All-solid-state batteries

Abstract

This invention provides an all-solid-state battery capable of suppressing short circuits caused by defects in the resin layer of the outer casing. An all-solid-state battery has an electrode structure sealed inside an outer casing. The outer casing has a metal layer, and the electrode structure has an electrode stack and an outermost solid electrolyte layer. The electrode stack includes at least one electrode body, which sequentially comprises a first current collector layer, a first active material layer, a first solid electrolyte layer, a second active material layer, a second current collector layer, a second active material layer, a second solid electrolyte layer, a first active material layer, and a first current collector layer. When the first current collector layer, disposed at at least one end in the stacking direction of the electrode stack, is used as the outermost first current collector layer, the area of ​​the outermost solid electrolyte layer is larger than the area of ​​the flat plate portion of the outermost first current collector layer when viewed along the stacking direction. The outermost solid electrolyte layer is stacked in such a way that it completely covers the flat plate portion of the outermost first current collector layer.

Description

Technical Field

[0001] This application relates to all-solid-state batteries. Background Technology

[0002] In recent years, in order to improve battery safety, efforts are being made to develop all-solid-state batteries that use solid electrolytes instead of non-aqueous electrolytes.

[0003] On the other hand, all-solid-state batteries using solid electrolytes suffer from structural instability due to volume changes caused by charging and discharging, and degradation of the solid electrolyte due to reaction with moisture in the air. The following techniques are known to address these issues.

[0004] Patent Document 1 discloses a technology for an all-solid-state battery in which a resin layer is disposed on the side of the electrode stack to improve the adhesion between the electrode stack and the resin layer. Patent Document 2 discloses a technology for an all-solid-state battery in which a solid electrolyte is disposed between the outer casing and the electrode stack to improve strength. Patent Document 3 discloses a technology for an all-solid-state battery in which, to prevent short circuits caused by direct contact between different electrode layers, the area of ​​the solid electrolyte layer is larger than the area of ​​the electrode layers, and the solid electrolyte layer is configured to cover these electrode layers. Patent Document 4 discloses a technology for an all-solid-state battery in which a resin layer covers the entire electrode stack to improve moisture resistance. Patent Document 5 discloses a technology for a bipolar lithium-ion battery in which single cells are stacked together with an adhesive resin layer in place to suppress misalignment.

[0005] Prior art literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-192610

[0007] Patent Document 2: Japanese Patent Application Publication No. 2014-235990

[0008] Patent document 3: Japanese Patent Application Publication No. 2018-142534

[0009] Patent Document 4: International Publication No. 2014 / 007215

[0010] Patent document 5: Japanese Patent Application Publication No. 2017-73374 Summary of the Invention

[0011] As an outer casing for all-solid-state batteries, laminated casings in which a metal layer is covered by a resin layer are known. All-solid-state batteries are manufactured by sealing the electrode structures into such casings.

[0012] On the other hand, when manufacturing all-solid-state batteries using laminated outer casing materials, conductive foreign matter can sometimes be mixed in between the current collector layer and / or the tabs disposed on the outermost layer of the electrode structure and the outer casing. If such conductive foreign matter is present, stress will concentrate on it due to external pressure, causing damage to the inner resin layer of the laminated outer casing. Furthermore, stress will concentrate at the corners of the current collector layer disposed on the outermost layer of the electrode structure due to external pressure, also causing damage to the inner resin layer of the laminated outer casing. If the resin layer of the laminated outer casing is damaged, the metal layer and current collector layer inside the outer casing will be electrically connected directly or via the conductive foreign matter, resulting in a short circuit. This stress is applied not only after the manufacturing of the all-solid-state battery but also during the heat-pressing process used to seal the electrode structure into the laminated outer casing. Therefore, from the perspective of manufacturing and safe use of all-solid-state batteries, suppressing short circuits caused by damage to the inner resin layer of the laminated outer casing is an important issue.

[0013] Therefore, the main objective of this disclosure is to provide an all-solid-state battery capable of suppressing short circuits caused by defects in the internal resin layer of the outer casing.

[0014] This disclosure provides an all-solid-state battery as one means to solve the above-mentioned problems. An electrode structure is sealed inside an outer casing. The outer casing has an outer resin layer, an inner resin layer, and a metal layer disposed between the outer and inner resin layers. The electrode structure has an electrode stack and an outermost solid electrolyte layer. The electrode stack includes at least one electrode body, which sequentially comprises a first current collector layer, a first active material layer, a first solid electrolyte layer, a second active material layer, a second current collector layer, a second active material layer, a second solid electrolyte layer, a first active material layer, and a first current collector layer. The first current collector layer and the second current collector layer each have an extension portion and a flat plate portion. The first current collector layer is disposed at at least one end in the stacking direction of the electrode stack. When the first current collector layer disposed at at least one end in the stacking direction of the electrode stack is used as the outermost first current collector layer, the outermost solid electrolyte layer is stacked on the surface of the outermost first current collector layer opposite to the side of the first active material layer. When viewed along the stacking direction, the area of ​​the outermost solid electrolyte layer is larger than the area of ​​the flat plate portion of the outermost first current collector layer. When viewed along the stacking direction, the outermost solid electrolyte layer is stacked in such a way that it covers the entire flat plate portion of the outermost first current collector layer.

[0015] In the aforementioned all-solid-state battery, the outermost solid electrolyte layer may contain a polymer electrolyte.

[0016] The aforementioned all-solid-state battery can have the following structure. Specifically, in the electrode structure, when the flat portion of the outermost first current collector layer sandwiched between the outermost solid electrolyte layer and the first solid electrolyte layer, and the first active material layer are considered as a stack A, when viewed along the stacking direction, at least one of the outermost solid electrolyte layer and the first solid electrolyte layer has an area larger than the stack A. When viewed along the stacking direction, at least one of the outermost solid electrolyte layer and the first solid electrolyte layer is stacked in a manner that covers the entire stack A. The outermost solid electrolyte layer and the first solid electrolyte layer are integrated at their outer edges, covering at least the sides of the stack A other than the side where the extension of the first current collector layer is disposed, thus housing the stack A within it. When viewed along the stacking direction, the extension of the outermost first current collector layer extends from the side of the integrated outermost solid electrolyte layer and the first solid electrolyte layer.

[0017] The aforementioned all-solid-state battery can have the following structure. Specifically, in the electrode body, when the second active material layer and the second current collector layer, sandwiched by the first and second solid electrolyte layers, form a stack B, when viewed along the stacking direction, at least one of the first and second solid electrolyte layers has an area larger than the stack B; when viewed along the stacking direction, at least one of the first and second solid electrolyte layers is stacked to cover the entire stack B; the first and second solid electrolyte layers are integrated at their outer edges to at least cover the sides of the stack B where the extension portion of the second current collector layer is disposed, thus housing the stack B within it; and when viewed along the stacking direction, the extension portion of the second current collector layer extends from the sides of the integrated first and second solid electrolyte layers.

[0018] The aforementioned all-solid-state battery can have the following structure. Specifically, the electrode structure can be an electrode stack consisting of multiple electrode bodies stacked together, electrically connected in parallel. When the first active material layer, the flat portion of the first current collector layer, the flat portion of the first current collector layer, and the first active material layer, sandwiched between the second solid electrolyte layers of one adjacent electrode body and the second solid electrolyte layer of another adjacent electrode body, form a stack C, when viewed along the stacking direction, at least one of the second solid electrolyte layers of one adjacent electrode body and the second solid electrolyte layer of the other electrode body has an area larger than the stack C. When viewed along the stacking direction, the area of ​​one adjacent electrode body... At least one of the second solid electrolyte layer and the second solid electrolyte layer of the other electrode is stacked in such a way that it covers the entire laminate C. The second solid electrolyte layers of the adjacent electrode and the second solid electrolyte layer of the other electrode are integrated at their outer edges in such a way that they at least cover the side of the laminate C where the extension of the first current collector layer is disposed, and the laminate C is housed therein. When viewed along the stacking direction, at least one of the extensions of the first current collector layer extends from the side of the second solid electrolyte layers of the adjacent electrode and the second solid electrolyte layer of the other electrode that are integrated.

[0019] In the all-solid-state battery disclosed herein, an outermost solid electrolyte layer serving as an insulating layer is disposed between the outer casing and the outermost first current collector layer. Therefore, even if conductive foreign matter is introduced between the outer casing and the electrode structure during manufacturing, and stress is concentrated on the conductive foreign matter due to external pressure, resulting in damage to the internal resin layer of the outer casing and exposure of the metal layer, the presence of the outermost solid electrolyte layer can suppress contact between the metal layer of the outer casing and the outermost first current collector layer.

[0020] Furthermore, in the all-solid-state battery of this disclosure, when viewed along the stacking direction, the area of ​​the outermost solid electrolyte layer is larger than the area of ​​the flat plate portion of the outermost first current collector layer, and when viewed along the stacking direction, the outermost solid electrolyte layer is stacked in such a way that it completely covers the flat plate portion of the outermost first current collector layer. Therefore, even under external pressure, the presence of the outermost solid electrolyte layer can suppress stress concentration at the corners of the flat plate portion of the outermost first current collector layer. Thus, it is possible to suppress internal resin layer defects in the outer casing caused by stress concentration at the corners of the flat plate portion of the outermost first current collector layer.

[0021] As described above, the all-solid-state battery according to this disclosure can suppress short circuits caused by defects in the internal resin layer of the outer casing. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an all-solid-state battery 1.

[0023] Figure 2 This is a three-dimensional view of the electrode structure 20 taken from the all-solid-state battery 1.

[0024] Figure 3 It is along Figure 2 A cross-sectional view of electrode structure 20 with the III-III section cut off.

[0025] Figure 4 This is a schematic diagram of the positive current collector layer 2111 as observed from the stacking direction.

[0026] Figure 5 It is from Figure 2 A schematic diagram of the electrode structure 20 as observed in the V direction.

[0027] Figure 6 (A) is from Figure 2 A side view of the electrode structure 20 as observed in the VIa direction. Figure 6 (B) is from Figure 2 A side view of the electrode structure 20 as observed in the VIb direction. Figure 6 (C) is from Figure 2 A side view of the electrode structure 20 as observed in the VIc direction.

[0028] Figure 7 This is an example of a method for manufacturing a bag-shaped negative electrode structure or a bag-shaped positive electrode structure.

[0029] Figure 8 This is a cross-sectional view of electrode structure 1020 taken from an all-solid-state battery of other types.

[0030] Explanation of reference numerals in the attached figures

[0031] 1. All-solid-state battery

[0032] 10 outer body

[0033] 20 Electrode Structure

[0034] 210 Electrode Stack

[0035] 211 Electrode

[0036] 2111 Positive current collector layer (first current collector layer)

[0037] 2112 Positive electrode active material layer (first active material layer)

[0038] 2113 First Solid Electrolyte Layer

[0039] 2114 Negative electrode active material layer (second active material layer)

[0040] 2115 Negative current collector layer (second current collector layer)

[0041] 2116 Negative electrode active material layer (second active material layer)

[0042] 2117 Positive electrode active material layer (first active material layer)

[0043] 2118 Positive current collector layer (first current collector layer)

[0044] 2119 Positive electrode active material layer (first active material layer)

[0045] 220 Outermost solid electrolyte layer

[0046] 1020 Electrode Structure

[0047] 1210 Electrode Stack

[0048] 1211 Electrode

[0049] 2211 Electrode

[0050] 12117 Second solid electrolyte layer

[0051] 12118 Positive electrode active material layer (first active material layer)

[0052] 12119 Positive current collector layer (first current collector layer)

[0053] 22111 Positive current collector layer (first current collector layer)

[0054] 22112 Positive electrode active material layer (first active material layer)

[0055] 22113 First Solid Electrolyte Layer Detailed Implementation

[0056] The all-solid-state battery of this disclosure will be described using an all-solid-state battery 1 as one embodiment and other types of all-solid-state batteries.

[0057] [All-Solid-State Battery 1]

[0058] The all-solid-state battery 1 has an electrode structure 20 sealed inside the outer casing 10. Figure 1 A schematic diagram of the all-solid-state battery 1 is shown. Figure 2 A perspective view of the electrode structure 20 removed from the all-solid-state battery 1 is shown. Additionally, Figure 3 Show along Figure 2 A cross-sectional view of electrode structure 20 with the III-III section cut off.

[0059] <Exterior body 10>

[0060] The outer casing 10 is a typical insulating laminated outer casing. The outer casing 10 includes an outer resin layer, an inner resin layer, and a metal layer disposed between the outer resin layer and the inner resin layer. However, the outer casing of this disclosure is not limited to this and may also include other layers. For example, the outer casing of this disclosure may be a multilayer structure further configured with resin layers, etc.

[0061] The outer resin layer is the outermost layer disposed on the outermost part of the outer casing 10. The outer resin layer is used to improve durability. Materials used for the outer resin layer include, for example, PET (polyethylene terephthalate).

[0062] The inner resin layer is the innermost layer disposed on the outermost side of the outer casing 10. The inner resin layer is used to enable heat fusion bonding. The material for the inner resin layer can be, for example, a thermoplastic resin such as polypropylene (PP).

[0063] The metal layer is a layer disposed inside the outer casing 10. As described above, in the all-solid-state battery 1, the metal layer is disposed between the outer resin layer and the inner resin layer. The metal layer is a layer (gas barrier layer) used to prevent moisture, air, or gases generated inside the all-solid-state battery 1 from entering or exiting. In addition, the metal layer also serves to strengthen the rigidity of the outer casing 10. Materials used for the metal layer include, for example, aluminum or iron.

[0064] <Electrode Structure 20>

[0065] like Figure 2 As shown, the electrode structure 20 is entirely covered by a solid electrolyte layer, except for the extension portion of the current collector layer. However, in the all-solid-state battery of this disclosure, there may also be a portion of the electrode structure 20 on the side where the extension portion of the current collector layer is disposed, where no solid electrolyte layer is disposed.

[0066] like Figure 3 As shown, the electrode structure 20 includes an electrode stack 210 and an outermost solid electrolyte layer 220, with the outermost solid electrolyte layer 220 stacked at both ends of the electrode stack 210 in the stacking direction. However, in the all-solid-state battery of this disclosure, the outermost solid electrolyte layer may be stacked at at least one end of the electrode stack in the stacking direction.

[0067] (Electrode laminate 210)

[0068] The electrode stack 210 includes one electrode body 211. In the all-solid-state battery of this disclosure, the electrode stack may include at least one electrode body. Examples of all-solid-state batteries with multiple electrode bodies in the electrode stack will be described later.

[0069] (Electrode 211)

[0070] The electrode body 211 sequentially comprises a positive current collector layer (first current collector layer) 2111, a positive active material layer (first active material layer) 2112, a first solid electrolyte layer 2113, a negative active material layer (second active material layer) 2114, a negative current collector layer (second current collector layer) 2115, a negative active material layer (second active material layer) 2116, a second solid electrolyte layer 2117, a positive active material layer (first active material layer) 2118, and a first current collector layer (first current collector layer) 2119.

[0071] As described above, in electrode body 211, the first current collector layer serves as the positive current collector layer, the first active material layer serves as the positive active material layer, the second current collector layer serves as the negative current collector layer, and the second active material layer serves as the negative active material layer. However, the all-solid-state battery of this disclosure is not limited to this; the first current collector layer may also serve as the negative current collector layer, the first active material layer as the negative active material layer, the second current collector layer as the positive current collector layer, and the second active material layer as the positive active material layer.

[0072] (Positive current collector layers 2111, 2119, negative current collector layer 2115)

[0073] Figure 4 A schematic diagram of the positive current collector layer 2111 as viewed from the upper side of the stacking direction is shown. Figure 4 As shown, the positive current collector layer 2111 includes an extension portion 2111a and a flat plate portion 2111b. The extension portion 2111a is a member extending from the side of the electrode body 211 and is connected to the positive terminal 1a directly or via a metal connector (not shown). The position of the extension portion 2111a is not particularly limited and can be appropriately set according to the arrangement of the positive terminal 1a. The flat plate portion 2111b is stacked on each electrode layer of the electrode body 2111. The flat plate portion 2111b is rectangular and therefore has four corner portions 2111c. The structure of the positive current collector layer 2119 is the same as that of the positive current collector layer 2111. The negative current collector layer 2115 also includes an extension portion 2115a and a flat plate portion 2115b, and the extension portion 2115a of the negative current collector layer 2115 is connected to the negative terminal 1b directly or via a metal connector.

[0074] Furthermore, in the all-solid-state battery 1, the positive terminal 1a and the negative terminal 1b are formed on the same side. Therefore, the extension portions of the positive current collector layers 2111, 2119 and the negative current collector layer 2115 also extend from the same side. However, the all-solid-state battery disclosed herein is not limited to this. The positive terminal and the negative terminal may also be formed on different sides. In this case, the positions of the extension portions of the positive current collector layer and the negative current collector layer may also be appropriately set in accordance with the positions of the electrode terminals.

[0075] In addition, such as Figure 2 As shown, the positive electrode current collector layers 2111 and 2119 are disposed at both ends of the electrode stack 210 (electrode body 211) in the stacking direction. Hereinafter, the positive electrode current collector layers 2111 and 2119 disposed at both ends of the electrode stack 210 in the stacking direction will be referred to as the outermost positive electrode current collector layers 2111 and 2119. However, in the all-solid-state battery of this disclosure, the outermost positive electrode current collector layer (outermost first current collector layer) may be disposed at at least one end of the electrode stack in the stacking direction.

[0076] Examples of materials used for the positive current collector layer include SUS, aluminum, nickel, and carbon. Examples of shapes for the positive current collector include a foil. Examples of materials used for the negative current collector layer include SUS, copper, nickel, and carbon. Examples of shapes for the negative current collector include a foil. Furthermore, to improve conductivity, both the positive and negative current collector layers may undergo a predetermined carbon coating process.

[0077] (Positive electrode active material layers 2112, 2118)

[0078] The positive electrode active material layers 2112 and 2118 can be positive electrode active material layers with the same structure or positive electrode active material layers with different structures. The following describes the positive electrode active material layers that are applicable here.

[0079] The positive electrode active material layer contains a positive electrode active material. Examples of positive electrode active materials include oxide active materials. Examples of oxide active materials include LiCoO2 and LiNi. 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and other layered active substances in rock salt, LiMn2O4, Li4Ti5O 12 Spinel-type active materials and olivine-type active materials such as LiFePO4 can be used. A protective layer containing a Li-ion-conducting oxide can be formed on the surface of the oxide active material. This is because it can inhibit the reaction between the oxide active material and the solid electrolyte. Examples of Li-ion-conducting oxides include LiNbO3. The thickness of the protective layer is, for example, 1 nm or more and 30 nm or less. Alternatively, Li2S can be used as a positive electrode active material. For example, granular materials can be used as the shape of the positive electrode active material. The average particle size (D) of the positive electrode active material... 50 There is no particular limitation; for example, it can be 10 nm or larger, or even 100 nm or larger. On the other hand, the average particle size (D) of the positive electrode active material... 50 For example, it can be below 50μm, or it can be below 20μm.

[0080] The content of the positive electrode active material in the positive electrode active material layer can be the same as before. For example, in the range of 50% to 99% by weight.

[0081] The average particle size (D) in this disclosure 50 For example, it can be calculated based on measurements using a laser diffraction particle size analyzer or a scanning electron microscope (SEM).

[0082] The positive electrode active material layer may optionally contain a conductive material. Adding a conductive material improves the electronic conductivity of the negative electrode layer. Examples of conductive materials include granular carbon materials such as acetylene black (AB) and Ketjen black (KB), as well as fibrous carbon materials such as carbon fibers, carbon nanotubes (CNTs), and carbon nanofibers (CNFs). The content of the conductive material in the positive electrode active material layer can remain the same as before, for example, in the range of 0.1% to 10% by weight.

[0083] The positive electrode active material layer may optionally contain a binder. By adding the binder, the constituent materials of the positive electrode active material layer are firmly bonded together. Examples of binders include fluoride-based binders, polyimide-based binders, and rubber-based binders. The content of the binder in the positive electrode active material layer can be the same as before, for example, in the range of 0.1% to 10% by weight.

[0084] The positive electrode active material layer may optionally contain a solid electrolyte. Inorganic solid electrolytes and polymer electrolytes are suitable solid electrolytes for use in the positive electrode active material layer. Preferred solid electrolytes used in the positive electrode active material layer are inorganic solid electrolytes (especially sulfide solid electrolytes) that exhibit high ionic conductivity.

[0085] Examples of inorganic solid electrolytes include sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes. Furthermore, inorganic solid electrolytes can be glass (amorphous), glass ceramics, or crystals. Glass is obtained, for example, by amorphizing the raw material. Glass ceramics are obtained, for example, by heat-treating glass. Crystals are obtained, for example, by heating the raw material.

[0086] The sulfide solid electrolyte preferably contains Li, A (A is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, In), and S. The sulfide solid electrolyte may also contain at least one of O (oxygen) and a halogen. Examples of halogens include F, Cl, Br, and I. The sulfide solid electrolyte may contain only one halogen or two or more halogens. Furthermore, when the sulfide solid electrolyte contains anionic elements other than S (e.g., O and halogens), S is preferably present in the highest molar proportion among all anionic elements.

[0087] Sulfide solid electrolytes preferably have an anionic structure with an ortho group (PS4). 3- Structure, SiS44- Structure, GeS4 4- Structure, AlS3 3- Structure, BS3 3- The original anionic structure is the main component of the anionic structure due to its high chemical stability. Compared to all anionic structures in sulfide solid electrolytes, the proportion of the original anionic structure is, for example, 50 mol% or more, 60 mol% or more, or even 70 mol% or more.

[0088] Sulfide solid electrolytes may contain crystalline phases with ionic conductivity. Examples of such crystalline phases include the Thio-LISICON type, the LGPS type, and the Argyrodite type.

[0089] Oxide solid electrolytes preferably contain, for example, Li, Z (Z is at least one selected from Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S) and O. A specific example of an oxide solid electrolyte is Li7La3Zr2O. 12 Garnet-type solid electrolytes; perovskite-type solid electrolytes such as (Li,La)TiO3; sodium superionic conductor-type solid electrolytes such as Li(Al,Ti)(PO4)3; Li-PO series solid electrolytes such as Li3PO4; and Li-BO series solid electrolytes such as Li3BO3. Furthermore, when oxide solid electrolytes contain anionic elements other than O (e.g., S and halogens), O is preferred to have the highest molar proportion among all anionic elements.

[0090] A halide solid electrolyte is an electrolyte containing a halogen (X). Examples of halogens include F, Cl, Br, and I. Examples of halide solid electrolytes include Li3YX6 (where X is at least one of F, Cl, Br, and I). Furthermore, when the halide solid electrolyte contains anionic elements other than halogens (e.g., S and O), it is preferable that the molar proportion of halogens is the highest among all anionic elements.

[0091] Examples of shapes for inorganic solid electrolytes include granular forms. The average particle size (D) of inorganic solid electrolytes... 50 There is no particular limitation; for example, it can be 10 nm or larger, or even 100 nm or larger. On the other hand, the average particle size (D) of inorganic solid electrolytes... 50 For example, it can be below 50μm, or it can be below 20μm.

[0092] Polymer electrolytes contain polymer components. Examples of polymer components include polyether polymers, polyester polymers, polyamine polymers, and polysulfide polymers, with polyether polymers being preferred due to their high ionic conductivity and excellent mechanical properties such as Young's modulus and tensile strength.

[0093] Polyether polymers have a polyether structure within repeating units. Furthermore, polyether polymers preferably have a polyether structure within the main chain of the repeating units. Examples of polyether structures include polyethylene oxide (PEO) and polypropylene oxide (PPO). Polyether polymers preferably have a PEO structure as the main repeating unit. In polyether polymers, the proportion of the PEO structure in all repeating units is, for example, 50 mol% or more, 70 mol% or more, or 90 mol% or more. Additionally, the polyether polymer can be, for example, a homopolymer or copolymer of an epoxy compound (e.g., ethylene oxide, propylene oxide).

[0094] The polymer component may have ion-conducting units as shown below. Examples of ion-conducting units include polyethylene oxide, polypropylene oxide, polymethacrylate, polyacrylate, polydimethylsiloxane, polyacrylic acid, polymethacrylic acid, polyvinyl acetate, polyimide, polyamine, polyamide, polyalkyl carbonate, polynitrile, polyphosphazene, polyolefin, and polydiene.

[0095] The weight-average molecular weight (Mw) of the polymer component is not particularly limited, but may be, for example, 1,000,000 or more and 10,000,000 or less. Mw is determined by gel permeation chromatography (GPC). Furthermore, the glass transition temperature (Tg) of the polymer component may be, for example, below 60°C, below 40°C, or below 25°C. Additionally, only one polymer component may be used, or two or more polymer components may be used.

[0096] Polymer electrolytes can be cross-linked polymer electrolytes obtained by cross-linking polymer components, or they can be uncross-linked polymer electrolytes where the polymer components are not cross-linked. Examples of polymerization initiators used to cross-link polymer components include peroxides such as benzoyl peroxide, di-tert-butyl peroxide, tert-butylbenzoyl peroxide, tert-butyl peroxyoctanoate, and cumene hydroxyperoxide; and azo compounds such as azobisisobutyronitrile.

[0097] Polymer electrolytes can be either dry polymer electrolytes or gel electrolytes. Dry polymer electrolytes refer to electrolytes with a solvent content of less than 5% by weight. The solvent content can be less than 3% by weight or less than 1% by weight.

[0098] The dry polymer electrolyte may contain a supporting salt. Examples of supporting salts include inorganic lithium salts such as LiPF6, LiBF4, LiClO4, and LiAsF6, and organic lithium salts such as LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiN(FSO2)2, and LiC(CF3SO2)3. The ratio of the supporting salt to the dry polymer electrolyte is not particularly limited. For example, when the dry polymer electrolyte has EO units (C2H5O units), the EO units may be 5 moles or more, 10 moles or more, or 15 moles or more, relative to 1 mole of supporting salt. On the other hand, the EO units may be 40 moles or less, or 30 moles or less, relative to 1 mole of supporting salt.

[0099] Gel electrolytes typically contain an electrolyte component in addition to the polymer component. The electrolyte component contains a supporting salt and a solvent. The supporting salt is the same as described above. Examples of solvents include carbonates. Examples of carbonates include cyclic esters (cyclic carbonates) such as ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC); and chain esters (chain carbonates) such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC). Other examples of solvents include acetate esters such as methyl acetate and ethyl acetate, and ethers such as 2-methyltetrahydrofuran. Furthermore, examples of solvents include γ-butyrolactone, sulfolane, N-methylpyrrolidone (NMP), and 1,3-dimethyl-2-imidazolinone (DMI). Water can also be used as a solvent.

[0100] The content of solid electrolyte in the positive electrode active material layer can remain the same as before. For example, it can be in the range of 1% to 50% by weight.

[0101] The thickness of the positive electrode active material layer is, for example, in the range of 0.1 μm or more and 1000 μm or less.

[0102] (Negative electrode active material layers 2114, 2116)

[0103] The negative electrode active material layers 2114 and 2116 can be negative electrode active material layers with the same structure or negative electrode active material layers with different structures. The following describes the negative electrode active material layers that are applicable here.

[0104] The negative electrode active material layer contains a negative electrode active material. Examples of negative electrode active materials include metallic active materials such as Si, Sn, and Li; carbon active materials such as graphite; and oxide active materials such as lithium titanate. Alternatively, the negative electrode active material can be a Si-based active material containing at least Si. Examples of Si-based active materials include elemental Si, Si alloys, and Si oxides. Si alloys preferably contain Si as a main component. In the Si alloy, the proportion of Si is, for example, 50 atomic percent or more, 70 atomic percent or more, or 90 atomic percent or more.

[0105] The shape of a negative electrode active material can be, for example, granular. The average particle size (D) of the negative electrode active material... 50 There is no particular limitation; for example, it can be 10 nm or larger, or even 100 nm or larger. On the other hand, the average particle size (D) of the negative electrode active material... 50 For example, it can be below 50μm, or it can be below 20μm.

[0106] The content of the negative electrode active material in the negative electrode active material layer can be the same as before. For example, it can be in the range of 20% by weight or more and 99% by weight or less.

[0107] The negative electrode active material layer may optionally contain a conductive material, a binder, or a solid electrolyte. The descriptions of conductive materials, binders, and solid electrolytes are the same as above and are therefore omitted here. When the negative electrode active material layer contains a solid electrolyte, a polymer electrolyte is preferred. Furthermore, when a sulfide solid electrolyte with high reactivity with polar solvents is used at the positive electrode, a dried polymer is preferred.

[0108] The thickness of the negative electrode active material layer is, for example, in the range of 0.1 μm or more and 1000 μm or less. From the viewpoint of suppressing Li dendrites, the area of ​​the negative electrode active material layer can be made larger than that of the positive electrode active material layer.

[0109] (First solid electrolyte layer 2113, second solid electrolyte layer 2117, outermost solid electrolyte layer 220)

[0110] The first solid electrolyte layer 2113, the second solid electrolyte layer 2117, and the outermost solid electrolyte layer 220 can be solid electrolyte layers with the same structure or solid electrolyte layers with different structures. The following describes solid electrolyte layers that are suitable for this application.

[0111] The solid electrolyte layer contains a solid electrolyte. The solid electrolyte used in the solid electrolyte layer is as described above. When the solid electrolyte layer contains an inorganic solid electrolyte, the content of the inorganic solid electrolyte in the solid electrolyte layer is not particularly limited, for example, in the range of 50% to 100% by weight. Additionally, when the solid electrolyte layer contains an inorganic solid electrolyte, an adhesive may optionally be included. The adhesive used in the solid electrolyte layer is as described above. The content of the adhesive in the solid electrolyte layer is not particularly limited, for example, in the range of 0.1% to 10% by weight.

[0112] When the solid electrolyte layer contains a polymer electrolyte, a cross-linked polymer electrolyte is preferably used. Furthermore, the solid electrolyte layer containing the polymer electrolyte is preferably self-supporting. "Self-supporting" means maintaining its shape even in the absence of other supports. For example, if the solid electrolyte layer to be applied is disposed on a substrate, and the solid electrolyte layer retains its shape when the substrate is peeled off, it can be described as "self-supporting." The proportion of the polymer electrolyte in the solid electrolyte layer is 50% by volume or more, and can be 70% by volume or more, or even 90% by volume or more. The solid electrolyte layer may contain only the polymer electrolyte.

[0113] The thickness of the solid electrolyte layer is, for example, in the range of 0.1 μm or more and 1000 μm or less.

[0114] (Structure of electrode structure 20)

[0115] (1) Figure 5 Show along Figure 2 A schematic diagram of the electrode structure 20 as observed in the V direction (upper side of the stacking direction). Figure 5 The dashed line shown represents the outermost positive current collector layer 2111 as seen through the light. (Example) Figure 3 , Figure 5 As shown, the outermost solid electrolyte layer 220 is stacked on the surface of the outermost positive electrode current collector layer 2111 opposite to the positive electrode active material layer 2112. By configuring the outermost solid electrolyte layer 220 in this way, an insulating layer, the outermost solid electrolyte layer 220, exists between the outer casing 10 and the outermost positive electrode current collector layer 2111. Therefore, even if conductive foreign matter is mixed between the outer casing 10 and the electrode structure 20 during the manufacture of the all-solid-state battery 1, and stress is subsequently concentrated on the conductive foreign matter due to external pressure, resulting in damage to the internal resin layer of the outer casing 10 and exposure of the metal layer, the presence of the outermost solid electrolyte layer 220 can suppress contact between the metal layer of the outer casing 10 and the outermost positive electrode current collector layer 2111, thus suppressing short circuits in the all-solid-state battery 1.

[0116] In addition, such as Figure 5As shown, when viewed along the stacking direction, the area of ​​the outermost solid electrolyte layer 220 is larger than the area of ​​the plate portion 2111b of the outermost positive current collector layer 2111. Furthermore, when viewed along the stacking direction, the outermost solid electrolyte layer 220 is stacked in such a way that it completely covers the plate portion 2111b of the outermost positive current collector layer 2111. In other words, the outer edge of the outermost solid electrolyte layer 220 is formed to be larger than the outer edge of the plate portion 2111b of the outermost positive current collector layer 2111. Therefore, even under external pressure, the presence of the outermost solid electrolyte layer 220 can suppress stress concentration at the corner 2111c of the plate portion 2111b of the outermost positive current collector layer 2111. That is, it can suppress damage to the internal resin layer of the outer casing 10 caused by stress concentration at the corner 2111c of the plate portion 2111b, and can suppress short circuits in the all-solid-state battery 1.

[0117] Furthermore, when the outermost solid electrolyte layer 220 contains a polymer electrolyte, the short-circuit suppression effect is improved. The electrode stack 210 (electrode body 211) expands and contracts during charging and discharging. Especially when using Si or Sn-based alloy negative electrode active material, the volume change becomes even larger. In this case, if an inorganic solid electrolyte is used for the outermost solid electrolyte layer 220, the outermost solid electrolyte layer 220 cannot keep up with the volume change of the electrode stack 210 caused by charging and discharging, which may lead to cracks and / or slippage. Especially since the end elongation is large and prone to cracking, stress concentration at the corner 2111c of the flat plate portion 2111b may cause damage to the internal resin layer of the outer casing 10. In contrast, if the outermost solid electrolyte layer 220 contains a highly flexible polymer electrolyte, the outermost solid electrolyte layer 220 can keep up with the volume change of the electrode stack 210 caused by charging and discharging, and cracking is suppressed.

[0118] Furthermore, the matters described in (1) above can also be applied to the positive electrode active material layer 2118, the outermost positive electrode current collector layer 2119 and the outermost solid electrolyte layer 220 disposed on the lower side of the stacking direction of the electrode structure 20.

[0119] (2) Figure 6 (A) shows along Figure 2 A side view of the electrode structure 20 as observed from the VIa direction. Figure 6 (B) shows along Figure 2 A side view of the electrode structure 20 as observed in the VIb direction. Figure 6 (C) shows along Figure 2 A side view of the electrode structure 20 as observed in the VIc direction. Additionally, Figure 6 The dashed lines in (A) represent the electrode layers other than the solid electrolyte layer, as seen through the image. Here, as... Figure 3As shown, in the electrode structure 20, the plate portion 2111b of the outermost positive current collector layer 2111 and the positive active material layer 2112 sandwiched between the outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113 are used as a laminate A.

[0120] Depend on Figure 2 , Figure 3 , Figure 5 , Figure 6 As can be seen, when viewed along the stacking direction, the area of ​​the outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113 is larger than that of the laminate A. When viewed along the stacking direction, the outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113 are stacked in a manner that covers the entire laminate A. The outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113 are integrated at the outer edge of the laminate A, covering the entire side surface of the laminate A (excluding the extension portion), thus housing the laminate A inside it. In addition, when viewed along the stacking direction, the extension portion 2111a of the outermost positive current collector layer 2111 extends from the side surface of the integrated outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113.

[0121] However, in the all-solid-state battery disclosed herein, the area of ​​at least one of the outermost solid electrolyte layer and the first solid electrolyte layer is larger than that of the stacked body A when viewed along the stacking direction; the outermost solid electrolyte layer and the first solid electrolyte layer are stacked in such a way that they cover the entire stacked body A; the outermost solid electrolyte layer and the first solid electrolyte layer are integrated at the outer edge of the outermost solid electrolyte layer and the first solid electrolyte layer in such a way that they cover the side of the stacked body A other than the side where the extension of the first current collector layer is disposed, and the stacked body A is housed inside it.

[0122] In this way, by integrating the outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113 on all sides of the laminate A and housing the laminate A within it, short circuits between the laminate A and the laminate B (negative electrode active material layer and negative electrode current collector layer, described later) can be prevented. Furthermore, by including a polymer electrolyte in the outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113, during the integration of the outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113 on the sides of the laminate A, chemical cross-linking of the polymer electrolyte can be achieved through UV and / or heat treatment, suppressing lamination deviations. Even without chemical integration, due to the adhesiveness of the solid electrolyte layers containing the polymer electrolyte, integration can be achieved simply by bringing the solid electrolyte layers into contact with each other.

[0123] Furthermore, on the side of the laminate A extending from the extension portion 2111a of the outermost positive current collector layer 2111, the outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113 are integrated, so that only the extension portion 2111a extends out. As a result, short circuits caused by the extension portion 2115a of the negative current collector layer 2115 coming into contact with the plate portion 2111b of the outermost positive current collector layer 2111 or the positive active material layer 2112 can be suppressed.

[0124] However, in the all-solid-state battery of this disclosure, the outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113 may not be integrated on the side of the laminate A extending from the extension 2111a of the outermost positive current collector layer 2111. That is, the outermost solid electrolyte layer 220 and the first solid electrolyte layer 2113 may be integrated only on the side other than the side of the laminate A extending from the extension 2111a of the outermost positive current collector layer 2111. In this case, an insulating resin or the like may also be coated at the position where the extension 2115b of the negative current collector layer 2115 can contact the extension 2111a of the outermost positive current collector layer 2111.

[0125] Furthermore, the matters described in (2) above can also be applied to the second solid electrolyte layer 2117, the positive electrode active material layer 2118, the outermost positive electrode current collector layer 2119 and the outermost solid electrolyte layer 220 disposed on the lower side of the stacking direction of the electrode structure 20.

[0126] (3)Reference Figure 2 , Figure 3 , Figure 5 , Figure 6 The structure of electrode structure 20 will be further explained. For example... Figure 3 As shown, in electrode body 211, the negative electrode active material layer 2114, the plate portion 2115b of negative electrode current collector layer 2115, and the negative electrode active material layer 2116 sandwiched between the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 are used as laminate B.

[0127] Depend on Figure 2 , Figure 3 , Figure 5 , Figure 6As can be seen, when viewed along the stacking direction, the areas of the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 are larger than that of the laminate B. When viewed along the stacking direction, the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 are stacked to cover the entire laminate B. The first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 are integrated at the outer edge of the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 to cover the entire side surface of the laminate B (excluding the extension portion), thus housing the laminate B inside it. In addition, when viewed along the stacking direction, the extension portion 2115a of the negative electrode current collector layer 2115 extends from the side surface of the integrated first solid electrolyte layer 2113 and the second solid electrolyte layer 2117.

[0128] However, in the all-solid-state battery disclosed herein, it may be that, viewed along the stacking direction, at least one of the first solid electrolyte layer and the second solid electrolyte layer has an area larger than the stacked body B; viewed along the stacking direction, at least one of the first solid electrolyte layer and the second solid electrolyte layer is stacked in such a way that it covers the entire stacked body B; the first solid electrolyte layer and the second solid electrolyte layer are integrated at the outer edge of the first solid electrolyte layer and the second solid electrolyte layer in such a way that they at least cover the side of the stacked body B where the extension of the second current collector layer is disposed, thereby housing the stacked body B inside it.

[0129] Thus, by integrating the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 on all sides of the laminate B and housing the laminate B within it, slippage caused by intralayer cracks in the negative electrode layer when using Si or Sn-based alloy negative electrodes as the negative electrode active material can be suppressed. Furthermore, by including a polymer electrolyte in the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117, and by performing UV and / or heat treatment during the integration of the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 on the sides of the laminate B, chemical cross-linking of the polymer electrolyte can be achieved, thus suppressing lamination deviations. Even without chemical integration, due to the adhesiveness of the solid electrolyte layers containing the polymer electrolyte, integration can be achieved simply by bringing the solid electrolyte layers into contact with each other. Furthermore, the outermost solid electrolyte layer 220, the first solid electrolyte layer 2113, and the second solid electrolyte layer 2117 contain polymer electrolytes. The first solid electrolyte layer 2113 is divided into two layers: an upper layer and a lower layer. The outermost solid electrolyte layer 220 and the upper layer of the first solid electrolyte layer 2113 are integrated, and the lower layer of the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 are integrated. This can also suppress the stacking deviation between integrated structures.

[0130] Furthermore, on the side of the laminate B extending from the extension portion 2115a of the negative electrode current collector layer 2115, the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 are integrated, and only the extension portion 2115a extends out. As a result, short circuits caused by contact between the extension portions 2111a and 2119a of the positive electrode current collector layers 2111 and 2119 and the flat plate portion 2115b of the negative electrode current collector layer 2115 or the negative electrode active material layers 2114 and 2116 can be suppressed.

[0131] However, in the all-solid-state battery of this disclosure, the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 may not be integrated on the side of the laminate B extending from the extension 2115a of the negative electrode current collector layer 2115. That is, the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 may be integrated only on the side other than the side of the laminate B extending from the extension 2115a of the negative electrode current collector layer 2115. In this case, an insulating resin or the like can be coated at the position where the extensions of the positive electrode current collector layers 2111 and 2119 can contact the extension 2115a of the negative electrode current collector layer 2115.

[0132] Furthermore, by integrating the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 containing the polymer electrolyte, the following problem can be solved. Conventionally, when solid electrolytes such as sulfide solid electrolytes are used in both the negative electrode active material layer and the solid electrolyte layer, problems arise such as peeling and / or cracking at the interface between the negative electrode active material layer and the solid electrolyte layer due to the expansion and contraction of the negative electrode active material during charging and discharging, as well as cracking within the solid electrolyte. To solve this problem, the inventors considered using a polymer electrolyte with high flexibility as the solid electrolyte. However, it was discovered that when a polymer electrolyte is used in the negative electrode active material layer, making the area of ​​the negative electrode active material layer larger than that of the positive electrode active material layer, a new problem arises: warping occurs in the electrode layer stack due to the pressing used to bond the electrode layers, leading to short circuits between different types of electrodes. To address this, the inventors further investigated and discovered, as described above, that by integrating the first solid electrolyte layer 2113 and the second solid electrolyte layer 2117 containing the polymer electrolyte, contact between different types of electrodes caused by the pressing used to bond the electrodes can be suppressed. Therefore, by integrating the first solid electrolyte layer 2113 containing the polymer electrolyte and the second solid electrolyte layer 2117, the aforementioned manufacturing problems can be solved, and electrode cracking caused by volume changes due to charging and discharging can be suppressed, thereby improving the cycle characteristics of the all-solid-state battery 1.

[0133] [Other types of all-solid-state batteries]

[0134] In other types of all-solid-state batteries, instead of the electrode structure 20 of all-solid-state battery 1, an electrode structure 1020 is used, which has an electrode stack 1210 having multiple electrode bodies 1211, 2211 stacked on top of each other. Since the structure other than the electrode structure 1020 is the same as that of all-solid-state battery 1, its description is omitted below. Figure 8 Is with Figure 2 The corresponding figure shows a schematic cross-sectional view of the electrode structure 1020 taken from an all-solid-state battery of other types.

[0135] like Figure 8 As shown, the electrode structure 1020 of the all-solid-state battery 2 includes an electrode stack 1210 having two electrode bodies 1211 and 2211 stacked together. The electrode bodies 1211 and 2211 are electrically connected in parallel. Specifically, the electrode bodies 1211 and 2211 are stacked such that the positive current collector layer 12119 of one adjacent electrode body 1211 is in contact with the positive current collector layer 22111 of the other adjacent electrode body 2211.

[0136] Here, the positive electrode active material layer 12118 of one adjacent electrode 1211, the plate portion 12119b of the positive electrode current collector layer 12119 of one adjacent electrode 1211, the plate portion 22111b of the positive electrode current collector layer 22111 of another adjacent electrode 2211, and the positive electrode active material layer 22112 of another adjacent electrode 2211 are referred to as laminate C, which is sandwiched between the second solid electrolyte layer 12117 of one adjacent electrode 1211 and the first solid electrolyte layer 22113 of another adjacent electrode 2211.

[0137] Viewed along the stacking direction, the area of ​​adjacent solid electrolyte layers is larger than that of the stack C. Viewed along the stacking direction, the adjacent solid electrolyte layers are stacked such that they cover the entire stack C. The adjacent solid electrolyte layers become one at their outer edges, covering the entire side surface of the stack C (excluding the extensions), thus housing the stack C within it. Furthermore, viewed along the stacking direction, the extensions 12119a and 22111a of the positive electrode current collector layers 12119 and 22111 extend from the side surface of the one-piece adjacent solid electrolyte layers.

[0138] However, in the all-solid-state battery of this disclosure, the area of ​​at least one of the second solid electrolyte layer of one adjacent electrode and the second solid electrolyte layer of the other electrode is larger than that of the stacked body C when viewed along the stacking direction; the second solid electrolyte layer of one adjacent electrode and the second solid electrolyte layer of the other electrode are stacked in such a way that they cover the entire stacked body C; and the second solid electrolyte layer of one adjacent electrode and the second solid electrolyte layer of the other electrode are integrally formed at their outer edges such that they at least cover the sides of the stacked body C other than the side where the extension of the first current collector layer is disposed, thus housing the stacked body C inside. Furthermore, in the all-solid-state battery of this disclosure, the extension of the positive electrode current collector layer (first current collector layer) extending from the side of the integrally formed adjacent solid electrolyte layers can be at least one of them.

[0139] Thus, by integrating adjacent solid electrolyte layers on all sides of the laminate C and housing the laminate C within it, lamination deviations of these layers can be suppressed. Furthermore, by including polymer electrolytes in adjacent solid electrolyte layers, during the integration of adjacent solid electrolyte layers on their sides, UV and / or heat treatment can chemically crosslink the polymer electrolytes, thereby suppressing lamination deviations. Even without chemical integration, due to the adhesiveness of the solid electrolyte layers containing polymer electrolytes, integration can be achieved simply by bringing the solid electrolyte layers into contact with each other.

[0140] Furthermore, on the side of the laminate C extending from the extension portions 12119a and 22111a of the positive current collector layers 12119 and 22111, by integrating adjacent solid electrolyte layers and extending the extension portions 12119a and 22111a, it is possible to suppress short circuits caused by contact between the extension portions of the negative current collector layer and the plate portions 12119a and 22111a of the positive current collector layers 12119 and 22111 or the positive active material layers 12118 and 22112.

[0141] However, in the all-solid-state battery of this disclosure, the adjacent solid electrolyte layers may not be integrated on the side of the laminate C extending from the positive current collector layer. That is, the adjacent solid electrolyte layers may be integrated only on the side other than the side of the laminate C extending from the positive current collector layer. In this case, an insulating resin or the like may be coated at the location where the extension of the negative current collector layer can contact the extension of the positive current collector layer.

[0142] [Manufacturing method of all-solid-state batteries]

[0143] The method for manufacturing the all-solid-state battery disclosed herein is not particularly limited; for example, the all-solid-state battery can be manufactured as follows.

[0144] First, a slurry is prepared by mixing and kneading the constituent materials of the positive electrode active material layer with a dispersion medium. The resulting slurry is coated onto a positive electrode current collector layer or a substrate, and then the dispersion medium is removed by drying to form a coating layer. Next, the coating layer is pressed to densify it, forming the positive electrode active material layer. Alternatively, after pressing, the substrate can be peeled off, and the positive electrode current collector layer can be attached. This produces a positive electrode current collector and a positive electrode structure with a positive electrode active material layer on one side. Similarly, a negative electrode current collector and a negative electrode structure with negative electrode active material layers on both sides are produced using the same method.

[0145] Next, when using an inorganic solid electrolyte as the solid electrolyte, the solid electrolyte layer can be fabricated using the same method as described above. That is, a slurry is prepared by mixing and kneading the constituent materials of the solid electrolyte layer with the dispersion medium. The resulting slurry is coated onto a substrate, and then the dispersion medium is removed by drying to form a coating layer. The coating layer is then pressed to densify it, thus forming the solid electrolyte layer.

[0146] When using a polymer electrolyte as a solid electrolyte, the solid electrolyte layer can be prepared, for example, as follows: A homogeneous polymer electrolyte solution is prepared by mixing and kneading the constituent materials of the solid electrolyte layer, a polymerization initiator, and a solvent. The resulting slurry is then coated onto a substrate, and the dispersion medium is removed by drying while the polymerization reaction proceeds. This creates a solid electrolyte layer on the substrate containing a crosslinked polymer electrolyte derived from the crosslinking of polymer components.

[0147] Alternatively, the solid electrolyte layer can be a pouch-shaped solid electrolyte with an internal space containing an electrode layer. The pouch-shaped solid electrolyte can be manufactured as follows. Figure 7 (A) to (D) illustrate the manufacturing process of bagged solid electrolytes. First, as... Figure 7 As shown in (A), a solid electrolyte (S) is prepared. Next, as... Figure 7 As shown in (B), inside the solid electrolyte, a negative electrode structure with negative electrode active material layers on both sides or a positive electrode structure with a positive electrode active material layer on one side is disposed (X). Then, as... Figure 7As shown in (C), the solid electrolyte is bent. Finally, as shown in (D), by attaching the outer edge of the solid electrolyte, a negative electrode structure or a positive electrode structure (bag-shaped negative electrode structure or bag-shaped positive electrode structure) can be formed and housed within the bag-shaped solid electrolyte. Furthermore, in the above process, a release liner such as a PET film can be used instead of a negative electrode structure to form a bag-shaped solid electrolyte, and then the negative electrode structure or positive electrode structure can be inserted inside. Additionally, while the bag-shaped solid electrolyte is formed by folding the solid electrolyte in half, it is not limited to this method. A bag-shaped solid electrolyte can also be formed by clamping the negative electrode structure or positive electrode structure with two solid electrolytes and attaching their outer edges together.

[0148] In this disclosure, the solid electrolyte layer can be fabricated to have a larger area than other electrode layers so that the solid electrolyte layers can be integrated with each other on the sides after the electrode layers are stacked.

[0149] Finally, the prepared electrode layers are stacked and laminated to obtain the electrode structure.

[0150] For example, electrode layers are stacked and pressed in a predetermined order. Next, except where the solid electrolyte layers are integrated sideways by pressing, the solid electrolyte layers are integrated sideways. Then, the positive and negative terminals are mounted onto the resulting electrode structure, housed inside the laminated outer casing, and sealed by heat sealing. Thus, an all-solid-state battery is obtained.

[0151] Furthermore, examples of using pouch-shaped solid electrolytes will be explained below. First, the case of fabricating an all-solid-state battery with a single electrode will be explained.

[0152] A bag-shaped positive electrode structure is stacked on both sides of a bag-shaped negative electrode structure and then pressed and molded to form an integral electrode structure. Alternatively, a bag-shaped positive electrode structure is stacked on both sides of a negative electrode structure and then pressed and molded to form an integral electrode structure. Next, the outer edges of the upper and lower bag-shaped positive electrode structures are brought into contact and integrated, covering the sides other than the side where the negative electrode current collector layer is disposed, to form an integral electrode structure. The positive and negative terminals are then mounted onto the obtained electrode structure, housed inside a laminated outer casing, and sealed by heat sealing. This yields an all-solid-state battery.

[0153] Next, we will explain the case of fabricating an all-solid-state battery with multiple electrode bodies.

[0154] An electrode body is obtained by sequentially stacking a bag-shaped positive electrode structure, a bag-shaped negative electrode structure, and a positive electrode structure. Then, two electrode bodies are stacked with the positive current collector layers in contact with each other. Next, the outer edges of the upper and lower bag-shaped negative electrode structures are brought into contact and integrated, covering the sides other than the sides where the positive current collector layers are located. This yields the electrode structure.

[0155] Alternatively, a bagged positive electrode structure (2) is fabricated, in which two positive electrode structures, with their positive current collector layers in contact with each other, are housed within a bagged solid electrolyte. Then, the bagged positive electrode structure, the bagged negative electrode structure, the bagged positive electrode structure (2), the bagged negative electrode structure, and the bagged positive electrode structure are sequentially stacked and pressed together to form an integrated structure. Thus, an electrode structure is obtained.

[0156] The positive and negative terminals are mounted onto the obtained electrode structure, housed inside the laminated outer casing, and sealed by heat fusion. This yields an all-solid-state battery.

[0157] Furthermore, electrode body 1 is obtained by sequentially stacking a pouch-shaped positive electrode structure, a negative electrode structure, and a positive electrode structure. Electrode body 2 is obtained by sequentially stacking a positive electrode structure, a pouch-shaped negative electrode structure, and a positive electrode structure. Then, electrode body 1, electrode body 2, and electrode body 1 are sequentially stacked with the positive current collector layers in contact with each other. Next, the outer edges of the upper and lower pouch-shaped positive and negative electrode structures are brought into contact and integrated, covering the sides other than the sides where the positive and negative current collector layers are arranged internally. This yields an electrode structure. The positive and negative terminals are mounted onto the obtained electrode structure, housed inside a laminated outer casing, and sealed by heat sealing. This yields an all-solid-state battery.

[0158] [Example]

[0159] The all-solid-state battery of this disclosure will be further described below based on embodiments.

[0160] [The fabrication of all-solid-state batteries]

[0161] <Example 1>

[0162] (Fabrication of the negative electrode structure)

[0163] Weigh out the negative electrode active material (Si particles, average particle size 2.5 μm), conductive material (VGCF-H: vapor-phase carbon fiber), and binder (PVdF-HFP: polyvinylidene fluoride-hexafluoropropylene) to a weight ratio of negative electrode active material: conductive material: binder = 94:4:2, and mix with a dispersion medium (diisobutyl ketone). Disperse the mixture using an ultrasonic homogenizer (UH-50, manufactured by SMT Co., Ltd.) to obtain a negative electrode slurry. Apply the obtained negative electrode slurry to a negative electrode current collector layer (Ni foil, thickness 15 μm) using a scraper coating method and dry at 100°C for 30 minutes. Then, by similarly coating the opposite side of the negative electrode current collector, a negative electrode structure intermediate with negative electrode active material layers on both sides of the negative electrode current collector layer is obtained.

[0164] Additionally, PEO (polyethylene oxide, Mw approximately 4,000,000) and LiTFSI (LiN(SO2CF3)2) were weighed to achieve a molar ratio of EO unit:Li = 20:1, mixed into acetonitrile, and stirred until a homogeneous solution was obtained. The obtained PEO-LiTFSI solution was coated onto one side of the negative electrode structure intermediate using a doctor blade coating method and dried at 100°C for 60 minutes. Then, the same PEO-LiTFSI solution was coated onto the other side of the negative electrode structure intermediate to obtain the negative electrode structure. After drying, the gap of the doctor blade was adjusted to a weight ratio of negative electrode active material:polymer electrolyte = 68:32. Then, it was densified by pressing, thereby obtaining a negative electrode laminate with negative electrode active material layers disposed on both sides of the negative electrode current collector layer.

[0165] (Fabrication of the positive electrode structure)

[0166] Weigh the positive electrode active material (LiNi) that has been coated with LiNbO3 in the rolling flow granulation coating device. 0.8 Co 0.15 Al 0.05O2, an average particle size of 10 μm, a sulfide solid electrolyte (10LiI·15LiBr·75(0.75Li2S·0.25P2S5) (mol%), an average particle size of 0.5 μm), a conductive material (VGCF-H), and a binder (SBR: styrene-butadiene rubber) were mixed with a dispersion medium (diisobutyl ketone) in a weight ratio of positive electrode active material: sulfide solid electrolyte: conductive material: binder = 85:13:1:1. The mixture was dispersed using an ultrasonic homogenizer (UH-50, manufactured by SMT Corporation) to obtain a positive electrode slurry. The obtained positive electrode slurry was coated onto an Al foil (15 μm thick) using a blade coating method, dried at 100°C for 30 minutes, and densified by pressing, thereby obtaining a positive electrode structure having a positive electrode layer and an Al foil.

[0167] (Fabrication of the solid electrolyte layer)

[0168] PEO (polyethylene oxide, Mw approximately 4,000,000) and LiTFSI (LiN(SO2CF3)2) were weighed to achieve a molar ratio of EO units:Li = 20:1 and mixed into acetonitrile. Initiator BPO (Benzoyl peroxide) was added to the resulting solution until the PEO-LiTFSI mixture reached 10% by weight, and the mixture was stirred until a homogeneous solution was obtained. The prepared polymer electrolyte solution was coated onto a PET film using a doctor blade coating method to a width of 7.4 cm. After drying at 100°C for 60 minutes, the film was cut into 14.2 cm lengths, thus obtaining a solid electrolyte layer containing the polymer electrolyte.

[0169] (The fabrication of an all-solid-state battery)

[0170] A 7.0cm × 7.0cm positive electrode active material layer is cut and bonded to a solid electrolyte layer, ensuring direct contact between the positive electrode structure and the solid electrolyte layer. The center of the end face of the positive electrode current collector layer, opposite to the side with the extended portion, aligns with the center of the end face of the solid electrolyte layer. The solid electrolyte layer is then bent along its long side, resulting in a bag-shaped positive electrode structure. Next, the bag-shaped positive electrode structure is bonded to both sides of a 7.0cm × 7.0cm negative electrode laminate, with direct contact between the positive electrode active material layers, at a speed of 0.5t / cm². 2 The electrode structure is then pressed. After welding the terminals, the electrode structure is sealed inside a laminated outer casing containing an Al metal layer to obtain the all-solid-state battery of Example 1.

[0171] <Example 2>

[0172] The fabrication of the negative electrode structure, the positive electrode structure, and the solid electrolyte layer are the same as in Example 1.

[0173] (The fabrication of an all-solid-state battery)

[0174] A 7.0cm × 7.0cm positive electrode structure is cut from the positive electrode active material layer and bonded to the solid electrolyte layer, ensuring direct contact between the positive electrode structure and the solid electrolyte layer. The center of the end face of the positive electrode current collector layer, opposite to the side with the extended portion, aligns with the center of the end face of the solid electrolyte layer. The solid electrolyte layer is then bent along its long side, thus obtaining a bag-shaped positive electrode structure. Next, on one side of the negative electrode stack, where the negative electrode active material layer is cut to a 7.0cm × 7.0cm shape, the bag-shaped positive electrode structure is bonded with the positive electrode active material layer side in direct contact. On the other side, the positive electrode structure is bonded with the positive electrode active material side in direct contact. Then, at a rate of 0.5t / cm... 2 The electrode body 1 is obtained by pressing.

[0175] In addition, a 7.0cm × 7.0cm negative electrode active material layer is cut and bonded to a solid electrolyte layer so that the negative electrode stack and the solid electrolyte layer are in direct contact. The center of the end face of the negative electrode current collector layer, opposite to the side with the extended portion, aligns with the center of the end face of the solid electrolyte layer. The solid electrolyte layer is then bent along its long side, thus obtaining a bag-shaped negative electrode structure. Next, a 7.0cm × 7.0cm positive electrode structure is bonded to both sides of the bag-shaped negative electrode structure in such a direct contact manner with the solid electrolyte layer. Then, a 0.5t / cm... 2 The electrode body 2 is obtained by pressing.

[0176] Electrode bodies 1 are stacked on both sides of electrode body 2 in such a way that the positive current collector layers are in direct contact with each other. Next, the outer edges of three pouch-shaped solid electrolytes are joined to the sides other than the sides where the current collector layers are arranged, thereby fixing the electrodes together. Then, after welding the terminals, the electrode structure is sealed inside the laminated outer casing containing an Al metal layer to obtain the all-solid-state battery of Example 2.

[0177] <Comparative Example 1>

[0178] The fabrication of the negative electrode structure, the positive electrode structure, and the solid electrolyte layer are the same as in Example 1.

[0179] (The fabrication of an all-solid-state battery)

[0180] On both sides of a negative electrode structure with a negative electrode active material layer cut to 7.2cm × 7.2cm, a solid electrolyte layer cut to 7.2cm × 7.2cm is bonded so that the negative electrode active material layer and the solid electrolyte layer are in direct contact, and the end face with the extended portion is aligned. On both sides of the resulting laminate, a positive electrode structure with a positive electrode active material layer cut to 7.0cm × 7.0cm is bonded so that the positive electrode active material layer and the solid electrolyte layer are in direct contact, at a ratio of 0.5t / cm. 2 The electrode body is obtained by pressing. Then, each terminal is soldered to the obtained electrode body, and the electrode body is sealed inside a laminated outer casing containing an Al metal layer to obtain the all-solid-state battery of Comparative Example 1.

[0181] <Comparative Example 2>

[0182] Three electrode bodies obtained in Comparative Example 1 were stacked, and the terminals were welded together. Then, the electrode bodies were sealed inside a laminated outer casing containing an Al metal layer to obtain the all-solid-state battery of Comparative Example 2.

[0183] [evaluate]

[0184] For the obtained all-solid-state battery, the welded portion of the laminated outer casing was removed to expose the Al metal layer. Then, a tester was used to measure the voltage between the Al metal layer and each terminal to evaluate the short-circuit rate through the laminated outer casing. A measured voltage of 0V was considered a short circuit, and a voltage greater than 0V was considered no short circuit. Ten tests were performed for each. The results are shown below.

[0185] Example 1: Short circuit rate 0 / 10

[0186] Example 2: Short circuit rate 0 / 10

[0187] Comparative Example 1: Short circuit rate 2 / 10

[0188] Comparative Example 2: Short circuit rate 4 / 10

[0189] Based on the above results, Examples 1 and 2, which use an electrode structure having an outermost solid electrolyte layer, are able to prevent short circuits through the laminated outer casing. On the other hand, Comparative Examples 1 and 2, which use an electrode structure without an outermost solid electrolyte layer, cannot prevent short circuits through the laminated outer casing.

[0190] Industrial applicability

[0191] The all-solid-state battery disclosed herein is typically an all-solid-state lithium-ion secondary battery. The applications of all-solid-state batteries are not particularly limited; examples include power sources for hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), gasoline vehicles, and diesel vehicles. They are particularly preferred for use as a power source for driving hybrid electric vehicles or electric vehicles. Furthermore, the all-solid-state batteries disclosed herein can be used as power sources for mobile bodies other than vehicles (e.g., railways, ships, and aircraft), and also as power sources for electrical appliances such as information processing devices.

Claims

1. A solid-state battery, wherein an electrode structure is sealed inside the outer casing. The outer casing includes an outer resin layer, an inner resin layer, and a metal layer disposed between the outer resin layer and the inner resin layer. The electrode structure comprises an electrode stack and an outermost solid electrolyte layer containing a polymer electrolyte. The electrode stack comprises at least one electrode body, which sequentially includes a first current collector layer, a first active material layer comprising an active material and an inorganic solid electrolyte, a first solid electrolyte layer comprising a polymer electrolyte, a second active material layer comprising a Si or Sn-based alloy active material and a polymer electrolyte, a second current collector layer, a second active material layer comprising a Si or Sn-based alloy active material and a polymer electrolyte, a second solid electrolyte layer comprising a polymer electrolyte, a first active material layer comprising an active material and an inorganic solid electrolyte, and a first current collector layer. The first current collector layer and the second current collector layer each have an extension portion and a flat plate portion. The first current collector layer is disposed at at least one end in the stacking direction of the electrode stack. When the first current collector layer disposed at at least one end in the stacking direction of the electrode stack is used as the outermost first current collector layer... The outermost solid electrolyte layer is stacked on the side of the outermost first current collector layer opposite to the side of the first active material layer. When viewed along the stacking direction, the area of ​​the outermost solid electrolyte layer is larger than the area of ​​the flat plate portion of the outermost first current collector layer. When viewed along the stacking direction, the outermost solid electrolyte layer is stacked in such a way that it completely covers the flat portion of the outermost first current collector layer. In the electrode structure, when the flat portion of the outermost first current collector layer and the first active material layer, which are sandwiched between the outermost solid electrolyte layer and the first solid electrolyte layer, are considered as laminate A, When viewed along the stacking direction, the area of ​​at least one of the outermost solid electrolyte layer and the first solid electrolyte layer is larger than that of the stack A. When viewed along the stacking direction, at least one of the outermost solid electrolyte layer and the first solid electrolyte layer is stacked in such a way that it covers the entire stack A. The outermost solid electrolyte layer and the first solid electrolyte layer are integrally formed at their outer edges, covering at least the sides of the laminate A other than the side where the extension of the first current collector layer is disposed, thus housing the laminate A within it. When viewed along the stacking direction, the extension of the outermost first current collector layer extends from the side of the outermost solid electrolyte layer and the first solid electrolyte layer, which are integrally formed. In the electrode body, when the second active material layer, the flat portion of the second current collector layer, and the second active material layer, which are sandwiched between the first solid electrolyte layer and the second solid electrolyte layer, are considered as a laminate B, When viewed along the stacking direction, at least one of the first solid electrolyte layer and the second solid electrolyte layer has an area larger than the stack B. When viewed along the stacking direction, at least one of the first solid electrolyte layer and the second solid electrolyte layer is stacked in such a way that it covers the entire stack B. The first solid electrolyte layer and the second solid electrolyte layer are integrally formed at their outer edges, covering at least the sides of the laminate B other than the side where the extension of the second current collector layer is disposed, thereby housing the laminate B within it. When viewed along the stacking direction, the extension of the second current collector layer extends from the side of the first solid electrolyte layer and the second solid electrolyte layer, which are integrally formed. The electrode structure comprises an electrode stack formed by stacking multiple electrode bodies. The electrode bodies are electrically connected in parallel. When the first active material layer, the flat portion of the first current collector layer, the flat portion of the first current collector layer, and the first active material layer are sandwiched between the second solid electrolyte layer of one adjacent electrode and the second solid electrolyte layer of another adjacent electrode, forming a laminate C, When viewed along the stacking direction, at least one of the second solid electrolyte layer of one adjacent electrode and the second solid electrolyte layer of the other electrode has an area larger than the stacked body C. When viewed along the stacking direction, at least one of the second solid electrolyte layer of one adjacent electrode and the second solid electrolyte layer of the other electrode is stacked in a manner that covers the entire stack C. The second solid electrolyte layer of one adjacent electrode and the second solid electrolyte layer of the other electrode are integrally formed at their outer edges, such that they at least cover the sides of the laminate C other than the side where the extension of the first current collector layer is disposed, thus housing the laminate C within it. When viewed along the stacking direction, at least one of the extensions of the first current collector layer extends from the side of the second solid electrolyte layer of one of the electrode bodies and the second solid electrolyte layer of the other electrode body, which are integrally formed with each other.

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