Solid-state battery and method for producing the same

Abstract

To provide a solid-state battery in which a short circuit can be suppressed, and a method for producing the solid-state battery.SOLUTION: There is provided a solid-state battery which includes a cathode layer, an anode layer, and a solid electrolyte layer disposed between the cathode layer and the anode layer. The anode layer includes at least one of a lithium metal or a lithium alloy, a ratio of a thickness of the solid electrolyte layer to a thickness of the anode layer is 0.65 or more and 0.77 or less, and a filling rate of the solid electrolyte layer is 82.3% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a solid-state battery and a method for manufacturing the solid-state battery. [Background technology]

[0002] Various techniques have been proposed for solid-state batteries as disclosed in Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-206469 [Patent Document 2] Japanese Patent Application Publication No. 2019-179604 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to improve the energy density of solid-state batteries, solid-state batteries containing Li element in the anode have been developed. Patent Document 1 discloses that short circuits in solid-state batteries are suppressed by focusing on the interface between the solid electrolyte layer and the positive electrode layer. However, short circuits in solid-state batteries still occur due to the relationship between the solid electrolyte layer and the negative electrode layer.

[0005] The present disclosure has been made in view of the above-described circumstances, and has as its main object to provide a solid-state battery capable of suppressing short circuits and a method for manufacturing the solid-state battery. [Means for solving the problem]

[0006] That is, the present disclosure includes the following aspects. <1> A solid-state battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the negative electrode layer comprises at least one of lithium metal and a lithium alloy; the ratio of the thickness of the solid electrolyte layer to the thickness of the negative electrode layer is 0.65 or more and 0.77 or less; A solid-state battery, wherein the filling rate of the solid electrolyte layer is 82.3% or more.

[0007] <2> The thickness of the negative electrode layer is 100 μm or less. <1> The solid-state battery according to claim 1.

[0008] <3> The thickness of the solid electrolyte layer is 65 μm or more. <1> or <2> The solid-state battery according to claim 1.

[0009] <4> A method for manufacturing a solid-state battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the method comprising: obtaining a laminate in which the solid electrolyte layer is disposed between the positive electrode layer and the negative electrode layer; a pressing step of vacuum-sealing the laminate to a laminate film and pressing the laminate; the negative electrode layer comprises at least one of lithium metal and a lithium alloy; the ratio of the thickness of the solid electrolyte layer to the thickness of the negative electrode layer is 0.65 or more and 0.77 or less; A method for producing a solid-state battery, wherein the filling rate of the solid electrolyte layer is 82.3% or more.

[0010] <5> In the pressing step, the pressing pressure is 400 MPa or less. <4> 10. A method for manufacturing the solid state battery according to claim 9. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a solid-state battery capable of suppressing a short circuit and a method for manufacturing the solid-state battery. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating an example of a solid state battery according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of a solid-state battery that does not characterize the present disclosure) can be understood as design matters for a person skilled in the art based on prior art in the relevant field. The present disclosure can be implemented based on the contents disclosed in this specification and common general technical knowledge in the relevant field. In the present disclosure, unless otherwise specified, the average particle size of particles is the median diameter (D50) value, which is the particle size at 50% of the cumulative value in the volume-based particle size distribution measured by laser diffraction / scattering particle size distribution measurement.

[0014] 1. Solid state battery The present disclosure provides a solid-state battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the negative electrode layer comprises at least one of lithium metal and a lithium alloy; the ratio of the thickness of the solid electrolyte layer to the thickness of the negative electrode layer is 0.65 or more and 0.77 or less; The present invention provides a solid-state battery in which the filling rate of the solid electrolyte layer is 82.3% or more.

[0015] Because lithium metal and lithium alloys are softer than other anode materials, when pressure is applied or when the anode layer is constrained to reduce the resistance at the interface between the solid electrolyte layer and the anode layer in a solid-state battery, the anode layer penetrates the solid electrolyte layer, penetrates through the solid electrolyte layer, and reaches the cathode, causing a short circuit. While increasing the thickness of the solid electrolyte layer is one way to prevent short circuits, this would decrease the volumetric energy density of the solid-state battery. The present disclosure specifies the filling rate of the solid electrolyte layer and the ratio of the thickness of the solid electrolyte layer to the thickness of the anode layer, thereby making it possible to reduce the amount of anode layer that penetrates into the solid electrolyte layer during pressing or restraint without reducing the volumetric energy density of the solid battery, thereby suppressing short circuits in the solid battery.

[0016] The solid-state battery of the present disclosure includes a positive electrode including a positive electrode layer, a negative electrode including a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. In the present disclosure, a solid-state battery refers to a battery containing a solid electrolyte. The solid-state battery may be a semi-solid-state battery that contains a solid electrolyte and a liquid-based material, or an all-solid-state battery that does not contain a liquid-based material. When a set of a positive electrode, a solid electrolyte layer, and a negative electrode is considered as a power generation unit, the solid-state battery may have only one power generation unit or may have two or more power generation units. When the solid-state battery has two or more power generation units, the power generation units may be connected in series or in parallel. When the solid state battery is viewed from above from the positive electrode layer side, the area of the positive electrode layer may be smaller than or the same as the area of the solid electrolyte layer. When the solid state battery is viewed from above from the negative electrode layer side, the area of the negative electrode layer may be smaller than or the same as the area of the solid electrolyte layer. The area of the positive electrode layer and the area of the negative electrode layer may be the same or different, and from the viewpoint of suppressing the deposition of Li metal dendrites, the area of the positive electrode layer may be smaller than the area of the negative electrode layer. When the solid state battery is viewed from above from the positive electrode layer side, the solid electrolyte layer may extend from all outer edges of the positive electrode layer toward the outside of the positive electrode layer. When the solid state battery is viewed from above from the negative electrode layer side, the solid electrolyte layer may extend from all outer edges of the negative electrode layer toward the outside of the negative electrode layer.

[0017] FIG. 1 is a cross-sectional view schematically illustrating an example of a solid state battery according to the present disclosure. The solid-state battery 100 includes a positive electrode layer 10 , a negative electrode layer 30 , and a solid electrolyte layer 20 disposed between the positive electrode layer 10 and the negative electrode layer 30 . In the solid-state battery 100, the area of the stacked surface of the positive electrode layer 10 is smaller than the area of the stacked surface of the solid electrolyte layer 20, the area of the stacked surface of the negative electrode layer 30 is smaller than the area of the stacked surface of the solid electrolyte layer 20, and the area of the stacked surface of the positive electrode layer 10 is smaller than the area of the stacked surface of the negative electrode layer 30.

[0018] The solid-state battery may optionally include an exterior body that houses the positive electrode layer, the negative electrode layer, the solid electrolyte layer, and the like. The material of the exterior body is not particularly limited as long as it is stable against the solid electrolyte, and examples thereof include metals such as aluminum, polypropylene, polyethylene, and resins such as acrylic resin.

[0019] Examples of the shape of the solid-state battery include coin type, laminate type, cylindrical type, and square type.

[0020] The solid-state battery may be a primary battery or a secondary battery. Examples of uses of the solid-state battery include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. In particular, the solid-state battery may be used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The solid-state battery may also be used as a power source for mobile objects other than vehicles (for example, trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices.

[0021] [Solid electrolyte layer thickness / Anode layer thickness] The ratio of the thickness of the solid electrolyte layer to the thickness of the negative electrode layer is 0.65 or more and 0.77 or less. Within this range, it is possible to suppress short circuits in the solid-state battery without reducing the volumetric energy density of the solid-state battery.

[0022] [Positive electrode] The positive electrode includes a positive electrode layer and, if necessary, a positive electrode current collector.

[0023] [Positive electrode layer] The positive electrode layer contains a positive electrode active material, and may also contain a solid electrolyte, a conductive material, a binder, and the like, as necessary.

[0024] The positive electrode active material may be, for example, sulfur alone, a sulfur mixture of sulfur with carbon, phosphorus, and lithium, lithium nickel cobalt aluminum oxide (NCA), LiCoO2, LiNi x Co 1-x O2(0 <x<1)、LiNi 1 / 3 Co1 / 3 Mn 1 / 3 Examples of the Li-Mn spinel substituted with different elements include O2, LiMnO2, LiMn2O4, LiNiO2, LiVO2, Li-Mn spinel substituted with different elements, lithium titanate, lithium metal phosphate, LiCoN, Li2SiO3, and Li4SiO4. The Li-Mn spinel substituted with different elements is, for example, LiMn 1.5 Ni 0.5 O4, LiMn 1.5 Al 0.5 O4, LiMn 1.5 Mg 0.5 O4, LiMn 1.5 Co 0.5 O4, LiMn 1.5 Fe 0.5 O4 and LiMn 1.5 Zn 0.5 O4, etc. Lithium titanate is, for example, Li4Ti5O 12 Lithium metal phosphates include, for example, LiFePO4, LiMnPO4, LiCoPO4, and LiNiPO4. The shape of the positive electrode active material is not particularly limited, but may be in the form of particles (positive electrode active material particles).The average particle size of the positive electrode active material particles is not particularly limited, and may be 1 nm to 100 μm. A coating layer containing a Li-ion conductive compound may be formed on the surface of the positive electrode active material, because this can suppress the reaction between the positive electrode active material and the solid electrolyte. Examples of Li-ion conductive compounds include LiNbO3 and Li4Ti5O 12 , and Li3PO4. The thickness of the coating layer is, for example, 0.1 nm or more, and may be 1 nm or more. On the other hand, the thickness of the coating layer is, for example, 100 nm or less, and may be 20 nm or less. The coverage of the coating layer on the surface of the positive electrode active material is, for example, 70% or more, and may be 90% or more.

[0025] Known conductive materials can be used, such as carbon materials and metal particles. Examples of carbon materials include acetylene black (AB), furnace black, VGCF, carbon nanotubes, and carbon nanofibers. Among them, from the viewpoint of electron conductivity, at least one selected from the group consisting of VGCF, carbon nanotubes, and carbon nanofibers may be used. Examples of metal particles include particles of Ni, Cu, Fe, and SUS. The content of the conductive material in the positive electrode layer is not particularly limited.

[0026] Examples of the solid electrolyte include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, hydride solid electrolytes, halide solid electrolytes, and nitride solid electrolytes, as well as organic polymer electrolytes such as polymer electrolytes. A relatively soft sulfide solid electrolyte may be used as the solid electrolyte to prevent the positive electrode layer and the negative electrode layer from peeling off from the solid electrolyte layer and further reduce the resistance of the solid battery. Only one type of solid electrolyte may be used alone, or two or more types may be used in combination.

[0027] Examples of sulfide solid electrolytes include solid electrolytes containing Li, A, and S. The A element is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In. The sulfide solid electrolyte may further contain at least one of O and a halogen element. Examples of the halogen element (X) include F, Cl, Br, and I. The sulfide solid electrolyte may be glass (amorphous), glass ceramic, or crystalline. When the sulfide solid electrolyte is crystalline, it has a crystalline phase. Examples of the crystalline phase include a Thio-LISICON-type crystalline phase, an LGPS-type crystalline phase, and an argyrodite-type crystalline phase. Examples of sulfide solid electrolytes include Li2S-P2S5, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-SiS2, Li2S-GeS2, and Li2S-P2S5-GeS2. The term "Li2S-P2S5" refers to a material made using a raw material composition containing Li2S and P2S5, and the same applies to other terms. The molar ratio of each element in the sulfide solid electrolyte can be controlled by adjusting the content of each element in the raw materials. The molar ratio and composition of each element in the sulfide solid electrolyte can be measured, for example, by ICP atomic emission spectrometry.

[0028] The oxide solid electrolyte may contain, for example, Li element, Z element (Z is Nb, B, Al, Si, P, Examples of oxide solid electrolytes include solid electrolytes containing at least one of Ti, Zr, Mo, W, and S, and O. Examples of oxide solid electrolytes include Li2O-B2O3-P2O5, Li2O-SiO2, Li2O-B2O3, Li 1.3 Al 0.3 Ti 0.7 (PO4)3, Li5La3Ta2O 12 , Li7La3Zr2O 12 , Li6BaLa2Ta2O 12 , Li 3.6 Si 0.6 P 0.4 O4, Li4SiO4, Li3PO4, and Li 3+x PO4-x N x (1≦x≦3) etc. may also be used. The hydride solid electrolyte contains, for example, Li and a complex anion containing hydrogen. The complex anion may be, for example, (BH4). - , (NH2) - , (AlH4) - , and (AlH6) 3- etc. Examples of halogenated solid electrolytes include LiF, LiCl, LiBr, LiI, and LiI-Al2O3. An example of the nitrogenated solid electrolyte is Li3N.

[0029] The solid electrolyte may be solid electrolyte particles. The average particle size (D50) of the solid electrolyte particles is not particularly limited, but may be 0.1 μm or more and 100 μm or less. The content of the solid electrolyte in the positive electrode layer is not particularly limited, but may be, for example, in the range of 1% to 80% by mass when the total mass of the positive electrode layer is taken as 100% by mass.

[0030] Examples of binders include rubber-based binders and fluoride-based binders. Examples of rubber-based binders include butadiene rubber, hydrogenated butadiene rubber, styrene butadiene rubber (SBR), hydrogenated styrene butadiene rubber, nitrile butadiene rubber, hydrogenated nitrile butadiene rubber, acrylonitrile butadiene rubber (ABR), and ethylene propylene rubber. Examples of fluoride-based binders include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-polyhexafluoropropylene copolymer (PVDF-HFP), polytetrafluoroethylene, and fluororubber. The content of the binder in the positive electrode layer is not particularly limited.

[0031] The thickness of the positive electrode layer is not particularly limited.

[0032] The positive electrode layer can be formed by a conventionally known method. For example, a positive electrode active material and, if necessary, other components are put into a solvent and stirred to prepare a positive electrode slurry, and the positive electrode slurry is applied to one surface of a support such as a positive electrode current collector and dried to obtain a positive electrode layer. Examples of the solvent include butyl acetate, butyl butyrate, heptane, and N-methyl-2-pyrrolidone. The method for applying the positive electrode slurry onto one surface of a support such as a positive electrode current collector is not particularly limited, and examples thereof include a doctor blade method, a metal mask printing method, an electrostatic application method, a dip coating method, a spray coating method, a roll coating method, a gravure coating method, and a screen printing method. The support can be appropriately selected from those having self-supporting properties and is not particularly limited, and examples thereof include metal foils such as Cu and Al foils.

[0033] [Positive electrode current collector] The positive electrode current collector may be a known metal that can be used as a current collector for solid-state batteries. Examples of such metals include metal materials containing one or more elements selected from the group consisting of Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Co, Cr, Zn, Ge, and In. Examples of the positive electrode current collector include SUS, aluminum, nickel, iron, titanium, and carbon. The form of the positive electrode current collector is not particularly limited, and it can be in various forms such as a foil form, a mesh form, or the like.

[0034] [Negative electrode] The negative electrode includes a negative electrode layer and, if necessary, a negative electrode current collector.

[0035] [Negative electrode layer] The negative electrode layer contains a negative electrode active material and may optionally contain at least one of a solid electrolyte, a conductive material, and a binder. The negative electrode layer contains at least one of lithium metal and a lithium alloy as a negative electrode active material. Examples of metal elements other than lithium contained in the lithium alloy include Mg, Ag, In, Sn, Si, Ga, Au, and Pt. The negative electrode layer may further contain, as the negative electrode active material, for example, a carbon-based active material, an oxide-based active material, an Si-based active material, and the like, in addition to lithium metal and a lithium alloy. Examples of carbon-based active materials include graphite, hard carbon, and soft carbon. An example of the oxide-based active material is lithium titanate. Examples of Si-based active materials include simple Si, Si alloys, and silicon oxide. The negative electrode active material may be in the form of particles, for example. The average particle size of the negative electrode active material particles is not particularly limited and may be 1 nm to 100 μm. Examples of the conductive material, solid electrolyte, and binder used in the negative electrode layer include the same conductive materials, solid electrolytes, and binders as those exemplified as the conductive material, solid electrolyte, and binder that can be contained in the positive electrode layer. The thickness of the negative electrode layer may be 0.1 μm or more and 100 μm or less.

[0036] [Negative electrode current collector] The material of the negative electrode current collector may be a material that does not alloy with Li, such as SUS, copper, or nickel. The negative electrode current collector may be in the form of, for example, a foil or a plate. The shape of the negative electrode current collector in plan view is not particularly limited, but may be, for example, a circle, an ellipse, a rectangle, or any polygonal shape. The thickness of the negative electrode current collector varies depending on the shape, but may be, for example, in the range of 1 μm to 50 μm, or in the range of 5 μm to 20 μm.

[0037] [Solid electrolyte layer] The solid electrolyte layer contains a solid electrolyte and, if necessary, a binder and the like. Examples of the solid electrolyte include the solid electrolytes that can be contained in the positive electrode layer described above. When two or more solid electrolytes are used, the two or more solid electrolytes may be mixed, or two or more solid electrolyte layers may be formed to form a multilayer structure. The proportion of the solid electrolyte in the solid electrolyte layer is not particularly limited, but may be, for example, 50 mass % or more and 99 mass % or less. Examples of the binder include the binders that can be contained in the positive electrode layer described above. When the solid electrolyte layer contains a binder, the content of the binder may be 0% by mass to 10% by mass with respect to the total amount of the solid electrolyte layer. The packing ratio of the solid electrolyte layer may be 82.3% or more, or may be 89.7% or less. If the packing ratio of the solid electrolyte layer is 82.3% or more, there are fewer voids, which contributes to suppressing short circuits in the solid-state battery. The packing ratio of the solid electrolyte layer indicates the volume excluding the voids inside the solid electrolyte layer relative to the total volume of the solid electrolyte layer. The packing ratio of the solid electrolyte layer can be calculated by determining the ratio of the volume calculated from the specific gravity of the material to the actual volume of the solid electrolyte layer. The thickness of the solid electrolyte layer may be 65 μm or more from the viewpoint of suppressing short circuits in the solid battery, and may be 100 μm or less, or 77 μm or less from the viewpoint of reducing the resistance of the solid battery.

[0038] The solid electrolyte layer can be formed, for example, by the following method. A solid electrolyte layer may be formed by preparing a solid electrolyte slurry containing a solid electrolyte, a binder, and a solvent, and applying the solid electrolyte slurry onto a release film. Examples of the solvent include the solvents that can be used to prepare the positive electrode slurry described above.

[0039] 2. Manufacturing method of solid-state batteries A method for manufacturing a solid-state battery according to the present disclosure is a method for manufacturing a solid-state battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the method comprising: obtaining a laminate in which the solid electrolyte layer is disposed between the positive electrode layer and the negative electrode layer; a pressing step of vacuum-sealing the laminate to a laminate film and pressing the laminate; the negative electrode layer comprises at least one of lithium metal and a lithium alloy; the ratio of the thickness of the solid electrolyte layer to the thickness of the negative electrode layer is 0.65 or more and 0.77 or less; The solid electrolyte layer has a packing rate of 82.3% or more.

[0040] The step of obtaining a laminate is a step of obtaining a laminate in which the solid electrolyte layer is disposed between the positive electrode layer and the negative electrode layer. The positive electrode layer, negative electrode layer, and solid electrolyte layer used in the step of obtaining the laminate may be the same as those exemplified in the solid state battery described above. In the step of obtaining a laminate, a solid electrolyte layer may be placed on a first electrode, either the positive electrode layer or the negative electrode layer, and then pre-pressed. Then, a second electrode, either the positive electrode layer or the negative electrode layer, may be placed on the solid electrolyte layer to obtain a laminate. The pressing method and pressure of the pre-pressing may be the same as the pressing method and pressure in the pressing step described below.

[0041] The pressing step is a step in which the laminate is vacuum sealed in a laminate film and pressed. The pressing pressure used to press the laminate in the pressing step is not particularly limited, but may be higher than the pressing pressure used in the pre-pressing, and from the viewpoint of suppressing a short circuit in the solid-state battery, the pressing pressure may be 400 MPa or less, or may be 300 MPa or less. The pressing method is not particularly limited, and examples thereof include cold isostatic pressing and roll pressing. The solid electrolyte contained in the solid electrolyte layer is not easily deformed by the pressing in the pressing step, and therefore the solid electrolyte contained in the solid electrolyte layer after the pressing is performed can be considered to be the same as the solid electrolyte contained in the solid electrolyte layer before the pressing is performed. [Example]

[0042] Example 1 [Preparation of positive electrode] A predetermined sulfur mixture was used as the positive electrode active material. Using butyl butyrate as a solvent, a sulfur mixture, a binder, and a conductive material were mixed so as to have a mass composition ratio of sulfur mixture:binder:conductive material=64.8:0.3:34.9 to prepare a positive electrode slurry. Next, the obtained positive electrode slurry was applied onto an aluminum foil serving as a positive electrode current collector with a coating gap of 200 μm. Thereafter, the obtained coating film was pre-dried at 50°C for a predetermined time, and then fully dried at 100°C for 1 hour, and coated on a positive electrode current collector with a basis weight of 7.8 mg / cm 2 , design capacity 5.84mAh / cm 2 A positive electrode having a positive electrode layer of the above formula was obtained. [Preparation of solid electrolyte layer] As the solid electrolyte, sulfide solid electrolyte particles with an average particle size (D50) of 0.5 μm were used. Using butyl butyrate as a solvent, the sulfide solid electrolyte and the binder were mixed so that the mass composition ratio of sulfide solid electrolyte:binder was 90.9:9.1, thereby obtaining a solid electrolyte slurry. Next, the solid electrolyte slurry was applied onto the release film with a coating gap of 300 to 800 μm. Thereafter, the resulting coating film was pre-dried at room temperature for about 3 hours and then fully dried at 165°C for 1 hour. Two 14.5 mm diameter coated foils were punched out from the dried coated foil, and the coated surfaces of the two foils were overlapped and pressed at 1 ton. After pressing, the release film was peeled off to obtain a free-standing solid electrolyte layer. The thickness of the solid electrolyte layer was 62 μm, and the filling rate was 89.7%. [Preparation of negative electrode] A 100 μm thick Li-Mg alloy foil was used as the negative electrode active material. Ni foil was used as the negative electrode current collector. The Li-Mg alloy foil was punched out to a diameter of 13.0 mm, and the Ni foil was punched out to a diameter of 14.5 mm, and a negative electrode layer made of the Li-Mg alloy foil was formed on the negative electrode current collector, resulting in a negative electrode with the negative electrode layer formed on the negative electrode current collector. [Fabrication of solid-state batteries] The fabricated positive electrode was punched out to a diameter of 11.28 mm, and a fabricated free-standing solid electrolyte layer with a diameter of 14.5 mm was placed between the positive electrode and the fabricated negative electrode to obtain a laminate. The positive electrode terminal was made of Al, and the negative electrode terminal was made of Ni. The laminate was vacuum-sealed in an exterior body made of a laminate film with positive and negative electrode terminals attached to it, to obtain a cell. The sealed cell was isostatically pressed at 300 MPa using CIP (cold isostatic pressing) to produce a laminate cell, which is a solid-state battery.

[0043] Example 2 A solid state battery was fabricated in the same manner as in Example 1, except that a solid electrolyte layer with a thickness of 77 μm and a packing rate of 82.3% was used.

[0044] (Comparative Example 1) A solid state battery was fabricated in the same manner as in Example 1, except that a negative electrode layer having a thickness of 150 μm and a solid electrolyte layer having a thickness of 55 μm and a packing rate of 94.2% were used.

[0045] (Comparative Example 2) A solid state battery was fabricated in the same manner as in Example 1, except that a solid electrolyte layer with a thickness of 54 μm and a packing rate of 95.9% was used.

[0046] (Comparative Example 3) A solid state battery was fabricated in the same manner as in Example 1, except that a solid electrolyte layer with a thickness of 105 μm and a packing rate of 66.7% was used.

[0047] [Yield evaluation during cell production] An arbitrary number (10 to 30) of solid state batteries of Examples 1 and 2 and Comparative Examples 1 to 3 were fabricated and evaluated for the presence or absence of short circuits, and the yield of solid state batteries evaluated as having no short circuits was calculated. The evaluation criteria were as follows: yield less than 40% was evaluated as x, 40 to 90% as △, and over 90% as ○. The results are shown in Table 1.

[0048] [Table 1]

[0049] As shown in Table 1, when the ratio of the thickness of the solid electrolyte layer to the thickness of the anode layer is 0.65 or more and 0.77 or less, and the filling rate of the solid electrolyte layer is 82.3% or more, the yield of solid batteries without short circuits exceeds 90%, which shows that short circuits can be suppressed more effectively than when the above conditions are not met. [Explanation of symbols]

[0050] 10 Positive electrode layer 20 Solid electrolyte layer 30 negative electrode layer 100 solid state battery

Claims

1. A solid-state battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the negative electrode layer comprises at least one of lithium metal and a lithium alloy; a ratio of a thickness of the solid electrolyte layer to a thickness of the negative electrode layer is 0.65 or more and 0.77 or less; A solid-state battery, wherein the filling rate of the solid electrolyte layer is 82.3% or more.

2. The solid state battery according to claim 1 , wherein the thickness of the negative electrode layer is 100 μm or less.

3. 3. The solid state battery according to claim 1, wherein the thickness of the solid electrolyte layer is 65 μm or more.

4. A method for manufacturing a solid-state battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the method comprising: obtaining a laminate in which the solid electrolyte layer is disposed between the positive electrode layer and the negative electrode layer; a pressing step of vacuum-sealing the laminate to a laminate film and pressing the laminate; the negative electrode layer comprises at least one of lithium metal and a lithium alloy; a ratio of a thickness of the solid electrolyte layer to a thickness of the negative electrode layer is 0.65 or more and 0.77 or less; The method for manufacturing a solid state battery, wherein the filling rate of the solid electrolyte layer is 82.3% or more.

5. The method for producing a solid-state battery according to claim 4 , wherein the pressing step applies a pressing pressure of 400 MPa or less.

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