Method for manufacturing all-solid-state battery

Abstract

The purpose of the present invention is to provide a method for manufacturing an all-solid-state battery in which warping of an electrode laminate is prevented and characteristics do not deteriorate. Provided is a method for manufacturing an all-solid-state battery, comprising: a step for forming an electrode laminate by laminating a negative electrode, a positive electrode, and a solid electrolyte membrane; a step in which the electrode laminate is exposed for 20 minutes or more in an environment having a dew point temperature of-40 DEG C and a moisture concentration of 127 ppm or less; and a step in which the electrode laminate is press-molded.

Description

TECHNICAL FIELD

[0001] The present application relates to a manufacturing method of an all-solid electrolyte. The all-solid battery of the present application includes a lithium ion secondary battery or the like. BACKGROUND

[0002] In recent years, development of a secondary battery that can be repeatedly charged and discharged as an energy source for a car or a home is advancing in consideration of the environment. Development of a secondary battery that can expect high capacity and high output is expected, and on the other hand, safety is also required to be further emphasized.

[0003] In a lithium ion secondary battery, which is one of representative secondary batteries, a solid battery using a solid electrolyte is known. An all-solid battery, which is one of the solid batteries, includes a solid electrolyte layer, a positive electrode layer formed on one of the surfaces of the solid electrolyte layer and a negative electrode layer formed on the other surface, and a positive electrode plate connected to the positive electrode layer and a negative electrode plate connected to the negative electrode layer.

[0004] As for the positive electrode layer, a slurry containing positive electrode active material particles, a binding agent (binder), a solid electrolyte, and a solvent is applied to a positive electrode current collector and dried to obtain. As the positive electrode current collector, an aluminum foil or the like can be used. On the other hand, as for the negative electrode, a slurry containing negative electrode active material particles, a binding agent (binder), a solid electrolyte, and a solvent is applied to a negative electrode current collector and dried to obtain. As the negative electrode current collector, a copper foil can be used. Alternatively, a material in which a lithium metal layer is formed on a stainless steel foil can also be used as the negative electrode. A conductive aid can also be contained in the positive electrode layer or the negative electrode layer.

[0005] As for the solid electrolyte layer, a solid electrolyte powder is dispersed in a solvent to make a slurry and is coated and dried to form. For example, the solid electrolyte layer can be formed directly on the surface of the negative electrode layer or the positive electrode layer. Alternatively, the solid electrolyte layer can be obtained by forming a solid electrolyte layer on the surface of a substrate such as a polyethylene terephthalate (PET) film and peeling the PET film.

[0006] The obtained positive electrode and negative electrode are pressed in a state of being stacked with a solid electrolyte, whereby an electrode laminate can be obtained. A positive electrode terminal and a negative electrode terminal are attached to the electrode laminate, and the electrode laminate is housed and sealed in an exterior container in a manner that one end of each of the terminals is drawn to the outside, whereby an all-solid battery can be obtained.

[0007] As a solid electrolyte, sulfide solid electrolytes are known. Sulfide solid electrolytes are known to be chemically unstable, and ion conductivity can decrease due to moisture when exposed to the atmosphere or the like. Therefore, in the case of using a sulfide solid electrolyte, the positive electrode active material or the negative electrode active material or the solid electrolyte material itself is also sufficiently dried in advance, and further, the dew point is strictly managed in a process of stacking the positive electrode, the negative electrode, the solid electrolyte layer, or the like, whereby assembly is rapidly performed on the basis of a low moisture concentration.

[0008] In Patent Literature 1, it is disclosed that, in a slurry drying process of forming an electrode layer of an all-solid battery, drying is performed in an atmosphere in which the concentration of volatile organic compounds is 100 ppm or less. In Patent Literature 2, it is disclosed that a lithium ion-conductive solid electrolyte is heated and dried in a temperature range of 80°C to 140°C.

[0009] Prior Art Documents

[0010] Patent Literature

[0011] Patent Literature 1: Japanese Patent Laid-Open No. 2019-200890

[0012] Patent Literature 2: Japanese Patent Laid-Open No. 2008-103145 SUMMARY

[0013] PROBLEMS TO BE SOLVED BY THE INVENTION

[0014] Even if an all-solid battery is assembled under dew point management, it is difficult to completely block exposure to moisture, and therefore it can be considered that it is desirable to complete the assembly as soon as possible up to the stage of sealing the electrode stack with an outer container. However, sometimes the characteristics of the all-solid battery can still decrease even if the all-solid battery is assembled in as short a time as possible.

[0015] The inventors and the like have made diligent studies, and as a result, it has been ascertained that, if the manufacturing process of the electrode stack including the positive electrode, the solid electrolyte film, and the negative electrode is not further improved, an all-solid battery having stable battery characteristics and durability characteristics cannot be obtained. Specifically, there is a problem that, due to a process of pressing the electrode including the positive electrode and the negative electrode or the solid electrolyte film by using high pressure, warping of the electrode or the solid electrolyte film sometimes occurs. In order to prevent exposure of the solid electrolyte to moisture, only by assembling the electrode stack in a short time, the warping problem of the electrode stack cannot sometimes be solved.

[0016] TECHNICAL MEANS FOR SOLVING THE PROBLEMS

[0017] The present application is a manufacturing method of an all-solid battery, including the following stages:

[0018] a negative electrode,

[0019] positive electrode, and

[0020] The stage of stacking solid electrolyte membranes to form an electrode stack;

[0021] exposing the electrode stack to an environment with a dew point temperature of -40°C and a water concentration of 127 ppm or less for 20 minutes or more; and

[0022] The electrode stack is press-formed.

[0023] Effects of the Invention

[0024] According to the manufacturing method of the present invention, a high-quality all-solid-state battery can be obtained in which the solid electrolyte does not suffer from a decrease in ion conductivity due to the influence of moisture, and in which a decrease in electrical characteristics or durability due to warping of the electrode stack is also suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] [ Figure 1 ] is a flowchart showing an outline of the assembly process of an all-solid-state battery. DETAILED DESCRIPTION

[0026] The following describes the embodiments of the present invention with reference to the accompanying drawings as appropriate. The present invention is not limited to the embodiments described below, but can be implemented within the scope of the present invention. The following are examples and do not limit the present invention in any way.

[0027] All-solid-state batteries

[0028] In this specification, the term "all-solid-state battery" refers to a battery whose electrolyte includes a solid electrolyte described below. In addition, the term "all-solid-state battery" in this specification includes secondary batteries and primary batteries.

[0029] <Negative electrode>

[0030] The negative electrode may be a negative electrode used in non-aqueous secondary battery materials, without particular limitation. For example, the negative electrode includes a negative electrode collector such as copper foil and a negative electrode layer comprising a negative electrode active material and a solid electrolyte. The negative electrode layer preferably includes a binder. Alternatively, a negative electrode may be used in which a negative electrode collector made of stainless steel is used instead of a negative electrode collector such as copper foil, and a lithium metal layer is formed on the surface of the negative electrode collector by rolling or the like to replace the negative electrode active material. The negative electrode layer comprising a negative electrode active material, a solid electrolyte and a binder may be formed on at least one surface of the negative electrode collector.

[0031] In the case where the negative electrode active material is used in the negative electrode, a carbon-based active material is preferably used. As the carbon-based active material, natural graphite, artificial graphite, hard carbon, soft carbon, carbon black, or any mixture thereof can be selected. The natural graphite includes natural graphite in which amorphous carbon is coated on the surface of the particles, and similarly, the artificial graphite includes artificial graphite in which amorphous carbon is coated on the surface of the particles. These natural graphite and artificial graphite can use primary particles or particles in which primary particles are agglomerated to form secondary particles, and a mixture thereof. In addition, the negative electrode active material can use a mixture of the carbon-based active material and a silicon-based active material. The negative electrode active material can include metal materials such as aluminum, silver, bismuth, calcium, cerium, indium, magnesium, tin, zinc, nickel, and the like.

[0032] As the binder used in the negative electrode layer, for example, fluororesins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl fluoride (PVF), conductive polymers such as polyaniline, polythiophene, polyacetylene, polypyrrole, synthetic rubbers such as styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), isoprene rubber (IR), acrylonitrile butadiene rubber (NBR), or polysaccharides such as carboxymethyl cellulose (CMC), xanthan gum, guar gum, pectin can be listed. In addition, as the binder, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, potassium polyacrylate, sodium polymethacrylate, potassium polymethacrylate; polyethyl acrylate, polyethyl acrylate, polybutyl acrylate, polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, and any mixture thereof can be used. The content of the binder is preferably 1% by mass or more and less than 10% by mass with respect to the total amount of the solid components of the negative electrode layer. If the content of the binder is too much, the portion of the surface of the negative electrode active material covered with the binder increases, and thus the ion conductivity and the electron conductivity can decrease. In addition, if the content of the binder is too little, the electrical contact between the negative electrode active material particles can not be properly made.

[0033] As the component of the binder, in addition to the inclusion of the compound, carboxymethylcellulose (referred to as "CMC") or a metal salt of carboxymethylcellulose (e.g., sodium carboxymethylcellulose, potassium carboxymethylcellulose) as a derivative of cellulose can be included. In the case where CMC or a metal salt of CMC is further added as a component of the binder, the content of CMC or the metal salt of CMC is preferably 0.05% by mass or more and 1.5% by mass or less with respect to the total amount of solid components of the negative electrode layer.

[0034] The negative electrode layer can further include a conductive aid. The conductive aid is a material for reducing the electrical resistance of the electrode. As the conductive aid, carbon black such as acetylene black, Ketjen black, activated carbon, graphite, mesoporous carbon, fullerenes, carbon nanotubes, carbon nanofibers, carbon fibers such as carbon brush, and the like can be exemplified.

[0035] In the case where carbon nanotubes or carbon nanofibers are used as the conductive aid, the content of these conductive aids is 0.01% by mass or more and 3% by mass or less, and is preferably 0.03% by mass or more and 1% by mass or less with respect to the total amount of solid components of the negative electrode layer.

[0036] Further, the negative electrode layer can be appropriately used, in addition to the use of the materials described above, with an adhesion promoter, a dispersant, a stabilizer, and the like as electrode additives that are generally used for the formation of an electrode.

[0037] < Solid electrolyte membrane >

[0038] The negative electrode, the solid electrolyte membrane, and the positive electrode used in the manufacturing method of the embodiment include a solid electrolyte. The solid electrolyte used here can exemplify an oxide-based solid electrolyte and a sulfide-based solid electrolyte. As the oxide-based solid electrolyte, for example, an oxide-based material of a garnet type, a sodium super ionic conductor (NASICON) type, or a perovskite type can be used. As the sulfide-based solid electrolyte, all known sulfide-based substances can be used, and for example, the following can be exemplified: a mixture, and the like. In the embodiment, it is preferable to use a sulfide-based solid electrolyte.

[0039] ​​​​​​​​​​​​The solid electrolyte membrane used in the embodiments is a thin, flat surface having a predetermined area and composed of a solid electrolyte. The solid electrolyte membrane may be a single layer (composed of a single solid electrolyte) or a multilayer (a stack of two or more solid electrolyte membranes).

[0040] In the present invention, the solid electrolyte membrane is preferably formed to a thickness of 15 μm to 150 μm. If the membrane thickness is less than this, short circuits are likely to occur when the solid electrolyte is pressed under high pressure. On the other hand, if the membrane thickness is greater than this, the cell volume increases excessively, and the energy density per unit volume of the all-solid-state battery does not increase.

[0041] <Positive electrode>

[0042] The positive electrode can be any positive electrode used in non-aqueous secondary battery materials, without particular limitation. For example, the positive electrode includes a positive electrode current collector and a positive electrode layer comprising a positive electrode active material and a solid electrolyte. The positive electrode layer preferably includes a binder. The positive electrode layer comprising the positive electrode active material, solid electrolyte, and binder can be formed on at least one surface of the positive electrode current collector.

[0043] As the positive electrode current collector, stainless steel, aluminum, nickel, titanium, or a positive electrode current collector obtained by surface-treating aluminum or stainless steel with carbon, nickel, titanium, or silver can be used.

[0044] The positive electrode active material preferably contains a lithium nickel composite oxide as the positive electrode active material. The so-called lithium nickel composite oxide is a general formula (Me is at least one metal selected from the group consisting of Al, Mn, Na, Fe, Co, Cr, Cu, Zn, Ca, K, Mg and Pb) and a transition metal composite oxide containing lithium and nickel. In addition, the positive electrode active material may include a lithium manganese composite oxide. Examples of lithium manganese composite oxides include lithium manganate ( )、spinel lithium manganate( ) etc. In addition, the positive electrode active material is particularly preferably a material comprising the general formula The lithium nickel manganese cobalt composite oxide having a layered crystal structure is represented by , y and z satisfy In order to obtain a high-capacity battery, it is particularly preferred to set 、 The lithium nickel composite oxide having the general formula is lithium nickel cobalt manganese composite oxide. The lithium nickel cobalt manganese composite oxide is a lithium nickel composite oxide suitable for achieving high capacity of batteries. In addition, the positive electrode active material may also contain the general formula (M is at least one selected from the group of Mn, Fe, Co, and Ni). A buffer layer can be formed on the surface of the positive electrode layer by coating with, for example, the same material as the positive electrode layer

[0045] As the binder with which the positive electrode layer is formed together with the positive electrode active material, there can be mentioned fluorine resins such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyvinyl fluoride (PVF), electrically conductive polymers such as polyaniline, polythiophene, polyacetylene, and polypyrrole, synthetic rubbers such as styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), isoprene rubber (IR), and acrylonitrile butadiene rubber (NBR), and polysaccharides such as carboxymethyl cellulose (CMC), xanthan gum, guar gum, and pectin.

[0046] In addition, the positive electrode layer can further contain an electrically conductive aid. As the electrically conductive aid, there can be mentioned carbon black such as acetylene black and Ketjen black, activated carbon, graphite, mesoporous carbon, fullerenes, carbon nanofibers, carbon nanotubes, carbon nanobrushes, and the like. In addition, it is also possible to use, as necessary, electrode additives such as tackifiers, dispersants, and stabilizers, which are generally used for the formation of electrodes.

[0047]

[0048] First, the production of the negative electrode will be described. There are several methods for producing the negative electrode. Regardless of which method is used to produce the negative electrode, it is preferable to produce the negative electrode in an environment with less moisture on the basis of dew point management, in order to suppress the adsorption of moisture onto the solid electrolyte.

[0049]

[0050] ​​​In the case of using a negative electrode in which a negative electrode active material is formed on a negative electrode current collector, a slurry obtained by dispersing a negative electrode active material, a solid electrolyte, and a binder in a dehydrated organic solvent is coated on a part or all of the surface of a negative electrode current collector such as a copper foil and dried to obtain a negative electrode precursor sheet. The obtained negative electrode precursor sheet can be compressed by a compression molding method such as roll pressing, uniaxial pressing, rubber pressing, isostatic pressing (Cold Isostatic Pressing (CIP), Warm Isostatic Pressing (WIP)), and particularly preferably Cold Isostatic Pressing, to obtain a negative electrode sheet. As the organic solvent, in addition to tertiary amine-based solvents such as acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, and triethylamine, heptane, hexane, tetrahydrofuran, toluene, and N-methylpyrrolidone, ether-based solvents, thiol-based solvents, and butyl butyrate can also be used, and all of them are preferably dehydrated.

[0051] Alternatively, a granulated body of a negative electrode active material containing at least a negative electrode active material, a solid electrolyte, and a binder can be transferred to a negative electrode current collector to obtain a negative electrode precursor sheet. At this time, a surface layer containing a polymer component such as a binder for improving the adhesion to the granulated body of the negative electrode active material can be formed on the surface of the negative electrode current collector in advance. In addition, a conductive aid can be contained in the negative electrode layer. The obtained negative electrode precursor sheet can be compressed by a compression molding method such as roll pressing, uniaxial pressing, rubber pressing, isostatic pressing (CIP, WIP) to obtain a negative electrode sheet.

[0052] Alternatively, a metal lithium layer such as a lithium foil can be arranged on a part or all of a stainless steel negative electrode current collector, and they can be made to adhere to each other by a calendering process or the like to obtain a negative electrode sheet.

[0053] <Manufacture of Solid Electrolyte Film>

[0054] Next, a solid electrolyte film is formed on the surface of the negative electrode. Regardless of the method used to form the solid electrolyte film, it is preferable to manufacture it in a low-moisture environment on the basis of dew point management to suppress the adsorption of moisture on the solid electrolyte.

[0055] A slurry obtained by dispersing a solid electrolyte in an organic solvent is coated on the surface of the negative electrode layer formed on a copper foil or the surface of metal lithium formed on a stainless steel foil and dried to form a solid electrolyte film on the surface of the negative electrode. As the organic solvent, in addition to tertiary amine-based solvents such as acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, and triethylamine, heptane, hexane, tetrahydrofuran, toluene, and N-methylpyrrolidone, ether-based solvents, thiol-based solvents, and butyl butyrate can also be used, and all of them are preferably dehydrated.

[0056] Alternatively, a slurry obtained by dispersing the solid electrolyte in an organic solvent is applied to the surface of a polyester film having polyester as a main component, and dried to form a solid electrolyte film, and then the polyester film is laminated together in a manner that the solid electrolyte film contacts the surface of the negative electrode layer or the surface of the metal lithium, whereby the solid electrolyte film can also be formed on the surface of the negative electrode.

[0057] The negative electrode and the solid electrolyte film that are laminated are compressed by a compression molding method such as roll pressing, uniaxial pressing, rubber pressing, isostatic pressing (CIP, WIP), and the like, to obtain a negative electrode-solid electrolyte film laminate. In the case where the solid electrolyte and the polyester sheet are laminated and pressed together, the polyester film is peeled off from the solid electrolyte film. At this time, it is also preferable to use a material on the surface of which a release agent such as silicone is applied, to make it easy to peel the polyester film from the solid electrolyte film.

[0058] <Manufacture of Positive Electrode>

[0059] Next, the manufacture of the positive electrode will be described. Regardless of which method is used to manufacture the positive electrode, it is preferable to manufacture it in a low-moisture environment based on dew point management, to suppress the adsorption of moisture.

[0060] A slurry obtained by dispersing the positive electrode active material, the solid electrolyte, and the binder in the organic solvent that has been subjected to dehydration treatment is applied to a part or all of the surface of the positive electrode current collector such as aluminum, and dried to obtain a positive electrode sheet. As the organic solvent, in addition to acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, tertiary amine solvents such as trimethylamine, heptane, hexane, tetrahydrofuran, toluene, N-methylpyrrolidone, and the like, ether solvents, thiol solvents, butyl butyrate, and the like can also be listed, and all of them are preferably subjected to dehydration treatment.

[0061] <Formation of Electrode Laminate>

[0062] The positive electrode sheet is laminated on the negative electrode-solid electrolyte film laminate, to obtain an electrode laminate precursor. In the case where a sulfide solid electrolyte is used as the solid electrolyte, the ion conductivity of the solid electrolyte can decrease due to exposure to moisture. Therefore, after the electrode laminate precursor is obtained, it is desirable to compress the electrode laminate precursor within a prescribed time by a method such as roll pressing, uniaxial pressing, rubber pressing, isostatic pressing (CIP, WIP), to obtain an electrode laminate. The prescribed time is, for example, within 2 days in an environment where the dew point is -40°C and the moisture concentration is 127 ppm or less. If a longer time elapses, there is a possibility that the performance will deteriorate due to water absorption of the solid electrolyte, and it is also less preferable from the viewpoint of productivity of the all-solid battery.

[0063] The positive electrode can be first rolled in a state where a sheet of the positive electrode layer having a small thickness is formed on the positive electrode current collector, and then laminated on the negative electrode-solid electrolyte membrane laminate. In addition, from the viewpoint of production efficiency, the positive electrode sheet alone can not be pressed or the pressure applied to the positive electrode sheet by the transfer arm of the laminator can be only to the extent of pressing the positive electrode sheet, and the positive electrode sheet can be placed on the negative electrode-solid electrolyte membrane laminate. The process is a process immediately before isostatic pressing for forming an electrode laminate.

[0064] In the case where the positive electrode sheet is rolled, the voids present in the positive electrode active material or the solid electrolyte are temporarily crushed, and the positive electrode is deformed due to springback that releases the pressure applied to the formed body. Since the positive electrode is extremely thin, the positive electrode sheet is warped soon after the pressing. However, if the positive electrode sheet is placed on the negative electrode-solid electrolyte membrane laminate in this state and is immediately subjected to isostatic pressing, the influence of the springback after the formation of the electrode laminate is significantly exhibited, and there is a possibility that fine peeling of the interface between the positive electrode sheet and the solid electrolyte membrane and the like occurs, which affects the battery characteristics.

[0065] On the other hand, if the positive electrode sheet is laminated on the negative electrode-solid electrolyte membrane laminate without substantially applying pressure to the positive electrode sheet and then isostatic pressing is intended to be performed, the positive electrode sheet is warped due to the influence of the gas present in the voids in the positive electrode layer when the laminate is vacuum-sealed in the pretreatment at the time of isostatic pressing. In this case, the influence of the warping of the positive electrode sometimes also affects the electrode laminate and the electrode laminate or the battery characteristics.

[0066] Therefore, during the period from the lamination of the positive electrode sheet and the negative electrode-solid electrolyte membrane laminate to the pressing into a shape, it is preferable to allow a lapse of time of a predetermined time or more. In this way, the influence of the warping of the positive electrode is mitigated, and the deformation and the like after the isostatic pressing are reduced. The predetermined time is, for example, 20 minutes or more in an environment where the dew point is -40°C and the moisture concentration is 127 ppm or less. Thereby, the warping of the electrode laminate is mitigated to the extent that the influence of the pressing into a shape does not occur. In the case where the negative electrode, the solid electrolyte membrane, and the positive electrode are laminated in multiple layers, it is preferable to perform the pressing into a shape after a lapse of a predetermined time after the lamination of the positive electrode sheet and the negative electrode-solid electrolyte membrane laminate.

[0067] <Sealing of the electrode laminate>

[0068] The obtained electrode stack is ideally quickly sealed in an outer casing. One end of a rectangular metal plate serving as a negative terminal is mounted on the negative electrode collector, and one end of a rectangular metal terminal serving as a positive terminal is mounted on the positive electrode collector, after which the electrode stack is housed in an aluminum outer casing. A resin layer such as polyolefin is preferably formed on at least the surface of the inner surface of the outer casing facing the electrode stack. The resin layer is heated to melt the resin and solidified again, thereby sealing the electrode stack with the aluminum outer casing. At this time, the other end of the positive terminal and the other end of the negative terminal are configured to be led out to the outside of the outer casing. In the portion where the positive terminal and the negative terminal are in contact with the resin layer on the inner surface of the outer casing, a resin layer of the same or different type as the resin used in the resin layer on the inner surface of the outer casing may also be provided, so that the outer casing of the aforementioned portion is firmly bonded.

[0069] Example

[0070] The battery is manufactured according to the process shown in the embodiment of the invention. Figure 1 is a flow chart outlining an embodiment of the invention.

[0071] [I] Formation of anode-solid electrolyte membrane stack

[0072] (1) A 10 μm thick stainless steel negative electrode current collector having a 20 μm thick metal lithium layer formed on its surface was prepared as a negative electrode (manufactured by Honjo Metal Co., Ltd.).

[0073] (2) Dispersing the solid electrolyte in xylene as an organic solvent The slurry obtained by coating the surface of a polyester film mainly composed of polyester with a thickness of 100 μm (D50: 8 μm) was applied and dried to obtain a solid electrolyte membrane. The obtained solid electrolyte membrane was laminated together with the polyester film so as to contact the surface of the metal lithium.

[0074] (3) The negative electrode-solid electrolyte membrane stack of (2) is laminated and vacuum-sealed in a nylon vacuum bag and maintained at a pressure of 400 MPa at room temperature (25°C) for 1 minute. Thereafter, while maintaining the laminated and sealed state, the negative electrode-solid electrolyte membrane stack is compressed by isostatic pressing to obtain a negative electrode-solid electrolyte membrane stack having a porosity of 7% in the negative electrode layer. The size of the stack of the negative electrode and the solid electrolyte membrane is .

[0075] (4) The polyester film is peeled off from the solid electrolyte membrane to obtain a negative electrode-solid electrolyte membrane laminate.

[0076] [II] Lamination of positive electrode sheet and negative electrode-solid electrolyte membrane stack

[0077] (1) 70 mass% of lithium cobaltate (D50: 8 μm) as a positive electrode active material, 25 mass% of a solid electrolyte of lithium phosphorus oxynitride (average particle diameter 1 μm), 2 mass% of acetylene black (manufactured by TIMCAL JAPAN, Inc.) and 3 mass% of styrene-butadiene rubber (SBR) as a binder were dispersed in xylene as an organic solvent, and the obtained slurry was coated on an aluminum foil (manufactured by UACJ Corporation) having a thickness of 10 μm and dried to form a positive electrode layer, thereby obtaining a positive electrode. (1) 70 mass% of lithium cobaltate (D50: 8 μm) as a positive electrode active material, 25 mass% of a solid electrolyte of lithium phosphorus oxynitride (average particle diameter 1 μm), 2 mass% of acetylene black (manufactured by TIMCAL JAPAN, Inc.) and 3 mass% of styrene-butadiene rubber (SBR) as a binder were dispersed in xylene as an organic solvent, and the obtained slurry was coated on an aluminum foil (manufactured by UACJ Corporation) having a thickness of 10 μm and dried to form a positive electrode layer, thereby obtaining a positive electrode.

[0078] (2) The positive electrode obtained in the above (1) was cut into The positive electrode and the negative electrode-solid electrolyte film of the negative electrode-solid electrolyte film laminated body prepared in [I] were laminated in such a manner that the positive electrode layer was in contact with the solid electrolyte film, thereby obtaining an electrode laminated body precursor. The number of laminated layers of the positive electrode and the negative electrode-solid electrolyte film laminated body was each one layer.

[0079] [III] Mitigation of warpage of the positive electrode sheet

[0080] The electrode laminated body precursor obtained in the above [II] was stored in an atmosphere managed to have a dew point temperature of -40°C and a moisture concentration of 127 ppm or less until the time of press forming. The time from the time of lamination of the last positive electrode sheet to the time of press forming was set to the time shown in Table 1 (Examples 1 to 3 and Comparative Examples 1 and 2).

[0081] [IV] Pressing of the electrode laminated body

[0082] (1) The electrode laminated body precursor obtained in each example was vacuum-sealed by lamination in a nylon-made vacuum bag, and held at a pressure of 400 MPa for 1 minute at room temperature (25°C). Then, the electrode laminated body precursor was compressed by an isostatic pressing method while maintaining the vacuum-sealed state, thereby obtaining an electrode laminated body having a void ratio of 5% in the positive electrode layer.

[0083] [V] Encapsulation into an outer case

[0084] (1) The electrode laminated body obtained in the above [IV] was encapsulated into an outer case by the method described in the embodiment, thereby obtaining a battery in which the positive electrode terminal and the negative electrode terminal were drawn outside of an outer case made of aluminum (manufactured by Dai Nippon Printing Co., Ltd.).

[0085] ​For the obtained battery, after constant current charging at 0.05 C until 4.25 V, the voltage was switched to constant voltage charging, and the charging was stopped at 0.005 C. Then, the discharge average operating voltage at 0.05 C when discharged to 2.5 V was obtained. Table 1 shows the discharge average operating voltage of other examples and comparative examples when the discharge average operating voltage of Example 1 is set to 1. In addition, regarding "wrinkles after pressing" in Table 1, after the electrode laminate precursor was compressed by an isostatic pressing method, the obtained electrode laminate was observed by visual observation, and a case where wrinkles were found was evaluated as "yes", and a case where no wrinkles were found was evaluated as "no".

[0086] [Table 1]

[0087]

[0088] As can be seen from Table 1, it is preferable that the time from the final lamination of the positive electrode sheet and the negative electrode-solid electrolyte film laminate to the pressing into a shape be left for 20 minutes or more.

[0089] The embodiment of the present application is only one example, and is not limited thereto. For example, although an aluminum laminated film was used for the outer case, it can be a solid aluminum case, and can be a cylindrical shape. Li6PS5Cl was used for the solid electrolyte, but as long as it is a sulfide-based solid electrolyte having low chemical stability with water, it can be applied to the present application. The positive electrode and the negative electrode were positive electrodes and negative electrodes that were previously adjusted to a prescribed size, but they can be laminated and then quickly cut to a prescribed shape. Furthermore, of course, design changes can be made within the scope of the present application.

Claims

1. A manufacturing method of an all-solid battery, comprising the following stages: stacking a negative electrode, a positive electrode, and a solid electrolyte film to form an electrode laminate; exposing the electrode laminate in an environment having a dew point temperature of -40°C and a moisture concentration of 127 ppm or less for 20 minutes or more; and subjecting the electrode laminate to press forming.

2. The method for manufacturing a full-solid battery according to claim 1, wherein exposing the electrode laminate in an environment having a dew point temperature of -40°C and a moisture concentration of 127 ppm or less for 2 days or less.

3. The method for manufacturing a full-solid battery according to claim 1 or 2, wherein subjecting the electrode laminate to press forming by an isostatic press method.

4. The method for manufacturing a full-solid battery according to claim 3, wherein The isostatic press method is a cold isostatic press method.

5. The method for manufacturing a full-solid battery according to any one of claims 1 to 4, wherein The solid electrolyte is a sulfide-based solid electrolyte.

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