JP2017152147A - Composite active material secondary particle, laminate green sheet, all-solid type secondary battery and manufacturing methods thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: composite active material secondary particles which contribute to the enhancement in performance of an all-solid type secondary battery, which enables the simplification of a manufacturing process, and enables the reduction in interface resistance of each layer; a laminate green sheet; an all-solid type secondary battery; and their manufacturing methods.SOLUTION: Composite active material secondary particles are produced by granulating active material particles, solid electrolyte particles and a carbon material through a binding agent. A method for producing an all-solid type secondary battery comprises the steps of: preparing a slurry of the composite active material secondary particles; producing each laminate green sheet 10 by using the slurry to stack, on a piece of first current collector foil 14, a first electrode layer green sheet 13, a solid electrolyte layer green sheet 12 and a second electrode layer green sheet 11 in this order; and putting a piece of second current collector foil 14 on the second electrode layer green sheet of the laminate green sheet 10, followed by collectively sintering. A method for producing a series all-solid type secondary battery comprises the steps of: successively laminating the laminate green sheets 10 on one another into a continuous laminate green sheet 15; and collectively sintering them.SELECTED DRAWING: Figure 4

Description

  The present invention relates to composite active material secondary particles including active material particles, a laminate green sheet using the composite active material secondary particles, an all-solid-state secondary battery using the laminate green sheet, and a method for manufacturing the same. .

  In recent years, power consumption has increased with the advancement of functions of small electronic devices typified by personal computers (PCs) and smartphones. In addition, demand for in-vehicle applications such as hybrid vehicles and electric vehicles, and stationary applications such as household storage batteries is increasing. Along with this, demands for higher energy density for secondary batteries are accelerating.

  Furthermore, the lithium ion secondary battery currently used for the above applications uses an organic electrolyte, and depending on the usage situation, there is a possibility of leakage of the electrolyte, ignition, etc. It has been.

  Therefore, the all-solid-state secondary battery, which does not use an organic electrolyte and is composed of only solid materials, has no possibility of leakage or ignition, has excellent safety, and is promising as a post-lithium ion secondary battery. It is.

  However, all solid-state secondary batteries currently in practical use are only thin-film all-solid secondary batteries and have a low energy density. Furthermore, since the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are produced by a vapor deposition method or a sputtering method, it is necessary to produce them under a reduced pressure atmosphere, which is not suitable for increasing the area and mass production.

  Therefore, a positive electrode layer green sheet, a solid electrolyte layer green sheet, and a negative electrode layer green sheet are prepared in a thick film by a coating method and a printing method in the same manner as in a conventional lithium ion secondary battery, and each layer green sheet is bonded together to form a laminate green. A high-capacity all-solid-state secondary battery manufactured by forming a sheet and batch firing and then sandwiching the sheet with a current collector foil is disclosed (Patent Documents 1 and 2).

JP 2000-340255 A International Publication No. 2011-111555

However, as in Patent Documents 1 and 2, the electrodes dispersed by the prior art have a problem that the ratio of the active material not in direct contact with the solid electrolyte is large and the internal resistance is high.
Further, as in Patent Documents 1 and 2, when a laminated fired body composed of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer is sandwiched between a positive electrode current collector foil and a negative electrode current collector foil, the positive electrode current collector foil, the positive electrode layer, and the negative electrode current collector There is a problem that the interfacial resistance between the electric foil and the negative electrode layer is high and the battery performance is poor, and there is a problem that there are two firings and the production efficiency is poor.

  An object of the present invention is to contribute to improving the performance of an all-solid secondary battery, simplify the manufacturing process, and suppress the interfacial resistance of each layer, a composite active material secondary particle, a laminate green sheet, and an all-solid secondary battery. It is to provide a secondary battery and a manufacturing method thereof.

  As a result of intensive studies to solve the above problems, the present inventors have determined that a composite material in which active material particles, solid electrolyte particles, and a carbon material are granulated through a binder before producing a green sheet. The inventors came up with the idea of producing secondary particles of active material. That is, the composite active material secondary particles according to one embodiment of the present invention are composite active material secondary particles in which active material particles, solid electrolyte particles, and a carbon material are granulated through a binder.

  The laminate green sheet according to one embodiment of the present invention includes a first electrode layer green sheet using the composite active material secondary particles as a positive electrode or a negative electrode, and a solid electrolyte layer green provided on the first electrode layer green sheet. And a second electrode layer green sheet using the composite active material secondary particles as a counter electrode of the first electrode layer green sheet.

  In the continuous laminate green sheet according to one embodiment of the present invention, the laminate green sheet is continuously laminated.

An all-solid-state secondary battery according to one embodiment of the present invention includes a first electrode layer using the composite active material secondary particles as a positive electrode or a negative electrode, a solid electrolyte layer provided over the first electrode layer, A second electrode layer using the composite active material secondary particles as a counter electrode of the first electrode layer is provided on the electrolyte layer.
An all solid state secondary battery according to one embodiment of the present invention includes an electrode including a first electrode layer, a solid electrolyte layer provided on the first electrode layer, and a second electrode layer provided on the solid electrolyte layer. In close contact with at least one of the first electrode layer and the second electrode layer between the laminated body and the laminated electrode laminated bodies and on the outer side in the laminating direction of the laminated electrode laminated bodies. And a provided current collector foil.
The all-solid-state secondary battery according to one embodiment of the present invention has a chemical bond between particles of adjacent layers at the interface between the current collector foil and at least one of the first electrode layer and the second electrode layer that are in close contact with the current collector foil. It may be formed.

  The manufacturing method of the laminated body green sheet which concerns on 1 aspect of this invention apply | coats or prints the slurry for 1st electrodes containing said composite active material secondary particle on 1st current collection foil, and slurry for 1st electrodes A first electrode slurry layer forming step for forming a layer, and a solid electrolyte slurry layer forming step for forming or forming a solid electrolyte slurry layer by applying or printing a solid electrolyte slurry containing a solid electrolyte material on the first electrode slurry layer And a second electrode slurry layer forming step of applying or printing the second electrode slurry containing the composite active material secondary particles on the solid electrolyte slurry layer to form a second electrode slurry layer. Including.

  The manufacturing method of the continuous laminated body green sheet which concerns on 1 aspect of this invention includes the green sheet lamination | stacking process of laminating | stacking continuously the laminated green sheet manufactured using the manufacturing method of said laminated green sheet. .

  The method for producing an all-solid-state secondary battery according to one aspect of the present invention includes the second electrode layer green sheet exposed on the surface of the laminate green sheet produced using the laminate green sheet production method described above. A second current collector foil laminating step for laminating the second current collector foil; and a firing step for firing the multilayer green sheet and the laminate including the second current collector foil bonded thereto.

  According to the present invention, it is possible to produce an all-solid secondary battery in which the production process of an all-solid secondary battery is simplified while suppressing the interface resistance between the active material particles and the solid electrolyte particles.

It is a schematic diagram of the composite active material secondary particle which concerns on 1 aspect of this invention. It is a schematic diagram of the laminated body green sheet which concerns on 1 aspect of this invention. It is a schematic diagram of the laminated body green sheet with the both-sides collector foil which concerns on 1 aspect of this invention. It is a schematic diagram of the continuous laminated body green sheet which concerns on 1 aspect of this invention. It is a schematic diagram of the continuous laminated body green sheet before the baking process which concerns on 1 aspect of this invention. 6 is a schematic diagram of a positive electrode layer / solid electrolyte layer green sheet of Comparative Example 3. FIG. 6 is a schematic diagram of a negative electrode layer green sheet of Comparative Example 3. FIG. 6 is a schematic diagram of a comparative laminate green sheet of Comparative Example 3. FIG. 5 is a schematic diagram of a three-layer sintered body with current collector foil laminated in five of Comparative Example 4. FIG. 6 is a schematic diagram of a series all solid state secondary battery of Comparative Example 4. FIG.

  Hereinafter, with reference to the drawings, a composite active material secondary particle, a laminate green sheet, an all-solid secondary battery, and a method for producing them will be described according to an embodiment of the present invention. Note that the embodiments of the present invention are not limited to the embodiments described below, and it is possible to make design changes based on the knowledge of those skilled in the art, and such changes have been made. Embodiments are also included in the scope of the embodiments of the present invention.

(Composite active material secondary particles)
As shown in FIG. 1, the composite active material secondary particle 1 according to this embodiment is formed by granulating an active material particle 2, a solid electrolyte particle 3, and a conductive additive 4 via a binder 5. .

  The active material particles 2 may be any material that can occlude and release lithium ions, and are not particularly limited. Among the active material particles 2, those showing a noble potential can be used as the positive electrode active material particles 2, and those showing a lower potential can be used as the negative electrode active material particles 2.

  Examples of the positive electrode active material particles 2 include lithium nickel cobalt manganate (LiNixCo1-y-xMnyO2), lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), lithium manganate (LiMn2O4), and lithium iron phosphate ( Lithium transition metal compounds such as LiFePO4), lithium cobalt phosphate (LiCoPO4), lithium manganese phosphate (LiMnPO4), and lithium vanadium phosphate (Li3V2 (PO4) 3) can be used.

  Examples of the active material particles 2 for the negative electrode include carbon materials such as hard carbon, soft carbon, and graphite, alloy materials such as Sn-based alloys and Si-based alloys, nitrides such as LiCoN, lithium titanate (Li4Ti5O12), phosphorus A lithium transition metal oxide such as lithium vanadium acid (Li3V2 (PO4) 3) can be used. Moreover, you may use metal lithium foil.

  The solid electrolyte particle 3 is not particularly limited as long as it is a material having low electron conductivity and high lithium ion conductivity. As the solid electrolyte particles 3, for example, an oxide solid electrolyte or a sulfide solid electrolyte amorphous body (glass body), a crystal body, glass ceramics, or the like can be used. In particular, an oxide-based solid electrolyte that can be fired at high temperature is preferable, and a NASICON type oxide, a perovskite type oxide, a LISICON type oxide, a garnet type oxide, an oxide glass, or the like can be used. For example, Li1 · 3Al0.3Ti1.7 (PO4) 3, Li1.5Al0.5Ge1.5 (PO4) 3, Li0.29La0.571TiO3, Li4SiO4-Li3PO4, Li3BO3-Li3PO4, Li7La3Zr2O12, Li3.4V0.6Si0.4O4, etc. Can be used.

  The conductive auxiliary agent 4 is not particularly limited as long as it is a conductive material. As the conductive assistant 4, for example, a conductive carbon material, particularly carbon black, activated carbon, carbon carbon fiber, or the like can be used. The content of the conductive auxiliary agent 4 is preferably less than 90% by mass with respect to the mass of the active material particles 2. When the content of the conductive auxiliary agent 4 is 90% by mass or more, the mass of the active material particles 2 may be insufficient and the lithium storage capacity may be reduced.

  The binder 5 is not particularly limited as long as it is a material that binds to the active material particles 2, the solid electrolyte particles 3, and the conductive additive 4 and decomposes under firing conditions described later. As the binder 5, for example, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl butyral, polyvinyl acetal, polyvinylidene fluoride, polytetrafluoroethylene, ethyl cellulose, an acrylic resin, or the like can be used.

  Examples of the granulation method of the composite active material secondary particles 1 according to the present embodiment include a rolling fluid coating method, a spray method, a dipping method, and a method using a spray dryer. About the average particle diameter of the material used in this embodiment, the active material particle 2 and the solid electrolyte particle 3 are several micrometers or more and several dozen micrometers or less, and the conductive support agent 4 is several dozen nm or more and several micrometers or less. The spray dryer method is particularly preferable from the viewpoint of compounding particles having different particle sizes at once.

(Laminated green sheet)
As shown in FIGS. 2 to 5, the laminate green sheet 10 according to this embodiment is formed on a current collector foil 14 in the order of a negative electrode layer green sheet 13, a solid electrolyte layer green sheet 12, and a positive electrode layer green sheet 11. The The arrangement of the positive electrode layer green sheet 11 and the negative electrode layer green sheet 13 may be reversed. That is, the laminate green sheet 10 according to this embodiment may be formed on the current collector foil 14 in the order of the positive electrode layer green sheet 11, the solid electrolyte layer green sheet 12, and the negative electrode layer green sheet 13.

  The current collector foil 14 is not particularly limited as long as it is a conductive material. As the current collector foil 14, for example, a metal material such as stainless steel, nickel, aluminum, iron, titanium, copper, palladium, gold, and platinum can be used. The material of the current collector foil 14 is preferably selected in consideration of not melting and decomposing under the firing conditions described later, and the battery operating potential and conductivity applied to the current collector foil 14.

The positive electrode layer green sheet 11 and the negative electrode layer green sheet 13 are formed using the composite active material secondary particles 1 according to this embodiment described above.
For example, the positive electrode layer green sheet 11 and the negative electrode layer green sheet 13 are prepared by mixing a binder 5 containing active material particles 2, solid electrolyte particles 3, and a conductive additive 4 together with a solvent to form a positive electrode slurry and a negative electrode slurry. The positive electrode slurry and the negative electrode slurry are formed by applying or printing on the current collector foil 14 and then drying. The method for preparing the positive electrode slurry and the negative electrode slurry is not particularly limited.

  The solid electrolyte layer green sheet 12 is formed by mixing the solid electrolyte particles 3 and the binder 5 together with a solvent to form a solid electrolyte slurry, which is coated or formed on the positive electrode layer green sheet 11 or the negative electrode layer green sheet 13 and then dried. Formed. The method for preparing the solid electrolyte slurry is not particularly limited.

  The solid electrolyte particles 3 in the positive electrode layer green sheet 11, the solid electrolyte layer green sheet 12, and the negative electrode layer green sheet 13 may be the same or different, and two or more kinds are used in the same green sheet. Also good.

  The binder 5 in the positive electrode layer green sheet 11, the solid electrolyte layer green sheet 12, and the negative electrode layer green sheet 13 is desirably 3% by mass or more and 40% by mass or less. When the amount is less than 3% by mass, sufficient binding cannot be achieved. When the amount is more than 40% by mass, the capacity per electrode volume is greatly reduced. More preferably, it is 3 mass% or more and 25 mass% or less.

  The solvent used for the positive electrode slurry, the solid electrolyte slurry, and the negative electrode slurry is not particularly limited as long as the binder 5 can be dissolved. Examples of the solvent include alcohols such as ethanol, isopropanol, and n-butanol, toluene, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethylene glycol ethyl ether, isophorone, butyl lactate, dioctyl phthalate, dioctyl adipate, Organic solvents such as benzyl alcohol, N, N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and water can be used. In addition, these solvents may be used independently and may use 2 or more types together. Since the slurry can be easily dried, the boiling point of the solvent is preferably 200 ° C. or lower.

  Although not shown, the positive electrode slurry, the solid electrolyte slurry, and the negative electrode slurry promote the formation of a matrix structure in each green sheet when the positive electrode layer green sheet 11, the solid electrolyte layer green sheet 12, and the negative electrode layer green sheet 13 are fired. You may further contain the baking auxiliary agent which reduces temperature. The firing aid is not particularly limited as long as it does not react with the active material particles 2 and the solid electrolyte particles 3 and has a softening point temperature lower than the firing temperature of the solid electrolyte particles 3. As the firing aid, for example, a boron compound can be used. By adjusting the content and firing temperature of the firing aid of each green sheet, when forming a laminated fired body by firing, it prevents cracking due to internal strain and internal stress of each layer and promotes the formation of a matrix structure can do.

  Thus, the positive electrode slurry, the solid electrolyte slurry, and the negative electrode slurry are mixed with the above-mentioned active material particles 2, solid electrolyte particles 3, conductive auxiliary agent 4, binder 5, as well as a solvent and, if necessary, a baking auxiliary agent. It is possible to make it. Moreover, the mixing method of a slurry is not specifically limited, You may add additives, such as a thickener, a plasticizer, an antifoamer, a leveling agent, and an adhesive provision agent, as needed.

  Specifically, the application method and printing method of the positive electrode slurry, the solid electrolyte slurry, and the negative electrode slurry include a doctor blade method, a calendar method, a spin coating method, a dip coating method, an ink jet method, an offset method, a die coating method, a spray method, and a screen. A printing method or the like can be used.

  The drying method of the positive electrode slurry, the solid electrolyte slurry, and the negative electrode slurry is not particularly limited. For example, heat drying, reduced pressure drying, heat reduced pressure drying and the like can be used. The drying atmosphere is not particularly limited. For example, it can be performed in an air atmosphere or a nitrogen atmosphere.

  The thickness of the positive electrode layer formed by the positive electrode layer green sheet 11 and the thickness of the negative electrode layer formed by the negative electrode layer green sheet 13 can be determined according to a desired battery capacity.

  The thickness of the solid electrolyte layer formed by the solid electrolyte layer green sheet 12 is preferably in the range of 1 μm to 500 μm. If it is thinner than 1 μm, the positive electrode layer and the negative electrode layer are short-circuited, and not only the performance of the all-solid-state secondary battery is lowered, but also the safety may be lowered. If it is thicker than 500 μm, the movement of conductive ions such as lithium ions in the solid electrolyte layer is hindered, and the output of the all-solid secondary battery may be lowered.

  The laminated fired body according to the present embodiment is formed by degreasing the binder 5 from the laminated green sheet 10 according to the present embodiment and sintering the particles in the firing step.

The heating temperature in the firing step is a temperature equal to or higher than the thermal decomposition temperature of the binder 5 contained in the laminate green sheet 10 and lower than the oxidation temperature of the active material particles 2 or lower than the combustion temperature of the current collector foil 14. Is preferably 300 ° C. or higher and 1100 ° C. or lower, and more preferably 300 ° C. or higher and 900 ° C. or lower. When the temperature is lower than 300 ° C., the binder 5 does not completely burn but becomes a residue, which may become a resistor in the layer. If the temperature is higher than 1100 ° C., the active material particles 2 and the solid electrolyte particles 3 may be melted and deteriorated to deteriorate the battery performance.
The atmosphere in the firing step is not particularly limited. For example, the reaction can be performed in an air atmosphere or a nitrogen atmosphere, but if there is a concern about the reaction between the active material particles 2 and the current collector foil 14 or a decrease in the conductivity of the current collector foil 14, it may be performed under an inert atmosphere. It is desirable to do in. The firing time is not particularly limited as long as the binder 5 to be used is sufficiently decomposed.

  The continuous laminate green sheet 15 according to this embodiment includes a current collector foil 14 of one laminate green sheet 10 and a positive electrode layer green sheet of the other laminate green sheet 10 among the plurality of laminate green sheets 10. 11 or the negative electrode layer green sheet 13 are bonded together so as to be adjacent to each other. The method for bonding the laminate green sheet 10 is not particularly limited. For example, a flat plate press, roll press, hot press, cold isostatic press, hot isostatic press and the like can be used.

  The continuous laminated fired body according to the present embodiment is formed by firing the continuous laminated green sheet 15. The firing conditions can be the same as the firing conditions in the formation of the laminated fired body.

  The all-solid-state secondary battery according to the present embodiment has another layer on the positive electrode layer green sheet 11 or the negative electrode layer green sheet 13 farthest from the first current collector foil 14 of the laminate green sheet 10 or the continuous laminate green sheet 15. The current collector foil 14 can be bonded together and fired at once. The firing conditions can be the same as the firing conditions in the formation of the laminated fired body.

  Alternatively, the all-solid-state secondary battery according to the present embodiment has another layer on the positive electrode layer green sheet 11 or the negative electrode layer green sheet 13 farthest from the first current collecting foil 14 of the laminated fired body or the continuous laminated fired body. The current collector foil 14 can be bonded to form. The method for bonding the current collector foil 14 is not particularly limited, and the same method as the method for bonding the laminate green sheet 10 can be used.

As described above, in the present embodiment, the composite active material secondary particles 1 in which the active material particles 2, the solid electrolyte particles 3, and the carbon material are granulated through the binder are produced.
Then, the composite active material secondary particles 1 are made into a slurry, and the first electrode layer green containing the composite active material secondary particles 1 as a positive electrode or a negative electrode on the first current collector foil by a coating method using the slurry. A laminate green sheet was produced by laminating a sheet, a solid electrolyte layer green sheet, and a second electrode layer green sheet containing the composite active material secondary particles 1 as a counter electrode in this order.
Then, the 2nd current collector foil was bonded together on the 2nd electrode layer green sheet of the laminated body green sheet, and the all-solid-state secondary battery was produced by baking at the same time.
In addition, the laminated green sheets are continuously laminated, and between the plurality of laminated green sheets and further outside the outer surface in the stacking direction of the laminated green sheets, Were laminated to produce a continuous laminate green sheet, and the continuous laminate green sheet was fired at once to produce a series all-solid secondary battery.
In addition, by batch firing, the chemistry of particles in adjacent layers at the interface between the first current collector foil and the first electrode layer green sheet and at the interface between the second current collector foil and the second electrode layer green sheet. A bond is formed.
As a result, the ratio of the active material particles 2 that are in direct contact with the solid electrolyte particles 3 is dramatically improved, and the interfacial resistance between the particles can be reduced.

  Unlike the conventional transfer method, the production process of the laminate green sheet according to the present embodiment can produce the laminate green sheet continuously. While suppressing the interface resistance between the positive electrode layer, the negative electrode current collector foil and the negative electrode layer, the firing process can be performed once.

  Moreover, it becomes possible to produce a continuous laminate green sheet by continuously laminating the laminate green sheet, and producing an all-solid-state secondary battery in series by collectively firing the continuous laminate green sheet. Became possible.

  1 to 10, a laminated green sheet according to the present embodiment, a continuous laminated green sheet obtained by continuously laminating the laminated green sheet, and an all solid using those fired bodies Specific examples and comparative examples relating to secondary batteries will be described. In addition, this embodiment is not restrict | limited by the following Example.

Example 1
<Granulation process of secondary active composite particles of positive electrode>
50 parts by mass of lithium cobaltate (LiCoO ₂ ) powder as the active material particles 2 of the positive electrode, 50 parts by mass of LAGP (Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ ) powder as the solid electrolyte particles 3, conductive A slurry was prepared using 6 parts by mass of acetylene black as auxiliary agent 4, 23 parts by mass of polyvinylpyrrolidone as binder 5, and water as a solvent. Particles were granulated from the produced slurry by a spray dryer method to produce composite active material secondary particles 1 of a positive electrode.

<Preparation of positive electrode slurry>
100 parts by mass of the powder of the composite active material secondary particles 1 of the positive electrode, 16 parts by mass of polyvinyl butyral (PVB) as the binder 5, 4.8 parts by mass of dibutyl phthalate (DBP) as the plasticizer, and a solvent (terpineol) are mixed. The slurry was defoamed to produce a positive electrode slurry.

<Preparation of solid electrolyte slurry>
100 parts by mass of LAGP powder as solid electrolyte particles 3, 16 parts by mass of PVB as binder 5, 4.8 parts by mass of DBP as plasticizer, and solvent (terpineol) are mixed to form a slurry, and the slurry is defoamed to obtain a solid electrolyte slurry. Produced.

<Granulation step of composite active material secondary particles of negative electrode>
50 parts by mass of lithium titanate (Li ₄ Ti ₅ O ₁₂ ) powder as the active material particles 2 of the negative electrode, 50 parts by mass of LAGP powder as the solid electrolyte particles 3, 6 parts by mass of graphite as the conductive additive 4, and polyvinylpyrrolidone 23 as the binder 5 A slurry was prepared using water as a mass part and a solvent. Particles were granulated from the produced slurry by a spray dryer method to produce composite active material secondary particles 1 for the negative electrode.

<Preparation of negative electrode slurry>
The negative electrode composite active material secondary particles 1 powder 100 parts by mass, PVB 16 parts by mass as binder 5, DBP 4.8 parts by mass as plasticizer, and solvent (terpineol) are mixed to form a slurry, and this slurry is defoamed. Thus, a negative electrode slurry was prepared.

<Laminated green sheet production process>
As shown in FIG. 2, a 15 μm nickel foil is used as the current collector foil 14, and this is used as a negative electrode current collector foil. A negative electrode slurry is applied on the current collector foil 14 and dried to produce a negative electrode layer green sheet 13. Then, the solid electrolyte slurry is applied on the negative electrode layer green sheet 13 and dried to produce the solid electrolyte layer green sheet 12, and the positive electrode slurry is applied on the solid electrolyte layer green sheet 12 and dried. The laminated body green sheet 10 was produced by producing the positive electrode layer green sheet 11.

<Cutting process>
As shown in FIG. 3, on the positive electrode layer green sheet 11 of the produced laminate green sheet 10, the same nickel foil as described above is placed as another current collector foil 14, and this is used as a positive electrode current collector foil. 14 was pressed at 80 ° C. and 1000 kgf / cm ² (98 MPa), and the positive electrode current collector foil and the negative electrode current collector foil were cut so as to be exposed on different surfaces of the laminate green sheet 10.

<Baking process>
The laminate green sheet 10 was heated in a nitrogen stream at a rate of temperature increase of 80 ° C./min. The temperature was raised from room temperature to 700 ° C. and held at that temperature for 30 minutes for firing. Then, it cooled to room temperature by standing to cool in a furnace, and produced the all-solid-state secondary battery which consists of a laminated fired body of Example 1.

(Example 2)
The same operation as in Example 1 was performed, except that the composite active material secondary particles 1 of the negative electrode were not prepared and a negative electrode slurry was prepared in the following manner. That is, the negative electrode layer green sheet of Example 2 is different from the negative electrode layer green sheet 13 of Example 1. Others are the same as in the first embodiment.

<Preparation of negative electrode slurry>
50 parts by mass of lithium titanate (Li ₄ Ti ₅ O ₁₂ ) powder as the active material particles 2 of the negative electrode, 50 parts by mass of LAGP powder as the solid electrolyte particles 3, 6 parts by mass of graphite as the conductive additive 4, and 16 parts by mass of PVB as the binder 5 Then, 4.8 parts by mass of DBP as a plasticizer and a solvent (terpineol) were mixed to form a slurry, and this slurry was defoamed to prepare a negative electrode slurry.

(Example 3)
The same operation as in Example 1 was performed except that the positive electrode composite active material secondary particles 1 were not prepared and a positive electrode slurry was prepared in the following manner. That is, the positive electrode layer green sheet of Example 3 is different from the positive electrode layer green sheet 11 of Example 1. Others are the same as in the first embodiment.

<Preparation of positive electrode slurry>
50 parts by mass of lithium cobaltate (LiCoO ₂ ) powder as the active material particles 2 of the positive electrode, 50 parts by mass of LAGP powder as the solid electrolyte particles 3, 6 parts by mass of acetylene black as the conductive additive 4, 16 parts by mass of PVB as the binder 5, and a plasticizer As a slurry, 4.8 parts by mass of DBP and a solvent (terpineol) were mixed, and this slurry was defoamed to prepare a positive electrode slurry.

Example 4
<Granulation and slurry preparation process>
Granulation of the composite active material secondary particles 1 for the positive electrode and the negative electrode and preparation of each slurry were performed in the same manner as in Example 1.

<Laminated green sheet production process>
The laminate green sheet 10 was produced in the same manner as in Example 1.

<Continuous laminate green sheet production process>
The produced laminate green sheet 10 was cut into a predetermined size. Five laminate green sheets 10 were produced. As shown in FIG. 4, the five laminated green sheets 10 were continuously laminated to produce a continuous laminated green sheet 15. Finally, as shown in FIG. 5, the same nickel foil as the laminate green sheet 10 is placed on the negative electrode layer green sheet 13 which is the outer surface in the stacking direction not in contact with the current collector foil 14 as the other current collector foil 14, The whole was pressurized at 80 ° C. and 1000 kgf / cm ² (98 MPa) to produce a continuous laminate green sheet 15 before the firing step of Example 2.

<Continuous laminated fired body manufacturing process>
The continuous laminate green sheet 15 was heated at a rate of temperature increase of 80 ° C./min. The temperature was raised from room temperature to 700 ° C. and held at that temperature for 30 minutes, and then cooled to room temperature by allowing it to cool in the furnace to produce a serial all-solid secondary battery comprising the continuously laminated fired body of Example 4.

(Comparative Example 1)
The composite active material secondary particles 1 of the positive electrode and the negative electrode were not prepared, and the positive electrode and the negative electrode slurry were prepared in the same manner as in Examples 2 and 3, and all of Comparative Example 1 was performed in the same manner as in Example 1. A solid secondary battery was produced. That is, the positive electrode layer green sheet and the negative electrode layer green sheet of Comparative Example 1 are different from the positive electrode layer green sheet 11 and the negative electrode layer green sheet 13 of Example 1 using the composite active material secondary particles 1. Others are the same as in the first embodiment.

(Comparative Example 2)
The composite active material secondary particles 1 of the positive electrode and the negative electrode were not prepared together, and the positive electrode and the negative electrode slurry were prepared by the same operation as in Examples 2 and 3, and the series of Comparative Example 2 was performed in the same manner as in Example 4. An all-solid secondary battery was produced. That is, the positive electrode layer green sheet and the negative electrode layer green sheet of Comparative Example 2 are different from the positive electrode layer green sheet 11 and the negative electrode layer green sheet 13 of Example 4 using the composite active material secondary particles 1. Others are the same as in Example 4.

(Comparative Example 3)
<Granulation and slurry preparation process>
Granulation of the composite active material secondary particles 1 for the positive electrode and the negative electrode and preparation of each slurry were performed in the same manner as in Example 1.

<Laminated green sheet production process>
As shown in FIG. 6, a negative electrode slurry is applied on a polyethylene terephthalate sheet-like support film (hereinafter referred to as PET film 21) and dried to produce a negative electrode layer green sheet 13. On the negative electrode layer green sheet 13, a solid The electrolyte slurry was applied and dried to prepare a solid electrolyte layer green sheet 12.

  Moreover, as shown in FIG. 7, the positive electrode slurry was apply | coated and dried on the other PET film 21, and the positive electrode layer green sheet 11 was produced.

8, the surface on the solid electrolyte layer green sheet 12 side on the PET film 21 shown in FIG. 6 and the surface on the positive electrode layer green sheet 11 side on the other PET film 21 shown in FIG. And this was pressurized at 80 ° C. and 1000 kgf / cm ² (98 MPa) to produce a comparative laminate green sheet 20 of Comparative Example 5.

<Cutting and firing process>
The produced comparative laminate green sheet 20 was cut into a predetermined size, the PET films 21 on both sides of the comparative laminate green sheet 20 were peeled off, and the temperature rising rate was 80 ° C./min. The temperature was raised from room temperature to 700 ° C. and held at that temperature for 30 minutes for firing. Then, it cooled to room temperature by standing in a furnace, and produced the three-layer fired body 30 in which the positive electrode layer 31, the solid electrolyte layer 32, and the negative electrode layer 33 as shown in FIGS. 9 and 10 were laminated in this order. The arrangement of the positive electrode layer 31 and the negative electrode layer 33 may be reversed.

  A nickel foil having a thickness of 15 μm was placed on the surface of the produced three-layer fired body 30 that is not in contact with the solid electrolyte layer 32 of the positive electrode layer 31 to form a positive electrode current collector foil. In addition, the same nickel foil as the other current collector foil 14 was placed on the surface of the three-layer fired body 30 that is not in contact with the solid electrolyte layer 32 of the negative electrode layer 33 to obtain a negative electrode current collector foil. The positive electrode current collector foil and the negative electrode current collector foil were exposed on different surfaces of the three-layer fired body 30.

The three-layer fired body 30 was laminated at 80 ° C. and 1000 kgf / cm ² (98 MPa) to produce an all-solid secondary battery of Comparative Example 5.

(Comparative Example 4)
From the <granulation and slurry preparation step> to the <cutting / firing step>, the same operation as in Comparative Example 3 was performed, and the three-layer fired body 30 was produced.

<Continuous laminated fired body manufacturing process>
A surface of the three-layer fired body 30 that is not in contact with the solid electrolyte layer 32 of the positive electrode layer 31 is placed with a 15 μm-thick nickel foil as the current collector foil 14 and laminated at 80 ° C. and 1000 kgf / cm ² (98 MPa). A positive electrode current collector foil was obtained.

Five three-layer fired bodies 30 with current collector foil were prepared and laminated as shown in FIG. Finally, as shown in FIG. 10, the same nickel foil as the current collector foil 14 is placed on the surface of the negative electrode layer 33 that is not in contact with the current collector foil, and the whole is 80 ° C. and 1000 kgf / cm ² (98 MPa). ) To produce a series all solid state secondary battery of Comparative Example 4.

<Electrochemical evaluation>
The electrochemical evaluation was performed by the following method.
(Battery evaluation methods of Examples 1, 2, and 3, Comparative Examples 1 and 3)
Ten all-solid secondary batteries were evaluated. The battery is charged to 2.7 V by a constant current method of 0.2 C, and then discharged to 1.5 V at 0.2 C. This discharge capacity is defined as a reference capacity X. The reference capacity X is an average value of 10 pieces. Thereafter, the battery is charged to 2.7 V at 0.2 C, discharged to 1.5 V at 5 C, and the 3 C discharge capacity Y is obtained. The 3C discharge capacity Y is also an average value of 10 pieces. A discharge capacity maintenance ratio represented by a ratio (Y / X (%)) of the discharge capacity between the 3C discharge capacity Y and the reference capacity X is obtained, and this is used as an evaluation standard for electrochemical evaluation, and is evaluated according to the following standard. The higher the evaluation, the better the output characteristics as a battery, that is, the smaller the internal resistance.
A: 70% or more B: 50% or more and less than 70% C: 40% or more and less than 50% D: 30% or more and less than 40% E: Less than 30%

(Battery evaluation method of Example 4, Comparative Examples 2 and 4)
Ten series all solid state secondary batteries were evaluated. The battery is charged to 13.5 V by a constant current method of 0.2 C, and then discharged to 7.5 V at 0.2 C. This discharge capacity is set as a reference capacity X. The reference capacity X is an average value of 10 pieces. Thereafter, the battery is charged to 13.5 V at 0.2 C, discharged to 7.5 V at 5 C, and the 3 C discharge capacity Y is obtained. The 3C discharge capacity Y is also an average value of 10 pieces. A discharge capacity maintenance ratio represented by a ratio (Y / X (%)) of the discharge capacity between the 3C discharge capacity Y and the reference capacity X is obtained, and this is used as an evaluation standard for electrochemical evaluation, and is evaluated according to the following standard. The higher the evaluation, the better the output characteristics as a battery, that is, the smaller the internal resistance.
A: 70% or more B: 50% or more and less than 70% C: 40% or more and less than 50% D: 30% or more and less than 40% E: Less than 30%

(Evaluation results)
The results of the evaluation are shown in Table 1 below.

  From Table 1, it can be seen that Examples 1, 2, and 3 using composite particles have a higher evaluation than Comparative Example 1, and the interfacial resistance between particles due to the composite of particles is reduced. I understood it. Further, Example 1 has a higher discharge capacity retention rate than Examples 2 and 3, and the composite of active material particles 2, solid electrolyte particles 3, and conductive additive 4 is most effective for reducing resistance in both the positive electrode and the negative electrode. It was confirmed that the use of the method of this embodiment is effective in improving the performance of the all-solid-state battery.

  Further, when Example 4 and Comparative Example 2 are compared, the result is the same as described above, and the effect of the present embodiment can be obtained even in a series all-solid secondary battery in which single-layer all-solid secondary batteries are stacked. Was confirmed.

  Moreover, when Example 1 and Comparative Example 3 were compared, Example 1 was higher in evaluation than Comparative Example 3. From this result, a positive electrode layer green sheet 11, a solid electrolyte layer green sheet 12, and a negative electrode layer green sheet 13 are formed on the current collector foil 14 by a coating method to produce a laminate green sheet 10. Further, the laminate green sheet 10 The present embodiment in which a continuous laminate green sheet 15 is produced by continuously laminating the laminate, and the laminate green sheet 10 or the continuous laminate green sheet 15 is collectively fired to produce an all-solid-state secondary battery is a comparative example. Compared with the all-solid-state secondary battery of No. 3 conventional transfer method, the battery performance is good. That is, it can be said that this is an all-solid secondary battery in which the interface resistance of each layer is suppressed. Furthermore, it can be said that the manufacturing method of the all-solid-state secondary battery according to the present embodiment is a manufacturing method in which the process is simplified as compared with the conventional method. This is the same in the case of producing a series all solid state secondary battery to be compared in Example 4 and Comparative Example 4.

  The present invention greatly contributes to the improvement of the performance of the all solid state secondary battery, and can simplify the manufacturing process of the all solid state secondary battery. Moreover, the all-solid-state secondary battery of the present invention is an all-solid-state secondary battery in which the interface resistance of each layer is suppressed, and it is an invention that can be used greatly industrially, having both cost reduction and battery performance.

DESCRIPTION OF SYMBOLS 1 ... Composite active material secondary particle 2 ... Active material particle 3 ... Solid electrolyte particle 4 ... Conductive auxiliary agent (carbon material)
5 ... Binder (binder)
DESCRIPTION OF SYMBOLS 10 ... Laminated body green sheet 11 ... Positive electrode layer green sheet 12 ... Solid electrolyte layer green sheet 13 ... Negative electrode layer green sheet 14 ... Current collection foil 15 ... Continuous laminated body green sheet 20 ... Laminate green sheet 21 for comparison 21 ... PET film 30 ... Three-layer fired body 31 ... Positive electrode layer 32 ... Solid electrolyte layer 33 ... Negative electrode layer

Claims (10)

  A composite active material secondary particle, wherein active material particles, solid electrolyte particles, and a carbon material are granulated through a binder. A first electrode layer green sheet using the composite active material secondary particles according to claim 1 as a positive electrode or a negative electrode;
A solid electrolyte layer green sheet provided on the first electrode layer green sheet;
A second electrode layer green sheet using the composite active material secondary particles according to claim 1 as a counter electrode of the first electrode layer green sheet;
A laminate green sheet comprising:   A continuous laminate green sheet, wherein the laminate green sheet according to claim 2 is continuously laminated. A first electrode layer using the composite active material secondary particles according to claim 1 as a positive electrode or a negative electrode;
A solid electrolyte layer provided on the first electrode layer;
A second electrode layer using the composite active material secondary particles according to claim 1 as a counter electrode of the first electrode layer on the solid electrolyte layer in the previous period;
An all-solid-state secondary battery comprising: An electrode stack comprising a first electrode layer, a solid electrolyte layer provided on the first electrode layer, and a second electrode layer provided on the solid electrolyte layer;
In close contact with at least one of the first electrode layer and the second electrode layer between the stacked electrode stacks and on the outer side in the stacking direction of the stacked electrode stacks. Current collector foil provided,
An all-solid-state secondary battery comprising:   The chemical bond between the particles of adjacent layers is formed at the interface between the current collector foil and at least one of the first electrode layer and the second electrode layer closely adhered to the current collector foil. Solid secondary battery. A first electrode slurry layer forming step of forming or slurrying a first electrode slurry layer on the first current collector foil by applying or printing the first electrode slurry containing the composite active material secondary particles according to claim 1. When,
A solid electrolyte slurry layer forming step of forming or solid electrolyte slurry layer by applying or printing a solid electrolyte slurry containing a solid electrolyte material on the first electrode slurry layer;
A second electrode slurry layer forming step of forming a second electrode slurry layer by applying or printing the second electrode slurry containing the composite active material secondary particles according to claim 1 on the solid electrolyte slurry layer. When,
The manufacturing method of the laminated body green sheet characterized by the above-mentioned. A green sheet laminating step of continuously laminating a laminate green sheet produced using the laminate green sheet producing method according to claim 7;
The manufacturing method of the continuous laminated body green sheet characterized by including this. A second current collector in which a second current collector foil is bonded onto the second electrode layer green sheet exposed on the surface of the multilayer green sheet produced using the method for producing a laminated green sheet according to claim 7. Foil bonding process,
A firing step of firing the laminate including the laminate green sheet and the second current collector foil bonded thereto;
The manufacturing method of the all-solid-state secondary battery characterized by including. A second current collector foil is bonded to the second electrode layer green sheet exposed on the surface of the multilayer green sheet produced using the method for producing a continuous laminate green sheet according to claim 8. A foil bonding process;
A firing step of firing the continuous laminate including the laminate green sheet and the second current collector foil bonded thereto;
The manufacturing method of the all-solid-state secondary battery characterized by including.

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