All-solid-state battery

Abstract

This all-solid-state battery includes a laminate, a first current collector, a second current collector, and an insulating frame. In the laminate, the following are laminated in the order given: a first support layer, a first active material layer, a solid electrolyte layer, a second active material layer, and a second support layer. The first current collector is in contact with the first support layer, and the second current collector is in contact with the second support layer. The insulating frame surrounds a lateral surface of the laminate, and is located between the first current collector and the second current collector in the lamination direction. At least one of the first support layer and the second support layer includes a metal foil and a conductive layer located closer to the solid electrolyte layer than the metal foil is. When viewed from the lamination direction, the proportion of overlap between the first active material layer and the solid electrolyte layer is from 95-105%, and the proportion of overlap between the solid electrolyte layer and the second active material layer is from 95-105%.

Description

all solid state battery

[0001] This disclosure relates to an all-solid-state battery. This application claims priority to Japanese Patent Application No. 2023-197933, filed on November 22, 2023, the contents of which are incorporated herein by reference.

[0002] In recent years, electronics technology has made remarkable progress, leading to efforts to make portable electronic devices smaller, lighter, thinner, and more multifunctional. Accordingly, there is a strong demand for batteries that serve as the power source for electronic devices to be smaller, lighter, thinner, and more reliable, and all-solid-state batteries that use solid electrolytes have attracted attention.

[0003] All-solid-state batteries are charged and discharged by the movement of lithium ions between a positive electrode and a negative electrode via a solid electrolyte. For example, Patent Documents 1 and 2 disclose all-solid-state batteries. Patent Documents 1 and 2 disclose that, in order to prevent a short circuit between the positive electrode and the negative electrode, the size of the positive electrode is made slightly smaller than that of the negative electrode, and the periphery of the positive electrode is covered with an insulating layer.

[0004] JP 2023-077223 A JP 2023-077228 A

[0005] One of the issues facing all-solid-state batteries is their cycle characteristics. The cycle characteristics are evaluated by the retention rate of discharge capacity after multiple charge-discharge cycles. As described in Patent Documents 1 and 2, if the positive and negative electrodes have different sizes, a load is not applied uniformly when the battery is constrained, which may result in a decrease in cycle characteristics.

[0006] The present disclosure has been made in view of the above problems, and aims to provide an all-solid-state battery with excellent cycle characteristics.

[0007] In order to solve the above problems, the following means are provided.

[0008] (1) An all-solid-state battery according to a first aspect includes a laminate, a first current collector, a second current collector, and an insulating frame. The laminate includes a first support layer, a first active material layer, a solid electrolyte layer, a second active material layer, and a second support layer stacked in this order. The first current collector is in contact with the first support layer. The second current collector is in contact with the second support layer. The insulating frame surrounds the periphery of the side surface of the laminate and is located between the first current collector and the second current collector in the stacking direction. At least one of the first support layer and the second support layer includes a metal foil and a conductive layer located closer to the solid electrolyte layer than the metal foil. When viewed from the stacking direction, the shape duplication ratio between the first active material layer and the solid electrolyte layer is 95% or more and 105% or less. When viewed from the stacking direction, the shape duplication ratio between the solid electrolyte layer and the second active material layer is 95% or more and 105% or less. The shape overlap rate is the ratio of the area of ​​one of the two layers to the area of ​​the other layer.

[0009] (2) In the all-solid-state battery according to the above aspect, the shape overlap ratio between the first support layer and the first active material layer may be 95% or more and 105% or less when viewed from the stacking direction.

[0010] (3) In the all-solid-state battery according to the above aspect, the shape overlap ratio between the second support layer and the second active material layer may be 95% or more and 105% or less when viewed from the stacking direction.

[0011] (4) In the all-solid-state battery according to the above aspect, the insulating frame may have a thickness in the stacking direction that is smaller than a thickness in the stacking direction of the stack.

[0012] (5) In the all-solid-state battery according to the above aspect, the first support layer may include a first metal foil and a first conductive layer. The first metal foil is located between the first current collector and the first conductive layer. The first current collector may have a thickness smaller than that of the first metal foil.

[0013] (6) In the all-solid-state battery according to the above aspect, the second support layer may include a second metal foil and a second conductive layer. The second metal foil may be located between the second current collector and the second conductive layer. The second current collector may be thinner than the second metal foil.

[0014] (7) In the all-solid-state battery according to the above aspect, the first support layer may include a first metal foil and a first conductive layer, and the second support layer may include a second metal foil and a second conductive layer. The first metal foil may be between the first current collector and the first conductive layer. The second metal foil may be between the second current collector and the second conductive layer. The thickness of the second metal foil may be 80% or more and 120% or less of the thickness of the first metal foil.

[0015] (8) In the all-solid-state battery according to the above aspect, an adhesive layer may be further provided between the insulating frame and the first current collector or between the insulating frame and the second current collector.

[0016] (9) In the all-solid-state battery according to the above aspect, the first current collector and the first support layer, or the second current collector and the second support layer, may contain the same metal element.

[0017] (10) In the all-solid-state battery according to the above aspect, the insulating frame and the laminate may be spaced apart from each other.

[0018] The all-solid-state battery according to the above embodiment has excellent cycle characteristics.

[0019] 1 is a cross-sectional view of an all-solid-state battery according to a first embodiment;

[0020] The present embodiment will be described in detail below with reference to the accompanying drawings. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity, and the dimensional proportions of each component may differ from the actual proportions. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present disclosure is not limited thereto. Appropriate modifications may be made within the scope of the present disclosure.

[0021] The directions are defined as follows. The stacking direction of the laminate 10 is the z direction, one direction in a plane perpendicular to the z direction is the x direction, and the direction perpendicular to the x direction and the z direction is the y direction. Hereinafter, one direction in the z direction may be expressed as "up" and the direction opposite to this direction as "down". Up and down do not necessarily coincide with the direction in which gravity is applied.

[0022] (All-Solid-State Battery) Fig. 1 is a cross-sectional view of an all-solid-state battery 100 according to the first embodiment. Fig. 2 is a plan view of the all-solid-state battery 100 according to the first embodiment.

[0023] The all-solid-state battery 100 includes a laminate 10 , a first current collector 11 , a second current collector 12 , an insulating frame 13 , a first adhesive layer 14 , and a second adhesive layer 15 .

[0024] <Laminate> The laminate 10 has a solid electrolyte layer 1, a positive electrode active material layer 2, a negative electrode active material layer 3, a first support layer 4, and a second support layer 5. The laminate 10 is sandwiched in the z direction between a first current collector 11 and a second current collector 12. The laminate 10 has, for example, a second support layer 5, a negative electrode active material layer 3, a solid electrolyte layer 1, a positive electrode active material layer 2, and a first support layer 4, arranged in this order on the second current collector 12. The planar shape of the laminate 10 is not limited to the rectangular shape shown in FIG. 2 and may be circular or irregular. The laminate 10 is charged or discharged by the exchange of ions between the positive electrode active material layer 2 and the negative electrode active material layer 3 via the solid electrolyte layer 1.

[0025] The solid electrolyte layer 1 is located between the positive electrode active material layer 2 and the negative electrode active material layer 3. The solid electrolyte layer 1 includes a solid electrolyte. The solid electrolyte is a material that can move ions by an externally applied electric field. For example, the solid electrolyte layer 1 conducts lithium ions and inhibits the movement of electrons. The solid electrolyte layer 1 may be, for example, a sintered body or a compressed body, with a compressed body being preferred.

[0026] The solid electrolyte is preferably a material having low electron conductivity and high lithium ion conductivity. The solid electrolyte may be any of an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a complex hydride-based solid electrolyte, and a halide-based solid electrolyte.

[0027] The solid electrolyte is, for example, Li ２ｘ Zr(SO ４ ) ｘ Cl ４ (x is 1.0 to 3.0), Li ２ ZrSO ４ I ４ , Li ２ ZrCO ３ Cl ４ , Li ２ Zr((COO)２ ) ０．５ Cl ５ , Li ２ Zr(CH ３ COO) ０．２ Cl ５．８ , Li ２ Zr(CF ３ COO) ０．２ Cl ５．８ , Li ２ Zr(HCOO) ０．４ Cl ５．６ , Li ２ ZrBO ２ Cl ５ , Li ２ ZrBF ４ Cl ５ , Li ３ YSO ４ Cl ４ , Li ３ YCO ３ Cl ４ , Li ３ YBO ２ Cl ５ , Li ３ YBF ４ Cl ５ , Li ７－ｘ P.S. ６－ｘ Cl ｘ (x is 1.0 to 1.9), Li ２ｘ ZrO ｘ Cl ４ (x is 1.0 to 7.0), xLi ２ S-(100-x)P ２ S ５ (x is 20 to 80).

[0028] The positive electrode active material layer 2 is in contact with one surface of the solid electrolyte layer 1. The positive electrode active material layer 2 contains a positive electrode active material. The positive electrode active material layer 2 may contain a solid electrolyte, a binder, and a conductive additive, as necessary. The positive electrode active material layer 2 is an example of a first active material layer.

[0029] The positive electrode active material layer 2 overlaps with the solid electrolyte layer 1 when viewed from the z direction. The size of the positive electrode active material layer 2 is approximately the same as the size of the solid electrolyte layer 1. When viewed from the z direction, the shape overlap ratio between the positive electrode active material layer 2 and the solid electrolyte layer 1 is 95% or more and 105% or less. The shape overlap ratio is the ratio of the area of ​​one of the two layers to the area of ​​the other layer when the area of ​​the other layer is used as a reference. For example, when viewed from the z direction, the area of ​​the positive electrode active material layer 2 is 95% or more and 105% or less of the area of ​​the solid electrolyte layer 1.

[0030] The positive electrode active material is not particularly limited as long as it can reversibly absorb and release lithium ions and insert and extract them (intercalate and deintercalate), and any positive electrode active material used in known all-solid-state batteries can be used. Examples of the positive electrode active material include lithium-containing metal oxides and lithium-containing metal phosphates.

[0031] The lithium-containing metal oxide is, for example, lithium cobalt oxide (LiCoO ２ ), lithium nickel oxide (LiNiO ２ ), lithium manganese spinel (LiMn ２ O ４ ), and the general formula: LiNi ｘ Co ｙ Mn ｚ O ２ A composite metal oxide represented by (x + y + z = 1), a lithium vanadium compound (LiVOPO ４ , Li ３ V ２ (P.O. ４ ) ３ ), olivine-type LiMPO ４ (wherein M represents at least one selected from Co, Ni, Mn, and Fe), lithium titanate (Li ４ Ti ５ O １２ ) etc.

[0032] The positive electrode active material may not contain lithium. Examples of such a positive electrode active material include lithium-free metal oxides (MnO ２ , V ２ O ５ etc.), lithium-free metal sulfides (MoS ２etc.), lithium-free fluorides (FeF ３ , V.F. ３ When a positive electrode active material that does not contain lithium is used, the negative electrode is doped with lithium ions in advance, or a negative electrode containing lithium ions is used.

[0033] The positive electrode active material layer 2 may contain a solid electrolyte. For example, the solid electrolyte may be the same as that which can be used for the solid electrolyte layer 1. The solid electrolyte of the positive electrode active material layer 2 may be the same as or different from the solid electrolyte of the solid electrolyte layer 1.

[0034] The content of the solid electrolyte in the positive electrode active material layer 2 is not particularly limited, but is preferably 1 mass % or more and 50 mass % or less, and more preferably 5 mass % or more and 30 mass % or less, based on the total mass of the positive electrode active material, the solid electrolyte, the conductive additive, and the binder.

[0035] The positive electrode active material layer 2 may contain a binder. Examples of the binder include polyvinylidene fluoride (PVDF) or a copolymer thereof, polytetrafluoroethylene (PTFE), polyamide (PA), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), polyethersulfone (PES), polyacrylic acid (PA) and a copolymer thereof, a metal ion crosslinked polyacrylic acid (PA) and a copolymer thereof, maleic anhydride-grafted polypropylene (PP), maleic anhydride-grafted polyethylene (PE), or a mixture thereof. Among these, PTFE is particularly preferred as the binder.

[0036] The content of the binder in the positive electrode active material layer 2 is not particularly limited, but is preferably 0.1 mass % or more and 10 mass % or less, and more preferably 0.1 mass % or more and 5 mass % or less, based on the total mass of the positive electrode active material, the solid electrolyte, the conductive additive, and the binder.

[0037] The positive electrode active material layer 2 may contain a conductive additive. The conductive additive improves the electronic conductivity of the positive electrode active material layer 2. Known conductive additives can be used. Examples of the conductive additive include carbon materials such as carbon black, graphite, carbon nanotubes, graphene, and carbon fibers; metals such as aluminum, copper, nickel, stainless steel, iron, and amorphous metals; conductive oxides such as ITO; and mixtures thereof. The conductive additive may be in the form of powder or fiber.

[0038] There are no particular limitations on the content of the conductive additive in the positive electrode active material layer 2. When the conductive additive is added, the mass ratio of the conductive additive is preferably 0.5 mass % or more and 20 mass % or less, and more preferably 1 mass % or more and 5 mass % or less, based on the total mass of the negative electrode active material, solid electrolyte, conductive additive, and binder.

[0039] The negative electrode active material layer 3 is in contact with the solid electrolyte layer 1. The negative electrode active material layer 3 contains a negative electrode active material. The negative electrode active material layer 3 may contain a solid electrolyte, a binder, and a conductive additive, as necessary. The negative electrode active material layer 3 is an example of a second active material layer.

[0040] The negative electrode active material layer 3 overlaps with the solid electrolyte layer 1 when viewed from the z direction. The size of the negative electrode active material layer 3 is approximately the same as the size of the solid electrolyte layer 1. When viewed from the z direction, the shape overlap ratio between the negative electrode active material layer 3 and the solid electrolyte layer 1 is 95% or more and 105% or less. For example, when viewed from the z direction, the area of ​​the negative electrode active material layer 3 is 95% or more and 105% or less of the area of ​​the solid electrolyte layer 1.

[0041] The size of the negative electrode active material layer 3 is approximately the same as the size of the positive electrode active material layer 2. When viewed from the z direction, the shape overlap ratio between the negative electrode active material layer 3 and the positive electrode active material layer 2 may be 95% or more and 105% or less.

[0042] The negative electrode active material is not particularly limited as long as it can reversibly absorb and release lithium ions and insert and extract lithium ions. The negative electrode active material can be any negative electrode active material used in known all-solid-state batteries. The negative electrode active material layer 3 may contain, for example, lithium metal as the negative electrode active material, and may be selected from graphite, silicon, tin, lithium titanate (Li４ Ti ５ O １２ ) and the like.

[0043] The negative electrode active material layer 3 may contain a solid electrolyte. For example, the same solid electrolyte as that which can be used for the solid electrolyte layer 1 can be used. The solid electrolyte of the negative electrode active material layer 3 may be the same as or different from the solid electrolyte of the solid electrolyte layer 1. The content of the solid electrolyte in the negative electrode active material layer 3 is, for example, preferably 1 vol% to 50 vol%, and more preferably 5 vol% to 40 vol%.

[0044] The binder and conductive additive contained in the negative electrode active material layer 3 are the same as the binder and conductive additive contained in the positive electrode active material layer 2 .

[0045] The first support layer 4 is located between the positive electrode active material layer 2 and the first current collector 11. The first support layer 4 has, for example, a first metal foil 4A and a first conductive layer 4B. The first metal foil 4A is located between the first current collector 11 and the first conductive layer 4B. The first metal foil 4A is an example of a metal foil. The first support layer 4 is not limited to this case. For example, the first support layer 4 may have a first metal foil 4A and a first conductive layer 4B sandwiching the first metal foil 4A. In this case, the two first conductive layers 4B sandwich the first metal foil 4A.

[0046] The first support layer 4 overlaps with the positive electrode active material layer 2 as viewed from the z direction. The size of the first support layer 4 is substantially the same as the size of the positive electrode active material layer 2. As viewed from the z direction, the shape overlap ratio between the first support layer 4 and the positive electrode active material layer 2 is 95% or more and 105% or less. For example, as viewed from the z direction, the area of ​​the first support layer 4 is 95% or more and 105% or less of the area of ​​the positive electrode active material layer 2. The shape overlap ratio of the first support layer 4 with the solid electrolyte layer 1 may be 95% or more and 105% or less, and the shape overlap ratio with the negative electrode active material layer 3 may be 95% or more and 105% or less.

[0047] The first metal foil 4A contains, for example, the same metal element as the first current collector 11 described below. When the first metal foil 4A and the first current collector 11 are made of the same material, electrical conductivity between them is increased. The first metal foil 4A is, for example, a metal or alloy containing at least one metal element selected from the group consisting of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), aluminum (Al), copper (Cu), nickel (Ni), titanium (Ti), and stainless steel.

[0048] The first conductive layer 4B is located between the first metal foil 4A and the positive electrode active material layer 2. The first conductive layer 4B may be any material as long as it is conductive. The first conductive layer 4B may contain, for example, a conductive material, a binder, and, optionally, a thickener, in a predetermined blend ratio. Examples of conductive materials include conductive carbon materials such as carbon black, acetylene black, graphite, carbon fiber, and carbon nanotubes. Examples of binders include acrylic binders and styrene-butadiene rubber binders. Examples of thickeners include carboxymethyl cellulose. The first conductive layer 4B enhances adhesion between the first metal foil 4A and the positive electrode active material layer 2. The presence of the first conductive layer 4B between the first metal foil 4A and the positive electrode active material layer 2 maintains electrical conductivity between the first metal foil 4A and the positive electrode active material layer 2, even if the volume of the positive electrode active material layer 2 changes during charge and discharge.

[0049] The second support layer 5 is located between the negative electrode active material layer 3 and the second current collector 12. The second support layer 5 has, for example, a second metal foil 5A and a second conductive layer 5B. The second metal foil 5A is located between the second current collector 12 and the second conductive layer 5B. The second metal foil 5A is an example of a metal foil. The second support layer 5 is not limited to this case. For example, the second support layer 5 may have a second metal foil 5A and a second conductive layer 5B sandwiching the second metal foil 5A. In this case, the two second conductive layers 5B sandwich the second metal foil 5A.

[0050] The second support layer 5 overlaps with the negative electrode active material layer 3 as viewed from the z direction. The size of the second support layer 5 is approximately the same as the size of the negative electrode active material layer 3. As viewed from the z direction, the shape overlap ratio between the second support layer 5 and the negative electrode active material layer 3 is 95% or more and 105% or less. For example, as viewed from the z direction, the area of ​​the second support layer 5 is 95% or more and 105% or less of the area of ​​the negative electrode active material layer 3. The shape overlap ratio of the second support layer 5 with the solid electrolyte layer 1 may be 95% or more and 105% or less, and the shape overlap ratio with the positive electrode active material layer 2 may be 95% or more and 105% or less.

[0051] The second metal foil 5A contains, for example, the same metal element as the second current collector 12 described below. When the second metal foil 5A and the second current collector 12 are made of the same material, electrical conductivity between them is increased. The second metal foil 5A is, for example, a metal or alloy containing at least one metal element selected from the group consisting of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), aluminum (Al), copper (Cu), nickel (Ni), titanium (Ti), and stainless steel.

[0052] Thickness T of the second metal foil 5A ５Ａ is the thickness T of the first metal foil 4A ４Ａ For example, the thickness T of the second metal foil 5A is preferably approximately the same as ５Ａ is the thickness T of the first metal foil 4A ４Ａ The thickness T of the first metal foil 4A is 80% or more and 120% or less of the thickness of the first metal foil 4A. ４Ａ and the thickness T of the second metal foil 5A ５Ａ When these are substantially the same, it is possible to alleviate stress from being applied unevenly to the laminate 10 during pressure molding in the production of the laminate, which will be described later.

[0053] The second conductive layer 5B is located between the second metal foil 5A and the anode active material layer 3. There are no particular restrictions on the material of the second conductive layer 5B as long as it is conductive. For example, the same material as that of the first conductive layer 4B is used for the second conductive layer 5B. The second conductive layer 5B improves the adhesion between the second metal foil 5A and the anode active material layer 3. The presence of the second conductive layer 5B between the second metal foil 5A and the anode active material layer 3 allows the electrical conductivity between the second metal foil 5A and the anode active material layer 3 to be maintained even if the volume of the anode active material layer 3 changes during charge and discharge.

[0054] <First Current Collector> The first current collector 11 is in contact with one surface of the laminate 10. The first current collector 11 is in contact with the first support layer 4. The first current collector 11 is in contact with, for example, the first metal foil 4A of the first support layer 4.

[0055] The first current collector 11 is an electrode that carries the electric charge generated in the laminate 10 to the outside. The first current collector 11 is larger than the laminate 10 when viewed in the z direction. The first current collector 11 may be in the form of a plate, a foil, a lattice, or a mesh.

[0056] The first current collector 11 is made of a conductive material, such as a metal or alloy containing at least one metal element selected from the group consisting of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), aluminum (Al), copper (Cu), nickel (Ni), titanium (Ti), and stainless steel. The first current collector 11 preferably contains the same metal as the first metal foil 4A.

[0057] Thickness T of the first current collector 11 １１ is, for example, the thickness T of the first metal foil 4A. ４Ａ The thickness T of the first current collector 11 is thinner. １１ When the thickness is thin, the energy density per unit volume of the battery can be increased.

[0058] <Second Current Collector> The second current collector 12 contacts one surface of the laminate 10. The second current collector 12 contacts the second support layer 5. The second current collector 12 contacts, for example, the second metal foil 5A of the second support layer 5.

[0059] The second current collector 12 is an electrode that carries the electric charge generated in the laminate 10 to the outside. The second current collector 12 is larger than the laminate 10 when viewed in the z direction. The second current collector 12 may be in the form of a plate, a foil, a lattice, or a mesh.

[0060] The second current collector 12 is made of a conductive material. For example, the second current collector 12 may be made of the same material as the first current collector 11. The second current collector 12 preferably contains the same metal as the second metal foil 5A.

[0061] Thickness T of the second current collector 12 １２ is, for example, the thickness T of the second metal foil 5A. ５Ａ The thickness T of the second current collector 12 is thinner.１２ When the thickness is thin, the energy density per unit volume of the battery can be increased.

[0062] <Insulating Frame> When viewed from the z direction, the insulating frame 13 surrounds the periphery of the side surface of the laminate 10. The insulating frame 13 may surround the entire periphery of the laminate 10, or may surround only a portion of it.

[0063] The insulating frame 13 is, for example, spaced apart from the laminate 10. The insulating frame 13 may be in contact with the laminate 10. When the insulating frame 13 is spaced apart from the laminate 10, when pressure is applied in the z direction of the all-solid-state battery 100, the crushed laminate 10 can spread in the in-plane direction, and pressure can be applied uniformly to the laminate 10.

[0064] The insulating frame 13 is located between the first current collector 11 and the second current collector 12. The outer periphery of the insulating frame 13 is, for example, outside the outer peripheries of the first current collector 11 and the second current collector 12. If the outer periphery of the insulating frame 13 is outside the outer peripheries of the first current collector 11 and the second current collector 12, a short circuit between the first current collector 11 and the second current collector 12 can be prevented when the all-solid-state battery 100 is fabricated. The outer periphery of the insulating frame 13 may, for example, coincide with the outer peripheries of the first current collector 11 and the second current collector 12, or may be inside the outer peripheries of the first current collector 11 and the second current collector 12. The insulating frame 13 supports the first current collector 11 and the second current collector 12. The insulating frame 13 prevents a short circuit between the positive electrode and the negative electrode when pressure is applied to the all-solid-state battery 100 in the z-direction.

[0065] The insulating frame 13 is made of an insulating material. There is no particular restriction on the material constituting the insulating frame 13 as long as it has insulating properties. The insulating frame 13 is, for example, an insulating polymer. Examples of insulating polymers include polyimide and polyethylene terephthalate (PET). The insulating frame 13 is, for example, a PET film with an opening in the center.

[0066] Thickness T of the insulating frame 13 １３ is, for example, the thickness T of the laminate 10 １０ When the all-solid-state battery 100 is constrained, pressure is applied to the all-solid-state battery 100 in the z direction. １３ is the thickness T of the laminate 10１０ A thinner thickness allows for more uniform pressure to be applied to the laminate 10 .

[0067] <First adhesive layer> The first adhesive layer 14 is located between the insulating frame 13 and the first current collector 11. Like the insulating frame 13, the first adhesive layer 14 surrounds the periphery of the laminate 10. The first adhesive layer 14 is an example of an adhesive layer. The first adhesive layer 14 is not necessary. The presence of the first adhesive layer 14 increases the adhesion between the insulating frame 13 and the first current collector 11. The first adhesive layer 14 also functions as a buffer layer that relieves pressure when pressure is applied in the z direction of the all-solid-state battery 100.

[0068] <Second adhesive layer> The second adhesive layer 15 is located between the insulating frame 13 and the second current collector 12. Like the insulating frame 13, the second adhesive layer 15 surrounds the periphery of the laminate 10. The second adhesive layer 15 is an example of an adhesive layer. The second adhesive layer 15 is not necessary. The presence of the second adhesive layer 15 increases the adhesion between the insulating frame 13 and the second current collector 12. The second adhesive layer 15 also functions as a buffer layer that relieves pressure when pressure is applied in the z direction of the all-solid-state battery 100.

[0069] (Method for manufacturing all-solid-state battery) First, the laminate 10 is produced. The laminate 10 can be produced using, for example, a powder molding method. A solid electrolyte is filled into the holes of a guide having holes. Thereafter, the surface of the solid electrolyte is flattened, and a positive electrode composite is filled on one side of the flattened surface. The positive electrode composite includes, for example, a positive electrode active material and a solid electrolyte. Next, a negative electrode composite is filled on the side of the solid electrolyte opposite to the side filled with the positive electrode composite. The negative electrode composite includes, for example, a negative electrode active material and a solid electrolyte. Next, metal foils having conductive layers are arranged on each side. Then, pressure is applied in the stacking direction of these laminates to pressure-molde them, thereby obtaining the laminate 10.

[0070] Next, an insulating frame 13 having an opening formed in the center is prepared. The insulating frame 13 can be produced, for example, by forming an opening in a PET film. Adhesive layers 14 and 15 are also prepared on both sides of the insulating frame 13. The insulating frame 13 is then placed around the laminate 10.

[0071] Next, the first current collector 11 and the second current collector 12, to which tab leads are attached, are arranged so as to sandwich the insulating frame 13 and the laminate 10. Next, they are inserted into an exterior body of aluminum laminate film and heat-sealed except for one peripheral location, and the remaining location is heat-sealed while reducing the pressure using a vacuum sealer. These are then restrained using a restraining jig. The restraining jig applies pressure in the z direction to the first current collector 11 and the second current collector 12, causing the first current collector 11, the laminate 10, and the second current collector 12 to come into close contact with each other. Through this procedure, the all-solid-state battery 100 according to this embodiment is obtained.

[0072] Here, an example is shown in which an aluminum laminate film is used as the exterior body, but the exterior body in the present disclosure is not limited to this example. Any known exterior body can be used as long as it can sandwich the insulating frame 13 and the laminate 10 and seal the first current collector 11 and the second current collector 12 from the outside. For example, a coin-shaped or rectangular metal can, a resin or ceramic package, or the like can be used as the exterior body.

[0073] The all-solid-state battery 100 according to this embodiment has excellent cycle characteristics. One of the reasons for this is thought to be that the positive electrode active material layer 2, the solid electrolyte layer 1, and the negative electrode active material layer 3 are all approximately the same size when viewed in the z direction. If the sizes of the layers are approximately uniform, when the all-solid-state battery 100 is constrained in the z direction, the load on each layer becomes uniform in-plane, and pressure is applied uniformly in-plane to each layer. As a result, the in-plane variation in the charge / discharge reaction of the all-solid-state battery 100 is reduced, and the charge / discharge reaction is stabilized.

[0074] Furthermore, the support layer (first support layer 4 or second support layer 5) connecting the current collector and the power generation unit has a conductive layer (first conductive layer 4B or second conductive layer 5B), which is also thought to be a factor in improving the cycle characteristics of the all-solid-state battery 100. The conductive layer improves adhesion between the current collector and the power generation element. Therefore, even if the power generation unit accumulates and expands during charge and discharge, the conductive layer maintains adhesion between the current collector and the power generation element, which is thought to improve the cycle characteristics of the all-solid-state battery 100.

[0075] The present embodiment has been described above in detail with reference to the drawings, but each configuration and their combination in the embodiment is an example, and addition, omission, substitution, and other modifications of the configuration are possible within the scope that does not deviate from the spirit of this disclosure.

[0076] For example, only one of the first support layer 4 and the second support layer 5 may have a conductive layer. That is, one of the first conductive layer 4B and the second conductive layer 5B may be absent.

[0077] Furthermore, for example, the laminate 10 may have a plurality of power generating elements each consisting of a positive electrode active material layer 2 , a solid electrolyte layer 1 , and a negative electrode active material layer 3 between the first support layer 4 and the second support layer 5 .

[0078] Example 1 A full cell of an all-solid-state battery was fabricated and its cycle characteristics were measured. The full cell was fabricated in the following manner.

[0079] In a glove box, 80 mg of solid electrolyte was filled into the container and pressed at a pressure of 0.6 tons for 1 minute. ２ ZrSO ４ Cl ４ It was decided.

[0080] A negative electrode composite was added to one side of the pressed solid electrolyte, and pressed for 1 minute at a pressure of 0.6 tons. The negative electrode composite contained a negative electrode active material and a solid electrolyte in a ratio of negative electrode active material:solid electrolyte:conductive additive = 55 parts by mass:40 parts by mass:5 parts by mass. The negative electrode active material was Li ４ Ti ５ O １２ The solid electrolyte contained in the negative electrode mixture was the same as the solid electrolyte described above. The conductive additive was carbon black. The negative electrode mixture was pressed to form a negative electrode active material layer.

[0081] Next, a positive electrode composite was added to the surface of the pressed solid electrolyte opposite to the surface on which the negative electrode composite was laminated, and pressed for 1 minute under a pressure of 0.6 tons. The positive electrode composite contained a positive electrode active material, a solid electrolyte, and a conductive additive in a ratio of 70 parts by mass:27 parts by mass:3 parts by mass. The positive electrode active material was lithium cobalt oxide (LiCoO ２The solid electrolyte contained in the positive electrode was the same as the solid electrolyte described above. The conductive additive was carbon black. The positive electrode mixture was pressed to form a positive electrode active material layer.

[0082] Then, aluminum foil coated with a conductor was placed on both sides of the battery element and pressed at 3 tons for 1 minute to produce a laminate. The conductor was made of carbon black. The conductor was pressed to form a conductive layer. The planar size of each layer constituting the laminate was approximately the same.

[0083] Next, an insulating frame was placed so as to surround the periphery of the laminate. The insulating frame was made of a PET film with an opening formed therein capable of accommodating the laminate. The thickness of the insulating frame was made thinner than the thickness of the laminate. Adhesive layers were provided on both the top and bottom surfaces of the insulating frame.

[0084] Next, the first current collector and the second current collector, each with a tab lead attached, were arranged so as to cover both the laminate and the insulating frame. These were then inserted into an exterior body of an aluminum laminate film and heat-sealed except for one peripheral location. The remaining location was then heat-sealed while reducing the pressure using a vacuum sealer to produce an all-solid-state battery. The all-solid-state battery was also restrained at 1 Nm using a restraining jig. Using this procedure, a full cell for charge / discharge evaluation was produced.

[0085] The cycle characteristics were measured using a secondary battery charge / discharge tester (manufactured by Meiden Hokuto Co., Ltd.) in the following manner.

[0086] The cycle characteristics were measured using a CC-CV charge-CC discharge method. Specifically, the battery was first charged at a constant current of 0.1 C at a charge rate up to a maximum charge voltage of 2.8 V, and then charged at a constant voltage of 2.8 V in a constant voltage mode (2.8 V). The battery was then discharged at a constant current of 0.1 C at a discharge rate until the battery voltage reached 1.3 V. The discharge capacity after the end of charge and discharge was measured, and the battery capacity Q before the cycle test was calculated. １ This battery capacity Q １ is the initial discharge capacity.

[0087] Next, the battery was charged at a constant current of 0.5C up to a charging upper limit voltage of 2.8V, and then charged at a constant voltage of 2.8V in a constant voltage mode (2.8V). The battery was then discharged at a constant current of 0.5C until the battery voltage reached 1.3V. The above charge / discharge cycle was counted as one cycle, and 100 charge / discharge cycles were performed. The discharge capacity after the end of the charge / discharge test was measured, and the battery capacity Q after the 100-cycle test was calculated. ２ asked for.

[0088] The cycle characteristics are the battery capacity Q after 100 cycles. ２ The initial battery capacity Q １ The cycle characteristic of Example 1 was 87%.

[0089] Example 2 Example 2 differs from Example 1 in that the planar size of the second support layer constituting the laminate was larger than the planar size of the negative electrode active material layer. The other conditions were the same as in Example 1, and the cycle characteristics were determined.

[0090] Example 3 Example 3 differs from Example 1 in that the planar size of the second support layer constituting the laminate was smaller than the planar size of the negative electrode active material layer. The other conditions were the same as in Example 1, and the cycle characteristics were determined.

[0091] Example 4 Example 4 differs from Example 1 in that the planar size of the second support layer constituting the laminate was larger than the planar size of the negative electrode active material layer, and the planar size of the first support layer was larger than the planar size of the positive electrode active material layer. The other conditions were the same as in Example 1, and the cycle characteristics were determined.

[0092] Example 5 differs from Example 1 in that the planar size of the second support layer constituting the laminate was smaller than the planar size of the negative electrode active material layer, and the planar size of the first support layer was smaller than the planar size of the positive electrode active material layer. The other conditions were the same as in Example 1, and the cycle characteristics were determined.

[0093] Comparative Example 1 Comparative Example 1 differs from Example 1 in that the first conductive layer and the second conductive layer were not provided. The other conditions were the same as in Example 1, and the cycle characteristics were determined.

[0094] Comparative Example 2 differs from Example 1 in that the planar size of the positive electrode active material layer constituting the laminate was larger than the planar size of the solid electrolyte layer, exceeding approximately the same range. The other conditions were the same as in Example 1, and the cycle characteristics were determined.

[0095] The results of Examples 1 to 5 and Comparative Examples 1 and 2 are summarized in the table below.

[0096]

[0097] Examples 1 to 5 had superior cycle characteristics compared to Comparative Examples 1 and 2. Comparative Example 1 did not have a conductive layer, and it is thought that this caused a gap to form between the current collector and the power generating element due to volume changes during charge and discharge, resulting in a deterioration in cycle characteristics. In Comparative Example 2, the layers constituting the laminate were not of uniform size, and pressure was not applied uniformly to each layer of the laminate when the battery was restrained, resulting in in-plane variation in the battery reaction and a deterioration in cycle characteristics.

[0098] REFERENCE SIGNS LIST 1 solid electrolyte layer 2 positive electrode active material layer 3 negative electrode active material layer 4 first support layer 4A first metal foil 4B first conductive layer 5 second support layer 5A second metal foil 5B second conductive layer 10 laminate 11 first current collector 12 second current collector 13 insulating frame 14 first adhesive layer 15 second adhesive layer 100 all-solid-state battery

Claims

1. A laminate comprising a first current collector, a second current collector, and an insulating frame, wherein the laminate is formed by stacking a first support layer, a first active material layer, a solid electrolyte layer, a second active material layer, and a second support layer in that order, wherein the first current collector is in contact with the first support layer, and the second current collector is in contact with the second support layer, the insulating frame surrounds the periphery of a side surface of the laminate and is between the first current collector and the second current collector in the stacking direction, at least one of the first support layer and the second support layer comprises a metal foil and a conductive layer located closer to the solid electrolyte layer than the metal foil, wherein the shape overlap rate between the first active material layer and the solid electrolyte layer is 95% or more and 105% or less when viewed from the stacking direction, and wherein the shape overlap rate between the solid electrolyte layer and the second active material layer is 95% or more and 105% or less when viewed from the stacking direction, The shape overlap ratio is a ratio of an area of ​​one of the two layers to an area of ​​the other layer.

2. The all-solid-state battery according to claim 1, wherein the shape overlap rate between the first support layer and the first active material layer is 95% or more and 105% or less when viewed from the stacking direction.

3. The all-solid-state battery according to claim 1, wherein the shape overlap rate between the second support layer and the second active material layer is 95% or more and 105% or less when viewed from the stacking direction.

4. The all-solid-state battery according to claim 1, wherein the thickness of the insulating frame in the stacking direction is thinner than the thickness of the laminate in the stacking direction.

5. The all-solid-state battery according to claim 1, wherein the first support layer has a first metal foil and a first conductive layer, the first metal foil is between the first current collector and the first conductive layer, and the first current collector has a thickness smaller than that of the first metal foil.

6. The all-solid-state battery according to claim 1, wherein the second support layer has a second metal foil and a second conductive layer, the second metal foil is between the second current collector and the second conductive layer, and the second current collector has a thickness smaller than that of the second metal foil.

7. The all-solid-state battery according to claim 1, wherein the first support layer has a first metal foil and a first conductive layer, the second support layer has a second metal foil and a second conductive layer, the first metal foil is between the first current collector and the first conductive layer, the second metal foil is between the second current collector and the second conductive layer, and a thickness of the second metal foil is 80% or more and 120% or less of a thickness of the first metal foil.

8. The all-solid-state battery according to claim 1, further comprising an adhesive layer between the insulating frame and the first current collector, or between the insulating frame and the second current collector.

9. The all-solid-state battery according to claim 1, wherein the first current collector and the first support layer, or the second current collector and the second support layer, contain the same metal element.

10. The all-solid-state battery according to claim 1, wherein the insulating frame and the laminate are spaced apart.

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