WO2018168550A1

WO2018168550A1 - All-solid secondary battery and production method therefor, and solid electrolyte sheet for all-solid secondary battery, and positive electrode active material sheet for all-solid secondary battery

Info

Publication number: WO2018168550A1
Application number: PCT/JP2018/008327
Authority: WO
Inventors: 真二今井
Original assignee: 富士フイルム株式会社
Priority date: 2017-03-13
Filing date: 2018-03-05
Publication date: 2018-09-20
Also published as: JP6948382B2; JPWO2018168550A1

Abstract

Provided are: an all-solid secondary battery having a battery element member, wherein the battery element member has at least a negative electrode collector, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode collector, and an end of the battery element member is provided with an inorganic insulative coating body which at least covers said end of the battery element member and which has a Young's modulus of 1 GPa or more at 25°C; a production method for such a battery; a solid electrolyte sheet for an all-solid secondary battery; and a positive electrode mixture material layer for an all-solid secondary battery.

Description

All-solid secondary battery, method for producing the same, solid electrolyte sheet for all-solid secondary battery, and positive electrode active material sheet for all-solid secondary battery

The present invention relates to an all solid secondary battery and a method of manufacturing the same. The present invention also relates to a solid electrolyte sheet for an all solid secondary battery and a positive electrode active material sheet for an all solid secondary battery.

A lithium ion secondary battery is a storage battery that has a negative electrode, a positive electrode, and an electrolyte sandwiched between the negative electrode and the positive electrode, and is capable of charging and discharging by reciprocating lithium ions between the two electrodes. . Conventionally, an organic electrolytic solution has been used as an electrolyte in a lithium ion secondary battery. However, the organic electrolyte is liable to leak, and there is a possibility that a short circuit may occur inside the battery due to overcharging or overdischarging, and there is a need for further improvement in reliability and safety.
Under such circumstances, development of an all-solid secondary battery using non-combustible inorganic solid electrolytes in place of organic electrolytes is in progress. In all solid secondary batteries, all of the negative electrode, electrolyte and positive electrode are solid, which can greatly improve the safety and reliability of the battery using organic electrolyte solution, and also can extend the life. It will be.

In the lithium ion secondary battery, electrons move from the positive electrode to the negative electrode during charging, and at the same time lithium ions are released from lithium oxide or the like constituting the positive electrode, and the lithium ions reach the negative electrode through the electrolyte and Stored in In this way, a part of lithium ions stored in the negative electrode takes in electrons and precipitates as metal lithium. When the metal lithium precipitates grow in a dendritic shape due to repeated charge and discharge, they eventually reach the positive electrode, causing an internal short circuit and failing to function as a secondary battery. Dendrite is very thin and can grow through cracks or pinholes or the like in the solid electrolyte layer even in an all solid secondary battery using a solid as an electrolyte. Therefore, preventing growth of dendrite even in the all solid secondary battery is important for prolonging the life of the battery.
In order to address the problem of internal short circuiting due to dendrite, Patent Document 1 describes a technique in which a single sulfur is excessively added to a solid electrolyte layer to inhibit the growth of dendrite by the single sulfur. In the technology described in Patent Document 1, since the solid electrolyte layer is formed using a mixture in which single sulfur is uniformly dispersed in solid electrolyte powder, the solid electrolyte layer is formed of a mixture of single sulfur powder and solid electrolyte powder. Form.

International Publication No. 2011/010552

The technique described in Patent Document 1 aims at preventing the growth of the dendrite from the negative electrode to the positive electrode. However, as a result of repeated investigations by the present inventor, expansion and contraction of the active material is repeated by repeating charge and discharge of the all solid secondary battery, and the battery capacity is lowered by the dendrite gradually protruding from the end of the battery element It turns out that there is a case. Then, it has been found that the protruding dendrite may cause a short circuit with the positive electrode and the battery outer package.
In the present inventors, when the all-solid battery is subjected to crushing load and the battery outer package is deformed and cracks or the like occur in the battery outer package, water gradually gradually flows from the end of the negative electrode layer or the positive electrode layer to the inside. We also focused on the possibility of contamination. When a sulfide-based electrolyte is used as the solid electrolyte, there is a concern that water and the electrolyte react to generate toxic hydrogen sulfide.

In the present invention, dendrites such as metallic lithium can be prevented from gradually sticking out from the electrode end to suppress a decrease in battery capacity, and all short circuits due to contact between dendrite and a positive electrode or battery outer body can be prevented. It is an object of the present invention to provide a solid secondary battery and a method of manufacturing the same. Further, according to the present invention, even when a crack or the like is generated in the battery outer package due to the crush load being applied to the all solid battery, the generation of hydrogen sulfide (H ₂ S) can be effectively prevented by the intrusion of water. It is an object of the present invention to provide an all-solid secondary battery that can Another object of the present invention is to provide a solid electrolyte sheet for an all solid secondary battery and a positive electrode active material sheet for an all solid secondary battery, which make it possible to obtain the all solid secondary battery.

As a result of intensive studies conducted by the inventor in view of the above problems, the phenomenon that dendrite deposited and grown from the negative electrode due to repeated charging and discharging flows out from the end of the battery is at least a specific inorganic insulation of the battery end. It can be effectively blocked by coating with a coating. As a result, it has been found that a decrease in battery capacity can be suppressed and an internal short circuit can be sufficiently suppressed. In addition, it has been conceived that the coating of the battery end can prevent the entry of moisture into the electrolyte even when a crack or the like is generated in the battery outer package. It has been found that the generation of hydrogen sulfide can be suppressed. The present invention has been further studied based on these findings and has been completed.

That is, the above-mentioned subject was solved by the following means.
[1]
An all solid secondary battery having battery element members, comprising:
The battery component member has at least a negative electrode current collector, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector,
The all-solid-state secondary battery which covers the edge part of the said battery element member at least the edge part of the said battery element member, and the inorganic insulating coating which has a Young's modulus at 25 degreeC 1 GPa or more is distribute | arranged.
[2]
The all-solid-state secondary battery as described in [1] which has the battery exterior body by which the said battery element member is inserted in the inside.
[3]
The above-mentioned inorganic insulating covering includes the inorganic insulating particles and a melt-solidified insulating inorganic material which is solid at 100 ° C. and melts in a temperature range of 200 ° C. or less. [1] or [2] Secondary battery.
[4]
The all-solid secondary battery according to [3], wherein the inorganic insulating covering contains an organic binder.
[5]
The all-solid secondary battery according to [3] or [4], wherein the inorganic insulating particles are aluminum oxide having a volume average particle size of 1 μm or less.
[6]
The all-solid secondary battery according to any one of [1] to [5], wherein the insulating inorganic material contains sulfur and / or reformed sulfur.
[7]
The all-solid secondary battery according to any one of the above [1] to [6], wherein the inorganic insulating covering prevents growth of metallic lithium growing from the negative electrode end during charge and discharge.
[8]
Placing a battery element member including at least a negative electrode current collector, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector in the battery case;
Arranging inorganic insulating particles and an insulating inorganic material which is solid at 100 ° C. and melts in a temperature range of 200 ° C. or less in an end portion of the battery element member in a space in the battery case;
And C. heating the battery casing in a temperature range of 200 ° C. or less to melt and then solidify the inorganic insulating covering to cover the end of the battery element member [1] to [1] The manufacturing method of the all-solid-state secondary battery as described in any one of 7].
[9]
It is a solid electrolyte sheet used for the all-solid-state secondary battery as described in any one of [1]-[7],
A solid electrolyte layer, and an inorganic insulating coating covering the end of the solid electrolyte layer,
The inorganic insulating covering is a solid electrolyte sheet for an all solid secondary battery having a Young's modulus at 25 ° C. of 1 GPa or more.
[10]
The all-solid secondary battery according to [9], wherein the inorganic insulating covering comprises inorganic insulating particles and a melt-solidified insulating inorganic material which is solid at 100 ° C. and melts in a temperature range of 200 ° C. or less Solid electrolyte sheet.
[11]
[10] The solid electrolyte sheet for an all solid secondary battery according to [10], wherein the insulating inorganic material comprises sulfur and / or modified sulfur.
[12]
The above-mentioned inorganic insulating covering includes an organic binder, The solid electrolyte sheet for an all-solid secondary battery according to any one of [9] to [11].
[13]
The solid electrolyte sheet for all solid secondary battery according to any one of [10] to [12], wherein the inorganic insulating particles are aluminum oxide.
[14]
It is a positive electrode active material sheet for use in the all solid secondary battery according to any one of [1] to [7],
A positive electrode active material layer, and an inorganic insulating covering covering both ends of the positive electrode active material layer;
The said inorganic insulating covering is a positive electrode active material sheet for an all solid secondary battery having a Young's modulus at 25 ° C. of 1 GPa or more.
[15]
[14] The positive electrode active material sheet for an all-solid secondary battery according to [14], wherein the inorganic insulating covering includes inorganic insulating particles and an insulating inorganic material which is solid at 100 ° C. and melts at 200 ° C. or less.
[16]
[15] The positive electrode mixture layer for an all solid secondary battery according to [15], wherein the insulating inorganic material contains sulfur and / or modified sulfur.
[17]
The said inorganic insulation coating body is a positive electrode active material sheet for all the solid secondary batteries as described in [15] or [16] containing an organic binder.
[18]
The positive electrode active material sheet for an all solid secondary battery according to any one of [15] to [17], wherein the inorganic insulating particles are aluminum oxide.

In the present invention, a numerical range represented using “to” means a range including the numerical values described before and after “to” as the lower limit value and the upper limit value.

The all solid secondary battery of the present invention can effectively prevent the outgrowth of dendrite from the end of the battery element member during charge and discharge to suppress the reduction of the battery capacity, and further, the dendrite and the positive electrode or battery outer package It is possible to prevent a short circuit due to contact with the Furthermore, even if a crushing load is applied to the all solid secondary battery and a crack or the like is generated in the battery, the generation of hydrogen sulfide (H ₂ S) can be suppressed.
Further, according to the manufacturing method of the all solid secondary battery of the present invention, the protrusion of the dendrite from the end of the battery element member is effectively prevented at the time of charging to suppress the decrease of the battery capacity, and the dendrite and the positive electrode or the battery exterior It is possible to obtain an all solid secondary battery that prevents a short circuit with the body. Furthermore, even when a crushing load is applied to the all solid secondary battery and a crack or the like is generated in the battery, it is possible to obtain an all solid secondary battery in which the generation of hydrogen sulfide (H ₂ S) is suppressed.
Furthermore, the solid electrolyte sheet for all solid secondary batteries and the positive electrode active material sheet for all solid secondary batteries of the present invention can be suitably used as a member (layer) of the all solid secondary battery of the present invention.

The above and other features and advantages of the present invention will become more apparent from the following description and the accompanying drawings.

FIG. 1 is a longitudinal sectional view schematically showing a basic configuration of a general all-solid secondary battery. FIG. 3 is a longitudinal sectional view schematically showing a cylindrical all solid secondary battery according to a preferred embodiment of the present invention and an enlarged sectional view of a portion A in FIG. 2.

In the all solid secondary battery of the present invention, the battery element member end is covered with the inorganic insulating covering, and the inorganic insulating covering effectively prevents the growth of dendrites that are going to protrude from the battery element member end. can do. In the present invention, "insulation" refers to having electronic insulation, that is, the property of not letting electrons pass. Further, in the present invention, when referring to “insulation”, “insulation” or “electronic insulation”, the material preferably has a conductivity of 10 ⁻⁹ S (Siemens) / cm or less at a measurement temperature of 25 ° C.
Hereinafter, a preferred embodiment of the present invention will be described with reference to FIGS.

[All solid secondary battery]
FIG. 1 shows the basic configuration of a general all-solid secondary battery. As shown in FIG. 1, the all-solid secondary battery 10 of the present embodiment is viewed from the negative electrode side, the negative electrode current collector 1, the negative electrode active material layer 2, the solid electrolyte layer 3, the positive electrode active material layer 4 and the positive electrode current collector It has a structure in which the bodies 5 are stacked in this order. Adjacent layers in each layer are in direct contact with each other.
According to the above structure, at the time of charge, electrons (e ⁻ ) are supplied to the negative electrode side, and at the same time, the alkali metal or alkaline earth metal constituting the positive electrode active material is ionized. The ionized ions move (conduct) through the solid electrolyte layer 3 and are accumulated in the negative electrode. For example, in a lithium ion secondary battery, lithium ions (Li ⁺ ) are accumulated at the negative electrode.
At the time of discharge, the above-mentioned alkali metal ion or alkaline earth metal ion accumulated in the negative electrode is returned to the positive electrode side, and supplies electrons to the operating portion 6. In the illustrated example, a light bulb is employed at the operation site 6 and is turned on by discharge.

In the all solid secondary battery of the present invention, it is also preferable that the solid electrolyte layer 3 and the negative electrode current collector 1 be in direct contact with each other without the negative electrode active material layer 2. In the all solid secondary battery of this embodiment, a phenomenon in which part of alkali metal ions or alkaline earth metal ions accumulated in the negative electrode during charging is combined with electrons and deposited as metal on the surface of the negative electrode current collector is utilized. That is, the all solid secondary battery of this embodiment causes the metal deposited on the negative electrode surface to function as a negative electrode active material layer. For example, metallic lithium is said to have a theoretical capacity of 10 times or more as compared with graphite generally used as a negative electrode active material. Therefore, by depositing metallic lithium on the negative electrode and pressing the deposited metallic lithium against the solid electrolyte layer, a layer of metallic lithium can be formed on the surface of the current collector, resulting in high capacity and high energy density. It will be possible to realize a secondary battery.
Further, in the all solid secondary battery in a form in which the negative electrode active material layer is removed, when the battery is in a form of a roll and the battery is thin, generation of cracks or the like in the solid electrolyte layer occurs. There is also an advantage that it is possible to reduce the In addition, since the number of turns can be increased, the battery capacity can be increased.
In the present invention, the all solid secondary battery having no negative electrode active material layer means that the negative electrode active material layer is not formed in the layer formation step in battery manufacture. Then, as described above, the negative electrode active material layer is formed between the solid electrolyte layer and the negative electrode current collector by charging.

As shown in FIG. 2, the cylindrical all solid secondary battery 30 realizes the layer configuration shown in FIG. 1 in a cylindrical form. In the cylindrical all solid secondary battery 30, power generation elements having the layer configuration shown in FIG. 1 as a basic unit are arranged in a laminated manner around the axis 22, and the battery element member 21 is formed by this laminated body. Is configured. That is, the battery element member 21 includes at least the negative electrode current collector 21 d, the solid electrolyte layer 21 a, the positive electrode active material layer 21 c, and the positive electrode current collector 21 b. In the embodiment shown in FIG. 2, the power generation element in which the negative electrode current collector 21d, the negative electrode active material layer 21e, the solid electrolyte layer 21a, the positive electrode active material layer 21c and the positive electrode current collector 21b are laminated in this order is multilayered. It is In this cylindrical all solid secondary battery 30, two power generation elements in contact with each other share one current collector. That is, a negative electrode active material layer is provided on both sides of one current collector, and a positive electrode active material layer is provided on both sides of one current collector.
Furthermore, the cylindrical all solid secondary battery 30 may be provided with a battery cover 23 which becomes a battery outer package if necessary.
In the battery cover 23, the inorganic insulating covering 24 which covers at least the end of the battery element member 21 and which has a Young's modulus at 25 ° C. of 1 GPa or more is disposed.
Furthermore, the positive electrode current collector 21b of the battery element member 21 is connected to the battery positive electrode through the positive electrode tab 25 electrically connected, and the negative electrode current collector 21d of the battery element member 21 is electrically connected the negative electrode tab 27. It is connected to the battery negative electrode 28 via the same.
By forming the laminated structure shown in FIG. 2, it is possible to achieve high battery capacity.

In the all solid secondary battery of the present invention, the thicknesses of the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer are not particularly limited. The thickness of each layer is preferably 10 to 1000 μm, and more preferably 20 μm or more and less than 500 μm, in consideration of general battery dimensions.

In the present invention, the positive electrode active material layer and the negative electrode active material layer may be collectively referred to as an electrode layer. The positive electrode active material layer contains a positive electrode active material, and the negative electrode active material layer contains a negative electrode active material. The term “active material” or “electrode active material” may be used simply to indicate either the positive electrode active material or the negative electrode active material, or to indicate both. The solid electrolyte layer usually does not contain a positive electrode active material and / or a negative electrode active material. The inorganic solid electrolyte constituting the solid electrolyte layer or the combination of the inorganic solid electrolyte constituting the solid electrolyte layer and the active material is referred to as an inorganic solid electrolyte material.

(Inorganic insulating coating)
The inorganic insulating covering has inorganic insulating particles and an insulating inorganic material. The insulating inorganic material is an inorganic material having electronic insulating properties and being solid at 100 ° C. (that is, having a melting point of over 100 ° C.), and having physical properties such as heat melting in a temperature range of 200 ° C. or less. “To thermally melt in a temperature range of 200 ° C. or less” means to thermally melt in a temperature range of 200 ° C. or less at 1 atm.
By using this insulating inorganic material, it can be easily heated to a temperature at which the insulating inorganic material melts. By this heating, the molten insulating inorganic material spreads so as to cover the end of the battery element member. At the same time, it is also possible to move the molten insulating inorganic material to the gaps in the battery element member by capillary action. Then, by cooling and solidifying the insulating inorganic material, it is possible to create a state in which the electronically insulating material is coated, with virtually no gap along the shape of the battery element member end.
That is, in the all-solid secondary battery of the present invention, the inorganic insulating covering is formed using a hot-melt coagulant of an insulating inorganic material which is heat-melted in a solid state at 100 ° C. and at a temperature of 200 ° C. or less. It is a thing.

In the present invention, the inorganic insulating coating is preferably made of a material harder than dendrite in the solid state in order to prevent the growth of dendrite. Therefore, in the present invention, the Young's modulus of the inorganic insulating covering is 1 GPa or more, and preferably 4 to 400 GPa.
Sulfur and / or modified sulfur, iodine, a mixture of iodine and sulfur, etc. may be mentioned as the above-mentioned insulating inorganic material constituting the above-mentioned inorganic insulating covering, and sulfur and / or modified sulfur can be suitably used. . Sulfur which can be used as the insulating inorganic material means elemental sulfur itself.
Further, the reformed sulfur is obtained by kneading the sulfur and the modifier. For example, pure sulfur and an olefin-based polymer which is a reforming additive can be kneaded to obtain a modified sulfur in which a part of the sulfur is reformed into a sulfur polymer. In addition, although modified sulfur may contain an organic polymer, "modified sulfur" shall be contained in an inorganic material in this invention. The presence of sulfur or modified sulfur in the inorganic insulating coating can more effectively block dendrites (alkali metals or alkaline earth metals) that have been grown on the inorganic insulating coating.

Moreover, when dendrite and sulfur come in contact, dendrite and sulfur react. For example, when metallic lithium dendrite contacts sulfur, a reaction of 2Li + S → Li ₂ S occurs, and the growth of dendrite stops in the inorganic insulating covering. By this reaction, the reaction product also coexists in the inorganic insulating coating. This reaction product is an electron-insulating compound harder than dendrite metal, and thus can prevent dendrite growth. That is, it is also preferable that the said inorganic insulation coating body is a form containing the compound containing the alkali metal and / or the compound containing alkaline-earth metal which arose by said reaction. By taking such a form, the volume of the inorganic insulating covering is expanded, and an effect of closing a slight gap between particles in the inorganic insulating covering or between the inorganic insulating covering and the battery element member can be expected. Therefore, the inorganic insulating covering can reliably cover the end of the battery element member.
The content of the insulating inorganic material in the inorganic insulating covering is preferably 5 to 50% by mass, more preferably 10 to 50% by mass, and still more preferably 10 to 20% by mass.

The inorganic insulating covering may contain an organic binder. By containing an organic binder, the binding property of particles can be enhanced, and a more coherent layer structure can be obtained, which is preferable.

(Organic binder)
An organic polymer is mentioned as said organic binder. For example, an organic binder made of a resin described below is preferably used.

Examples of the fluorine-containing resin include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and a copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP).
Examples of the hydrocarbon-based thermoplastic resin include polyethylene, polypropylene, styrene butadiene rubber (SBR), hydrogenated styrene butadiene rubber (HSBR), butylene rubber, acrylonitrile-butadiene rubber, polybutadiene, and polyisoprene.
As the acrylic resin, various (meth) acrylic monomers, (meth) acrylamide monomers, and copolymers of monomers constituting these resins (preferably, copolymers of acrylic acid and methyl acrylate) may be mentioned. Be
In addition, copolymers (copolymers) with other vinyl monomers are also suitably used. For example, a copolymer of methyl (meth) acrylate and styrene, a copolymer of methyl (meth) acrylate and acrylonitrile, and a copolymer of butyl (meth) acrylate, acrylonitrile and styrene can be mentioned. In the present specification, the copolymer may be either a statistical copolymer or a periodic copolymer, and a block copolymer is preferred.
Examples of other resins include polyurethane resin, polyurea resin, polyamide resin, polyimide resin, polyester resin, polyether resin, polycarbonate resin, and cellulose derivative resin.
One of these may be used alone, or two or more of these may be used in combination.

The above-mentioned resin is selected as the above-mentioned organic binder for the suppression of exfoliation from the current collector and the improvement of the cycle life by the binding of the solid interface, which exhibit strong binding properties. That is, at least one selected from the group consisting of an acrylic resin, a polyurethane resin, a polyurea resin, a polyimide resin, a fluorine-containing resin, and a hydrocarbon-based thermoplastic resin is preferable.

The organic binder preferably has a polar group in order to enhance wettability and adsorption to the particle surface. The polar group is preferably a monovalent group containing a hetero atom, for example, a monovalent group containing a structure in which a hydrogen atom is bonded to any of an oxygen atom, a nitrogen atom and a sulfur atom, and a specific example is a carboxy group Examples include hydroxy, amino, phosphate and sulfo.

The average particle diameter of the organic binder is preferably 10 nm to 30 μm, and more preferably 10 to 1000 nm.

10,000 or more are preferable, as for the weight average molecular weight (Mw) of the said organic binder, 20,000 or more are more preferable, and 30,000 or more are still more preferable. As an upper limit, 1,000,000 or less is preferable, 200,000 or less is more preferable, 100,000 or less is still more preferable.
When the inorganic insulating covering contains an organic binder, the content of the organic binder in the inorganic insulating covering is preferably 0.5 to 6% by mass, and more preferably 1 to 3% by mass.

In the present invention, the inorganic insulating covering preferably contains, in addition to the insulating inorganic material, inorganic insulating particles different from the insulating inorganic material. The inorganic insulating particles also have the function of blocking the growth of dendrites. Examples of the inorganic insulating particles include aluminum oxide, zirconium oxide, silicon oxide, zeolite, cubic boron nitride, hexagonal boron nitride, and cerium oxide. The inorganic insulating particles are usually fine particles, and the volume average particle diameter thereof is preferably 1 μm or less, more preferably 700 nm or less. The presence of these materials in the inorganic insulating coating makes it easy for the thermal melt to infiltrate into the gaps of the inorganic insulating coating by capillary action, making it possible to have a high dendrite resistance with less gaps.
In the inorganic insulating covering, the content of the inorganic insulating particles is preferably 50 to 90% by mass, and more preferably 70 to 85% by mass.

(Solid electrolyte layer)
The solid electrolyte layer of the present invention contains an inorganic solid electrolyte material. The inorganic solid electrolyte material constituting the solid electrolyte layer is an inorganic solid electrolyte, or a mixture of an inorganic solid electrolyte and an active material, and is usually made of an inorganic solid electrolyte. The preferred form of the inorganic solid electrolyte is described below. The active material will be described later.

The inorganic solid electrolyte is an inorganic solid electrolyte, and the solid electrolyte is a solid electrolyte capable of transferring ions in its inside. An organic solid electrolyte (a polymer electrolyte represented by polyethylene oxide (PEO) or the like, an organic electrolyte represented by lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) or the like because it does not contain an organic substance as a main ion conductive material It is clearly distinguished from electrolyte salt). In addition, since the inorganic solid electrolyte is solid in a steady state, it is not usually dissociated or released into cations and anions. In this respect, it is also clearly distinguished from inorganic electrolyte salts (LiPF ₆ , LiBF ₄ , LiFSI, LiCl, etc.) in which cations and anions are dissociated or liberated in the electrolytic solution or polymer. The inorganic solid electrolyte is not particularly limited as long as it has ion conductivity of a metal belonging to

periodic group

1 or 2 and is generally non-electron conductive.

In the present invention, the inorganic solid electrolyte has the ion conductivity of a metal belonging to

Group

1 or 2 of the periodic table. As the inorganic solid electrolyte, a solid electrolyte material to be applied to this type of product can be appropriately selected and used. As the inorganic solid electrolyte, generally (i) a sulfide-based inorganic solid electrolyte and / or (ii) an oxide-based inorganic solid electrolyte is used.

(I) Sulfide-Based Inorganic Solid Electrolyte The sulfide-based inorganic solid electrolyte contains a sulfur atom (S), has ion conductivity of a metal belonging to

periodic group

1 or 2 and is an electron. Those having insulating properties are preferred. The sulfide-based inorganic solid electrolyte contains at least Li, S and P as elements and preferably has lithium ion conductivity, but depending on the purpose or case, other than Li, S and P. It may contain an element.
For example, a lithium ion conductive inorganic solid electrolyte satisfying the composition represented by the following formula (I) can be mentioned.

L _a1 M _b1 P _c1 S _d1 A _e1 formula (I)

In the formula, L represents an element selected from Li, Na and K, and Li is preferred. M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al and Ge. A represents an element selected from I, Br, Cl and F. a1 to e1 represent composition ratios of respective elements, and a1: b1: c1: d1: e1 satisfies 1 to 12: 0 to 5: 1: 2 to 12: 0 to 10. Further, a1 is preferably 1 to 9, and more preferably 1.5 to 7.5. b1 is preferably 0 to 3. Furthermore, 2.5 to 10 is preferable, and 3.0 to 8.5 is more preferable. Further, 0 to 5 is preferable, and 0 to 3 is more preferable.

The composition ratio of each element can be controlled by adjusting the compounding amount of the raw material compound at the time of producing a sulfide-based inorganic solid electrolyte as described below.

The sulfide-based inorganic solid electrolyte may be non-crystalline (glass) or crystallized (glass-ceramicized), or only part of it may be crystallized. For example, a Li—P—S-based glass containing Li, P and S, or a Li—P—S-based glass ceramic containing Li, P and S can be used.
The sulfide-based inorganic solid electrolyte includes, for example, lithium sulfide (Li ₂ S), phosphorus sulfide (for example, diphosphorus pentasulfide (P ₂ S ₅ )), single phosphorus, single sulfur, sodium sulfide, hydrogen sulfide, lithium halide (for example, It can be produced by the reaction of at least two or more of LiI, LiBr, LiCl) and sulfides of elements represented by the above M (for example, SiS ₂ , SnS, GeS ₂ ).

The ratio of Li ₂ S to P ₂ S _{5 in the} Li-P-S-based glass and Li-P-S-based glass ceramic is preferably a molar ratio of Li ₂ S: P ₂ S ₅ of 60:40 to 90:10, more preferably 68:32 to 78:22. By setting the ratio of Li ₂ S to P ₂ S ₅ in this range, the lithium ion conductivity can be made high. Specifically, the lithium ion conductivity can be preferably 1 × 10 ⁻⁴ S / cm or more, more preferably 1 × 10 ⁻³ S / cm or more. There is no particular upper limit, but it is practical to be 1 × 10 ⁻¹ S / cm or less.

Examples of combinations of raw materials are shown below as specific examples of the sulfide-based inorganic solid electrolyte. For _{_{_{_{example, Li 2 S-P 2 S}}}} 5, Li 2 S-P 2 S 5 -LiCl, Li 2 S-P 2 S 5 -H 2 S, Li 2 S-P 2 S 5 -H 2 S-LiCl, Li ₂ S-LiI-P ₂ S ₅ , Li ₂ S-LiI-Li ₂ O-P ₂ S ₅ , and Li ₂ S-LiBr-P ₂ S ₅ can be mentioned. The _{_{_{_{Li 2 S-Li 2 O-}}}} P 2 S 5, Li 2 S-Li 3 PO 4 -P 2 S 5, Li 2 S-P 2 S 5 -P 2 O 5, Li 2 S-P 2 S 5 _{_{_{_{-SiS 2, Li 2 S-P}}}} 2 S 5 -SiS 2 -LiCl, Li 2 S-P 2 S 5 -SnS, include _{Li 2 S-P 2 S 5} -Al 2 S 3. Furthermore _{_{_{_{Li 2 S-GeS 2, Li}}}} 2 S-GeS 2 -ZnS, Li 2 S-Ga 2 S 3, Li 2 S-GeS 2 -Ga 2 S 3, Li 2 S-GeS 2 -P 2 S 5, _{_{_{_{Li 2 S-GeS 2 -Sb 2}}}} S 5, Li is _{_{_{2 S-GeS 2 -Al 2 S}}} 3 and the like. Furthermore, Li ₂ S-SiS ₂ , Li ₂ S-Al ₂ S ₃ , Li ₂ S-SiS ₂ -Al ₂ S ₃ , Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI, Li ₂ S-SiS _{_{_{_{2 -LiI, Li 2 S-SiS}}}} 2 -Li 4 SiO 4, Li 2 S-SiS 2 -Li 3 PO 4, Li 10 GeP 2 S 12, and the like. However, the mixing ratio of each raw material does not matter. As a method of synthesizing a sulfide-based inorganic solid electrolyte material using such a raw material composition, for example, an amorphization method can be mentioned. As the amorphization method, for example, any of mechanical milling method, solution method and melting and quenching method can be mentioned. These methods can be processed at normal temperature, and can simplify the manufacturing process.

(Ii) Oxide-Based Inorganic Solid Electrolyte The oxide-based inorganic solid electrolyte contains an oxygen atom (O) and has ion conductivity of a metal belonging to

Periodic Table Group

1 or 2 and And compounds having electron insulating properties are preferred.

As a specific compound example, for example, Li _xa La _ya TiO ₃ [xa = 0.3 to 0.7, ya = 0.3 to 0.7] (LLT) can be mentioned. Further, Li _xb La _yb Zr _z ^Mbb _mb O _nb ( ^Mbb is at least one or more elements selected from Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, Sn, etc. Xb is 5 ≦ xb ≦ 10, yb is 1 ≦ yb ≦ 4, zb is 1 ≦ zb ≦ 4, mb is 0 ≦ mb ≦ 2, and nb is 5 ≦ nb ≦ 20. Further, Li _xc B _yc M ^cc _z c O _nc (M ^cc is at least one or more elements selected from C, S, Al, Si, Ga, Ge, In, Sn, etc., and xc is 0 ≦ xc ≦ 5, yc is 0 ≦ yc ≦ 1, zc is 0 ≦ zc ≦ 1, and nc satisfies 0 ≦ nc ≦ 6, and xc + yc + zc + nc ≠ 0. _{_{Furthermore, Li xd (Al, Ga)}} yd (Ti, Ge) zd Si ad P md O nd (1 ≦ xd ≦ 3,0 ≦ yd ≦ 1,0 ≦ zd ≦ 2,0 ≦ ad ≦ 1,1 ≦ md ≦ 7 and 3 ≦ nd ≦ 13), Li _(3-2xe) M ^ee _xe D ^ee O (xe represents a number of 0 or more and 0.1 or less, M ^ee represents a divalent metal atom, D ^ee Represents a halogen atom or a combination of two or more types of halogen atoms. Furthermore, Li _xf Si _yf O _zf (1 ≦ xf ≦ 5, 0 <yf ≦ 3, 1 ≦ zf ≦ 10), Li _xg S _yg O _zg (1 ≦ xg ≦ 3, 0 <yg ≦ 2, 1 ≦ zg ≦ 10), Li ₃ BO ₃ -Li ₂ SO ₄ , Li ₂ O-B ₂ O ₃ -P ₂ O ₅ , Li ₂ O-SiO ₂ , Li ₆ BaLa ₂ Ta ₂ O ₁₂ , Li ₃ PO ₍₄ -3/2 w ₎ N _w (w is <1), Li _3.5 Zn _0.25 GeO ₄ having a LISICON (Lithium superionic conductor) type crystal structure, La _0.55 Li ₀ having a perovskite type crystal structure _{_{_{.35 TiO 3, NASICON LiTi 2 P}}} 3 O 12 having a (Natrium super ionic conductor) crystal structure, _{Li 1 + xh + yh} _{_{Al, Ga) xh (Ti,}} Ge) 2-xh Si yh P 3-yh O 12 ( provided that, 0 ≦ xh ≦ 1,0 ≦ yh ≦ 1), Li 7 having a garnet-type crystal structure _La 3 _Zr 2 O ₁₂ (LLZ) and the like. Also desirable are phosphorus compounds containing Li, P and O. For example, lithium phosphate (Li ₃ PO ₄ ), LiPON in which part of oxygen of lithium phosphate is replaced by nitrogen, LiPOD ¹ (D ¹ is Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr And at least one selected from Nb, Mo, Ru, Ag, Ta, W, Pt, Au and the like. Further, LiA ¹ ON (A ¹ is at least one selected from Si, B, Ge, Al, C, Ga, etc.) and the like can also be preferably used.

The particle size (volume average particle size) of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.1 μm or more. The upper limit is preferably 100 μm or less, more preferably 50 μm or less. In addition, the measurement of the average particle diameter of inorganic solid electrolyte particle | grains is performed in the following procedures. The inorganic solid electrolyte particles are diluted with water (heptane for water labile substances) in a 20 ml sample bottle to dilute a 1% by weight dispersion. The diluted dispersed sample is irradiated with 1 kHz ultrasound for 10 minutes, and used immediately thereafter for the test. Using this dispersion liquid sample, using a laser diffraction / scattering particle size distribution analyzer LA-920 (manufactured by HORIBA), data acquisition is carried out 50 times using a quartz cell for measurement at a temperature of 25 ° C. Get the diameter. For other detailed conditions, etc., refer to the description in JIS Z 8828: 2013 "Particle diameter analysis-dynamic light scattering method" as necessary. Make five samples per level and adopt the average value.

(Positive electrode active material layer)
The positive electrode active material layer 4 contains the inorganic solid electrolyte described above and a positive electrode active material.
The preferable form of a positive electrode active material is demonstrated.

-Positive electrode active material-
The positive electrode active material is preferably one that can reversibly insert and release lithium ions. The material is not particularly limited as long as it has the above characteristics, and may be a transition metal oxide, an organic substance, an element capable of being complexed with Li such as sulfur, a complex of sulfur and a metal, or the like.
Among them, it is preferable to use a transition metal oxide as the positive electrode active material, and a transition metal oxide having a transition metal element M ^a (one or more elements selected from Co, Ni, Fe, Mn, Cu and V) Are more preferred. Further, in this transition metal oxide, an element M ^b (an element of Group 1 (Ia) other than lithium, an element of Group 1 (Ia) of the metal periodic table, an element of Group 2 (IIa), Al, Ga, In, Ge, Sn, Pb, Elements such as Sb, Bi, Si, P or B may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the amount (100 mol%) of the transition metal element M ^a . It is more preferable to be synthesized by mixing so that the molar ratio of Li / Ma is 0.3 to 2.2.
Specific examples of the transition metal oxide include a transition metal oxide having a (MA) layered rock salt type structure, a transition metal oxide having a (MB) spinel type structure, a (MC) lithium-containing transition metal phosphate compound, (MD And the like) lithium-containing transition metal halogenated phosphoric acid compounds and (ME) lithium-containing transition metal silicate compounds.

As specific examples of transition metal oxides having a layered rock salt type structure, LiCoO ₂ (lithium cobaltate [LCO]), LiNi ₂ O ₂ (lithium nickelate), LiNi _0.85 Co _0.10 Al _{0. 05} O ₂ (lithium nickel cobalt aluminate [NCA]), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (lithium nickel manganese cobaltate [NMC]) and LiNi _0.5 Mn _0.5 O ₂ ( And lithium manganese nickelate).
Specific examples of transition metal oxides having a (MB) spinel structure include LiMn ₂ O ₄ (LMO), LiCoMnO _4, Li ₂ FeMn ₃ O ₈ , Li ₂ CuMn ₃ O ₈ , Li ₂ CrMn ₃ O ₈ and Li ₂ NiMn ₃ O ₈ and the like.
Examples of (MC) lithium-containing transition metal phosphate compounds include olivine-type iron phosphates such as LiFePO ₄ and Li ₃ Fe ₂ (PO ₄ ) ₃ , iron pyrophosphates such as LiFeP ₂ O ₇ , LiCoPO ₄ etc. And cobalt salts of monoclinic Nasacon-type vanadium phosphate such as Li ₃ V ₂ (PO ₄ ) ₃ (lithium vanadium phosphate).
(MD) as the lithium-containing transition metal halogenated phosphate compound, for _example, Li 2 FePO ₄ F such fluorinated phosphorus iron _salt, Li 2 MnPO ₄ hexafluorophosphate manganese salts such as F and _Li 2 CoPO ₄ F And cobalt fluoride phosphates.
Examples of the (ME) lithium-containing transition metal silicate compound include Li ₂ FeSiO ₄ , Li ₂ MnSiO ₄ and Li ₂ CoSiO ₄ .
In the present invention, transition metal oxides having a (MA) layered rock salt type structure are preferred, and LCO, LMO, NCA or NMC are more preferred.

The shape of the positive electrode active material is not particularly limited, but is preferably in the form of particles. The volume average particle diameter (sphere conversion average particle diameter) of the positive electrode active material is not particularly limited. For example, it can be 0.1 to 50 μm. In order to make the positive electrode active material have a predetermined particle diameter, a usual pulverizer or classifier may be used. The positive electrode active material obtained by the firing method may be used after washing with water, an acidic aqueous solution, an alkaline aqueous solution and an organic solvent. The volume average particle size (sphere-equivalent average particle size) of the positive electrode active material particles can be measured using a laser diffraction / scattering type particle size distribution measuring apparatus LA-920 (trade name, manufactured by HORIBA).

The positive electrode active materials may be used alone or in combination of two or more.
When forming a positive electrode active material layer, the mass (mg) (area weight) of the positive electrode active material per unit area (cm ² ) of the positive electrode active material layer is not particularly limited. It can be determined appropriately depending on the designed battery capacity.

The content of the positive electrode active material in the positive electrode active material layer is not particularly limited, and is preferably 10 to 95% by mass, more preferably 30 to 90% by mass, still more preferably 50 to 85% by mass, and 55 to 80% by mass Is particularly preferred.

(Anode active material layer)
The negative electrode active material layer 2 contains the above-mentioned inorganic solid electrolyte and a negative electrode active material. As described above, it is also preferable that the all-solid-state secondary battery of the present invention does not form the negative electrode active material layer in advance.
The preferable form of a negative electrode active material is demonstrated.

-Negative electrode active material-
It is preferable that the negative electrode active material be capable of reversibly storing and releasing lithium ions. The material is not particularly limited as long as it has the above-mentioned characteristics. The materials include carbonaceous materials, metal oxides such as tin oxide, silicon oxides, metal complex oxides, lithium alone such as lithium and lithium aluminum alloys, and lithium and alloys such as Sn, Si, Al and In. The metal etc. which can be formed are mentioned. Among them, carbonaceous materials or lithium composite oxides are preferably used from the viewpoint of reliability. Moreover, as a metal complex oxide, it is preferable that lithium can be occluded and released. The material is not particularly limited, but it is preferable in view of high current density charge and discharge characteristics that titanium and / or lithium is contained as a component.

The carbonaceous material used as the negative electrode active material is a material substantially consisting of carbon. For example, various kinds of synthesis such as petroleum pitch, carbon black such as acetylene black (AB), graphite (natural graphite, artificial graphite such as vapor grown graphite etc.), and PAN (polyacrylonitrile) resin and furfuryl alcohol resin etc. The carbonaceous material which baked resin can be mentioned. Furthermore, various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA (polyvinyl alcohol) -based carbon fiber, lignin carbon fiber, glassy carbon fiber and activated carbon fiber The kind can be mentioned. Mention may also be made of mesophase microspheres, graphite whiskers and flat graphite.

As the metal oxide and the metal complex oxide applied as the negative electrode active material, an amorphous oxide is particularly preferable, and chalcogenide which is a reaction product of a metal element and an element of Periodic Group 16 is also preferably used. Be The term "amorphous" as used herein means an X-ray diffraction method using a CuKα ray having a broad scattering band having a peak in the region of a diffraction angle 2θ of 20 ° to 40 °, and is a crystalline diffraction. It may have a line.

Among the group of compounds consisting of the above amorphous oxides and chalcogenides, amorphous oxides of semimetal elements and chalcogenides are more preferable. In particular, one or a combination of two or more thereof selected from elements of groups 13 (IIIA) to 15 (VA) of the periodic table, Al, Ga, Si, Sn, Ge, Pb, Sb and Bi And oxides consisting of and chalcogenides are preferred. Specific examples of preferred amorphous oxides and chalcogenides include Ga ₂ O ₃ , SiO, GeO, SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₈ Bi ₂ O ₃ , Sb ₂ O ₈ Si ₂ O ₃ , Bi ₂ O ₄ , SnSiO ₃ , SnSiO ₃ , GeS, SnS, SnS ₂ , PbS, PbS ₂ , Sb ₂ S ₃ , Sb ₂ S ₅ and SnSiS ₃ . They may also be complex oxides with lithium oxide, such as Li ₂ SnO ₂ .

The negative electrode active material also preferably contains a titanium atom. More specifically, Li ₄ Ti ₅ O ₁₂ (lithium titanate [LTO]) is excellent in rapid charge / discharge characteristics because the volume fluctuation at the time of lithium ion absorption and release is small, and the deterioration of the electrode is suppressed, and lithium ion secondary It is preferable at the point which the lifetime improvement of a battery is attained.

In the present invention, it is also preferable to apply a Si-based negative electrode. In general, a Si negative electrode can store more Li ions than a carbon negative electrode (graphite, acetylene black, etc.). That is, the storage amount of Li ions per unit mass increases. Therefore, the battery capacity can be increased. As a result, there is an advantage that the battery operating time can be extended.

The shape of the negative electrode active material is not particularly limited, but is preferably in the form of particles. The particle diameter (volume average particle diameter) of the negative electrode active material is preferably 0.1 to 60 μm. In order to obtain a predetermined particle size, a usual pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling flow jet mill, a sieve and the like are suitably used. At the time of pulverization, wet pulverization in the presence of water or an organic solvent such as methanol can also be carried out as necessary. It is preferable to carry out classification in order to obtain a desired particle size. The classification method is not particularly limited, and a sieve, an air classifier or the like can be used as required. Classification can be used both dry and wet. The volume average particle size of the negative electrode active material particles can be measured by the same method as the above-mentioned method of measuring the volume average particle size of the positive electrode active material.

The negative electrode active materials may be used alone or in combination of two or more.
When forming a negative electrode active material layer, the mass (mg) (area weight) of the negative electrode active material per unit area (cm ² ) of the negative electrode active material layer is not particularly limited. It can be determined appropriately depending on the designed battery capacity.

The content of the negative electrode active material in the solid electrolyte composition is not particularly limited, and is preferably 10 to 80% by mass, and more preferably 20 to 80% by mass, with respect to 100% by mass of the solid content.

The electrode surface containing the positive electrode active material or the negative electrode active material may be surface-treated with sulfur or phosphorus. In addition, the particle surface of the positive electrode active material or the negative electrode active material may be subjected to surface treatment with an actinic ray or active gas (such as plasma) before and after the surface coating.

In the all solid secondary battery of the present invention, a lithium salt, a conductive support agent, and a binder (preferably an organic binder which can be contained in the above-mentioned inorganic insulating covering) are preferably used for the solid electrolyte layer, the positive electrode active material layer and the negative electrode active material layer, It is also preferable that a dispersant and the like be included.

[Current collector (metal foil)]
The positive electrode current collector 5 and the negative electrode current collector 1 are preferably electron conductors.
In the present invention, one or both of the positive electrode current collector and the negative electrode current collector may be simply referred to as a current collector.
In addition to aluminum, aluminum alloy, stainless steel, nickel and titanium as materials for forming a positive electrode current collector, aluminum or stainless steel surface treated with carbon, nickel, titanium or silver (a thin film is formed Are preferred. Among these, aluminum and an aluminum alloy are more preferable.
As materials for forming the negative electrode current collector, in addition to aluminum, copper, copper alloy, stainless steel, nickel and titanium etc., carbon, nickel, titanium or silver is treated on the surface of aluminum, copper, copper alloy or stainless steel It is preferable that Among them, aluminum, copper, copper alloy and stainless steel are more preferable.

The shape of the current collector is usually in the form of a film sheet, but a net, a punch, a lath body, a porous body, a foam, a molded body of a fiber group and the like can also be used.
The thickness of the current collector is not particularly limited, but is preferably 1 to 500 μm. Further, it is also preferable to make the current collector surface uneven by surface treatment.

In the present invention, functional layers, members and the like are appropriately interposed or disposed between or outside each layer of the negative electrode current collector, the negative electrode active material layer, the solid electrolyte layer, the positive electrode active material layer and the positive electrode current collector. You may Each layer may be composed of a single layer or multiple layers.

<Method of manufacturing all solid secondary battery>
Although an example of the manufacturing method of the all-solid-state secondary battery of this invention is shown below, the manufacturing method of the all-solid-state secondary battery of this invention is not limited to these forms.
(Aspect in which the entire end of the battery element member is covered with an inorganic insulating coating)
The composition (composition for positive electrode) containing the component which comprises a positive electrode active material layer is apply | coated on a base material (for example, metal foil used as a collector), a positive electrode active material layer is formed, and all-solid secondary A battery positive electrode sheet is produced. Next, a composition containing at least the inorganic solid electrolyte material is applied onto the positive electrode active material layer to form a solid electrolyte layer.
After that, by stacking the negative electrode active material layer and the negative electrode current collector (metal foil) on the solid electrolyte layer, the entire solid having a structure in which the solid electrolyte layer is sandwiched between the positive electrode active material layer and the negative electrode active material layer Get a secondary battery. Then, these battery element members are packed in a housing which is to be a battery outer package.
Next, the mixture of the insulating inorganic material and the inorganic insulating particles described above is disposed at the end of the battery element member in the housing. Then, the insulating inorganic material is heated to a temperature at which it melts (preferably 200 ° C. or less), and the insulating inorganic material melt is spread among the particles constituting the mixture to the end of the battery element member Form an inorganic insulating covering.

In addition, the formation method of each layer is reversed, a negative electrode active material layer, a solid electrolyte layer, and a positive electrode active material layer are formed on the negative electrode current collector, and the positive electrode current collector is stacked to produce an all solid secondary battery. You can also In addition, a laminate of a two-layer structure consisting of a substrate / anode active material layer and a laminate of a three-layer structure consisting of a substrate / a cathode active material layer / a solid electrolyte layer are prepared, and these are superposed to form the present invention. It is also possible to obtain an all solid secondary battery of In addition, a laminate of a two-layer structure consisting of a base material / a positive electrode active material layer and a laminate of a three-layer structure consisting of a base material / a negative electrode active material layer / a solid electrolyte layer are prepared, You can also get

In addition, as described below, (a) only the end of the solid charge lipid layer, (b) only the end of the positive electrode active material layer and the end of the solid charge lipid layer, or (c) the positive electrode collection It may be provided only at the end of the current collector, the end of the positive electrode active material layer, and the end of the solid charge lipid layer. These forms are also preferable as the form of the all-solid secondary battery of the present invention.
(Aspect of covering a part of the end of the battery element member with the inorganic insulating coating)
The composition (composition for positive electrode) containing the component which comprises a positive electrode active material layer is apply | coated on a base material (for example, metal foil used as a collector), a positive electrode active material layer is formed, and all-solid secondary A battery positive electrode sheet is produced. Next, a composition containing at least the inorganic solid electrolyte material is applied onto the positive electrode active material layer to form a solid electrolyte layer. Furthermore, a mixture of the above-described insulating inorganic material and inorganic insulating particles is disposed at both ends of the solid electrolyte layer. The mixture may be formed up to the substrate end and / or the end of the positive electrode active material layer. Then, the insulating inorganic material is heated to a temperature at which it melts (preferably 200 ° C. or less), and the insulating inorganic material melt is spread over the end of the inorganic solid electrolyte material, and also among the particles constituting the mixture. Let Then, an inorganic insulating covering is formed on the end of the solid electrolyte layer, the end of the positive electrode active material layer and the end of the solid electrolyte layer, or the end of the positive electrode current collector, the end of the positive electrode active material layer, and the end of the solid charge lipid layer Do.
Then, on the solid electrolyte layer, a composition containing a component for forming a negative electrode active material layer is applied as a negative electrode material to form a negative electrode active material layer. An all-solid secondary battery having a structure in which a solid electrolyte layer is sandwiched between a positive electrode active material layer and a negative electrode active material layer by overlapping a negative electrode current collector (metal foil) on the negative electrode active material layer Can. If necessary, it can be enclosed in a case that will be a battery outer package to obtain a desired all-solid secondary battery.

Furthermore, a solid electrolyte sheet having an inorganic insulating covering at an end, and / or a positive electrode active material sheet having an inorganic insulating covering at an end, which will be described later, are prepared in advance. Can also be made into the all solid secondary battery of the present invention.

In the above example, the heating for melting the insulating inorganic material is performed immediately after the mixture is placed at the end of interest. Also, the present invention is not limited to this embodiment. That is, heating may be performed at any stage of the manufacturing process of the all-solid secondary battery, as long as the mixture is used and disposed at the desired end. Alternatively, the step of disposing the mixture at the target end may be performed at a temperature higher than the melting temperature of the insulating inorganic material, in which case it is necessary to separately provide a heating step for melting the insulating inorganic material. It may not be.

(How to form each layer)
In the production of the all-solid secondary battery of the present invention, the method of forming the solid electrolyte layer and the active material layer is not particularly limited, and can be appropriately selected. For example, application (preferably wet application), spray application, spin coating application, dip coating, slit application, stripe application and bar coating application can be mentioned.
At this time, a drying process may be performed after application, or a drying process may be performed after multi-layer application. The drying temperature is not particularly limited. The lower limit is preferably 30 ° C. or more, more preferably 60 ° C. or more, and still more preferably 80 ° C. or more. 300 degrees C or less is preferable, 250 degrees C or less is more preferable, and 200 degrees C or less is still more preferable. By heating in such a temperature range, the (C) dispersion medium can be removed to be in a solid state. Moreover, it is preferable because the temperature is not excessively high and the members of the all solid secondary battery are not damaged. Thereby, in the all solid secondary battery, excellent overall performance can be exhibited, and good binding can be obtained.

It is preferable to pressurize the produced all solid secondary battery. A hydraulic cylinder press machine etc. are mentioned as a pressurization method. The pressure is not particularly limited, and in general, the pressure is preferably in the range of 50 to 1,500 MPa.
The applied solid electrolyte composition may be heated simultaneously with pressurization. The heating temperature is not particularly limited, and generally in the range of 30 to 300 ° C. It is also possible to press at a temperature higher than the glass transition temperature of the inorganic solid electrolyte.
The pressurization may be performed in a state where the coating solvent or the dispersion medium is dried in advance, or may be performed in a state where the solvent or the dispersion medium remains.

The atmosphere during pressurization is not particularly limited, and may be under air, under dry air (dew point −20 ° C. or less), under inert gas (eg, in argon gas, in helium gas, in nitrogen gas).
The pressing time may be high pressure for a short time (for example, within several hours), or may be medium pressure for a long time (one day or more). In the case of an all-solid secondary battery other than the all-solid secondary battery sheet, for example, a restraint (screw tightening pressure or the like) of the all-solid secondary battery can also be used to keep applying medium pressure.
The pressing pressure may be uniform or different with respect to a pressure receiving portion such as a sheet surface.
The press pressure can be changed according to the area and film thickness of the pressure-receiving portion. It is also possible to change the same site in stages with different pressures.
The press surface may be smooth or roughened.

In addition, the battery is formed in a sheet shape, and the battery sheet is formed into a cylindrical shape in which the battery sheet is wound in a roll shape around the axial center, and pressure is applied in the axial direction from the outermost layer of the cylindrical battery. You can also.

(Initialize)
The all-solid secondary battery produced as described above is preferably subjected to initialization after production or before use. The method of initialization is not particularly limited. For example, initial charging and discharging may be performed in a state where the press pressure is increased, and then the pressure may be released until the general working pressure of the all solid secondary battery is reached.

<Applications of all solid secondary battery>
The all solid secondary battery of the present invention can be applied to various applications. Although there is no limitation in particular in an application aspect, For example, it is mounted in an electronic device. Examples of the electronic devices include laptop computers, pen-based personal computers, mobile personal computers, electronic book players, mobile phones, cordless handsets, pagers, handy terminals, mobile fax machines, mobile copying machines, mobile printers and the like. It is also installed in audio and visual equipment such as headphone stereos, video movies, LCD TVs, portable CD players, mini disc players, portable tape recorders, radios and the like. Further, as mounted devices, handy cleaners, electric shavers, transceivers, electronic organizers, desk-top computers, memory cards, backup power supplies, etc. may be mentioned. Other consumer products include automobiles, electric vehicles, motors, lighting devices, toys, game machines, road conditioners, watches, strobes, cameras, medical devices (pace makers, hearing aids, shoulder machines, etc.). Furthermore, it can be used for various military and space applications. It can also be combined with a solar cell.

Among them, application to applications requiring high capacity and high rate discharge characteristics is preferable. For example, in a power storage facility or the like expected to have a large capacity in the future, high safety is essential, and further compatibility of battery performance is required. In addition, electric vehicles and the like are equipped with a high-capacity secondary battery, and are expected to be used for daily charging at home. According to the present invention, it is possible to exhibit the excellent effect by suitably corresponding to such a use form.

[Solid electrolyte sheet for all solid secondary battery]
The solid electrolyte sheet for the all solid secondary battery of the present invention (hereinafter, also simply referred to as "the electrolyte sheet of the present invention") is suitably used as a member for providing the solid electrolyte layer of the all solid secondary battery of the present invention. Can. That is, the electrolyte sheet of the present invention has a solid electrolyte layer and an inorganic insulating covering that covers both ends of the solid electrolyte layer. The inorganic insulating covering has a Young's modulus of 1 GPa or more. Such inorganic insulating coverings include those described above.

[Positive Electrode Active Material Sheet for All Solid Secondary Battery]
The positive electrode active material sheet for all solid secondary batteries of the present invention (hereinafter, also simply referred to as "the positive electrode active material sheet of the present invention") is a member for providing the positive electrode active material layer of the all solid secondary battery of the present invention It can be used suitably. That is, the positive electrode active material sheet of the present invention has an inorganic insulating covering that covers both ends of the positive electrode active material layer. This inorganic insulating covering has a Young's modulus of 1 GPa or more. Such inorganic insulating coverings include those described above.

The solid electrolyte sheet can be produced, for example, as follows.
A composition containing the above-mentioned inorganic solid electrolyte material is applied on a substrate (for example, metal foil to be a negative electrode current collector) to form a solid electrolyte layer, and a solid electrolyte sheet for an all solid secondary battery is produced. . Next, a mixture of the above-mentioned insulating inorganic material and inorganic insulating particles is disposed on both ends of the solid electrolyte layer by application. The above mixture may be formed up to the end of the substrate. Then, the insulating inorganic material is heated to a temperature at which it melts (preferably 200 ° C. or less), and the insulating inorganic material melt is spread over the end of the inorganic solid electrolyte material, and also among the particles constituting the mixture. Then, an inorganic insulating covering is formed at the end of the solid electrolyte layer.
Moreover, the said positive electrode active material sheet can be produced as follows, for example.
The composition (composition for positive electrode) containing the component which comprises a positive electrode active material layer is apply | coated on a base material (for example, metal foil used as a collector), a positive electrode active material layer is formed, and all-solid secondary A positive electrode active material sheet for battery is produced. Next, a mixture of the above-described insulating inorganic material and inorganic insulating particles is disposed on both ends of the positive electrode active material layer by application. The above mixture may be formed up to the end of the substrate. Next, the insulating inorganic material is heated to a temperature at which it melts (preferably 200 ° C. or less), and the insulating inorganic material melt is distributed to the end of the positive electrode active material layer, and is dispersed among the particles constituting the mixture. Then, an inorganic insulating covering is formed at the end of the positive electrode active material layer.
The application of the mixture of insulating inorganic materials can be performed, for example, using a dispersion of a mixture of particles of sulfur and aluminum oxide (alumina) dispersed in toluene.

The present invention will be described in more detail based on examples, but the present invention is not limited to these embodiments.

Reference Example 1 Synthesis of Inorganic Solid Electrolyte Lithium sulfide (Li ₂ S, manufactured by Aldrich, purity> 99.98%) 2.42 g, pentasulfide disulphide, in a glove box under an argon atmosphere (dew point −70 ° C.) 3.90 g of phosphorus (P ₂ S ₅ , manufactured by Aldrich, purity> 99%) was individually weighed and placed in an agate mortar. Li ₂ S and P ₂ S ₅ have a molar ratio of Li ₂ S: P ₂ S ₅ = 75: 25. The mixture was mixed for 5 minutes using a pestle made from agate on a mortar made from agate.
66 zirconia beads with a diameter of 5 mm were charged into a 45 mL container made of zirconia (manufactured by Fritsch), the whole mixture was charged, and the container was completely sealed under an argon atmosphere. A container is set in a Fritsch planetary ball mill P-7, and mechanical milling is performed at 25 ° C. and a rotation number of 510 rpm for 20 hours to obtain a yellow powder sulfide-based inorganic solid electrolyte (Li / P / S glass, hereinafter “ Also referred to as “LPS”.) 6.2 g was obtained.
The volume average particle diameter of the obtained LPS was 8 μm as a result of measurement using a laser diffraction / scattering type particle size distribution analyzer LA-920 (trade name, manufactured by HORIBA).

Reference Example 2 Preparation of a Mixture of Sulfur and Inorganic Insulating Particles Under the atmosphere, 1.2 g of sulfur (S, manufactured by Aldrich, purity> 99.98%), aluminum oxide nanoparticles (Al ₂ O ₃ , purity> 99%, particle size 500 nm, 1.2 g manufactured by EM Japan Co., Ltd. were respectively weighed. They were introduced into a mortar made of agate and mixed for 10 minutes using a pestle made of agate.

Production Example Production of All-Solid Secondary Battery In a 45 mL container made of zirconia (180 pieces of zirconia beads with a diameter of 5 mm) were charged, and 2.0 g of LPS synthesized above and styrene butadiene rubber (product code 182907, Then, 0.1 g of Aldrich Co., Ltd. and 22 g of octane as a dispersion medium were charged. Thereafter, this container was set in a Fritsch planetary ball mill P-7, and stirred at a temperature of 25 ° C. at a rotational speed of 300 rpm for 2 hours. Thereafter, 7.9 g of the positive electrode active material LiNi _0.85 Co _0.10 Al _0.05 O ₂ (lithium nickel cobalt aluminum oxide) is charged into a container, and this container is again set in the planetary ball mill P-7, and the temperature 25 Mixing was continued for 15 minutes at 100 ° C. and 100 ° C. Thus, a composition for a positive electrode was obtained.
Next, a composition (composition for positive electrode) containing a component constituting the positive electrode active material obtained above on a 20 μm thick aluminum foil serving as a current collector by a conventional method is combined with 2% by mass of a baker type applicator C. for 2 hours to dry the positive electrode composition. Thereafter, using a heat press, the composition for a positive electrode layer dried to a predetermined density was pressurized (600 MPa, 1 minute) while heating (120 ° C.). Thus, a positive electrode sheet for an all solid secondary battery having a positive electrode active material with a thickness of 110 μm was produced.

Subsequently, the inorganic solid electrolyte prepared according to the above-mentioned reference example 1 was dispersed in toluene at normal temperature together with 2% by mass of a binder to obtain a coating liquid having a solid content of 20% by mass. The coating solution was applied on a positive electrode at a normal temperature by bar coating and heated at 120 ° C. for drying to obtain a solid electrolyte layer having a width of 50 mm and a film thickness of 100 μm.
Then, a 50 mm wide stainless steel (SUS) foil serving as a negative electrode current collector was stacked on the solid electrolyte layer to form a laminate sheet for an all solid secondary battery.
A commercially available insulating separator (50 mm in width) is stacked on the outer periphery of the positive electrode current collector of this laminate sheet, and wound around the outer periphery of a stainless steel cylindrical shaft core so that the current collector does not short circuit. It was packed in a stainless steel cylindrical battery case of 1 mm and length 65 mm. The cylindrical axis is a cylinder with a diameter of 18 mm, a thickness of 0.1 mm and a length of 65 mm with slits (length 9 mm, width 0.1 mm, spacing between slits 1 mm) so that it can be broken by internal pressure It is.
Thereafter, a stainless steel, 5 mm thick reinforced cylindrical cover was fitted to the outside of the cylindrical battery case.

Then, the activated carbon is filled in the cylindrical shaft core, compressed with a pressure of 24 Pa from both sides of the cylindrical shaft core by a press machine, the slit width of the cylindrical shaft core is expanded, and the diameter of the cylindrical shaft core is increased. The Due to the increase in the diameter, a predetermined restraint pressure was applied to the laminate between the outer case and the cylindrical shaft core.
The negative electrode current collector was electrically connected to the battery case, and the positive electrode current collector was electrically connected to the shaft so that the current could be taken out.
The mixture obtained in Reference Example 2 was placed at both ends of the battery element member located between the cylindrical shaft core and the outer case, compressed using a press at a pressure of 24 Pa, and pressed.
The laminate in the state of being covered with the insulation coating was heated on a hot plate at 150 ° C. for 30 minutes to thermally melt the filler sulfur.
After that, natural cooling was performed to seal the case, and an all solid secondary battery having an inorganic insulating covering was obtained. The inorganic insulating coating after natural cooling had a Young's modulus at 25 ° C. of 50 GPa.
Moreover, the all-solid-state secondary battery which does not have an inorganic insulation coating body obtained by the same process except not performing the process which distribute | arranges an inorganic insulator coating body for comparison was obtained.

Test Example 1 Charge / Discharge Test (Test Method)
Charge / discharge is performed under the following conditions using each all solid secondary battery manufactured as described above, and the ratio of the initial discharge capacity to the initial charge capacity (discharge efficiency (%) = 100 × [initial discharge capacity / initial charge capacity]) Was calculated.
The charge and discharge conditions were a temperature of 30 ° C. in a measurement environment, a current density of 0.09 mA / cm ² (corresponding to 0.05 C), and a charge and discharge under constant current conditions of 4.2 V.

[Test Example 2] Charge-discharge cycle characteristic test (test method)
The charge / discharge cycle characteristic test was conducted under the following conditions using an all solid secondary battery (made one with an inorganic insulating covering and one without an insulating insulating coating) manufactured in the same manner as the above manufacturing example. Then, the ratio of the discharge capacity in the second cycle to the initial discharge capacity in the charge and discharge cycle (discharge capacity retention ratio (%) = 100 × [discharge capacity in second cycle / initial discharge capacity]) was calculated.
The charge and discharge conditions were a temperature of 30 ° C. in a measurement environment, a current density of 0.09 mA / cm ² (corresponding to 0.05 C), and a charge and discharge under constant current conditions of 4.2 V.
The results are shown in the table below.

As shown in the above table, it was found that the discharge efficiency is enhanced and the discharge capacity retention rate is also enhanced by having the inorganic insulating covering at the end of the battery element member.

The present application claims priority based on Japanese Patent Application No. 2017-047772 filed in Japan on March 13, 2017, the contents of which are incorporated herein by reference. Capture as part.

10 all solid secondary battery 1 negative electrode current collector 2 negative electrode active material layer 3 solid electrolyte layer 4 positive electrode active material layer 5 positive electrode current collector 6 working region 21a solid electrolyte layer 21b positive electrode current collector 21c positive electrode active material layer 21d negative electrode collection Current collector 21 e negative electrode active material layer 22 axis 23 battery cover 24 inorganic insulating covering 25 positive electrode tab 26 electrode positive electrode 27 negative electrode tab 28 battery negative electrode

Claims

An all solid secondary battery having battery element members, comprising:
The battery component member has at least a negative electrode current collector, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector,
The all-solid-state secondary battery which covers the edge part of the said battery element member at least the edge part of the said battery element member, and the inorganic insulating coating which has a Young's modulus at 25 degreeC 1 GPa or more is distribute | arranged.
The all-solid-state secondary battery according to claim 1, further comprising a battery case in which the battery element member is inserted.
The all-solid secondary according to claim 1 or 2, wherein the inorganic insulating covering comprises inorganic insulating particles and a melt-solidified insulating inorganic material which is solid at 100 ° C and melts in a temperature range of 200 ° C or less. battery.
The all-solid-state secondary battery according to claim 3, wherein the inorganic insulating covering comprises an organic binder.
The all-solid-state secondary battery according to claim 3, wherein the inorganic insulating particles are aluminum oxide having a volume average particle diameter of 1 μm or less.
The all-solid secondary battery according to any one of claims 1 to 5, wherein the insulating inorganic material contains sulfur and / or modified sulfur.
The all-solid secondary battery according to any one of claims 1 to 6, wherein the inorganic insulating covering blocks the growth of metallic lithium that grows from the negative electrode end during charge and discharge.
Placing a battery element member including at least a negative electrode current collector, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector in the battery case;
Arranging inorganic insulating particles and an inorganic insulating covering which is solid at 100 ° C. and melts in a temperature range of 200 ° C. or less in an end portion of the battery element member in a space in the battery case;
And heating the battery outer package in a temperature range of 200 ° C. or less to melt and solidify the inorganic insulating covering to cover the end of the battery element member. The manufacturing method of the all-solid-state secondary battery of 1 item.
A solid electrolyte sheet for use in the all solid secondary battery according to any one of claims 1 to 7, comprising:
A solid electrolyte layer, and an inorganic insulating coating covering the end of the solid electrolyte layer,
The inorganic insulating covering is a solid electrolyte sheet for an all solid secondary battery having a Young's modulus at 25 ° C. of 1 GPa or more.
10. The all-solid secondary battery according to claim 9, wherein the inorganic insulating covering comprises inorganic insulating particles and a melt-solidified insulating inorganic material which is solid at 100 ° C. and melts in a temperature range of 200 ° C. or less. Solid electrolyte sheet.
The solid electrolyte sheet for an all solid secondary battery according to claim 10, wherein the insulating inorganic material contains sulfur and / or modified sulfur.
The solid electrolyte sheet for an all solid secondary battery according to any one of claims 9 to 11, wherein the inorganic insulating covering comprises an organic binder.
The solid electrolyte sheet for an all solid secondary battery according to any one of claims 10 to 12, wherein the inorganic insulating particles are aluminum oxide.
It is a positive electrode active material sheet used for the all-solid-state secondary battery of any one of Claims 1-7, Comprising:
A positive electrode active material layer, and an inorganic insulating covering covering both ends of the positive electrode active material layer,
The inorganic insulating covering is a positive electrode active material sheet for an all solid secondary battery, having a Young's modulus at 25 ° C. of 1 GPa or more.
The all-solid-state secondary battery positive electrode active material sheet according to claim 14, wherein the inorganic insulating covering includes inorganic insulating particles and an insulating inorganic material which is solid at 100 ° C and melts at 200 ° C or less.
The positive electrode active material sheet for an all solid secondary battery according to claim 15, wherein the insulating inorganic material contains sulfur and / or modified sulfur.
The positive electrode active material sheet for an all solid secondary battery according to claim 15, wherein the inorganic insulating covering contains an organic binder.
The positive electrode active material sheet for an all solid secondary battery according to any one of claims 15 to 17, wherein the inorganic insulating particles are aluminum oxide.