All-solid-state battery

Abstract

Provided is an all-solid-state battery capable of improving cycling characteristics. The all-solid-state battery includes a first current collector layer, a first active material layer, a second current collector layer, a second active material layer, and a solid electrolyte layer. The first current collector layer is quadrilateral and has a first current collector tab protruding from one side of the quadrilateral. The first active material layer is laminated on the first current collector layer. The second current collector layer is quadrilateral and has a second current collector tab protruding from one side of the quadrilateral. The second active material layer is laminated on the second current collector layer. The solid electrolyte layer is disposed between the first active material layer and the second active material layer and contains a polymer electrolyte. On three sides other than the side where the first current collector tab is disposed, the solid electrolyte layer is configured to further cover the end faces of the first current collector layer and the first active material layer.

Description

Technical Field

[0001] The present disclosure relates to all-solid-state batteries. Background Art

[0002] Patent Document 1 discloses an all-solid-state battery having a resin layer covering the side surface of an all-solid-state battery laminate, and shows the use of a sulfide solid electrolyte.

[0003] Patent Document 2 discloses a bipolar lithium-ion battery having a bipolar electrode current collector in which a first current collector, an adhesive resin layer having through holes, and a second current collector are sequentially laminated, and the first current collector and the second current collector are bonded via the adhesive resin layer.

[0004] Patent Document 3 discloses a structure in which a solid electrolyte layer and an insulating portion on the side surface of a laminate contain a solid electrolyte material composed of a sulfide solid electrolyte material or an oxide solid electrolyte material.

[0005] Patent Document 4 discloses a structure in which a solid electrolyte layer and the side surface of a laminate are the same member.

[0006] Prior Art Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-192610

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2017-073374

[0009] Patent Document 3: Japanese Patent Application Laid-Open No. 2014-235990

[0010] Patent Document 4: Japanese Patent Application Laid-Open No. 2018-142534 Summary of the Invention

[0011] In an all-solid-state battery, the cycle characteristics (e.g., capacity retention rate) are reduced due to volume changes of the negative electrode active material during charge and discharge. This is because the mechanical properties of the sulfide solid electrolyte cannot withstand the expansion and contraction of the negative electrode active material caused by charge and discharge, and peeling and cracking occur at the interface between the negative electrode layer and the solid electrolyte layer, at the interface between the negative electrode active material and the solid electrolyte layer, and within the solid electrolyte layer.

[0012] Therefore, in the present disclosure, in view of the above problems, an object is to provide an all-solid-state battery capable of improving cycle characteristics.

[0013] In an all-solid-state battery, ions and electrons are conducted through the interface between solids, so the bonding state of the interface has a significant impact on battery performance. On the other hand, when expansion and contraction (volume change) of the active material occurs during charge and discharge, a good bonding state cannot be maintained at the interface, and the resistance increases.

[0014] For example, Si-based active materials are well-known as high-capacity negative electrode active materials, but they have a large volume change associated with charge and discharge. In order to suppress the degradation of battery performance caused by the expansion and contraction of the negative electrode active material, the inventors considered using a soft polymer electrolyte as the solid electrolyte for the negative electrode layer. However, the ionic conductivity of polymer electrolytes is mostly lower than that of inorganic solid electrolytes. Therefore, from the viewpoint of improving battery performance, it is envisaged to use an inorganic solid electrolyte for the positive electrode layer. Moreover, by using a polymer electrolyte and an inorganic solid electrolyte in combination, it is possible to obtain good battery performance while suppressing the deterioration of the bonding state at the solid-solid interface in the negative electrode layer.

[0015] However, the inventors obtained the following insight: In a all-solid-state battery where one of the positive electrode layer and the negative electrode layer contains an inorganic solid electrolyte and the other contains a polymer electrolyte, the inorganic solid electrolyte is generally harder than the polymer electrolyte. Therefore, the layer containing the inorganic solid electrolyte (for example, the positive electrode layer) becomes a hard layer, and the layer containing the polymer electrolyte (for example, the negative electrode layer) becomes a soft layer. As a result, when pressing to bond the layers, the layer containing the polymer electrolyte is likely to deform (for example, elongate, warp). If the positive electrode layer and the negative electrode layer come into contact due to such deformation, an internal short circuit occurs and the cycle characteristics deteriorate.

[0016] Based on the above insight, as one means for solving the above problems, the present application discloses an all-solid-state battery including a first current collector layer, a first active material layer, a second current collector layer, a second active material layer, and a solid electrolyte layer. The first current collector layer is quadrilateral and has a first current collector tab protruding from one side of the quadrilateral. The first active material layer is laminated on the first current collector layer. The second current collector layer is quadrilateral and has a second current collector tab protruding from one side of the quadrilateral. The second active material layer is laminated on the second current collector layer. The solid electrolyte layer is disposed between the first active material layer and the second active material layer and contains a polymer electrolyte. On the three sides other than the side where the first current collector tab is disposed, the solid electrolyte layer is disposed so as to also cover the end faces of the first current collector layer and the first active material layer.

[0017] In the above all-solid-state battery, the second current collector layer, the second active material layer, the solid electrolyte layer, the first active material layer, the first current collector layer, the first active material layer, the solid electrolyte layer, the second active material layer, and the second current collector layer may be laminated in sequence to form a power generation element.

[0018] In the above all-solid-state battery, the end faces of the second current collector layer and the second active material layer may also be covered with a solid electrolyte layer on at least one side other than the side where the second current collector tab is disposed. Further, a plurality of such power generation elements may be stacked, and the plurality of power generation elements are joined through a solid electrolyte layer covering the end faces of the second current collector layer and the second active material layer.

[0019] In the all-solid-state battery according to the present disclosure, even when a polymer electrolyte is used for the negative electrode active material layer, it is difficult to cause a short circuit. Therefore, the polymer electrolyte can be used for the negative electrode active material layer. As a result, peeling and cracking at the interface between the negative electrode layer and the solid electrolyte layer during charge and discharge can be suppressed, and good cycle characteristics can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is an external perspective view of the power generation element 10.

[0021] Figure 2 It is a top view of the power generation element 10.

[0022] Figure 3 It is a front view of the power generation element 10.

[0023] Figure 4 It is a left view of the power generation element 10.

[0024] Figure 5 It is a sectional view taken along the line V-V of the power generation element 10.

[0025] Figure 6 It is a sectional view taken along the line VI-VI of the power generation element 10.

[0026] Figure 7 It is a diagram illustrating an example in which a solid electrolyte layer covers a negative electrode laminate.

[0027] Figure 8 It is a diagram illustrating an example in which a solid electrolyte layer covers a negative electrode laminate.

[0028] Figure 9 It is a diagram illustrating an example in which a solid electrolyte layer covers a negative electrode laminate.

[0029] Figure 10 It is a diagram illustrating the structure of the all-solid-state battery 1.

[0030] Figure 11 It is a sectional view of the power generation element 20.

[0031] Figure 12 It is a sectional view of the power generation element 20.

[0032] Figure 13 It is a diagram showing the stacked manner of the power generation elements 20.

[0033] Description of Reference Numerals

[0034] 1 All-solid-state battery

[0035] 10 Power generation element

[0036] 11 Negative electrode current collector layer

[0037] 11a Negative electrode current collector tab

[0038] 12 Negative electrode active material layer

[0039] 13 Solid electrolyte layer

[0040] 14 Positive electrode active material layer

[0041] 15 Positive electrode current collector layer

[0042] 15a Positive electrode current collector tab

[0043] 16 Insulating layer Detailed Implementation Modes

[0044] 1. Power generation element

[0045] The all-solid-state battery of the present disclosure has one or more unit elements capable of generating electricity as a single cell, i.e., power generation elements, which are housed in an outer package (case) not shown and have an expected capacity. First, the power generation element will be described.

[0046] Figures 1 to 6 FIG. showing a power generation element 10 for explaining one embodiment. Figure 1 is a perspective view of the power generation element 10, Figure 2 is a top view of the power generation element 10 (viewed from the direction indicated by arrow II in Figure 1 ), Figure 3 is a front view of the power generation element 10 (viewed from the direction indicated by arrow III in Figure 1 ), Figure 4 is a left view of the power generation element 10 (viewed from the direction indicated by arrow IV in Figure 1 ), Figure 5 is Figure 3 a cross-sectional view taken along the V-V direction, and Figure 6 is Figure 4 a cross-sectional view taken along the VI-VI direction.

[0047] In each of the figures shown from Figures 1 to 6 onward, for ease of viewing as needed, the shape (e.g., thickness, width, etc.) may be exaggerated, and a part of the repeated reference numerals may be omitted. In addition, for ease of understanding, the directions of the three-dimensional orthogonal coordinate system (x, y, z) may be shown together.

[0048] 1.1. Constituent members of the power generation element

[0049] As shown in Figures 1 to 6 FIG. 1, the power generation element 10 includes a negative electrode current collector layer 11, a negative electrode active material layer 12, a solid electrolyte layer 13, a positive electrode active material layer 14, a positive electrode current collector layer 15, and an insulating layer 16. Further, in this embodiment, the negative electrode current collector layer 11, the negative electrode active material layer 12, the positive electrode active material layer 14, and the positive electrode current collector layer 15 are all sheet-like members having a quadrilateral front and back surface in the xy plane and a thin thickness between the front and back surfaces.

[0050] 1.1a. Negative electrode current collector layer (first current collector layer)

[0051] In this embodiment, the negative electrode current collector layer 11 is one of the members constituting the negative electrode laminate as the first current collector layer, and is quadrilateral when viewed from above (when viewed from the Figure 2 viewing direction), and is made of a metal foil, a metal mesh, or the like. A metal foil is particularly preferred, and examples of the metal include Cu, Ni, Fe, Ti, Co, Zn, stainless steel, etc. The negative electrode current collector layer 11 may have a certain coating layer on its surface for adjusting the contact resistance. As the material constituting the coating layer, for example, carbon can be cited. The thickness (size in the z direction) of the negative electrode current collector layer 11 is not particularly limited, preferably 0.1 μm or more and 1 mm or less, more preferably 1 μm or more and 100 μm or less.

[0052] The negative electrode current collector layer 11 includes a negative electrode current collector tab 11a that functions as the first current collector tab. Through the negative electrode current collector tab 11a, the negative electrode current collector layers 11 can be easily electrically connected to each other. The material of the negative electrode current collector tab 11a may be the same as or different from that of the negative electrode current collector layer 11. In addition, the thickness of the negative electrode current collector tab 11a may be the same as or different from that of the negative electrode current collector layer 11.

[0053] In this embodiment, the negative electrode current collector tab 11a is arranged to protrude in the x direction from one side (x-direction end) of the negative electrode current collector layer 11, and its thickness (size in the z direction) is the same as that of the negative electrode current collector layer 11. In addition, the width (size in the y direction) of the negative electrode current collector tab 11a is smaller than that of the negative electrode current collector layer 11.

[0054] 1.1b. Negative electrode active material layer (first active material layer)

[0055] In this embodiment, the negative electrode active material layer 12 is one of the members constituting the negative electrode laminate as the first active material layer, and is quadrilateral when viewed from above (when viewed from the Figure 2 viewing direction). In this embodiment, it may contain at least a negative electrode active material and a polymer electrolyte as a solid electrolyte, and may optionally contain a conductive material and an adhesive.

[0056] The thickness (size in the z direction) of the negative electrode active material layer is, for example, not less than 0.1 μm and not more than 1000 μm.

[0057] [Negative electrode active material]

[0058] Examples of negative electrode active materials include metal active materials such as Si, Sn, and Li; carbon active materials such as graphite; and oxide active materials such as lithium titanate. In addition, the negative electrode active material may be a Si-based active material containing at least Si. Si-based active materials undergo large volume changes associated with charge and discharge, and are therefore prone to reduction in battery performance due to expansion and contraction. In response to this, by containing a soft polymer electrolyte, reduction in battery cycle characteristics due to expansion and contraction can be suppressed. Examples of Si-based active materials include Si single substance, Si alloy, and Si oxide. Si alloys preferably contain Si element as a main component. In Si alloys, the proportion of Si is, for example, 50 atomic % or more, 70 atomic % or more, or 90 atomic % or more.

[0059] The shape of the negative electrode active material may be, for example, a granular shape. The average particle size (D50) of the negative electrode active material may be, for example, greater than 10 nm, or greater than 100 nm. On the other hand, the average particle size (D50) of the negative electrode active material may be, for example, less than 50 μm, or less than 20 μm. The average particle size (D50) may be calculated, for example, by measurement using a laser diffraction particle size distribution meter or a scanning electron microscope (SEM).

[0060] The proportion of the negative electrode active material in the negative electrode active material layer is, for example, 20 wt % or more, 40 wt % or more, or 60 wt % or more. On the other hand, the proportion of the negative electrode active material in the negative electrode active material layer is, for example, 80 wt % or less.

[0061] [Polymer Electrolyte]

[0062] The polymer electrolyte contains at least a polymer component. Examples of the polymer component include polyether polymers, polyester polymers, polyamine polymers, and polysulfide polymers, of which polyether polymers are preferred because they have high ion conductivity and excellent mechanical properties such as Young's modulus and breaking strength.

[0063] The polyether-based polymer has a polyether structure within the repeating unit. Additionally, the polyether-based polymer preferably has a polyether structure within the main chain of the repeating unit. As the polyether structure, for example, a polyethylene oxide (PEO) structure and a polypropylene oxide (PPO) structure can be cited. The polyether-based polymer preferably has a PEO structure as the main repeating unit. In the polyether-based polymer, the proportion of the PEO structure in all the repeating units is, for example, 50 mol% or more, can be 70 mol% or more, or can be 90 mol% or more. Additionally, the polyether-based polymer can also be, for example, a homopolymer or copolymer of an epoxide (such as ethylene oxide, propylene oxide).

[0064] The polymer component can have an ion-conductive unit as shown below. As the ion-conductive unit, for example, polyethylene oxide, polypropylene oxide, polymethacrylate, polyacrylate, polydimethylsiloxane, polyacrylic acid, polymethacrylic acid, polyvinyl acetate, polyimide, polyamine, polyamide, polyalkyl carbonate, polyacrylonitrile, polyphosphazene, polyolefin, polybutadiene can be cited.

[0065] The weight-average molecular weight (Mw) of the polymer component is not particularly limited and is, for example, 1,000,000 or more and 10,000,000 or less. Mw is determined by gel permeation chromatography (GPC). Additionally, the glass transition temperature (Tg) of the polymer component is, for example, 60°C or lower, can be 40°C or lower, or can be 25°C or lower. Additionally, the polymer electrolyte can contain only one type of polymer component or can contain two or more types. Additionally, the polymer electrolyte can be a crosslinked polymer electrolyte formed by crosslinking the polymer component or can be an uncrosslinked polymer electrolyte in which the polymer component is not crosslinked.

[0066] The polymer electrolyte can be a dry polymer electrolyte or a gel electrolyte. The dry polymer electrolyte refers to an electrolyte in which the content rate of the solvent component is 5 wt% or less. The content rate of the solvent component can be 3 wt% or less or can be 1 wt% or less. Furthermore, when a sulfide solid electrolyte having high reactivity with a polar solvent is used in the positive electrode active material layer, it is preferable to use a dry polymer electrolyte.

[0067] The dry polymer electrolyte may contain a supporting salt. Examples of the supporting salt include inorganic lithium salts such as LiPF6, LiBF4, LiClO4, LiAsF6, etc., and organic lithium salts such as LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiN(FSO2)2, LiC(CF3SO2)3. The proportion of the supporting salt relative to the dry polymer electrolyte is not particularly limited. For example, when the dry polymer electrolyte has an EO unit (C2H5O unit), relative to 1 mole of the supporting salt, the EO unit is, for example, 5 moles or more, can be 10 moles or more, or can be 15 moles or more. On the other hand, relative to 1 mole of the supporting salt, the EO unit is, for example, 40 moles or less, or can be 30 moles or less.

[0068] The gel electrolyte usually contains 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 above. Examples of the solvent include carbonates. Examples of the carbonate include cyclic esters (cyclic carbonates) such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC); chain esters (chain carbonates) such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC). In addition, examples of the solvent include acetate esters such as methyl acetate, ethyl acetate, and ethers such as 2-methyltetrahydrofuran. Furthermore, examples of the solvent include γ-butyrolactone, sulfolane, N-methylpyrrolidone (NMP), and 1,3-dimethyl-2-imidazolidinone (DMI). Additionally, the solvent can also be water.

[0069] The proportion of the polymer electrolyte relative to all solid electrolytes is, for example, 50% by volume or more, can be 70% by volume or more, or can be 90% by volume or more. As the solid electrolyte, it can also be a form containing only the polymer electrolyte.

[0070] The proportion of the polymer electrolyte in the negative electrode active material layer is, for example, 20% by volume or more, can be 30% by volume or more, or can be 40% by volume or more. On the other hand, the proportion of the polymer electrolyte in the negative electrode active material layer is, for example, 70% by volume or less, or can be 60% by volume or less.

[0071] [Conductive material]

[0072] By adding a conductive material, the electron conductivity of the negative electrode active material layer is improved. Examples of the conductive material include particulate carbon materials such as acetylene black (AB), Ketjen black (KB), fibrous carbon materials such as carbon fiber, carbon nanotube (CNT), and carbon nanofiber (CNF).

[0073] [Binder]

[0074] By adding an adhesive, the constituent materials of the negative electrode active material layer are firmly bonded. Examples of the adhesive include fluoride-based adhesives, polyimide-based adhesives, and rubber-based adhesives.

[0075] 1.1c. Solid electrolyte layer

[0076] The solid electrolyte layer 13 is a layer containing a solid electrolyte, and is quadrilateral when viewed from above (viewed from the Figure 2 perspective direction). In the present disclosure, a polymer electrolyte is contained as the solid electrolyte.

[0077] The polymer electrolyte contained in the solid electrolyte layer 13 is a crosslinked polymer electrolyte formed by crosslinking polymer components. The polymer electrolyte contained in the solid electrolyte layer 13 is the same as the polymer electrolyte described in the negative electrode active material layer 12 except that the polymer components are crosslinked.

[0078] Examples of the polymerization initiator for crosslinking the polymer components include peroxides such as benzoyl peroxide, di-tert-butyl peroxide, tert-butyl benzoyl peroxide, tert-butyl peroxyoctanoate, and cumene hydroperoxide; and azo compounds such as azobisisobutyronitrile. The composition of the polymer electrolyte in the solid electrolyte layer and the polymer electrolyte in the negative electrode active material layer may be the same or different. Furthermore, in the case where a sulfide solid electrolyte having high reactivity with a polar solvent is used in the positive electrode active material layer, a dry polymer electrolyte is preferably used.

[0079] Here, the solid electrolyte layer 13 preferably can be self-supporting. "Can be self-supporting" means that it can maintain its shape even in the absence of other supports. For example, when the material of the solid electrolyte as an object is wet-coated on a substrate and the substrate is peeled off after drying or the like, and the solid electrolyte layer maintains its shape, it can be said to be "self-supporting".

[0080] The solid electrolyte layer 13 preferably contains a polymer electrolyte as the main component of the solid electrolyte. In the solid electrolyte layer, the proportion of the polymer electrolyte relative to all the solid electrolytes is, for example, 50% by volume or more, can be 70% by volume or more, and can also be 90% by volume or more. The solid electrolyte layer may contain only the polymer electrolyte as the solid electrolyte.

[0081] The thickness (size in the z direction) of the solid electrolyte layer 13 is, for example, 0.1 μm or more and 1000 μm or less.

[0082] 1.1d. Positive electrode active material layer (second active material layer)

[0083] In this embodiment, the positive electrode active material layer 14 is a member constituting the positive electrode laminate as the second active material layer, and when viewed from above (viewed from the Figure 2When viewed from the perspective of [description], it is a quadrilateral. In this method, it contains at least a positive electrode active material and a solid electrolyte, and may also optionally contain a conductive material, a binder, etc. Regarding the conductive material and the binder, the content described in the negative electrode active material layer 12 is the same, so the description is omitted here.

[0084] The thickness (size in the z direction) of the positive electrode active material layer is, for example, 0.1 μm or more and 1000 μm or less.

[0085] [Positive Electrode Active Material]

[0086] As the positive electrode active material, for example, an oxide active material can be cited. As the oxide active material, for example, LiCoO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and other rock salt layered active materials, LiMn2O4, Li4Ti5O 12 and other spinel type active materials, LiFePO4 and other olivine type active materials, S, Li2S, transition metal sulfides and other sulfur based active materials.

[0087] A protective layer containing a Li ion conductive oxide can be formed on the surface of the oxide active material. Because this can inhibit the reaction between the oxide active material and the solid electrolyte. As the Li ion conductive oxide, for example, LiNbO3 can be cited. The thickness of the protective layer is, for example, 1 nm or more and 30 nm or less.

[0088] As the shape of the positive electrode active material, for example, a granular shape can be cited. The average particle size (D50) of the positive electrode active material is not particularly limited, for example, it is 10 nm or more, and can also be 100 nm or more. On the other hand, the average particle size (D50) of the positive electrode active material is, for example, 50 μm or less, and can also be 20 μm or less.

[0089] [Solid Electrolyte]

[0090] As the solid electrolyte of the positive electrode active material layer, an inorganic solid electrolyte can be used. As the inorganic solid electrolyte, for example, a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte can be cited. In addition, the inorganic solid electrolyte can be glass (amorphous), can be glass ceramic, or can be crystal. Glass is obtained, for example, by amorphizing the raw material. Glass ceramic is obtained, for example, by heat treating the glass. Crystal is obtained, for example, by heating the raw material.

[0091] The sulfide solid electrolyte preferably contains, for example, Li, A (where A is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, In), and S. The sulfide solid electrolyte may further contain at least one of O (oxygen) and a halogen. As the halogen, for example, F, Cl, Br, and I can be cited. The sulfide solid electrolyte may contain only one kind of halogen or may contain two or more kinds of halogens. Further, when the sulfide solid electrolyte contains an anion element other than S (for example, O and a halogen), it is preferable that the molar ratio of S is the highest among all the anion elements.

[0092] The sulfide solid electrolyte preferably has an anion structure of the original composition (PS4 3- structure, SiS4 4- structure, GeS4 4- structure, AlS3 3- structure, BS3 3- structure) as the main component of the anion structure. Because of its high chemical stability. The proportion of the anion structure of the original composition is, for example, 50 mol% or more, can be 60 mol% or more, or can be 70 mol% or more, relative to all the anion structures in the sulfide solid electrolyte.

[0093] The sulfide solid electrolyte may have a crystalline phase having ion conductivity. As the above crystalline phase, for example, a Thio-LISICON type crystalline phase, an LGPS type crystalline phase, and a thiogermanate type crystalline phase can be cited.

[0094] Further, the oxide solid electrolyte preferably contains, for example, Li, Z (where Z is at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W, S), and O. As a specific example of the oxide solid electrolyte, garnet type solid electrolytes such as Li7La3Zr2O 12 etc.; perovskite type solid electrolytes such as (Li,La)TiO3; NASICON type solid electrolytes such as Li(Al,Ti)(PO4)3; Li-P-O based solid electrolytes such as Li3PO4; Li-B-O based solid electrolytes such as Li3BO3. Further, when the oxide solid electrolyte contains an anion element other than O (for example, S and a halogen), it is preferable that the molar ratio of O is the highest among all the anion elements.

[0095] The halide solid electrolyte is an electrolyte containing a halogen (X). As the halogen, for example, F, Cl, Br, and I can be cited. As the halide solid electrolyte, for example, Li3YX6 (where X is at least one of F, Cl, Br, I) can be cited. Further, when the halide solid electrolyte contains an anion element other than a halogen (for example, S and O), it is preferable that the molar ratio of the halogen is the highest among all the anion elements.

[0096] Examples of the shape of the inorganic solid electrolyte include granular. The average particle diameter (D50) of the inorganic solid electrolyte is not particularly limited, and is, for example, 10 nm or more, and may be 100 nm or more. On the other hand, the average particle diameter (D50) of the inorganic solid electrolyte is, for example, 50 μm or less, and may be 20 μm or less.

[0097] The positive electrode active material layer 14 preferably contains an inorganic solid electrolyte as the main component of the solid electrolyte. In the positive electrode active material layer 14, the proportion of the inorganic solid electrolyte relative to all solid electrolytes is, for example, 50% by volume or more, may be 70% by volume or more, and may be 90% by volume or more. The positive electrode active material layer 14 may also contain only an inorganic solid electrolyte as the solid electrolyte.

[0098] The proportion of the inorganic solid electrolyte in the positive electrode active material layer 14 is, for example, 10% by volume or more, and may be 20% by volume or more. On the other hand, the proportion of the inorganic solid electrolyte in the positive electrode active material layer 14 is, for example, 60% by volume or less, and may be 50% by volume or less.

[0099] 1.1e. Positive electrode current collector layer (second current collector layer)

[0100] In this embodiment, the positive electrode current collector layer 15 is one of the components constituting the positive electrode laminate as the second current collector layer, and is quadrangular when viewed from above (when viewed from the Figure 2 viewing direction), and may be composed of a metal foil, a metal mesh, or the like. A metal foil is particularly preferred, and examples of the metal include Ni, Cr, Au, Pt, Al, Fe, Ti, Zn, stainless steel, and the like. The positive electrode current collector layer 15 may have a certain coating layer on its surface for adjusting the resistance, and examples thereof include a carbon coating layer. The thickness (size in the z direction) of the positive electrode current collector layer 15 is not particularly limited. For example, it is preferably 0.1 μm or more and 1 mm or less, and more preferably 1 μm or more and 100 μm or less.

[0101] In the positive electrode current collector layer 15, a positive electrode current collector tab 15a is disposed as the second current collector tab. Through the positive electrode current collector tab 15a, the positive electrode current collector layers 15 can be easily electrically connected to each other. The material of the positive electrode current collector tab 15a may be the same as or different from that of the positive electrode current collector layer 15. In addition, the thickness of the positive electrode current collector tab 15a may be the same as or different from that of the positive electrode current collector layer 15.

[0102] In this embodiment, the positive electrode current collector tab 15a is disposed to protrude in the x direction from one side (x-direction end portion) of the positive electrode current collector layer 15, and its thickness is the same as that of the positive electrode current collector layer 15. In addition, the width (size in the y direction) of the positive electrode current collector tab 15a is smaller than that of the positive electrode current collector layer 15.

[0103] 1.1f. Insulating layer

[0104] The insulating layer 16 is a layer made of an electrical insulator. The insulating layer 16 can be applied without particular limitation as long as it is a member capable of electrical insulation, and examples thereof include an insulating film, an insulating tape, etc.

[0105] 1.2. Structure of the power generation element

[0106] In this embodiment, the power generation element 10 is formed by arranging the above-described respective constituent members as follows.

[0107] First active material layers are arranged on the front and back of the first current collector layer. That is, in this embodiment, negative electrode active material layers 12 are arranged on the front and back of the negative electrode current collector layer 11. At this time, it can be seen from Figure 5 , Figure 6 that the end face 12t of the negative electrode active material layer 12 is located inside (does not protrude) with respect to the end face 11t of the negative electrode current collector layer 11.

[0108] A solid electrolyte layer is arranged on the side opposite to the surface of the first active material layer that contacts the first current collector layer. In this embodiment, a solid electrolyte layer 13 is arranged on the side opposite to the surface of the negative electrode active material layer 12 that contacts the negative electrode current collector layer 11.

[0109] Furthermore, in this embodiment, it can be seen from Figure 5 , Figure 6 that the end face 11t of the negative electrode current collector layer 11, which is the first current collector layer, and the end face 12t of the negative electrode active material layer 12, which is the first active material layer, are covered by the solid electrolyte layer 13 on the three sides other than the side where the negative electrode current collector tab 11a, which is the first current collector tab, is provided. Thus, for example, even when there is deformation such as when the negative electrode active material layer 12 is pressed using a soft polymer electrolyte, since the negative electrode active material layer 12 is covered by the solid electrolyte layer 13, it is possible to suppress a short circuit due to contact with the positive electrode active material layer 14 and / or the positive electrode current collector layer 15.

[0110] Moreover, in this embodiment, the end face 11t of the side of the negative electrode current collector layer 11 where the negative electrode current collector tab 11a is provided is arranged to protrude from the end face 12t of the negative electrode active material layer 12 and the end face of the solid electrolyte layer 13 (refer to Figure 6 ).

[0111] On the side opposite to the surface of the solid electrolyte layer 13 that contacts the surface of the negative electrode active material layer, which is the first current collector layer, a positive electrode active material layer 14, which is the second active material layer, is arranged. In addition, on the side opposite to the surface of the positive electrode active material layer 14, which is the second active material layer, that contacts the solid electrolyte layer 13, a positive electrode current collector layer 15, which is the second current collector layer, is arranged.

[0112] In addition, in this method, the negative electrode current collector tab 11a and the positive electrode current collector tab 15a are arranged to protrude in the same direction. However, it is clearly known from Figure 2 , Figure 4 that the negative electrode current collector tab 11a and the positive electrode current collector tab 15a are arranged to have different positions in the width direction (y direction) and are positioned so as not to overlap when viewed from Figure 2 the perspective (top view).

[0113] Moreover, an insulating layer 16 is disposed on the front and back of the negative electrode current collector layer 11 at a portion where the part protruding in the x direction in the negative electrode current collector layer 11 and the positive electrode current collector tab 15a overlap when viewed from above. Thereby, a short circuit can be more effectively suppressed.

[0114] In this method, the description has been made with the "first" as the negative electrode and the "second" as the positive electrode. That is, the configuration of each component has been described with the first current collector layer as the negative electrode current collector layer, the first current collector tab as the negative electrode current collector tab, the first active material layer as the negative electrode active material layer, the second current collector layer as the positive electrode current collector layer, the second current collector tab as the positive electrode current collector tab, and the second active material layer as the positive electrode active material layer. However, it is not limited thereto, and conversely, each component may be arranged with the "first" as the positive electrode and the "second" as the negative electrode. The same applies to the following description.

[0115] 1.3. Manufacturing Method of Power Generation Element

[0116] The manufacturing method of the power generation element 10 is not particularly limited, and for example, it can be manufactured as follows.

[0117] The material for the positive electrode active material layer 14 is coated on the surface of the positive electrode current collector layer 15 by a wet method and dried, and is densified by pressing, thereby obtaining a positive electrode laminate (a laminate of the positive electrode current collector layer 15 and the positive electrode active material layer 14).

[0118] On the other hand, the material for the negative electrode active material layer 12 is coated on the front and back of the negative electrode current collector layer 11 by a wet method and dried, and is densified by pressing, thereby obtaining a negative electrode laminate (a laminate of the negative electrode current collector layer 11 and the negative electrode active material layer 12).

[0119] The solid electrolyte layer is arranged so as to cover the negative electrode laminate, and the positive electrode laminates are respectively arranged on the outer two sides of the solid electrolyte layer, and are integrally formed by pressing, thereby obtaining the power generation element 10. The pressing pressure at this time is not particularly limited, and for example, it is preferably 0.5 tons / cm 2 or more.

[0120] Here, the method of arranging the solid electrolyte layer so as to cover the negative electrode laminate is not particularly limited, and for example, it can be carried out as follows. Figures 7 to 9Shows a diagram for illustration. Figures 7 to 9 Shows a top view of its upper part and a diagram showing the stacked state in the thickness direction at the lower part (a cross-section at the center along the y direction).

[0121] First, as Figure 7 shown, a material 13' serving as a solid electrolyte layer is stacked on a release sheet (e.g., polyethylene terephthalate sheet, PET sheet) 17.

[0122] Next, as Figure 8 shown, a negative electrode laminate 18 is further stacked on the material 13'. At this time, one end 18a in the x direction of the negative electrode laminate 18 is arranged so as to protrude from the end of the material 13', and the other end 18b in the x direction of the negative electrode laminate 18 is arranged at the position of the approximate center line C in the x direction of the material 13'. In addition, the length in the x direction of the negative electrode active material layer of the negative electrode laminate 18 is approximately half of the length in the x direction of the solid electrolyte layer. Moreover, in the width direction (y direction), the width of the negative electrode laminate 18 is made smaller than the width of the material 13', and exposed portions 13'c of the material 13' are formed at both ends in the width direction (y direction) of the material 13'.

[0123] From Figure 8 the arrangement method, as Figure 8 shown by the arrow D, the release sheet 17 and the material 13' on the side where the negative electrode laminate 18 is not stacked are folded inward within the center line C, and the material 13' is stacked on the negative electrode laminate 18. Then, if the release sheet 17 at the bent portion is peeled off, it becomes as Figure 9 shown. That is, in Figure 9 the arrangement method, the material 13' is wound around the front and back of the negative electrode laminate 18 to form a bag-shaped material 13'.

[0124] Thus, the solid electrolyte layer can be arranged so as to cover the negative electrode laminate. Moreover, since the upper and lower materials 13' obtained by bending are easily attached, they are joined by contact, but physical joining using pressing or chemical joining by fusion welding, ultraviolet irradiation, or thermal cross-linking reaction can also be performed.

[0125] Here, an example of bending the material serving as the solid electrolyte layer to cover the negative electrode laminate is shown, but it is not limited to this. The solid electrolyte layer can also be arranged so as to cover the negative electrode laminate by preparing two sheet materials serving as the solid electrolyte layer, arranging the negative electrode laminate therebetween, and joining them. In addition, instead of the negative electrode laminate 18, a release sheet such as a PET film can be arranged to form a bag-shaped solid electrolyte layer, and then the release sheet can be removed and the negative electrode laminate can be arranged.

[0126] 2. All-solid-state battery

[0127] The all-solid-state battery in the present disclosure is formed by laminating the above-described power generation element 10. Figure 10 A diagram for illustration is shown. From Figure 10 As can be seen, the all-solid-state battery is laminated by overlapping the positive electrode current collector layer 15 and the positive electrode current collector tab 15a of the power generation element 10. Also, a plurality of negative electrode current collector tabs 11a are electrically connected, and a plurality of positive electrode current collector sheets 15a are electrically connected, thereby forming the positive and negative electrodes of the all-solid-state battery. In addition, in the all-solid-state battery, the laminated power generation elements 10 are housed in an outer package. As the outer package, for example, a laminated outer package or a can-type outer package can be cited.

[0128] Typically, the all-solid-state battery in the present disclosure is an all-solid-state lithium-ion secondary battery. The use of the all-solid-state battery is not particularly limited, and for example, it can be cited as a power source for vehicles such as hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), gasoline vehicles, and diesel vehicles. It is particularly preferably used as a driving power source for hybrid electric vehicles or battery electric vehicles. In addition, the all-solid-state battery in the present disclosure can be used as a power source for moving bodies other than vehicles (e.g., railways, ships, airplanes), and can also be used as a power source for electrical appliances such as information processing devices.

[0129] 3. Other exemplary embodiments

[0130] 3.1. Other exemplary embodiment 1

[0131] Figures 11 to 13 A diagram showing the power generation element 20 used in the all-solid-state battery of other exemplary embodiment 1 is shown. Figure 11 It is a diagram with the same Figure 5 viewpoint as Figure 12 It is a diagram with the same Figure 6 viewpoint as

[0132] The power generation element 20 is an example in which a solid electrolyte layer 23 is applied instead of the solid electrolyte layer 13 of the power generation element 10. Regarding other constituent elements, they can be considered in the same manner as the power generation element 10, so the same reference numerals are given here and the description is omitted.

[0133] The solid electrolyte layer 23, outside the structure of the solid electrolyte layer 13 of the power generation element 10, covers the end faces (11t, 12t) of the first current collector layer (negative electrode current collector layer 11) and the first active material layer (negative electrode active material layer 12) on one or more sides other than the side where the first current collector tab (negative electrode current collector tab 11a) is disposed. The width ( Figure 11 W1) and / or length ( Figure 12 L1) of the solid electrolyte layer is larger than the width ( Figure 11 W2) and / or length ( Figure 12The L2) is larger. Further, in this larger portion, the end faces of the second active material layer (the end face 14t of the positive electrode active material layer 14) and the second current collector layer (the end face 15t of the positive electrode current collector layer 15) are also covered with the solid electrolyte layer 23. Thereby, a short circuit can be further prevented.

[0134] In addition, as Figure 13 shown, a structure can be formed in which on a side other than the side where the first current collector tab (negative electrode current collector tab 11a) and the second current collector tab (positive electrode current collector tab 15a) are arranged, two or more power generation elements 20 are joined to each other by solid electrolyte layers covering the end faces of the first current collector layer, the first active material layer, the second current collector layer, and the second active material layer. By integrating in this way, misalignment and the like can be suppressed.

[0135] 3.2. Other Example 2

[0136] So far, in the power generation element 10, the negative electrode current collector layer 11 and the negative electrode active material layer 12 are shown, and in the power generation element 20, in addition to these, all sides other than the side where the negative electrode current collector tab 11a and the positive electrode current collector tab 15a are arranged in the positive electrode current collector layer 15 and the positive electrode active material layer 14 are covered with the solid electrolyte layer, and an example in which the negative electrode current collector tab 11a and the positive electrode current collector tab 15a are arranged in the same direction is shown.

[0137] However, it is not limited thereto, and the negative electrode current collector tab 11a and the positive electrode current collector tab 15a may be arranged in different directions.

[0138] That is, it has: a first current collector layer having a first current collector tab protruding from one side, a first active material layer laminated on the first current collector layer, a second current collector layer having a second current collector tab protruding from one side (not limited to the side at the same position as the first current collector tab), a second active material layer laminated on the second current collector layer, and a solid electrolyte layer disposed between the first active material layer and the second active material layer and containing a polymer electrolyte. Among the three sides other than the side where the first tab is arranged, the solid electrolyte layer is arranged to further cover the end faces of the first current collector layer and the first active material layer.

[0139] In addition, the following structure can be formed: on one or more sides other than the side where at least the first current collector tab is disposed, the width and / or length of the solid electrolyte layer covering the end faces (11t, 12t) of the first current collector layer (negative current collector layer 11) and the first active material layer (negative active material layer 12) is greater than the width and / or length of the second current collector layer (positive current collector layer 14) and the second active material layer (positive active material layer 15). The solid electrolyte layer of the power generation element also covers the end face (end face 14t of the positive active material layer 14) of the second active material layer and the end face (end face 15t of the positive current collector layer 15) of the second current collector layer. On the sides other than the side where the first current collector tab (negative current collector tab 11a) and the second current collector tab (positive current collector tab 15a) are disposed, two or more power generation elements are joined together by solid electrolyte layers covering the end faces of the first current collector layer, the first active material layer, the second current collector layer, and the second active material layer.

[0140] 4. Effects, etc.

[0141] For the power generation element and the all-solid-state battery using the same according to the present disclosure, in order to suppress a decrease in battery performance caused by the expansion and contraction of the negative active material, a soft polymer electrolyte is used as the solid electrolyte of the negative electrode layer. Therefore, it is possible to suppress a decrease in battery performance caused by the expansion and contraction of the negative active material during charge and discharge.

[0142] In addition, for the power generation element and the all-solid-state battery using the same according to the present disclosure, the end faces of the first current collector layer (negative current collector layer) and the first active material layer (negative active material layer) on three sides other than the side where the first current collector tab (negative current collector tab) is disposed are covered with a solid electrolyte layer. Thus, even when there is deformation, for example, when the soft polymer electrolyte is pressed in the negative active material layer, since the negative active material layer is covered with the solid electrolyte layer, it is possible to suppress a short circuit caused by contact with the positive active material layer and the positive current collector layer. And since no short circuit occurs, it is possible to suppress peeling and cracking at the interface between the negative electrode layer and the solid electrolyte layer during charge and discharge, and good cycle characteristics can be obtained.

[0143] 5. Examples

[0144] 5.1. Fabrication of the all-solid-state battery of Example 1

[0145] 5.1a. Fabrication of the negative electrode laminate

[0146] Weigh the negative electrode active material (Si particles, average particle size 2.5 μm), conductive material (VGCF-H: Showa Denko K.K., VGCF is a registered trademark), and binder (PVdF-HFP) so that the weight ratio of the negative electrode active material: conductive material: binder = 94:4:2, and mix them together with a dispersion medium (diisobutyl ketone). Disperse the resulting mixture using an ultrasonic homogenizer (UH-50, manufactured by SMT Co., Ltd.) to obtain a negative electrode paste. Coat the obtained negative electrode paste onto a negative electrode current collector layer (Ni foil, thickness 15 μm) by doctor blade coating using a coater, and dry it at 100 °C for 30 minutes. Then, obtain an intermediate body having a negative electrode active material layer and negative electrode active material layers laminated on both sides of the negative electrode current collector layer by similarly coating the opposite side of the negative electrode current collector layer.

[0147] In addition, weigh PEO (polyethylene oxide, Mw of about 4,000,000) and LiTFSI (LiN(SO2CF3)2) to have a molar ratio of EO:Li = 20:1, mix them with acetonitrile, and stir until a homogeneous solution is obtained. Coat the obtained PEO-LiTFSI solution onto the intermediate body by doctor blade coating using a coater, and dry it at 100 °C for 60 minutes. Then, similarly coat the opposite side of the negative electrode current collector layer. Furthermore, after drying, adjust the gap of the blade so that the weight ratio of the negative electrode active material: polymer electrolyte = 68:32. Then, densify it by pressing to obtain a negative electrode laminate having negative electrode active material layers disposed on both sides of the negative electrode current collector layer.

[0148] 5.1b. Fabrication of the positive electrode material layer

[0149] Weigh the positive electrode active material (LiNi 0.8 Co 0.15 Al 0.05 O2, average particle size 10 μm) onto which LiNbO3 has been coated in a rolling fluidized granulation coating apparatus, sulfide solid electrolyte (10LiI·15LiBr·75(0.75Li2S·0.25P2S5) (mol%), average particle size 0.5 μm), conductive material (VGCF-H: Showa Denko K.K.), and binder (SBR) so that the weight ratio of the positive electrode active material: sulfide solid electrolyte: conductive material: binder = 85:13:1:1, and mix them together with a dispersion medium (diisobutyl ketone). Disperse the resulting mixture using an ultrasonic homogenizer (UH-50, manufactured by SMT Co., Ltd.) to obtain a positive electrode paste. Coat the obtained positive electrode paste onto an Al foil (thickness 15 μm) by doctor blade coating using a coater, and dry it at 100 °C for 30 minutes, and densify it by pressing to obtain a positive electrode mixture having a positive electrode active material layer laminated on the Al foil.

[0150] 5.1c. Fabrication of the solid electrolyte layer

[0151] Weigh PEO (polyethylene oxide, Mw ≈ 4,000,000) and LiTFSI (LiN(SO2CF3)2) to achieve a molar ratio of EO:Li = 20:1, and mix them into acetonitrile. Mix the initiator BPO (Benzoyl peroxide) into this solution to reach 10 wt% of the PEO-LiTFSI solution, and then stir until a homogeneous solution is obtained. Use a coater to coat the prepared polymer electrolyte solution onto a PET film by the doctor blade method, making its width 7.4 cm. After drying at 100 °C for 60 minutes, cut it into a length of 14.0 cm to obtain a self-supporting crosslinked solid electrolyte layer.

[0152] 5.1d. Fabrication of the all-solid-state battery

[0153] Bond the negative electrode laminate cut into 7.0 cm × 7.0 cm and the solid electrolyte layer so that the negative electrode laminate and the solid electrolyte layer are in direct contact, and the end face on the opposite side of the negative electrode current collector tab coincides with the central part of the solid electrolyte layer. Bend the solid electrolyte layer in the long side direction to stack the negative electrode laminate and the solid electrolyte layer. Then, bond the positive electrode mixture cut into 7.0 cm × 7.0 cm so that the positive electrode mixture is in direct contact with the solid electrolyte layer, and press at 0.5 t / cm 2 Then, after welding each terminal, perform lamination unitization (configure it inside the outer packaging material) to fabricate an all-solid-state battery.

[0154] 5.2. Fabrication of the all-solid-state battery of Example 2

[0155] The fabrication of the all-solid-state battery shown below is the same as that of Example 1 until

[0156] 5.2a. Fabrication of the all-solid-state battery

[0157] Stack two power generation elements obtained in Example 1, bond the solid electrolyte layer without the side opposite to the current collector tab side to fix the electrodes, weld each terminal, and then perform lamination unitization (configure it inside the outer packaging material) to fabricate an all-solid-state battery.

[0158] 5.3. Fabrication of the all-solid-state battery of Comparative Example 1

[0159] The fabrication of the all-solid-state battery shown below is the same as that of Example 1 until

[0160] 5.3a. Fabrication of the all-solid-state battery

[0161] The negative electrode laminate cut to 7.2 cm × 7.2 cm and the solid electrolyte layer cut to 7.2 cm × 7.2 cm were laminated so that the negative electrode mixture layer and the solid electrolyte layer were in direct contact and the current collector side end faces were aligned, and the PET film was peeled off, whereby the solid electrolyte was laminated. Next, the positive electrode mixture cut to 7.0 cm × 7.0 cm was laminated so that the positive electrode mixture was in direct contact with the solid electrolyte layer, and pressed at 0.5 t / cm 2 Then, after welding each terminal, lamination unitization (configured into the exterior material) was performed to fabricate a all-solid-state battery.

[0162] 5.4. Fabrication of the all-solid-state battery of Comparative Example 2

[0163] Up to the fabrication of the all-solid-state battery shown below was the same as in Comparative Example 1.

[0164] 5.4a. Fabrication of the all-solid-state battery

[0165] Two power generation elements obtained in Comparative Example 1 were laminated, each terminal was welded, and lamination unitization (configured into the exterior material) was performed to fabricate a all-solid-state battery.

[0166] 5.5. Evaluation and results

[0167] For the all-solid-state batteries of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 obtained, the voltages of 10 each were measured using a tester, and the short-circuit rate was evaluated. When the measured voltage was 0 V, it was determined to be short-circuited, and when it was greater than 0 V, it was determined not to be short-circuited.

[0168] As a result, 9 of Example 1 and 8 of Example 2 were not short-circuited. On the other hand, in the comparative examples, only 6 of Comparative Example 1 and only 2 of Comparative Example 2 were not short-circuited, and the others were short-circuited.

Claims

1. A all-solid-state battery includes a negative electrode current collector layer, a negative electrode active material layer, a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, and an insulating layer. The negative electrode current collector layer is quadrilateral and has a negative electrode current collector tab protruding from one side of the quadrilateral. The negative electrode active material layer is laminated on the negative electrode current collector layer and contains a negative electrode active material and a polymer electrolyte as a solid electrolyte. The positive electrode current collector layer is quadrilateral and has a positive electrode current collector tab protruding from one side of the quadrilateral. The negative electrode current collector tab and the positive electrode current collector tab are configured to protrude in the same direction and not overlap in a top view. The positive electrode active material layer is laminated on the positive electrode current collector layer and contains a positive electrode active material and an inorganic solid electrolyte. The solid electrolyte layer is disposed between the negative electrode active material layer and the positive electrode active material layer and contains a polymer electrolyte. The end face of the side of the negative electrode current collector layer where the negative electrode current collector tab is provided is configured to protrude from the end face of the negative electrode active material layer and the end face of the solid electrolyte layer. The insulating layer is disposed in a portion of the protruding portion of the negative electrode current collector layer that overlaps the positive electrode current collector tab in a top view. On the three sides other than the side where the negative electrode current collector tab is disposed, the solid electrolyte layer is configured to further cover the end faces of the negative electrode current collector layer and the negative electrode active material layer. On the side, the end faces of the negative electrode current collector layer and the negative electrode active material layer are not covered by the solid electrolyte layer.

2. The all-solid-state battery according to claim 1, wherein the positive electrode current collector layer, the positive electrode active material layer, the solid electrolyte layer, the negative electrode active material layer, the negative electrode current collector layer, the negative electrode active material layer, the solid electrolyte layer, the positive electrode active material layer, and the positive electrode current collector layer are laminated in sequence to form a power generation element.

3. The all-solid-state battery according to claim 1 or 2, wherein the end faces of the positive electrode current collector layer and the positive electrode active material layer are also covered by the solid electrolyte layer on at least one side other than the side where the positive electrode current collector tab is disposed.

4. The all-solid-state battery according to claim 2, which is formed by laminating a plurality of the power generation elements.

5. The all-solid-state battery according to claim 2, wherein a plurality of the power generation elements are laminated, and the plurality of power generation elements are joined by the solid electrolyte layer covering the end faces of the positive electrode current collector layer and the positive electrode active material layer.

Images