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 deterioration in characteristics is prevented; and an all-solid-state battery obtained by the manufacturing method. The present invention is a method for manufacturing an all-solid-state battery, the method comprising a step for forming an electrode laminate by laminating a negative electrode, a solid electrolyte membrane, and a positive electrode, comprising the steps of: forming the solid electrolyte membrane by applying a slurry containing a solid electrolyte in a solvent onto a membrane surface on which a release agent layer containing a release agent is formed; removing the film from the release agent layer; and laminating the solid electrolyte membrane including the release agent layer exposed after the membrane has been removed on the positive electrode, and laminating the solid electrolyte membrane and the positive electrode such that the release agent is present between the solid electrolyte membrane and the positive electrode at a density of not less than the density of not more than the density of not more than the density of not more than the density of not more than the density of not more than the density of not more than the density of not more than the density of not more than the density of not more than the density of not more than the density of the release agent.

Description

TECHNICAL FIELD

[0001] The present application relates to an all-solid battery including a solid electrolyte film and a manufacturing method of an all-solid battery. 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 capable of repeated charge and discharge as an energy source for automobiles or households 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 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 polyester substrate such as a polyethylene terephthalate (PET) film and peeling the substrate.

[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 is obtained.

[0007] A release agent layer, such as a silicone compound, is typically formed on the surface of a polyester film to facilitate removal of the solid electrolyte layer. If this release agent layer transfers to the solid electrolyte layer, there are concerns about poor bonding between the solid electrolyte layer and the electrode, or irreversible capacity due to electrolyte ions being taken into the release agent layer. Therefore, countermeasures are being developed to prevent silicone compounds from transferring to the solid electrolyte layer.

[0008] In addition, there is a problem that the positive electrode, negative electrode, and solid electrolyte layer used in all-solid-state batteries are easily peeled off at the bonding interface between them. In order to improve the strength of the bonding interface between them, a measure has been taken to stack them via an adhesive layer.

[0009] Patent Document 1 discloses a technique in which an antistatic layer is formed on the surface of a polyester film and then subjected to pretreatment such as anchor coating, corona treatment, plasma treatment, or atmospheric pressure plasma treatment to prevent transfer of a release agent to the solid electrolyte layer. Furthermore, Patent Document 2 discloses a technique for bonding a solid electrolyte layer to an electrode via an adhesive layer.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-142259

[0013] Patent Document 2: International Publication No. 2020 / 137354 Summary of the Invention

[0014] Problems to be solved by the invention

[0015] However, if an electrode such as a positive or negative electrode is bonded to a solid electrolyte, or if solid electrolytes are bonded to each other via an adhesive layer, the components of the adhesive layer become resistors, adversely affecting battery characteristics. On the other hand, if the adhesive layer is completely removed, the bonding between the positive or negative electrode and the solid electrolyte, or between the solid electrolytes, becomes weak, and the bonded surfaces may peel.

[0016] The inventors conducted intensive research and found that by allowing an appropriate amount of release agent transferred from the membrane to the solid electrolyte to remain on the surface of the solid electrolyte or electrode, the resistance of the all-solid-state battery can be suppressed to the minimum allowable range, thereby preventing battery insulation.

[0017] Technical means to solve the problem

[0018] The present application is a manufacturing method of an all-solid battery including a step of laminating a negative electrode, a solid electrolyte film, and a positive electrode to form an electrode laminate. The manufacturing method of an all-solid battery is characterized by including a step of forming the solid electrolyte film by applying a slurry containing a solid electrolyte in a solvent on a surface of a film formed with a release agent layer containing a release agent, a step of removing the film from the release agent layer, and a step of laminating the solid electrolyte film containing the release agent layer exposed after the removal of the film between the solid electrolyte film and the positive electrode with the release agent in the release agent layer. The above and The solid electrolyte film and the positive electrode are laminated in the following manner in which the density exists.

[0019] Effects of the Invention

[0020] According to the manufacturing method of the present application, a high-quality all-solid battery in which peeling at the boundary between the electrode and the solid electrolyte film is suppressed, the possibility of short circuit is low, and the cycle characteristics are excellent can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0021] [ Figure 1 ] is a flowchart showing an outline of an assembling step of an all-solid battery. DETAILED DESCRIPTION

[0022] Embodiments of the present application will be described below with appropriate reference to the accompanying drawings. Furthermore, the present application is not limited to the embodiments described below, and can be implemented within the scope of the gist of the present application. The following is an example, and does not limit the present application in any way.

[0023] <All-solid battery>

[0024] In the present specification, the all-solid battery refers to a battery in which the electrolyte contains a solid electrolyte described later. In addition, the term of the all-solid battery in the present specification includes a secondary battery and a primary battery.

[0025] <Negative electrode>

[0026] The negative electrode can use a negative electrode used in a nonaqueous secondary battery material, and is not particularly limited. For example, the negative electrode includes a negative electrode current collector such as a copper foil, and a negative electrode layer containing a negative electrode active material and a solid electrolyte. The negative electrode layer preferably contains a binder. A negative electrode in which a negative electrode current collector made of stainless steel is used instead of a negative electrode current collector such as a copper foil, and a lithium metal layer is formed on the surface of the negative electrode current collector by calendering or the like instead of a negative electrode active material can also be used. The negative electrode layer containing a negative electrode active material, a solid electrolyte, and a binder can be formed on at least one face of the negative electrode current collector.

[0027] 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.

[0028] 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.

[0029] In addition to the aforementioned compounds, the binder component may also contain carboxymethyl cellulose (referred to as "CMC"), a cellulose derivative, or a metal salt of carboxymethyl cellulose (e.g., sodium carboxymethyl cellulose, potassium carboxymethyl cellulose). When CMC or a metal salt of CMC is further added as a binder component, the content of CMC or the CMC metal salt is preferably 0.05% by mass to 1.5% by mass relative to the total solid content of the negative electrode layer.

[0030] The negative electrode layer may further include a conductive additive. A conductive additive is a material used to reduce the resistance of the electrode. Examples of conductive additives include carbon black such as acetylene black and Ketjen black, activated carbon, graphite, mesoporous carbon, fullerenes, carbon nanotubes, carbon nanofibers, and carbon fibers such as carbon brushes.

[0031] When carbon nanotubes or carbon nanofibers are used as the conductive additive, the content of these conductive additives is 0.01% by mass to 3% by mass, preferably 0.03% by mass to 1% by mass, based on the total solid content of the negative electrode layer.

[0032] Furthermore, in addition to the materials described above, electrode additives generally used for forming electrodes, such as thickeners, dispersants, and stabilizers, may be appropriately used in the negative electrode layer.

[0033] Solid electrolyte membrane

[0034] The negative electrode, solid electrolyte membrane, and positive electrode used in the manufacturing method of the embodiment include a solid electrolyte. Examples of the solid electrolyte used here include oxide-based solid electrolytes and sulfide-based solid electrolytes. As the oxide-based solid electrolyte, oxide-based materials such as garnet-type, sodium superion conductor (NASICON)-type, or perovskite-type can be used, but are not limited to these. As the sulfide-based solid electrolyte, all known sulfide-based substances can be used, for example: 、 mixture, 、 、 、 、 、 、 、 、 、 、 、 、 In the embodiment, it is preferable to use a sulfide-based solid electrolyte.

[0035] The solid electrolyte film used in the embodiments refers to a flat surface in a thin shape having a prescribed area, and is a substance composed of a solid electrolyte. The solid electrolyte film can be a single layer (a solid electrolyte film composed of one kind of solid electrolyte), or can be a multilayer (a solid electrolyte film in which two or more kinds of solid electrolyte films are laminated).

[0036] In the present application, the film thickness of the solid electrolyte film is preferably 15 μm to 150 μm. If less than the film thickness, in the case where the solid electrolyte is press-formed at a high pressure, the battery is likely to be short-circuited. On the other hand, if more than the film thickness, the excess increase in the volume of the cell is likely to result, and the energy density per unit volume of the all-solid battery is not likely to increase.

[0037] <Release sheet>

[0038] The release sheet refers to a flexible sheet in which a release agent layer that makes the solid electrolyte film easily peel off is formed on the surface of the sheet member. As the flexible sheet, for example, a general sheet in which a polyester is filmized can be used, and a film mainly containing a component selected from the group consisting of polyethylene terephthalate, polyethylene 2,6-naphthalate, polybutylene terephthalate, polypropylene terephthalate, and a mixture thereof can be used, but is not limited thereto. As the release agent that constitutes the release agent layer, a silicone-based, an alkyd-based, an olefin-based, a fluorine-based, or an alkyl-based release agent, or a combination thereof can be used. Among them, it is preferable to use a release agent that contains a silicone resin having a reactive functional group that is hardened by ultraviolet rays or heat, and that can easily control the transfer amount of the release agent by controlling the temperature.

[0039] <Positive electrode>

[0040] The positive electrode can use a positive electrode used in a nonaqueous secondary battery material, and is not particularly limited. For example, the positive electrode includes a positive electrode current collector, and a positive electrode layer containing a positive electrode active material and a solid electrolyte. The positive electrode layer preferably contains a binder. The positive electrode layer containing the positive electrode active material, the solid electrolyte, and the binder can be formed on at least one face of the positive electrode current collector.

[0041] The positive electrode current collector can use a stainless steel, an aluminum, a nickel, a titanium, and a positive electrode current collector obtained by surface-treating the surface of an aluminum or a stainless steel with carbon, nickel, titanium, or silver.

[0042] The positive electrode active material preferably contains a lithium nickel-based complex oxide as the positive electrode active material. The lithium nickel-based complex oxide is a general formula (Me represents a transition metal complex oxide containing lithium and nickel, and Me is at least one or more metals selected from the group consisting of Al, Mn, Na, Fe, Co, Cr, Cu, Zn, Ca, K, Mg, and Pb). In addition, the positive electrode active material can include a lithium-manganese complex oxide. The lithium-manganese complex oxide can include, for example, lithium manganate having a sawtooth layer structure (LiMn2O4) ), spinel lithium manganate (LiMn2O3) ), and the like. In addition, the positive electrode active material is particularly preferably a lithium-nickel-manganese-cobalt complex oxide having a layered crystal structure represented by the general formula . Here, x in the general formula is , y and z are positive numbers satisfying , and the value of y is 0.5 or more. In order to obtain a high-capacity battery, it is particularly preferable to set , . The lithium-nickel complex oxide having the general formula, i.e., the lithium-nickel-cobalt-manganese complex oxide. The lithium-nickel-cobalt-manganese complex oxide is a lithium-nickel complex oxide suitable for achieving high capacity of a battery. In addition, the positive electrode active material can include a complex oxide represented by the general formula (M is at least one selected from the group consisting of Mn, Fe, Co, and Ni). The surface of the positive electrode active material can be coated with a substance such as LiNbO3 to form a buffer layer. Regarding the buffer layer, the buffer layer-forming substance can be formed to be 10 nm or less, thereby suppressing the interfacial resistance between the positive electrode layer and the solid electrolyte membrane. The buffer layer can be formed on the surface of the positive electrode layer using a sol-gel method or the like.

[0043] As the binder with which the positive electrode layer is formed together with the positive electrode active material, a fluorine resin such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), or polyvinyl fluoride (PVF), a conductive polymer such as polyaniline, polythiophene, polyacetylene, or polypyrrole, a synthetic rubber such as styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR), isoprene rubber (IR), or acrylonitrile butadiene rubber (NBR), or a polysaccharide such as carboxymethyl cellulose (CMC), xanthan gum, guar gum, or pectin can be exemplified.

[0044] In addition, a conductive aid can be further included in the positive electrode layer. As the conductive aid, carbon black such as acetylene black or ketjen black, activated carbon, graphite, mesoporous carbon, a fullerene, a carbon nanofiber, a carbon nanotube, a carbon nanobrush, or the like can be exemplified. Furthermore, an adhesion promoter, a dispersant, a stabilizer, or the like, which is generally used for forming an electrode, can be appropriately used in the positive electrode layer.

[0045]

[0046] ​First, the production of the negative electrode will be described. There are several methods for producing the negative electrode, but whichever method is used to produce the negative electrode, it is preferable to produce it in a low-moisture environment on the basis of dew point management to suppress moisture from being adsorbed on the solid electrolyte.

[0047] <Production of the negative electrode>

[0048] In the case where a negative electrode having a negative electrode layer formed on a negative electrode current collector is used, a slurry obtained by dispersing a negative electrode active material, a solid electrolyte, and a binder in a dehydrated organic solvent is applied to 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 using a press forming method such as roll pressing, uniaxial pressing, rubber pressing, isostatic pressing (Cold Isostatic Pressing (CIP), Warm Isostatic Pressing (WIP)), and the like to obtain a negative electrode sheet. As the organic solvent, in addition to acetonitrile, xylene, dimethoxyethane, a tertiary amine-based solvent such as dimethylamide, heptane, hexane, tetrahydrofuran, toluene, N-methylpyrrolidone, and the like, ether-based solvents, thiol-based solvents, butyl butyrate, and the like can be listed, and all of them are preferably dehydrated.

[0049] 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 close contact with 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 using a press forming method such as roll pressing, uniaxial pressing, rubber pressing, isostatic pressing (CIP, WIP), and the like to obtain a negative electrode sheet.

[0050] Alternatively, a metal lithium layer such as a lithium foil can be arranged on a part or all of a negative electrode current collector made of stainless steel, and they can be made to be in close contact by a calendering process or the like to obtain a negative electrode sheet.

[0051] <Production of the solid electrolyte film>

[0052] Next, a solid electrolyte film is formed on the surface of the negative electrode. Whichever method is used to form the solid electrolyte film, it is preferable to produce it in a low-moisture environment on the basis of dew point management to suppress moisture from being adsorbed on the solid electrolyte.

[0053] A slurry obtained by dispersing a solid electrolyte in an organic solvent is applied to the surface of the negative electrode layer formed on the copper foil or the surface of the lithium metal formed on the stainless steel foil, and dried, whereby a solid electrolyte film can be formed on the surface of the negative electrode. As the organic solvent, in addition to acetonitrile, dimethylbenzene, 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 be mentioned, and all of them are preferably subjected to a dehydration treatment.

[0054] Alternatively, a slurry obtained by dispersing a 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 lithium metal, whereby a solid electrolyte film can be formed on the surface of the negative electrode. At this time, it is preferable to form a solid electrolyte film on the surface of the release sheet to which a release agent layer is applied, and then laminate the release sheet together in a manner that the solid electrolyte film contacts the surface of the negative electrode layer or the surface of the lithium metal. If the release film is peeled off from the obtained laminate, a negative electrode-solid electrolyte film laminate can be obtained, and on the surface of the solid electrolyte film, it is very preferable to transfer a little of the release agent layer of the release sheet, and the release agent remains on the surface of the solid electrolyte film. By laminating this negative electrode-solid electrolyte film laminate on the positive electrode described later, the release agent can be present between the solid electrolyte film and the positive electrode. It is very preferable that the release agent be present between the solid electrolyte film and the positive electrode in a state of being in contact with the surface of the positive electrode. The above and The following density exists.

[0055] The laminated negative electrode and the solid electrolyte film are compressed by a compression molding method such as roll pressing, uniaxial pressing, rubber pressing, isostatic pressing (CIP, WIP), and the like, whereby a negative electrode-solid electrolyte film laminate is obtained. Further, in the case where the solid electrolyte is laminated together with the polyester sheet and is pressed, 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, so that the polyester film is easily peeled off from the solid electrolyte film.

[0056] <Manufacture of Positive Electrode>

[0057] 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 on the basis of dew point management, so as to suppress the adsorption of moisture.

[0058] A slurry obtained by dispersing the positive electrode active material, solid electrolyte, and binder in a dehydrated organic solvent is applied to part or all of the surface of a positive electrode current collector such as aluminum, and dried to obtain a positive electrode sheet. Examples of the organic solvent include tertiary amine solvents such as acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, and triethylamine, heptane, hexane, tetrahydrofuran, toluene, and N-methylpyrrolidone, as well as ether solvents, mercaptan solvents, and butyl butyrate, all of which are preferably dehydrated.

[0059] <Formation of Electrode Stack>

[0060] The positive electrode sheet is stacked on the negative electrode-solid electrolyte membrane stack to obtain an electrode stack precursor. When a sulfide-based solid electrolyte is used as the solid electrolyte, the ion conductivity of the solid electrolyte will decrease due to exposure to moisture. Therefore, after obtaining the electrode stack precursor, it is ideal to compress the electrode stack precursor using a press forming method such as roller pressing, uniaxial pressing, rubber pressing, isostatic pressing (CIP, WIP) within a specified time to obtain the electrode stack. The so-called specified time is an environment with a dew point of -40°C and a moisture concentration of 127 ppm or less, for example, within 2 days. If a longer time passes, the performance may deteriorate due to water absorption by the solid electrolyte, which is also undesirable from the perspective of reducing the productivity of the entire Dongfeng battery.

[0061] The positive electrode can be first rolled as a thin sheet with only the positive electrode layer formed on the positive electrode current collector, and then laminated on the negative electrode-solid electrolyte membrane stack. In addition, from the perspective of production efficiency, the positive electrode sheet itself can be placed on the negative electrode-solid electrolyte membrane stack without being pressurized, or the laminator's transport arm can be used to apply only enough pressure to press the positive electrode sheet. This process is the process immediately before the isostatic pressing to form the electrode stack.

[0062] So far, an embodiment of overlapping the positive electrode sheet after producing the negative electrode-solid electrolyte membrane stack has been described, but the positive electrode and the solid electrolyte membrane formed on the surface of the polyester sheet can also be stacked and pressed, and then the polyester sheet can be peeled off to produce the positive electrode-solid electrolyte membrane stack, and then the negative electrode sheet can be overlapped on the surface where the release agent remains.

[0063] Sealing of the Electrode Stack

[0064] The obtained electrode stack is desirably 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. 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 at 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.

[0065] The above method can produce an all-solid-state battery comprising an electrode stack formed by stacking a negative electrode, a solid electrolyte membrane, and a positive electrode. Another embodiment of the present invention is an all-solid-state battery, wherein the negative electrode comprises at least a negative electrode layer, the positive electrode comprises at least a positive electrode layer, the negative electrode layer is in contact with the solid electrolyte membrane, and the positive electrode layer is in contact with the solid electrolyte membrane, and a release agent layer comprising a silicone resin and a conductive powder is present at at least one of the boundaries between the negative electrode layer and the solid electrolyte membrane and the boundaries between the positive electrode layer and the solid electrolyte membrane.

[0066] Example

[0067] 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.

[0068] [I] Formation of anode-solid electrolyte membrane stack

[0069] (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.).

[0070] (2) Dispersing the solid electrolyte in xylene as an organic solvent The resulting slurry, obtained by coating a polyester film with a release agent layer formed on a polyester film primarily composed of polyester, was applied to the surface of a release film (release sheet) and dried to produce a solid electrolyte membrane. The resulting solid electrolyte membrane was then laminated together with the polyester film so that it came into contact with the surface of the lithium metal.

[0071] (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 negative electrode-solid electrolyte membrane stack is .

[0072] (4) The polyester film is peeled off from the solid electrolyte membrane to obtain a negative electrode-solid electrolyte membrane laminate.

[0073] [II] Peeling off the release sheet

[0074] (1) By adjusting the temperature during the isostatic pressing method in [I] (3) above, the amount of the release agent transferred onto the negative electrode-solid electrolyte membrane stack obtained in [I] (4) above was changed as shown in Table 1.

[0075] [III] Lamination of positive electrode sheet and negative electrode-solid electrolyte membrane stack

[0076] (1) The surface of the particles of the positive electrode active material is coated with a 10 nm thick of A positive electrode was obtained by dispersing 70% by mass of lithium ion battery (D50: 8 μm), 25% by mass of Li6PS5Cl (average particle size 1 μm) as a solid electrolyte, 2% by mass of acetylene black (manufactured by TIMCAL JAPAN Co., Ltd.), and 3% by mass of styrene-butadiene rubber (SBR) as a binder in xylene as an organic solvent. The obtained slurry was applied on an aluminum foil with a thickness of 10 μm (manufactured by UACJ Co., Ltd.) and dried to form a positive electrode layer.

[0077] (2) Cut the positive electrode obtained in (1) into The negative electrode-solid electrolyte membrane stack in [I] is stacked so that the surface on which the release agent layer is transferred is in contact with the positive electrode layer, thereby obtaining an electrode stack precursor. The positive electrode and negative electrode-solid electrolyte membrane stacks are stacked in a single layer each.

[0078] [IV] Pressurization of the Electrode Stack

[0079] (1) The electrode stack precursor obtained in each example was 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. While the laminate was sealed, the electrode stack precursor was compressed by isostatic pressing to obtain an electrode stack having a positive electrode layer porosity of 5%.

[0080] [V] Sealing of the outer case

[0081] (1) The electrode stack obtained in [IV] is sealed in an outer case by the method described in the embodiment, thereby obtaining a battery in which the positive and negative terminals are drawn out to the outside of an aluminum outer case (manufactured by Dai Nippon Printing Co., Ltd.).

[0082] For the obtained battery, the resistance value at 1 kHz at 25°C and the presence or absence of short-circuiting after charge-discharge (20 cycles) are shown in Table 1.

[0083] The 1 kHz resistance is a value obtained by measuring the resistance value using the four-terminal method (HIOKI 3560 AC Hitester). It is known that the 1 kHz resistance changes in accordance with the amount of release agent transferred to the solid electrolyte film.

[0084] In addition, as to the presence or absence of short-circuiting after 20 cycles of charge-discharge, the battery is evaluated as "yes" in the case where short-circuiting occurs and as "no" in the case where short-circuiting does not occur, by repeating the following charge-discharge conditions 20 times: constant current charging at 0.05 C until the upper limit voltage of 4.2 V in a thermostat at 45°C, followed by constant voltage charging at a total charge time of 1 cycle of 20 hours, constant current discharging at 0.05 C until 3.0 V, and applying power to the battery.

[0085] [Table 1]

[0086]

[0087] The embodiment of the present application is merely one example and is not limited thereto. For example, although an aluminum laminated film is used for the outer case, it can be a strong case of aluminum or a cylindrical type. Li6PS5Cl is 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 and negative electrodes are those of a predetermined size, but they can also be cut into a predetermined shape after being stacked. Furthermore, of course, design changes can be made without affecting the scope of the application.​

Claims

1. A method for manufacturing an all-solid battery, comprising a step of laminating a negative electrode, a solid electrolyte film, and a positive electrode to form an electrode laminate, the method for manufacturing an all-solid battery characterized by comprising the steps of: applying a slurry containing a solid electrolyte in a solvent to a surface of a film formed with a release agent layer containing a release agent to form the solid electrolyte film; removing the film from the release agent layer; and laminating the solid electrolyte film containing the release agent layer exposed after the removal of the film to the positive electrode, The release agent is present between the solid electrolyte film and the positive electrode The above and The solid electrolyte film and the positive electrode are laminated in such a manner that the density of the release agent exists between the solid electrolyte film and the positive electrode.

2. The method for manufacturing a full-solid battery according to claim 1, wherein the release agent layer containing a silicone resin.

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