applying an n-heptane dispersion of a water repellent made of a fluororesin to portions of the battery 21 excluding the positive electrode external current collector 82 and the negative electrode external current collector 83. The battery thus obtained was designated as battery 27.

(Battery 28)
72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% Na ₂ O-3 wt% MgO-4 wt% CaO (softening point 750) is provided on the battery 21 except for the positive electrode external current collector 82 and the negative electrode external current collector 83. C.) was applied. The applied slurry was dried and then heat-treated at 700 ° C. Thereby, as shown in FIG. 66, the portion of the battery 21 excluding the positive electrode external current collector 82 and the negative electrode external current collector 83 was coated with the glass layer 98. The battery thus obtained was designated as battery 28.

(Battery 29)
A transparent soot slurry having a softening point of 750 ° C. represented by (0.3Na ₂ O-0.7CaO) 0.5Al ₂ O ₃ .4.5SiO ₂ was used as a positive electrode external current collector and a negative electrode external current collector of the battery 21. It applied to the part except. The applied slurry was dried and then heat-treated at 700 ° C. Thus, the portion of the battery 21 excluding the positive electrode external current collector and the negative electrode external current collector was coated with the glaze. The battery thus obtained was designated as battery 29.

  Battery 21 and batteries 27 to 29 were stored for 30 days at a constant voltage of 2.2 V in a high-temperature and high-humidity tank having an atmospheric temperature of 60 ° C. and a relative humidity of 90%. Then, those batteries were taken out from the tank and discharged at a constant current of 10 μA, and the discharge capacity was determined. The obtained results are shown in Table 9.

After being stored in a hot and humid state, the battery 21 was hardly discharged. On the other hand, in the batteries 27 to 29, a relatively good discharge capacity was obtained.
In the battery 21, the solid electrolyte in the outermost package of the battery may not be sufficiently sintered and may be porous. Thus, when the outermost solid electrolyte layer is porous, when the battery is held in a humid atmosphere, moisture penetrates into the battery, and the positive electrode current collector made of gold is ionized. The gold moves in the solid electrolyte layer and is reduced by the negative electrode active material layer, and gold is deposited there. When gold is thus precipitated, a short circuit occurs between the positive electrode active material layer and the negative electrode active material layer. For this reason, it is considered that the battery 21 could hardly be discharged.

  In the battery 27 whose surface has been subjected to water repellent treatment, the battery 28 baked with low-melting glass, and the battery 29 baked with glaze, moisture can be prevented from entering the battery from the outside. For this reason, it is considered that an internal short circuit did not occur and a good discharge capacity was obtained.

  As described above, according to this example, it can be seen that a highly reliable all solid lithium secondary battery can be provided even when stored in a high temperature and high humidity atmosphere.

<< Example 1-8 >>
(Battery 30)
First, a solid electrolyte powder represented by Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ and a positive electrode active material powder represented by LiFePO ₄ were prepared.
A solid electrolyte layer slurry is prepared by adding polyvinyl butyral resin as a binder, n-butyl acetate as a solvent, and dibutyl phthalate as a plasticizer, and mixing with a zirconia ball in a ball mill for 24 hours. did.
The positive electrode active material layer forming slurry was also prepared in the same manner as when the solid electrolyte layer forming slurry was prepared.

  Next, a solid electrolyte layer forming slurry was applied onto a carrier film 99 containing a polyester resin as a main component using a doctor blade. Thereafter, the applied slurry was dried to obtain a solid electrolyte green sheet 100 (thickness: 10 μm) as shown in FIG. Note that a release agent layer containing Si as a main component is formed on the surface of the carrier film 99.

On another carrier film 99, a row 102 in which five positive electrode active material green sheets 101 are linearly arranged as shown in FIG. 68 is arranged in a zigzag pattern by screen printing the slurry for forming the positive electrode active material layer. The applied pattern was applied and dried to obtain a plurality of positive electrode active material green sheets 101 arranged in a predetermined pattern. Here, the thickness of the positive electrode active material green sheet was 3 μm. The width X ₁ of the positive electrode active material green sheet was 1.5 mm, and the length X ₂ of the positive electrode active material green sheet was 6.8 mm. The spacing Y ₁ between the positive electrode active material green sheets in each row was 0.4 mm, and the spacing Y ₂ between each row was 0.3 mm.

  Next, when a copper paste using a commercially available polyvinyl butyral resin as a binder is prepared, and this copper paste is screen-printed on the carrier film 99 to produce a positive electrode active material green sheet as shown in FIG. A plurality of positive electrode current collector green sheets 103 (thickness: 1 μm) were produced by applying and drying in the same pattern.

Next, the copper paste is screen-printed on the carrier film 99, as shown in FIG. 70, in a pattern in which the zigzag protruding direction is opposite to that of the positive electrode active material green sheet, It apply | coated and dried and the some negative electrode collector green sheet 104 (thickness: 1 micrometer) was produced. At this time, the width X _{1 of} the negative electrode current collector green sheet, the length X ₂ of the negative electrode current collector green sheet, the interval Y ₁ between the negative electrode current collector green sheets in each row, and the interval Y ₂ between each row are: The same as in the case of the positive electrode active material green sheet.

  Next, a polyester film 106 with an adhesive on both sides thereof was pasted on the support base 105. Next, as shown in FIG. 71, the surface of the solid electrolyte green sheet 100 on the side not in contact with the carrier film 99 was placed on the polyester film 106.

Next, a temperature of 70 ° C. was applied from above the carrier film 99 while applying a pressure of 80 kg / cm ² , and the carrier film 99 was peeled from the solid electrolyte green sheet 100 as shown in FIG.

Next, the solid electrolyte green sheet 100 ′ formed on another carrier film 99 ′ produced as described above was placed on the solid electrolyte green sheet 100. Next, by applying pressure and temperature from above the carrier film 99 ′, the carrier film 99 ′ was peeled from the green sheet 100 ′ while bonding the green sheets 100 and 100 ′.
This operation was repeated 20 times to produce a solid electrolyte green sheet group 107 (thickness: about 200 μm) as shown in FIG.

Next, as shown in FIG. 74, on the solid electrolyte green sheet 100 formed on the carrier sheet 99, a plurality of negative electrode current collector green sheets 104 formed on the carrier film 99 manufactured as described above. The negative electrode current collector green sheet 104 was placed in contact with the solid electrolyte green sheet 100. Next, the carrier film 99 was peeled from the negative electrode current collector green sheet 104 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² on the carrier film 99 carrying a plurality of negative electrode current collector green sheets. In this way, as shown in FIG. 75, a negative electrode / solid electrolyte sheet 108 including the solid electrolyte green sheet 100 and the negative electrode current collector green sheet 104 carried thereon was obtained.

Next, as shown in FIG. 76, on the solid electrolyte green sheet 100 formed on the carrier sheet 99, a plurality of positive electrode active material green sheets 101 formed on the carrier film 99 manufactured as described above are disposed. The positive electrode active material green sheet was placed in contact with the solid electrolyte green sheet. Next, the carrier film 99 was peeled from the positive electrode active material green sheet 101 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² on the carrier film 99 carrying a plurality of positive electrode active material green sheets.

Next, a plurality of positive electrode current collector green sheets 103 supported on a carrier sheet 99 were laminated on the positive electrode active material green sheet 101 so as to overlap the positive electrode active material green sheet 101. The carrier film 99 was peeled from the positive electrode current collector green sheet 103 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² on the carrier film 99 carrying the positive electrode current collector green sheet 103 group. Further, the positive electrode active material green sheet 101 was laminated on the positive electrode current collector green sheet 103 in the same manner as described above to obtain a laminate as shown in FIG. Here, a laminate including the solid electrolyte green sheet 100 and a plurality of positive electrode active material green sheets carried thereon and a positive electrode current collector green sheet sandwiched between the two green sheets. Was used as the positive electrode laminate 109.

Next, as shown in FIG. 78, the negative electrode / solid electrolyte sheet 108 was placed on the solid electrolyte green sheet group 107 installed on the support base 105. The carrier film 99 was peeled from the negative electrode / solid electrolyte sheet 108 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from above the carrier film 99. In this manner, the negative electrode / solid electrolyte sheet 108 was laminated on the solid electrolyte green sheet group so that the negative electrode current collector green sheet 104 was in contact with the solid electrolyte green sheet group 107.

Similarly, the positive electrode laminate 109 was placed on the negative electrode / solid electrolyte sheet 108 so that the solid electrolyte green sheet of the negative electrode / solid electrolyte sheet 108 was in contact with the positive electrode active material green sheet of the positive electrode laminate 109. The carrier film 99 was peeled from the positive electrode laminate 109 by applying a temperature of 70 ° C. while applying a pressure of 80 kg / cm ² from above the carrier film 99. In this way, the positive electrode laminate 109 was laminated on the negative electrode / solid electrolyte sheet 108. When the negative electrode / solid electrolyte sheet and the positive electrode laminate are stacked, the zigzag pattern is opposite to the line in which the negative electrode current collector green sheets are arranged in a straight line and the line in which the positive electrode active material green sheets are arranged in a straight line I tried to become.

  The above operation was repeated to obtain a laminate 110 composed of a solid electrolyte green sheet laminate, a five-layer negative electrode / solid electrolyte sheet, and a four-layer cathode laminate as shown in FIG. Note that, in the stacking direction of the laminate 110, the negative electrode / solid electrolyte sheet 108 is disposed at the end opposite to the solid electrolyte green sheet group side.

  Finally, 20 layers of solid electrolyte green sheets were laminated on the negative electrode / solid electrolyte layer opposite to the solid electrolyte green sheet group side of the laminate 110 to obtain a laminate sheet. Thereafter, the laminated sheet was peeled from the support base 105 provided with the polyester film 106.

  The obtained laminated sheet was cut to obtain a green chip 111. The obtained green chip is shown in FIGS. Here, FIG. 80 is a top view of the green chip 111. FIG. 81 is a longitudinal sectional view taken along line XX. FIG. 82 is a longitudinal sectional view taken along line YY.

  As shown in FIG. 82, in the obtained green chip 111, the positive electrode active material laminate including the positive electrode active material green sheet 101 and the positive electrode current collector green sheet 103, and the negative electrode including the negative electrode current collector green sheet 104 A plurality of cum-solid electrolyte sheets are laminated. By sintering such a green chip, a laminate including at least one set in which the positive electrode active material layer and the negative electrode / solid electrolyte layer are integrated can be obtained. Note that the number of integrated sets can be adjusted by changing the number of stacked positive electrode laminates and negative electrode / solid electrolyte layers.

Further, the green chip obtained in this example has a hexahedron shape, and as shown in FIG. 81, one end of the negative electrode current collector green sheet 104 is formed on one surface of the hexahedron. Exposed. One surface of the positive electrode active material green sheet 101 and the positive electrode current collector green sheet 103 is exposed on the surface opposite to this surface. That is, by using the manufacturing method as described above, the positive electrode current collector and the negative electrode current collector can be exposed to different regions on the surface of the laminate. Further, the positive electrode current collector and the negative electrode current collector may be exposed to different regions on the surface of the laminate using a method other than the above.
In the present embodiment, the surfaces other than these two are covered with a solid electrolyte layer.

The green chip was heat-treated in a sintering furnace in an atmosphere gas composed of a first atmosphere gas and water vapor. A low oxygen partial pressure gas having a composition of CO ₂ / H ₂ / N ₂ = 4.99 / 0.01 / 95 was used as the first atmosphere gas. The volume of water vapor contained in the atmospheric gas was 5%. The flow rate of the atmospheric gas into the furnace was 12 L / min at a temperature of 700 ° C. and 1 atm. Supply of atmospheric gas to the furnace was started when the temperature of the furnace reached 200 ° C.

  The green chip was heated to 700 ° C. at a temperature rising rate of 100 ° C./h and held at 700 ° C. for 5 hours. Then, it heated up to 900 degreeC with the temperature increase rate of 400 degreeC / h, and then cooled to room temperature rapidly with the cooling rate of 400 degreeC / h. The gas supply was stopped when the furnace temperature reached 200 ° C. In this way, the green chip was sintered to obtain a sintered body. The dimensions of the obtained sintered body were about 3.2 mm in width, about 1.6 mm in depth, and about 0.45 mm in height.

  Further, when the polished cross section of the sintered body was observed by SEM, the thicknesses of the positive electrode current collector and the negative electrode current collector were each about 0.3 μm. Moreover, the thickness of the positive electrode active material layer carried on one surface of the positive electrode current collector was about 1 μm. Further, it was confirmed that the sintered body was densely sintered with almost no pores.

  An external current collector paste containing copper and glass frit was applied to each of the positive electrode current collector exposed surface 113 and the negative electrode current collector exposed surface 114 of the obtained sintered body 112. Thereafter, the sintered body coated with the external current collector paste is heat-treated at 600 ° C. for 1 hour in a nitrogen atmosphere, so that the positive electrode external current collector 115 and the negative electrode external current collector as shown in FIG. 83 are obtained. A body 116 was formed. In this way, an all-solid lithium secondary battery was produced. The obtained battery was designated as battery 30.

In the low oxygen partial pressure gas having the composition of CO ₂ / H ₂ / N ₂ = 4.99 / 0.01 / 95 as described above, the following formulas (2) and (3):
CO ₂ → CO + 1 / 2O ₂ (2)
H ₂ + 1 / 2O ₂ → H ₂ O (3)
The following equilibrium reaction occurs. Oxygen is generated by the reaction of the formula (2), and oxygen is consumed by the reaction of the formula (3). Therefore, oxygen exists in the atmospheric gas and its partial pressure is a substantially constant value. Will be maintained.

(Batteries 31-34)
Batteries 31 to 34 were produced in the same manner as the production method of the battery 30 except that the amount of water vapor contained in the mixed gas was 20% by volume, 30% by volume, 50% by volume, or 90% by volume.

(Reference battery 35)
The reference battery was the same as the battery 30 except that a gas having a composition of CO ₂ / H ₂ / N ₂ = 4.99 / 0.01 / 95 was used as the low oxygen partial pressure gas and no water vapor was added. 35 was produced.

(Reference battery 36)
Except that air was used instead of the low oxygen partial pressure gas having a composition of CO ₂ / H ₂ / N ₂ = 4.99 / 0.01 / 95, and the amount of water vapor contained in the atmospheric gas was 30% by volume. A reference battery 36 was produced in the same manner as the battery 30.

(Reference battery 37)
Instead of a low oxygen partial pressure gas having a composition of CO ₂ / H ₂ / N ₂ = 4.99 / 0.01 / 95, high purity argon gas with a purity of 4N is used, and the amount of water vapor contained in the atmospheric gas is 30 volumes. A reference battery 37 was produced in the same manner as the battery 30 except that the percentage was changed to%.

(Reference battery 38)
Instead of a low oxygen partial pressure gas having a composition of CO ₂ / H ₂ / N ₂ = 4.99 / 0.01 / 95, high purity CO ₂ gas with a purity of 4N is used, and the amount of water vapor contained in the atmospheric gas is 30 Except for the volume%, the same as the battery 30. A reference battery 38 was produced.

(Reference battery 39)
Instead of a low oxygen partial pressure gas having a composition of CO ₂ / H ₂ / N ₂ = 4.99 / 0.01 / 95, high purity H ₂ gas with a purity of 4N is used, and the amount of water vapor contained in the atmospheric gas is 30 A reference battery 39 was produced in the same manner as the battery 30 except that the volume% was set.

(Battery 40)
A battery 40 was produced in the same manner as the battery 32 except that LiCoPO ₄ was used as the positive electrode active material.

For the batteries 30 to 34 and the battery 40 and the reference batteries 35 to 39, the filling rate of the sintered body was assumed that all of the sintered body was Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) _3. Obtained in the same manner as -2. Table 10 shows the obtained results. Table 10 also shows the type of the first atmosphere, the amount of water vapor added, and the -log ₁₀ PO ₂ value.

In each of the batteries 30 to 34, the filling rate was relatively good at about 80% regardless of the amount of water vapor. Also in the battery 40, the filling rate was a relatively good value of 85%.
On the other hand, in the reference battery 35 and the reference battery 39, the filling rate was less than 60%, and it was found that the sintering was hardly progressed. In these reference batteries, the sintered body was black. Therefore, in these reference batteries, it is considered that the sintering of the green chip was hindered because the binder and the plasticizer were carbonized by thermal decomposition.
In the reference battery 39, in the atmosphere gas of H ₂ / H ₂ O = ^7/3 , the equilibrium oxygen partial pressure at 700 ° C. is an extremely small amount of about 10 ⁻²² atm. it is conceivable that.
Further, these reference batteries 35 and 39 were fragile and collapsed during handling during application of the external current collector.

In the batteries 30 to 34 and the battery 40, the sintered body was almost white. The equilibrium oxygen partial pressure at 700 ° C. in the atmospheric gas as shown in Table 10 was estimated to be about 10 ⁻¹⁶ atm. In this case, the binder and the plasticizer are reduced in molecular weight by water vapor and quickly discharged out of the system. At the same time, the carbon as a by-product is removed by a small amount of oxygen, and the sintering proceeds. Conceivable.
Moreover, although the filling rate in the reference batteries 36 to 38 was slightly inferior to that of the batteries 30 to 34 and the battery 40, the sintered body was almost white.

  Next, using the batteries 30 to 34 and 40 and the reference batteries 36 to 38, in an atmosphere having a dew point of −50 ° C. and an environmental temperature of 25 ° C., the upper limit cut voltage is 2.0 V, the lower limit cut voltage is 0 V, and a current of 10 μA. The value was charged and discharged once. Moreover, in the battery 40, charge / discharge was performed in the same manner as described above except that the upper limit cut voltage was 5.0V and the lower limit cut voltage was 0V. Table 11 shows the discharge capacity at that time as the initial discharge capacity.

In the batteries 30 to 34, an initial discharge capacity exceeding 6 μAh was obtained. For the battery 40, an initial discharge capacity of 2.8 μAh was obtained. On the other hand, the reference batteries 36 to 38 could hardly be charged / discharged. In particular, in the reference battery 36, since firing was performed in an air atmosphere, LiFePO ₄ was changed to a Fe (III) compound such as Li ₃ Fe ₂ (PO ₄ ) ₃ and Cu as a current collector material was oxidized. It is thought that charging / discharging was impossible because the current collector did not function.

On the other hand, in the atmospheric gas for producing the reference batteries 37 to 38, the equilibrium oxygen partial pressure at 700 ° C. is estimated to be about 10 ⁻⁷ atm. For this reason, it is considered that LiFePO ₄ was changed to a Fe (III) compound such as Li ₃ Fe ₂ (PO ₄ ) ₃ and hardly discharged.

Here, it is calculated from the equation (1), the equilibrium oxygen partial pressure at 700 ° C. is 10 ^-11.8 atm 10 ^-17.1 atm. In the batteries 30 to 34 in which the equilibrium oxygen partial pressure falls within the above range, the binder and the plasticizer are thermally decomposed while the oxidation of the current collector and the oxidation of Fe (II) as the active material to Fe (III) are suppressed. It can be seen that the carbon produced during the removal is removed by oxygen. For this reason, it is considered that an all-solid lithium secondary battery having a good charge / discharge capacity can be produced by appropriately adjusting the oxygen partial pressure.

At this time, the low oxygen partial pressure gas is composed of a gas capable of releasing oxygen, such as CO ₂ , and H ₂ so that the oxygen partial pressure contained in the low oxygen partial pressure gas atmosphere is maintained constant. It is preferable to include a mixture of a gas that reacts with oxygen.

<< Example 2-1 >>
Next, the following batteries and comparative batteries were prepared, charged and discharged under predetermined conditions, and their discharge capacities were determined.
(Battery 2-1)
Amorphous oxide powder represented by 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% Na ₂ O-3 wt% MgO-4 wt% CaO having a softening point of 750 ° C. in the slurry for forming the solid electrolyte layer Were mixed so that the weight ratio of the solid electrolyte powder to the amorphous oxide powder was 97: 3. In addition, the maximum temperature of green chip sintering was changed from 900 ° C to 700 ° C. A battery 2-1 was produced in the same manner as the battery 7 except for these.
Although the positive electrode active material is most easily sintered and the solid electrolyte layer is most difficult to sinter, the easiness of sintering between the positive electrode active material and the negative electrode active material is not significantly changed. For this reason, in this embodiment, an amorphous oxide is added only to the solid electrolyte layer.

In addition, since the positive electrode active material layer and the negative electrode active material layer are sufficiently thin as compared with the solid electrolyte layer as in Example 1-2, all of the sintered chips are Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) Assuming that ₃ , the filling rate of the green chip after sintering was determined. As a result, the filling rate was about 73%. Here, the filling rate of the chip was determined by [{(chip weight) / (chip volume)} / (X-ray density of solid electrolyte)] × 100.

  Further, regarding the positive electrode active material layer and the negative electrode active material layer, the polished cross-section of the green chip after sintering was observed with an SEM. The positive electrode active material layer and the negative electrode active material layer had a thickness of about 1 μm, and It was confirmed that the positive electrode active material layer and the negative electrode active material layer had almost no voids and were sintered densely.

(Battery 2-2)
When performing the sintering, instead of increasing the temperature to 700 ° C. at a temperature increase rate of 400 ° C./h, the battery 2-1 was prepared except that the temperature was increased to 800 ° C. at a temperature increase temperature of 400 ° C./h. An all-solid battery was produced in the same manner as the method. The obtained battery was designated as battery 2-2. The filling rate of the green chips after sintering was 93% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 2-3)
When performing sintering, instead of increasing the temperature to 700 ° C. at a temperature increase temperature of 400 ° C./h, the battery 2-1 was manufactured except that the temperature was increased to 900 ° C. at a temperature increase temperature of 400 ° C./h. An all-solid battery was produced in the same manner as the method. The obtained battery was designated as battery 2-3. The filling rate of the green chips after sintering was 95% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 2-4)
When performing sintering, instead of increasing the temperature to 700 ° C. at a temperature increase temperature of 400 ° C./h, the battery 2-1 was manufactured except that the temperature was increased to 1000 ° C. at a temperature increase temperature of 400 ° C./h. An all-solid battery was produced in the same manner as the method. The obtained battery was designated as battery 2-4. The filling rate of the green chips after sintering was 95% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 2-5)
When preparing the slurry for forming the solid electrolyte layer, Li ₄ P ₂ O ₇ was added as an amorphous oxide. Moreover, when performing sintering, it heated up to 800 degreeC with the temperature rising temperature of 400 degreeC / h instead of making it heat up to 700 degreeC with the temperature rising temperature of 400 degreeC / h. A battery 2-5 was produced in the same manner as the battery 2-1, except for these. The filling rate of the green chips after sintering was 93% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Comparative battery 2-1)
The battery 2-1 was manufactured except that the temperature was raised to 700 ° C. at 400 ° C./h instead of raising the temperature to 700 ° C. at 400 ° C./h when the sintering was performed. Comparative battery 2-1 was produced in the same manner as the method. The filling factor of the green chips after sintering was 57% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Comparative battery 2-2)
Production of battery 2-1 was performed except that the temperature was raised to 1100 ° C. at 400 ° C./h instead of raising the temperature to 700 ° C. at 400 ° C./h when the sintering was performed. Comparative battery 2-2 was fabricated in the same manner as the method. The filling rate of the green chips after sintering was 93% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Comparative battery 2-3)
No amorphous oxide was added when preparing the slurry for forming the solid electrolyte layer. Moreover, when performing sintering, it heated up to 800 degreeC with the temperature rising temperature of 400 degreeC / h instead of making it heat up to 700 degreeC with the temperature rising temperature of 400 degreeC / h. A comparative battery 2-3 was fabricated in the same manner as the battery 2-1, except for these. The filling rate of the green chips after sintering was 55% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 2-6)
When performing the sintering, instead of increasing the temperature to 800 ° C. at a temperature increase temperature of 400 ° C./h, the temperature was increased to 900 ° C. at a temperature increase temperature of 400 ° C./h. A battery 2-6 was made in the same manner as the comparative battery 2-3, except for this. The filling rate of the green chips after sintering was 83% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 2-7)
When performing the sintering, instead of increasing the temperature to 800 ° C. at a temperature increase temperature of 400 ° C./h, the temperature was increased to 1000 ° C. at a temperature increase temperature of 400 ° C./h. A battery 2-7 was produced in the same manner as the comparative battery 2-3, except for this. The filling rate of the green chips after sintering was 87% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

  Using batteries 2-1 to 2-7 and comparative batteries 2-1 to 2-3 produced as described above, a range of 2.3 V to 1.0 V in an atmosphere having a dew point of −50 ° C. and a temperature of 25 ° C. Then, charging / discharging was performed once at a current value of 10 μA. Table 12 shows the discharge capacity at that time. Moreover, the impedance at 1 kHz was measured about the battery after charging / discharging. The results obtained are shown in Table 12.

The discharge capacity was 0 in comparative batteries 2-1 to 2-3. Moreover, in the comparative batteries 2-1 to 2-3, the impedance was very large. This is presumably because the sintering of the solid electrolyte did not proceed and the lithium ion conductivity became very small. In particular, the impedance after charging / discharging of the comparative battery 2-2 was outside the measurement range (10 ⁷ Ω or more). This is considered that the lithium ion conductivity was lost because the solid electrolyte could not withstand high temperature and was modified.
On the other hand, the batteries 2-1 to 2-5 according to the present invention all obtained a relatively good discharge capacity and low impedance.

Further, from the comparison between the batteries 2-1 to 2-4 and the comparative batteries 2-1 to 2-2, since the sintering temperature was 700 ° C. or higher and 1000 ° C. or lower, charging / discharging was possible. Clearly the range is desirable.
In addition, in comparison between the batteries 2-1 to 2-4, the comparative battery 2-3, and the batteries 2-6 to 2-7, the addition of the sintering aid has a lower impedance, It is clear that it is excellent.
<< Example 2-2 >>

Next, the amount of sintering aid added was examined.
(Battery 2-8)
When preparing a slurry for forming a solid electrolyte layer, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ as a solid electrolyte and 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% as an amorphous oxide Na ₂ O-3 wt% MgO-4 wt% CaO was mixed at a weight ratio of 99.9: 0.1. A battery 2-8 was produced in the same manner as the battery 2-2 (sintering temperature: 800 ° C.), except for this. The filling rate of the green chips after sintering was 72% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 2-9)
When preparing a slurry for forming a solid electrolyte layer, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ as a solid electrolyte and 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% as an amorphous oxide Na ₂ O-3 wt% MgO-4 wt% CaO was mixed at a weight ratio of 99: 1. A battery 2-9 was produced in the same manner as the battery 2-2 (sintering temperature: 800 ° C.), except for this. The filling factor of the green chips after sintering was 89% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 2-10)
When preparing a slurry for forming a solid electrolyte layer, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ as a solid electrolyte and 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% as an amorphous oxide Na ₂ O-3 wt% MgO-4 wt% CaO was mixed at a weight ratio of 95: 5. A battery 2-10 was produced in the same manner as the battery 2-2 (sintering temperature: 800 ° C.), except for this. The filling rate of the green chips after sintering was 94% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 2-11)
When preparing a slurry for forming a solid electrolyte layer, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ as a solid electrolyte and 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% as an amorphous oxide A battery 2-11 was prepared in the same manner as the production method of the battery 2-2 (sintering temperature: 800 ° C.) except that Na ₂ O-3 wt% MgO-4 wt% CaO was mixed at a weight ratio of 90:10. Was made. The filling rate of the green chips after sintering was 94% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Comparative battery 2-4)
When preparing a slurry for forming a solid electrolyte layer, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ as a solid electrolyte and 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% as an amorphous oxide Na ₂ O-3 wt% MgO-4 wt% CaO was mixed at a weight ratio of 99.95: 0.05. Except for this, a comparative battery 2-4 was produced in the same manner as the production method of the battery 2-2 (sintering temperature: 800 ° C.). The filling factor of the green chips after sintering was 57% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Battery 2-12)
When preparing a slurry for forming a solid electrolyte layer, Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ as a solid electrolyte and 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% as an amorphous oxide Na ₂ O-3 wt% MgO-4 wt% CaO was mixed at a weight ratio of 85:15. A battery 2-12 was produced in the same manner as the battery 2-2 (sintering temperature: 800 ° C.), except for this. The filling rate of the green chips after sintering was 93% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

  Using the batteries 2-8 to 2-12 and the comparative battery 2-4 produced as described above, the discharge capacity and the impedance at 1 kHz were measured in the same manner as in Example 2-1. The obtained results are shown in Table 13. For reference, the results for battery 2-2 and comparative battery 2-3 are also shown.

  The comparative battery 2-4 had a discharge capacity of 0. In Comparative Battery 2-4, since the amount of the sintering aid added was too small, it was considered that the sintering did not proceed and the impedance was increased. On the other hand, in the battery 2-12, since the addition amount is too large, it is considered that the ionic conductivity in the solid electrolyte layer is lowered and the impedance is increased.

  From the above results, the sintering aid to be added preferably occupies 0.1 to 10% by weight of the layer to be added.

<< Example 2-3 >>
Next, the kind of sintering aid added to the solid electrolyte layer and the softening point of the sintering aid were examined.
(Battery 2-13)
_{72wt% SiO 2 -1wt% Al 2} O 3 -20wt% Na 2 instead of O-3wt% MgO-4wt% CaO, 80wt% SiO 2 -14wt% B 2 O 3 -2wt% Al 2 O 3 -3. An amorphous oxide represented by 6 wt% Na ₂ O-0.4 wt% K ₂ O was used. A battery 2-10 was produced in the same manner as the battery 2-2, except for this. The filling rate of the green chips after sintering was 91% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Comparative battery 2-5)
Instead of 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ -20 wt% Na ₂ O-3 wt% MgO-4 wt% CaO, Al ₂ O ₃ powder was used. A comparative battery 2-5 was produced in the same manner as the battery 2-2, except for this. The filling rate of the green chips after sintering was 55% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Comparative battery 2-6)
72 wt% SiO ₂ −1 wt% Al ₂ O ₃ −20 wt% Na ₂ O −3 wt% MgO −4 wt% CaO instead of 72 wt% SiO ₂ −1 wt% Al ₂ O ₃ −14 wt% Na with a softening point of 600 ° C. ₂ O-3 wt% MgO-10 wt% CaO powder was used. A comparative battery 2-6 was produced in the same manner as the battery 2-2, except for this. The filling factor of the green chips after sintering was 97% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

(Comparative battery 2-7)
Instead of _{72wt% SiO 2 -1wt% Al 2} O 3 -20wt% Na 2 O-3wt% MgO-4wt% CaO, 62wt% SiO 2 having a softening point of _{1020 ℃ -15wt% Al 2 O 3} -8wt% CaO -15 wt% BaO powder was used. A comparative battery 2-7 was produced in the same manner as the battery 2-2, except for this. The filling rate of the green chips after sintering was 58% when all the green chips were assumed to be Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ .

  Using the battery 2-13 and comparative batteries 2-5 to 2-7 produced as described above, the discharge capacity and the impedance at 1 kHz were measured in the same manner as in Example 2-1. The obtained results are shown in Table 14. For reference, the results for the battery 2-2 are also shown.

The discharge capacity and impedance of the battery 2-13 were almost the same as the discharge capacity and impedance of the battery 2-2.
On the other hand, in Comparative Battery 2-5 using Al ₂ O ₃ which is generally used as a sintering aid, the discharge capacity was 0. This is presumably because sintering of the laminate did not proceed during sintering. In other words, in the system using Al ₂ O ₃ , since Al ₂ O ₃ reacts with Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) _{3 which} is a solid electrolyte and an impurity phase is generated in the solid solid electrolyte layer, It is thought that the causality decreased.

  Further, the comparative battery 2-6 to which an amorphous oxide having a softening point of 600 ° C. was added also had a discharge capacity of 0. This is because the sintering reaction proceeds and the diffusion of the active material and the solid electrolyte It is considered that charging / discharging became impossible due to the progress of.

  In Comparative Battery 2-7 to which an amorphous oxide having a softening point of 1020 ° C. was added, the discharge capacity was 0, but this was considered because the softening point of the additive was too high and did not contribute to sintering. It is done.

  From the above results, by adding an amorphous oxide having a softening point of 700 ° C. or more and 950 ° C. or less to at least one of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer, good charge / discharge performance is achieved. It was shown that an all-solid-state battery showing the above can be produced.

<< Example 2-4 >>
A comparative battery 2-3, a comparative battery 2-4, a battery 2-8, a battery 2-9, and a battery 2-2 are provided except that the negative electrode active material layer is not provided and the maximum sintering temperature is 800 ° C. The laminated body which consists of a positive electrode active material layer and a solid electrolyte layer was obtained like the manufacturing method of the battery 2-10, the battery 2-11, or the battery 2-12. The obtained laminates were respectively referred to as comparative laminate 2-3, comparative laminate 2-4, laminate 2-8, laminate 2-9, laminate 2-2, laminate 2-10, and laminate 2. −11 and laminate 2-12. The amount of warpage of these laminates was examined. Here, the amount of warpage is the vertical distance from the upper side of the end face of the laminate to the positive electrode active material layer side when the laminate is placed on a predetermined flat plate with the positive electrode active material layer facing up. Say. In addition, the thickness of the green chip | tip before sintering of these laminated bodies is about 500 micrometers, The size is 7 mm x 7 mm.
Table 15 shows simultaneously the amount of amorphous oxide added to the solid electrolyte layer forming green sheet and the maximum sintering temperature.

  From Table 15, it can be seen that the greater the amount of amorphous oxide added, the smaller the warp of the laminate. Therefore, in order to suppress warpage, the amount of amorphous oxide added is preferably 0.1% by weight or more.

<< Example 3-1 >>
(Battery 3-1)
When producing the positive electrode current collector green sheet and the negative electrode current collector green sheet, a palladium paste was used instead of the gold paste. The amount of palladium was 25% by weight of this paste. The thickness of the positive electrode current collector green sheet and the negative electrode current collector green sheet was 10 μm, respectively. Further, the maximum temperature when the green chip was sintered was changed from 900 ° C. to 950 ° C. A battery 3-1 was produced in the same manner as the production method of the battery 21 except for these.

The sintered body obtained by sintering the green chip had a width of about 3.2 mm, a depth of about 1.6 mm, and a height of about 0.45 mm. As in Example 1-2, assuming that all the sintered bodies were Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ , the filling rate of the sintered bodies was determined. As a result, the filling rate was about 85%.
Further, when the polished cross section of the sintered body was observed by SEM, the thicknesses of the positive electrode active material layer and the negative electrode active material layer were about 1 μm and about 2 μm, respectively. The thickness of the negative electrode current collector in each of the positive electrode current collector layer and the negative electrode active material layer disposed in the positive electrode active material layer was about 4 μm.

The porosity of the positive electrode current collector layer and the negative electrode current collector layer can be determined, for example, as follows.
In the positive electrode current collector green sheet or the negative electrode current collector green sheet, the weight of palladium per unit area is obtained. When sintered, the current collector green sheet shrinks. The palladium weight per unit area after shrinkage is calculated using the palladium weight per unit area of the green sheet. Next, the apparent thickness of the current collector layer after sintering is measured by SEM. Thus, the volume of the current collector layer and the amount of palladium contained therein can be determined. Using these values, the porosity of the current collector layer can be determined. In the following examples, the porosity was thus determined.
As a result, the porosity of the positive electrode current collector layer and the negative electrode current collector layer was 50%, respectively.

(Battery 3-2)
A battery 3-2 was produced in the same manner as the battery 3-1, except that the amount of palladium in the palladium paste was 65% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 20%, respectively.

(Battery 3-3)
A battery 3-3 was produced in the same manner as the battery 3-1, except that the amount of palladium in the palladium paste was 20% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 60%.

(Battery 3-4)
A comparative battery 3-1 was produced in the same manner as the battery 3-1, except that the amount of palladium in the palladium paste was 70% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 15%, respectively.

(Battery 3-5)
A comparative battery 3-2 was produced in the same manner as the battery 3-1, except that the amount of palladium in the palladium paste was 10% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 70%.

For batteries 3-1 to 3-5, 10 cells each were subjected to constant current charging and discharging once at a current value of 10 μA in an atmosphere with a dew point of −50 ° C. and a temperature of 25 ° C. At this time, the upper limit cut voltage was 2.2 V, and the lower limit cut voltage was 1.0 V.
For each battery, Table 16 shows the initial discharge capacity of the cells that could be charged and discharged without being damaged, and the number of cells in which structural defects occurred.

  The batteries 3-1 to 3-3 could be charged / discharged. On the other hand, the batteries 3-4 and 3-5 could be charged / discharged. The initial discharge capacity of the battery 3-5 was reduced as compared with other batteries. Note that the battery capacity can be increased by increasing the number of stacked layers.

  Regarding the battery 3-4, cracks and delamination were observed in the four cells. For cells in which they were observed, a sufficient discharge capacity could not be obtained.

Batteries 3-1 to 3-3 have a current collector porosity of 20 to 60%, and are considered to play a role in mitigating volume fluctuations associated with charge and discharge of the active material. In contrast, in the battery 3-4 in which the porosity of the current collector is 15%, the volume change of the active material due to insertion and extraction of lithium ions cannot be reduced, and it is considered that the number of batteries that are damaged increased.
Moreover, in the battery 3-5 in which the porosity of the current collector was 70%, the battery was not damaged, but the capacity dropped to about 60 to 70%. Such a decrease in capacity is considered to be due to a decrease in the current collecting property of the current collector. Therefore, the porosity of the positive electrode current collector layer and the negative electrode current collector layer is preferably 20 to 60%.

  As described above, by setting the porosity of the current collector layer to 20 to 60%, it is possible to suppress delamination caused by expansion and contraction of the active material that occurs during charging and discharging, and cracks in the stacked all-solid battery, It can be seen that a highly reliable stacked all-solid lithium secondary battery can be manufactured.

<< Example 3-2 >>
In this example, it was examined that the porosity of the current collector affects the discharge capacity and structural defects even when other active material is used.
(Battery 3-6)
Instead of LiCoPO _4, except for the use of LiMnPO ₄ as a positive electrode active material was obtained in the same manner as the battery 3-1, the battery was fabricated 3-6.

(Battery 3-7)
LiFePO ₄ was used as the positive electrode active material instead of LiCoPO ₄ . Further, the green chip was fired in an atmospheric gas containing CO ₂ and H ₂ with the oxygen partial pressure controlled to a predetermined value. The binder contained in the green chip was decomposed by maintaining at 600 ° C. for 5 hours. In this atmosphere gas, the mixing ratio of CO ₂ and H ₂ was 10 ³ : 1.
A battery 3-7 was produced in the same manner as the battery 3-1, except for the above.

(Battery 3-8)
Instead of LiCoPO ₄ , LiMn _0.7 Fe _0.3 PO ₄ was used as the positive electrode active material. Further, the green chip was fired in an atmospheric gas containing CO ₂ and H ₂ with the oxygen partial pressure controlled to a predetermined value. The binder contained in the green chip was decomposed by maintaining at 600 ° C. for 5 hours. In this atmosphere gas, the mixing ratio of CO ₂ and H ₂ was 10 ³ : 1.
A battery 3-8 was produced in the same manner as the battery 3-1, except for the above.

(Battery 3-9)
A battery 3-9 was produced in the same manner as the battery 3-1, except that FePO ₄ was used as the negative electrode active material instead of Li ₃ Fe ₂ (PO ₄ ) ₃ .

(Battery 3-10)
A battery 3-10 was produced in the same manner as the battery 3-1, except that LiFeP ₂ O ₇ was used as the negative electrode active material instead of Li ₃ Fe ₂ (PO ₄ ) ₃ .

(Battery 3-11)
A battery 3-11 was produced in the same manner as the battery 3-1, except that Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ was used instead of Li ₃ Fe ₂ (PO ₄ ) ₃ .

(Battery 3-12)
A battery 3-12 was produced in the same manner as the battery 3-6, except that the amount of palladium in the palladium paste was 75% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 10%, respectively.

(Battery 3-13)
A battery 3-13 was produced in the same manner as the battery 3-7, except that the amount of palladium in the palladium paste was 75% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 10%, respectively.

(Battery 3-14)
A battery 3-14 was produced in the same manner as the battery 3-8, except that the amount of palladium in the palladium paste was 75% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 10%, respectively.

(Battery 3-15)
A battery 3-15 was produced in the same manner as the battery 3-9, except that the amount of palladium in the palladium paste was 75% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 10%, respectively.

(Battery 3-16)
A battery 3-16 was produced in the same manner as the battery 3-10, except that the amount of palladium in the palladium paste was 75% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 10%, respectively.

(Battery 3-17)
A battery 3-17 was produced in the same manner as the battery 3-11 except that the amount of palladium in the palladium paste was 75% by weight. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 10%, respectively.

  For batteries 3-6 to 3-17, 10 cells each were charged and discharged at a constant current once at a current value of 10 μA in an atmosphere with a dew point of −50 ° C. and a temperature of 25 ° C. Table 17 shows the upper limit cut voltage and lower limit cut voltage of each battery at this time. Table 17 shows the initial discharge capacities of the cells that were able to be charged and discharged without being damaged for each battery. Table 18 shows the number of cells in which structural defects occurred.

  The batteries 3-6 to 3-11 could be charged / discharged. The batteries 3-12 to 3-17 can also be charged / discharged, and the initial discharge capacities thereof substantially coincided with those of the batteries 3-6 to 3-11.

  However, in batteries 3-12 to 3-17, there were cells in which cracks and delamination were observed. For the cells where they were observed. A sufficient discharge capacity could not be obtained.

  On the other hand, about the batteries 3-6 to 3-11, compared with the batteries 3-12 to 3-17, there were few cells in which the structural defect generate | occur | produced. This is because the current collector layer plays a role as a buffer layer by setting the porosity of the current collector layer to 20 to 60%, and the current collector layer has sufficient volume change due to charging / discharging of the active material. It is thought that it was able to absorb it.

<< Example 3-3 >>
In this example, a current collector made of a base metal material was used.
(Battery 3-18)
LiCoPO ₄ was used as the positive electrode active material, and Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ was used as the solid electrolyte. The solid electrolyte layer also serves as a negative electrode active material.
Copper was used as the metal material contained in the positive electrode current collector layer and the negative electrode current collector layer. The amount of copper in the current collector material paste was 30% by weight of the paste.
The green chip was sintered in an atmospheric gas containing CO ₂ and H _{2 in} which the oxygen partial pressure was controlled to a predetermined small value. In the atmospheric gas, the volume ratio of CO ₂ and H ₂ was 10 ³ : 1.
In the sintering of the green chip, the decomposition temperature of the binder was 600 ° C.
A battery 3-18 was produced in the same manner as the battery 3-1, except for the above. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 50%, respectively.

(Battery 3-19)
Cobalt was used for the metal material contained in the positive electrode current collector layer and the negative electrode current collector layer. The volume ratio of CO ₂ and H ₂ in the atmospheric gas when firing the green chip was changed to 10: 1. Further, the binder contained in the green chip was decomposed by heating at 600 ° C. for 72 hours. A battery 3-19 was produced in the same manner as the battery 3-18, except for the above. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 50%, respectively.

(Battery 3-20)
Nickel was used for the metal material contained in the positive electrode current collector layer and the negative electrode current collector layer. The volume ratio of CO ₂ and H ₂ in the atmospheric gas when firing the green chip was changed to 40: 1. Further, the binder contained in the green chip was decomposed by heating at 600 ° C. for 48 hours. A battery 3-20 was produced in the same manner as the battery 3-18, except for the above. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 50%, respectively.

(Battery 3-21)
Stainless steel was used for the metal material contained in the positive electrode current collector layer and the negative electrode current collector layer. The maximum temperature of green chip firing was changed to 1000 ° C. A battery 3-21 was produced in the same manner as the battery 3-18, except for the above. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 50%, respectively.

(Comparative battery 3-1)
Titanium was used as the metal material contained in the positive electrode current collector layer and the negative electrode current collector layer. The maximum temperature of green chip firing was changed to 900 ° C. A comparative battery 3-1 was produced in the same manner as the battery 3-18, except for these. The porosity of the positive electrode current collector layer and the negative electrode current collector layer after firing was 50%, respectively.

  For batteries 3-18 to 3-21 and comparative battery 3-1, 10 cells each were charged and discharged at a constant current under the same conditions as battery 3-11 (upper cut voltage 2.5 V, lower cut voltage 1.0 V). Went. Table 19 shows the initial discharge capacity of the cells that could be charged and discharged without causing defects and the number of cells in which structural defects occurred in each battery.

  From the results of the batteries 3-18 to 3-21, even when a base metal is used as the current collector material, the current collector material can be obtained by firing the green chip while controlling the oxygen partial pressure of the atmospheric gas during firing. Can be prevented from being oxidized. For this reason, the solid battery using a base metal as a current collector material can be charged and discharged.

  In Comparative Battery 3-1, there was no cell in which cracks and / or delamination occurred. However, the comparative battery 3-1 could not be charged / discharged. This is considered to be because titanium itself constituting the current collector layer was oxidized, and the current collector layer could not maintain current collecting properties. Note that it is conceivable that the green chip is fired in an atmosphere in which titanium is not oxidized. However, when such an atmosphere is used, the binder cannot be decomposed.

  As described above, it is understood that a metal material that is resistant to oxidation to some extent can be used as the current collector material by adjusting the oxygen partial pressure of the atmospheric gas.

<< Example 3-5 >>
In this example, the porosity of the positive electrode current collector layer and the negative electrode current collector layer was 10%.
(Battery 3-22)
In the copper paste for forming the positive electrode current collector layer and the negative electrode current collector layer, the amount of copper was 70% by weight of the paste. A battery 3-22 was produced in the same manner as the battery 3-18, except for this. The porosity of each of the positive electrode current collector layer and the negative electrode current collector layer was 10%.

(Battery 3-23)
In the cobalt paste for forming the positive electrode current collector layer and the negative electrode current collector layer, the amount of cobalt was 70% by weight of the paste. A battery 3-23 was produced in the same manner as the battery 3-19, except for this. The porosity of each of the positive electrode current collector layer and the negative electrode current collector layer was 10%.

(Battery 3-24)
In the nickel paste for forming the positive electrode current collector layer and the negative electrode current collector layer, the amount of nickel was 70% by weight of the paste. A battery 3-24 was produced in the same manner as the battery 3-20, except for this. The porosity of each of the positive electrode current collector layer and the negative electrode current collector layer was 10%.

(Battery 3-25)
In the stainless steel paste for forming the positive electrode current collector layer and the negative electrode current collector layer, the amount of stainless steel was 70% by weight of the paste. A battery 3-25 was produced in the same manner as the battery 3-21, except for this. The porosity of each of the positive electrode current collector layer and the negative electrode current collector layer was 10%.

  For batteries 3-22 to 3-25, each cell was charged and discharged at a constant current under the same conditions (upper limit cut voltage 2.5 V, lower limit cut voltage 1.0 V) as battery 3-18. Table 20 shows the initial discharge capacity of the cells that could be charged and discharged without causing defects and the number of cells in which structural defects occurred in each battery.

  The initial discharge capacities of the batteries 3-22 to 2-25 were almost the same as the initial discharge capacities of the batteries 3-18 to 3-21. In batteries 3-22 to 3-25, since the porosity of the positive electrode current collector layer and the negative electrode current collector layer is 10%, the current collector layer buffers the volume change of the active material that occurs during charging and discharging. It becomes difficult. For this reason, in the batteries 3-22 to 3-25, it is considered that the number of cells in which the structural defect has occurred increased.

  As described above, a current collector layer made of a base metal that is resistant to oxidation to some extent in addition to a noble metal can be used. Moreover, the delamination and / or crack which generate | occur | produce by the volume change of the active material at the time of charging / discharging can be suppressed by making the porosity into 20 to 60%. Therefore, a highly reliable all-solid lithium secondary battery can be provided.

  The laminate of the present invention has an electrochemically active active material / solid electrolyte interface and a low internal resistance while the solid electrolyte layer and the active material layer are densified or crystallized by heat treatment. Rather than using such a laminate, for example, it is possible to provide an all-solid lithium secondary battery having a large capacity and excellent high-rate characteristics.

LiCoPO ₄ and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of _3. LiNiPO ₄ and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of _3. It is a graph showing the before and after X-ray diffraction pattern heat treatment of the mixed powder of LiCoO ₂ and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) 3. Is a graph showing the LiMn ₂ O ₄ and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) before and after the heat treatment of the mixed powder of ₃ X-ray diffraction pattern. LiCoPO is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of ₄ and Li _0.33 La _0.56 TiO _3. LiNiPO is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of ₄ and Li _0.33 La _0.56 TiO _3. Is a graph showing the before and after X-ray diffraction pattern heat treatment of the mixed powder of LiCoO ₂ and Li _0.33 La _0.56 TiO _3. It is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of LiMn ₂ O ₄ and Li _0.33 La _0.56 TiO _3. LiCo _0.5 Ni _0.5 PO ₄ and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of _3. FePO ₄ and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of _{3. Li 3 Fe 2 (PO 4)} 3 and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of _3. LiFeP ₂ O ₇ and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of _3. Is a graph showing a Li ₄ Ti ₅ O ₁₂ and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) before and after the heat treatment of the mixed powder of ₃ X-ray diffraction pattern. Nb ₂ O ₅ and _{Li 1.3 Al 0.3 Ti 1.7 (PO} 4) is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of _3. FePO is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of ₄ and Li _0.33 La _0.56 TiO _3. Li ₃ Fe ₂ (PO ₄₎ is a graph showing the X-ray pattern before and after the heat treatment of the mixed powder of ₃ and Li _0.33 La _0.56 TiO _3. LiFeP is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of ₂ O ₇ and Li _0.33 La _0.56 TiO _3. Li is a ₄ Ti ₅ O ₁₂ and Li _0.33 La _0.56 graph showing X-ray diffraction pattern before and after the heat treatment of the mixed powder of TiO _3. It is a graph showing the X-ray diffraction pattern before and after the heat treatment of the mixed powder of Nb ₂ O _5, Li _0.33 La _0.56 TiO _3. It is a perspective view which shows roughly the solid electrolyte green sheet formed on the carrier film. It is a perspective view which shows roughly the active material green sheet formed on the carrier film. It is a longitudinal cross-sectional view which shows schematically the solid electrolyte green sheet and carrier film which were mounted on the support stand provided with a polyester film. It is a longitudinal cross-sectional view which shows roughly the state by which the carrier film was peeled off from the solid electrolyte green sheet. It is a longitudinal cross-sectional view which shows roughly the state in which 20 solid electrolyte green sheets and one active material green sheet were mounted on the support stand provided with a polyester film. It is a longitudinal cross-sectional view which shows the state which piled up two green chips and pinched | interposed them with the ceramic board. It is a longitudinal cross-sectional view which shows roughly the green chip | tip (namely, laminated body of this invention) after sintering, and the gold thin film formed on it. 1 is a longitudinal sectional view schematically showing a battery 1. FIG. It is a longitudinal cross-sectional view which shows schematically the all-solid-state lithium secondary battery which concerns on another embodiment of this invention. It is a perspective view which shows roughly the solid electrolyte green sheet formed on the carrier film. It is a perspective view which shows roughly the positive electrode active material green sheet formed on the carrier film. It is a perspective view which shows roughly the negative electrode active material green sheet formed on the carrier film. It is a longitudinal cross-sectional view which shows schematically the negative electrode active material green sheet and carrier film which were mounted on the support stand provided with a polyester film. It is a longitudinal cross-sectional view which shows roughly the state by which the carrier film was peeled off from the negative electrode active material green sheet. It is a longitudinal cross-sectional view which shows roughly the state by which the negative electrode active material green sheet, 20 solid electrolyte green sheets, and the positive electrode active material green sheet were laminated | stacked in order on the support stand provided with a polyester film. It is a longitudinal cross-sectional view which shows the state which piled up two green chips and pinched | interposed them with the ceramic board. It is a longitudinal cross-sectional view which shows schematically the laminated body after sintering, and the gold thin film (battery 7) formed on it. FIG. 6 is a longitudinal sectional view schematically showing a battery 11 produced in Example 4. 6 is a longitudinal sectional view schematically showing a battery 18 produced in Example 6. FIG. FIG. 10 is a longitudinal sectional view schematically showing a battery 19 produced in Example 6. It is a perspective view which shows roughly the solid electrolyte green sheet formed on the carrier film. It is a top view which shows roughly the some positive electrode active material green sheet arrange | positioned with the predetermined pattern on the carrier film. It is a top view which shows roughly the some positive electrode collector green sheet arrange | positioned with the predetermined pattern on the carrier film. It is a top view which shows roughly the some negative electrode active material green sheet arrange | positioned with the predetermined pattern on the carrier film. It is a top view which shows roughly the some negative electrode collector green sheet arrange | positioned with the predetermined pattern on the carrier film. It is a longitudinal cross-sectional view which shows schematically the solid electrolyte green sheet and carrier film mounted on the support stand provided with a polyester film. It is a longitudinal cross-sectional view which shows roughly the state by which the carrier film was peeled off from the solid electrolyte green sheet. It is a longitudinal cross-sectional view which shows roughly the state by which 20 solid electrolyte green sheets were laminated | stacked on the support stand provided with a polyester film. It is a longitudinal cross-sectional view which shows roughly the state which is going to laminate | stack the some negative electrode active material green sheet carry | supported on the surface of a carrier film on the solid electrolyte green sheet formed on the carrier film. It is a longitudinal cross-sectional view which shows roughly the state by which the negative electrode active material green sheet, the negative electrode collector green sheet, and the negative electrode active material green sheet were laminated | stacked in order on the solid electrolyte green sheet. It is a longitudinal cross-sectional view which shows roughly the state which is going to laminate | stack the some positive electrode active material green sheet carry | supported by the surface of a carrier film on the solid electrolyte green sheet formed on the carrier film. It is a longitudinal cross-sectional view which shows roughly the state by which the positive electrode active material green sheet, the positive electrode collector green sheet, and the positive electrode active material green sheet are laminated | stacked in order on the solid electrolyte green sheet. The negative electrode active material green sheet, the negative electrode current collector green sheet, and the negative electrode active material green sheet, which are supported on the surface of the solid electrolyte green sheet, are sequentially stacked on the solid electrolyte green sheet laminate. It is a longitudinal section showing roughly. It is a longitudinal section showing roughly the state where five layers of negative electrode laminates and four layers of positive electrode laminates are alternately laminated on a solid electrolyte green sheet laminate. It is a top view of the green chip obtained by cut | disconnecting a lamination sheet. It is a longitudinal cross-sectional view which shows a green chip roughly when the green chip of FIG. 54 is cut by line XX. It is a longitudinal cross-sectional view which shows a green chip roughly when the green chip of FIG. 54 is cut by line YY. It is a longitudinal cross-sectional view which shows roughly the sintered compact by which the positive electrode external electrical power collector and the negative electrode external electrical power collector were each provided in the exposed end surface of the positive electrode electrical power collector, and the exposed end surface of the negative electrode electrical power collector. It is a top view which shows roughly the positive electrode active material green sheet arrange | positioned by the predetermined pattern on the solid electrolyte green sheet on a carrier film. It is a top view which shows roughly the negative electrode active material green sheet arrange | positioned by the predetermined pattern on the solid electrolyte green sheet on a carrier film. It is a longitudinal cross-sectional view which shows schematically the state which laminated | stacked the negative electrode active material green sheet carry | supported on the surface of the solid electrolyte green sheet on the solid electrolyte green sheet laminated body. It is a longitudinal cross-sectional view which shows schematically the state by which the negative electrode sheet of 5 layers and the positive electrode sheet of 4 layers are laminated | stacked on the solid electrolyte green sheet laminated body. It is a top view of the green chip obtained by cut | disconnecting a lamination sheet. FIG. 63 is a longitudinal sectional view schematically showing the green chip when the green chip in FIG. 62 is cut along line XX. FIG. 63 is a longitudinal sectional view schematically showing the green chip when the green chip in FIG. 62 is cut along line YY. It is a longitudinal cross-sectional view which shows schematically the sintered compact by which the positive electrode external electrical power collector and the negative electrode external electrical power collector were each provided in the exposed end surface of the positive electrode active material layer, and the exposed end surface of the negative electrode active material layer. It is a longitudinal cross-sectional view which shows roughly the sintered compact coat | covered with the glass layer except the part coat | covered with the positive electrode external electrical power collector and the negative electrode external electrical power collector. It is a perspective view which shows roughly the solid electrolyte green sheet formed on the carrier film. It is a top view which shows roughly the some positive electrode active material green sheet arrange | positioned with the predetermined pattern on the carrier film. It is a top view which shows roughly the some positive electrode collector green sheet arrange | positioned with the predetermined pattern on the carrier film. It is a top view which shows roughly the some negative electrode collector green sheet arrange | positioned with the predetermined pattern on the carrier film. It is a longitudinal cross-sectional view which shows schematically the solid electrolyte green sheet and carrier film mounted on the support stand provided with a polyester film. It is a longitudinal cross-sectional view which shows roughly the state by which the carrier film was peeled off from the solid electrolyte green sheet. It is a longitudinal cross-sectional view which shows roughly the state by which 20 solid electrolyte green sheets were laminated | stacked on the support stand provided with a polyester film. It is a longitudinal cross-sectional view which shows roughly the state which is going to laminate | stack the some negative electrode collector green sheet carry | supported on the surface of a carrier film on the solid electrolyte green sheet formed on the carrier film. It is a longitudinal cross-sectional view which shows roughly the state by which the negative electrode active material green sheet and the negative electrode collector green sheet are laminated | stacked on the solid electrolyte green sheet. It is a longitudinal cross-sectional view which shows roughly the state which is going to laminate | stack the some positive electrode active material green sheet carry | supported by the surface of a carrier film on the solid electrolyte green sheet formed on the carrier film. It is a longitudinal cross-sectional view which shows roughly the state by which the positive electrode active material green sheet, the positive electrode collector green sheet, and the positive electrode active material green sheet are laminated | stacked in order on the solid electrolyte green sheet. It is a longitudinal cross-sectional view which shows roughly the state which laminated | stacked the negative electrode collector green sheet carry | supported on the surface of the solid electrolyte green sheet on the solid electrolyte green sheet laminated body. FIG. 5 is a longitudinal sectional view schematically showing a state in which five layers of a negative electrode / solid electrolyte sheet and four layers of a positive electrode laminate are alternately laminated on a solid electrolyte green sheet laminate. It is a top view of the green chip obtained by cut | disconnecting a lamination sheet. It is a longitudinal cross-sectional view which shows a green chip roughly when the green chip of FIG. 80 is cut | disconnected by line XX. It is a longitudinal cross-sectional view which shows a green chip roughly when the green chip of FIG. 80 is cut by line YY. It is a longitudinal cross-sectional view which shows roughly the sintered compact by which the positive electrode external electrical power collector and the negative electrode external electrical power collector were each provided in the exposed end surface of the positive electrode electrical power collector, and the exposed end surface of the negative electrode electrical power collector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 3 Carrier film 2 Solid electrolyte green sheet 4 Positive electrode active material green sheet 5 Support stand 6 Polyester film 7 Solid electrolyte green sheet group 8 Green chip 9 Solid electrolyte surface 10 Ceramic board 11 1st laminated body 11a Positive electrode active material layer 11b Solid Electrolyte layer 12 Gold thin film 13 Laminate side surface 14 Metal lithium foil 15 SUS plate 16, 27 PEO-LiTFSI layer 17 Solid electrolyte surface 21 Layer made of silicon nitride 22 Single crystal silicon plate 23 Titanium thin film 24 Gold thin film 25 LiCoPO ₄ thin film 26 LiTi ₂ (PO ₄ ) ₃ thin film 28 Metal lithium thin film 29 Copper thin film

DESCRIPTION OF SYMBOLS 30 Carrier film 31 Solid electrolyte green sheet 32 Positive electrode active material green sheet 33 Negative electrode active material green sheet 34 Support stand 35 Polyester film 36 Solid electrolyte green sheet group 37 Green chip 38 Ceramic board 39 2nd laminated body 39a Positive electrode active material layer 39b Solid Electrolyte layer 39c Negative electrode active material layer 40, 41 Gold thin film 42 Each side of the laminate 43 Layer made of silicon nitride 44 Single crystal silicon substrate 45 Titanium thin film layer 46 Gold thin film 47 LiCoPO ₄ thin film 48 LiTi ₂ (PO ₄ ) ₃ thin film 49 Li ₃ Fe ₂ (PO ₄ ) ₃ thin film 50 Copper thin film 51 Metal case 52 Metal sealing plate 53 Nylon gasket 54 Nickel sponge metal piece 55, 56 Silver thin film 57 Copper lead 58 Solder 59 Epoxy resin

60 Carrier film 61, 75 Solid electrolyte green sheet 62, 74 Positive electrode active material green sheet 63 A row of positive electrode active material green sheets arranged in a straight line 64, 77 Positive electrode current collector green sheet 65, 76 Negative electrode active material green sheet 66, 78 Negative electrode current collector green sheet 67 Support base 68 Polyester film 69 Solid electrolyte green sheet group 70 Negative electrode laminate 71 Positive electrode laminate 72 Laminate 73 Green chip 79 Sintered body 80, 94 Positive electrode current collector exposed surface 81, 95 Negative electrode Current collector exposed surface 82, 96 Positive electrode external current collector 83, 97 Negative electrode external current collector 84, 90 Positive electrode active material green sheet including three-dimensional network current collector 85 Positive electrode sheet 86, 92 Three-dimensional network Negative electrode active material green sheet including current collector 87 Negative electrode sheet 88 Laminate 89 Glee Chip 90 Solid electrolyte green sheet 93 Sintered body 98 Glass layer

99 Carrier film 100 Solid electrolyte green sheet 101 Positive electrode active material green sheet 102 Row 103 Positive electrode current collector green sheet 104 Negative electrode current collector green sheet 105 Support base 106 Polyester film 107 Solid electrolyte green sheet group 108 Negative electrode / solid electrolyte sheet 109 Positive electrode Laminate 110 Laminate 111 Green chip 112 Sintered body 113 Positive electrode current collector exposed surface 114 Negative electrode current collector exposed surface 115 Positive electrode external current collector 116 Negative electrode external current collector

Claims (63)

An all-solid lithium secondary battery laminate including an active material layer and a solid electrolyte layer sintered and joined to the active material layer,
The active material layer includes a crystalline first material capable of releasing and occluding lithium ions,
The solid electrolyte layer includes a crystalline second material having lithium ion conductivity,
The laminate is a laminate for an all-solid lithium secondary battery in which components other than the constituent components of the active material layer and the constituent components of the solid electrolyte layer are not detected when analyzed by an X-ray diffraction method.   The first substance includes a crystalline first phosphate compound capable of releasing and occluding lithium ions, and the second substance includes a crystalline second phosphate compound having lithium ion conductivity. The laminated body for all-solid-state lithium secondary batteries of description.   The laminate for an all solid lithium secondary battery according to claim 1, wherein at least a filling factor of the solid electrolyte layer exceeds 70%.   The laminate for an all solid lithium secondary battery according to claim 1, wherein at least one of the active material layer and the solid electrolyte layer contains an amorphous oxide.   The all-solid-state lithium secondary battery laminate according to claim 4, wherein at least one of the active material layer and the solid electrolyte layer contains 0.1 to 10 wt% of the amorphous oxide.   The laminate for an all solid lithium secondary battery according to claim 4, wherein the softening point of the amorphous oxide is 700 ° C. or higher and 950 ° C. or lower. The first phosphoric acid compound has the following general formula:
LiMPO ₄
(M is at least one selected from the group consisting of Mn, Fe, Co and Ni)
The laminated body for all-solid-state lithium secondary batteries of Claim 2 represented by these. The second phosphate compound has the following general formula:
Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃
(M ^III is at least one metal ion selected from the group consisting of Al, Y, Ga, In and La, and 0 ≦ X ≦ 0.6)
The laminated body for all-solid-state lithium secondary batteries of Claim 2 represented by these. An all-solid lithium secondary battery comprising a laminate including at least one set including a positive electrode active material layer and a solid electrolyte layer sintered and bonded to the positive electrode active material layer,
The positive electrode active material layer includes a crystalline first material capable of releasing and occluding lithium ions,
The solid electrolyte layer includes a crystalline second material having lithium ion conductivity,
The laminated body is an all solid lithium secondary battery in which components other than the constituent components of the active material layer and the constituent components of the solid electrolyte layer are not detected when analyzed by an X-ray diffraction method.   10. The first substance is a crystalline first phosphate compound capable of releasing and occluding lithium ions, and the second substance is a crystalline second phosphate compound having lithium ion conductivity. The all-solid-state lithium secondary battery as described.   The set includes a negative electrode active material layer facing the positive electrode active material layer through the solid electrolyte layer, and the solid electrolyte layer and the negative electrode active material layer are joined, and the negative electrode active material layer is The all-solid-state lithium secondary battery according to claim 9, comprising a crystalline tertiary phosphate compound capable of releasing and occluding lithium ions or an oxide containing Ti.   The all-solid lithium secondary battery according to claim 9, wherein a filling rate of the solid electrolyte layer exceeds 70%. The first phosphoric acid compound has the following general formula:
LiMPO ₄
(M is at least one selected from the group consisting of Mn, Fe, Co and Ni)
The all-solid-state lithium secondary battery of Claim 10 represented by these. The second phosphate compound has the following general formula:
Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃
(M ^III is at least one metal ion selected from the group consisting of Al, Y, Ga, In and La, and 0 ≦ X ≦ 0.6)
The all-solid-state lithium secondary battery of Claim 10 represented by these. The all solid lithium secondary battery according to claim 11, wherein the third phosphoric acid compound is at least one selected from the group consisting of FePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ , and LiFeP ₂ O ₇ . The second phosphate compound is Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃ (M ^III is at least one metal ion selected from the group consisting of Al, Y, Ga, In and La) The solid electrolyte secondary battery according to claim 10, wherein the solid electrolyte layer also serves as a negative electrode active material layer.   The all-solid lithium battery according to claim 9, wherein at least one of the positive electrode active material layer and the solid electrolyte layer contains an amorphous oxide.   The all-solid lithium secondary battery according to claim 17, wherein the amorphous oxide accounts for 0.1 to 10% by weight of the layer in which the amorphous oxide is contained.   The all-solid lithium secondary battery according to claim 17, wherein a softening point of the amorphous oxide is 700 ° C. or higher and 950 ° C. or lower. The all-solid lithium secondary battery according to claim 9, wherein at least one of the positive electrode active material layer and the solid electrolyte layer contains Li ₄ P ₂ O ₇ , and a filling rate of the solid electrolyte layer exceeds 70%. Li ₄ P ₂ O ₇ The all-solid lithium secondary battery according to claim 20, wherein occupies 0.1 to 10% by weight of the layer in which it is contained.   10. The all solid according to claim 9, wherein a surface of the solid electrolyte layer that is not joined to the positive electrode active material layer is joined to metallic lithium or a current collector through a layer made of an electrolyte having reduction resistance. Lithium secondary battery.   The all-solid lithium secondary battery according to claim 9, wherein the set is sandwiched between a positive electrode current collector and a negative electrode current collector.   The all-solid-state lithium secondary battery according to claim 11, wherein the positive electrode active material layer includes a positive electrode current collector, and the negative electrode active material layer includes a negative electrode current collector.   The all-solid-state lithium secondary battery according to claim 24, wherein a thin-film current collector is provided in at least one active material layer of the positive electrode and the negative electrode.   The all-solid-state lithium secondary battery according to claim 25, wherein at least one porosity of the positive electrode current collector and the negative electrode current collector is 20% or more and 60% or less.   26. The all-solid-state lithium secondary battery according to claim 25, wherein at least one of the thin-film positive electrode current collector and the thin-film negative electrode current collector is disposed at a central portion in the thickness direction of the active material layer.   The all-solid-state lithium secondary battery according to claim 24, wherein a current collector is arranged in a three-dimensional network throughout at least one of the positive electrode active material layer and the negative electrode active material layer.   A current collector on at least one of the surface of the positive electrode active material layer opposite to the surface in contact with the solid electrolyte layer and the surface of the negative electrode active material layer opposite to the surface in contact with the solid electrolyte An all-solid lithium secondary battery according to claim 24.   The all-solid-state lithium according to claim 24, wherein the pair is two or more, and the positive electrode current collector and the negative electrode current collector are connected in parallel by a positive electrode external current collector and a negative electrode external current collector, respectively. Secondary battery.   The all-solid lithium secondary battery according to claim 24, wherein the positive electrode current collector and the negative electrode current collector are made of a conductive material.   32. The all solid lithium secondary battery according to claim 31, wherein the conductive material includes at least one selected from the group consisting of stainless steel, silver, copper, nickel, cobalt, palladium, gold, and platinum.   The all-solid-state lithium secondary battery according to claim 30, wherein the positive electrode external current collector and the negative electrode external current collector are made of a mixture of metal and glass frit. A step of obtaining an active material layer forming slurry 1 by dispersing an active material in a solvent containing a binder and a plasticizer;
A step of dispersing the solid electrolyte in a solvent containing a binder and a plasticizer to obtain a solid electrolyte layer forming slurry 2;
Using the slurry 1 to obtain an active material green sheet;
Using the slurry 2 to obtain a solid electrolyte green sheet;
Including laminating the active material green sheet and the solid electrolyte green sheet and heat-treating to obtain a laminate;
The active material includes a first phosphate compound that can release and occlude lithium ions,
The said solid electrolyte is a manufacturing method of the laminated body which consists of an active material layer and a solid electrolyte layer containing the 2nd phosphate compound which has lithium ion conductivity.   The manufacturing method of the laminated body of Claim 34 which contains an amorphous oxide in at least one of the said slurry 1 and the said slurry 2, and performs the said heat processing at 700 to 1000 degreeC.   The ratio of the amorphous oxide in the total of the amorphous oxide and the active material or the solid electrolyte in the at least one slurry is 0.1 wt% to 10 wt%. The manufacturing method of the laminated body of description.   The method for producing a laminate according to claim 35, wherein the softening point of the amorphous oxide is 700 ° C or higher and 950 ° C or lower. Depositing an active material on a substrate to form an active material layer;
Depositing a solid electrolyte on the active material layer to form a solid electrolyte layer;
Including a step of heat-treating and crystallizing the active material layer and the solid electrolyte layer,
The active material comprises a crystalline primary phosphate compound capable of releasing and occluding lithium ions,
The said solid electrolyte is a manufacturing method of the laminated body which consists of an active material layer and solid electrolyte layer which consist of a crystalline 2nd phosphate compound which has lithium ion conductivity.   The method for manufacturing a laminate according to claim 38, wherein the active material and the solid electrolyte are deposited on the substrate by a sputtering method. (A) A step of dispersing the positive electrode active material in a solvent containing a binder and a plasticizer to obtain a positive electrode active material layer forming slurry 1;
(B) Dispersing the solid electrolyte in a solvent containing a binder and a plasticizer to obtain a solid electrolyte layer forming slurry 2;
(C) Dispersing the negative electrode active material in a solvent containing a binder and a plasticizer to obtain a negative electrode active material layer forming slurry 3;
(D) a step of obtaining a positive electrode active material green sheet using the slurry 1;
(E) A step of obtaining a solid electrolyte green sheet using the slurry 2;
(F) Step of obtaining a negative electrode active material green sheet using the slurry 3;
(G) forming a first green sheet group including at least one set including the solid electrolyte sheet and the positive electrode active material green sheet and the negative electrode active material green sheet disposed so as to sandwich the solid electrolyte sheet; And (h) heat treating the first green sheet group to obtain a laminate including at least one set in which the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are integrated,
The positive electrode active material includes a crystalline first phosphate compound that can release and occlude lithium ions,
The solid electrolyte includes a second phosphate compound having lithium ion conductivity,
The said negative electrode active material is a manufacturing method of the all-solid-state lithium secondary battery containing the oxide containing a 3rd phosphate compound or Ti which can discharge | release and occlude lithium ion.   41. The method for producing an all-solid lithium secondary battery according to claim 40, wherein at least one selected from the group consisting of the slurry 1, the slurry 2 and the slurry 3 contains an amorphous oxide.   The manufacturing method of the all-solid-state lithium secondary battery of Claim 41 which performs the said heat processing at 700 to 1000 degreeC in the said process (h). Li ₄ P ₂ O ₇ is added to at least one selected from the group consisting of the slurry 1, the slurry 2 and the slurry 3;
The manufacturing method of the all-solid-state lithium secondary battery of Claim 40 which performs the said heat processing at 700 degreeC or more and 1000 degrees C or less in the said process (h). In the step (g), the set is configured using at least two positive electrode active material green sheets, at least two negative electrode active material green sheets, and a solid electrolyte green sheet,
A positive electrode current collector is provided between the at least two positive electrode active material green sheets, and a negative electrode current collector is provided between the at least two negative electrode active material green sheets;
41. The method for manufacturing an all solid lithium secondary battery according to claim 40, wherein one end of the positive electrode current collector and one end of the negative electrode current collector are exposed in different regions of the surface of the laminate. . In the step (a) and the step (c), the material constituting the positive electrode current collector and the material constituting the negative electrode current collector are further mixed into the slurry 1 and the slurry 3, respectively.
41. The method for producing an all-solid lithium secondary battery according to claim 40, wherein one end of the positive electrode active material layer and one end of the negative electrode active material layer are exposed in different regions of the surface of the laminate. . (A) obtaining a first group comprising a positive electrode active material layer, a negative electrode active material layer, and a set including a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer; And a step of heat-treating the first group at a predetermined temperature so that the positive electrode active material layer, the solid electrolyte layer and the negative electrode active material layer are integrated and crystallized.
The step (A)
(I) depositing a positive electrode active material or a negative electrode active material on a predetermined substrate to form a first active material layer;
(Ii) a step of depositing a solid electrolyte on the first active material layer to form a solid electrolyte layer; and (iii) a step different from the first active material layer on the solid electrolyte layer. Including stacking two active material layers to obtain a laminate including a set of the first active material layer, the solid electrolyte layer, and the second active material layer,
The positive electrode active material includes a crystalline first phosphate compound that can release and occlude lithium ions,
The solid electrolyte includes a second phosphate compound having lithium ion conductivity,
The method for manufacturing an all-solid lithium secondary battery, wherein the negative electrode active material includes a third phosphate compound capable of releasing and occluding lithium ions or an oxide containing titanium.   47. The all solid according to claim 46, wherein the step (iii) further includes a step of stacking at least two of the sets via a solid electrolyte layer to obtain a first group before the step (B). A method for producing a lithium secondary battery.   47. The method for producing an all-solid lithium secondary battery according to claim 46, wherein the active material and the solid electrolyte are deposited on the substrate by sputtering or thermal evaporation. The second phosphate compound and the third phosphate compound are Li _{1 + X} M ^III _X Ti ^IV _2-X (PO ₄ ) ₃ (M ^III is a group consisting of Al, Y, Ga, In and La). At least one metal ion selected, 0 ≦ X ≦ 0.6)
The heat treatment is performed in an atmospheric gas containing water vapor and a low oxygen partial pressure gas,
The water vapor accounts for 5 to 90% by volume of the atmospheric gas,
45. The method for producing an all-solid lithium secondary battery according to claim 44, wherein a maximum temperature of the heat treatment is 700 ° C. or higher and 1000 ° C. or lower. The first phosphoric acid compound has the following general formula:
LiMPO ₄
(M is at least one selected from the group consisting of Mn, Fe, Co and Ni)
And the first phosphate compound contains Fe,
The heat treatment is performed in an atmospheric gas containing water vapor and a low oxygen partial pressure gas,
The water vapor accounts for 5 to 90% by volume of the atmospheric gas,
41. The method for producing an all solid lithium secondary battery according to claim 40, wherein a maximum temperature of the heat treatment is 700 ° C. or higher and 1000 ° C. or lower. In the atmospheric gas, when the equilibrium oxygen partial pressure PO ₂ (atmospheric pressure) is T ° C. as the constant maintenance temperature of the heat treatment, the following formula:
−0.0310T + 33.5 ≦ −log ₁₀ PO ₂ ≦ −0.0300T + 38.1
The manufacturing method of the all-solid-state lithium secondary battery of Claim 49 satisfy | filling. In the atmospheric gas, when the equilibrium oxygen partial pressure PO ₂ (atmospheric pressure) is T ° C. as the constant maintenance temperature of the heat treatment, the following formula:
−0.0310T + 33.5 ≦ −log ₁₀ PO ₂ ≦ −0.0300T + 38.1
The manufacturing method of the all-solid-state lithium secondary battery of Claim 50 satisfy | filling these. The first phosphoric acid compound has the following general formula:
LiMPO ₄
(M is at least one selected from the group consisting of Mn, Fe, Co and Ni)
And the first phosphate compound contains Fe,
The heat treatment is performed in an atmospheric gas containing water vapor and a low oxygen partial pressure gas,
The water vapor accounts for 5 to 90% by volume of the atmospheric gas,
The method for manufacturing a laminate according to claim 34, wherein a maximum temperature of the heat treatment is 700 ° C or higher and 1000 ° C or lower. In the atmospheric gas, when the equilibrium oxygen partial pressure PO ₂ (atmospheric pressure) is T ° C. as the constant maintenance temperature of the heat treatment, the following formula:
−0.0310T + 33.5 ≦ −log ₁₀ PO ₂ ≦ −0.0300T + 38.1
The manufacturing method of the laminated body of Claim 53 which satisfy | fills.   54. The method for manufacturing a laminate according to claim 53, wherein the low oxygen partial pressure gas includes a mixture of a gas capable of releasing oxygen and a gas that reacts with oxygen. At least one of the positive electrode current collector and the negative electrode current collector is made of one selected from the group consisting of silver, copper, and nickel,
The heat treatment is performed in an atmospheric gas having an oxygen partial pressure lower than the redox equilibrium oxygen partial pressure of the electrode;
45. The method for producing an all-solid lithium secondary battery according to claim 44, wherein a maximum temperature of the heat treatment is 700 ° C. or higher and 1000 ° C. or lower.   57. The atmospheric gas includes 3% by volume or less of carbon dioxide gas and hydrogen gas, and an oxygen partial pressure of the atmospheric gas is adjusted by changing a mixing ratio of the carbon dioxide gas and the hydrogen gas. The manufacturing method of the all-solid-state lithium secondary battery of description. At least one of the positive electrode current collector and the negative electrode current collector contains at least one material selected from the group consisting of silver, copper and nickel,
The heat treatment is performed in an atmospheric gas containing water vapor and a low oxygen partial pressure gas,
The water vapor accounts for 5 to 90% by volume of the atmospheric gas,
45. The method for producing an all-solid lithium secondary battery according to claim 44, wherein a maximum temperature of the heat treatment is 700 ° C. or higher and 1000 ° C. or lower. At least one of the positive electrode current collector and the negative electrode current collector contains at least one material selected from the group consisting of silver, copper and nickel;
The heat treatment is performed in an atmospheric gas containing water vapor and a low oxygen partial pressure gas,
The water vapor accounts for 5 to 90% by volume of the atmospheric gas,
46. The method for producing an all-solid lithium secondary battery according to claim 45, wherein a maximum temperature of the heat treatment is 700 ° C. or higher and 1000 ° C. or lower. In the above atmospheric gas, when the equilibrium oxygen partial pressure PO ₂ (atmospheric pressure) is a constant maintenance temperature of the heat treatment at T ° C., the following formula:
−0.0310T + 3.5 ≦ −log ₁₀ PO ₂ ≦ −0.0300T + 38.1
59. An all solid lithium secondary battery according to claim 58, wherein: In the above atmospheric gas, when the equilibrium oxygen partial pressure PO ₂ (atmospheric pressure) is a constant maintenance temperature of the heat treatment at T ° C., the following formula:
−0.0310T + 3.5 ≦ −log ₁₀ PO ₂ ≦ −0.0300T + 38.1
60. An all solid lithium secondary battery according to claim 59, wherein:   50. The method for manufacturing an all-solid lithium secondary battery according to claim 49, wherein the low oxygen partial pressure gas includes a mixture of a gas capable of releasing oxygen and a gas that reacts with oxygen. (A) A step of dispersing the positive electrode active material in a solvent containing a binder and a plasticizer to obtain a positive electrode active material layer forming slurry 1;
(B) Dispersing the solid electrolyte in a solvent containing a binder and a plasticizer to obtain a solid electrolyte layer forming slurry 2;
(C) using the slurry 1 to obtain a positive electrode active material green sheet;
(D) a step of obtaining a solid electrolyte green sheet using the slurry 2;
(E) forming a second green sheet group including at least one set including the positive electrode active material green sheet and the solid electrolyte green sheet; and (f) heat-treating the second green sheet group to form a positive electrode. Including a step of obtaining a laminate including at least one set in which an active material layer and a solid electrolyte layer are integrated;
In the step (e), the set is configured by using at least two positive electrode active material green sheets and at least two solid electrolyte green sheets, and between the at least two positive electrode active material green sheets. A positive current collector is provided, and a negative current collector is provided between the at least two solid electrolyte green sheets;
The positive electrode active material includes a first phosphate compound that can release and occlude lithium ions,
The solid electrolyte includes a second phosphoric acid compound having lithium ion conductivity, and the solid electrolyte also serves as a negative electrode active material,
At least one of the positive electrode current collector and the negative electrode current collector is selected from the group consisting of silver, copper, and nickel;
The manufacturing method of the all-solid-state lithium secondary battery with which the said heat processing is performed in atmospheric gas containing water vapor | steam and low oxygen partial pressure gas.

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