All-solid-state battery and method for manufacturing all-solid-state battery

Abstract

This all-solid-state battery comprises: a positive electrode having a positive electrode active material layer (1) containing a positive electrode active material, a binder, a solid electrolyte (A1), and a conductive additive; a solid electrolyte layer (5); and a negative electrode having a negative electrode active material layer (2). In a volume-based particle size distribution obtained by a laser diffraction scattering particle size distribution measurement method, the median diameter (D50) of the positive electrode active material is 0.5-6.0 μm. The surface of the particles of the positive electrode active material has a composite layer of a solid electrolyte (A2) and the positive electrode active material, and the solid electrolyte (A2) contains a sulfide-based solid electrolyte.

Description

All-solid-state battery and method for manufacturing an all-solid-state battery

[0001] This invention relates to an all-solid-state battery and a method for manufacturing an all-solid-state battery.

[0002] A solid-state battery comprises, for example, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in that order. Patent Document 1 describes a technology related to solid-state batteries.

[0003] Patent Document 1 discloses a positive electrode composite material for use in an all-solid-state battery, with the aim of providing a positive electrode composite material with a high energy density per unit volume, comprising a first positive electrode active material, a second positive electrode active material, and a sulfide solid electrolyte, characterized in that the ratio of the average particle size of the first positive electrode active material to the average particle size of the second positive electrode active material is 2.0 or more and 4.3 or less.

[0004] Japanese Patent Publication No. 2019-106286

[0005] The present invention provides an all-solid-state battery that can improve the performance balance between capacity and resistance, and a method for manufacturing an all-solid-state battery that can improve the performance balance between capacity and resistance.

[0006] According to the present invention, the following all-solid-state battery and a method for manufacturing an all-solid-state battery are provided.

[0007] [1] A positive electrode comprising a positive electrode having a positive electrode active material layer containing a positive electrode active material, a binder, a solid electrolyte (A1), and a conductive additive, a negative electrode comprising a solid electrolyte layer and a negative electrode active material layer, wherein the median diameter D of the positive electrode active material in the volume-based particle size distribution measured by laser diffraction scattering particle size distribution measurement method ５０ [1] A solid-state battery in which the particle size is 0.5 μm or more and 6.0 μm or less, and the particle surface of the positive electrode active material has a composite layer of a solid electrolyte (A2) and the positive electrode active material, and the solid electrolyte (A2) contains a sulfide-based solid electrolyte. [2] The solid-state battery according to [1], wherein the sulfide-based solid electrolyte contains an argyrodite-type sulfide-based solid electrolyte. [3] A solid electrolyte (A2) contains Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Brｘ (where 0 ≤ x ≤ 2) and Li ７－ｘ P S ６－ｘ I ｘ[1] or [2] an all-solid-state battery according to [1] or [2], comprising one or more selected from the group consisting of (where 0 ≤ x ≤ 2). [4] An all-solid-state battery according to any one of [1] to [3], wherein the content of the solid electrolyte (A1) in the positive electrode active material layer is 10.0 parts by mass or more and 40.0 parts by mass or less when the total amount of the positive electrode active material layer is 100 parts by mass. [5] An all-solid-state battery according to any one of [1] to [4], wherein the binder comprises a fluorine-based elastomer (B). [6] The all-solid-state battery according to [5], wherein the fluorine-based elastomer (B) comprises a constituent unit derived from vinylidene fluoride (VdF) and one or more constituent units selected from the group consisting of constituent units derived from hexafluoropropylene (HFP), constituent units derived from trifluoropropylene (TFP), constituent units derived from tetrafluoroethylene (TFE), constituent units derived from 2,3,3,3-tetrafluoropropylene, constituent units derived from 1,3,3,3-tetrafluoropropylene and constituent units derived from perfluoroalkyl vinyl ether (PAVE). [7] The all-solid-state battery according to [5] or [6], wherein the fluorine-based elastomer (B) comprises one or more selected from the group consisting of copolymers of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), and copolymers of vinylidene fluoride (VdF) and trifluoropropylene (TFP). [8] The all-solid-state battery according to any one of [5] to [7], wherein the content of constituent units derived from vinylidene fluoride (VdF) in the fluorine-based elastomer (B) is 20 mol% or more. [9] The all-solid-state battery according to any one of [5] to [8], wherein the mass-average molecular weight (Mw) of the fluorine-based elastomer (B) is 10,000 or more and 10,000,000 or less.

[10] The all-solid-state battery according to any one of [1] to [9], wherein the content of the binder in the positive electrode active material layer is 0.1 parts by mass or more and 10.0 parts by mass or less when the total amount of the positive electrode active material layer is 100 parts by mass.

[11] The all-solid-state battery according to any one of [1] to

[10] , wherein the positive electrode active material contains a lithium composite oxide.

[12] The all-solid-state battery according to

[11] , wherein the lithium composite oxide comprises one or more composite oxides selected from the group consisting of lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium-manganese composite oxide, lithium-nickel-manganese composite oxide, lithium-nickel-cobalt composite oxide, lithium-nickel-aluminum composite oxide, lithium-nickel-cobalt-aluminum composite oxide, lithium-nickel-manganese-aluminum composite oxide, lithium-nickel-cobalt-manganese-aluminum composite oxide, and lithium-nickel-cobalt-manganese composite oxide.

[13] The all-solid-state battery according to

[11] or

[12] , wherein the lithium composite oxide comprises lithium-nickel-cobalt-manganese composite oxide.

[14] The all-solid-state battery according to any one of

[11] to

[13] , wherein when the total content of metal elements other than lithium in the lithium composite oxide is taken as 100 mol%, the nickel content is 75 mol% or more.

[15] The all-solid-state battery according to any one of [1] to

[14] , wherein the conductive additive comprises one or more selected from the group consisting of carbon black and carbon nanotubes.

[16] The all-solid-state battery according to any one of [1] to

[15] , wherein the content of the conductive additive in the positive electrode active material layer is 1.0 part by mass or more and 10.0 parts by mass or less when the total amount of the positive electrode active material layer is 100 parts by mass.

[17] The all-solid-state battery according to any one of [1] to

[16] , wherein the discharge capacity measured by the following method 1 is 210 mAh / g or more. (Method 1) At 25°C, the all-solid-state battery is charged with a constant current to 4.25V at a charge rate of 0.05C, then switched to constant voltage charging and the charge is cut off at 0.005C. Then, it is discharged with a constant current to 2.5V at a discharge rate of 0.05C. The initial discharge capacity (mAh) is calculated by the above charge and discharge, and the discharge capacity (mAh / g) is obtained by dividing the initial discharge capacity (mAh) by the amount (g) of the positive electrode active material in the all-solid-state battery.

[18] The resistance value measured by the method 2 below is 40 Ω / cm. ２The all-solid-state battery described in any of [1] to

[17] below. (Method 2) At 25°C, the all-solid-state battery is charged with a constant current at a charge rate of 0.05C to 4.25V, then switched to constant voltage charging and cut off charging at 0.005C. Next, it is discharged with a constant current at a discharge rate of 0.05C to 3.65V, then switched to constant voltage discharge and cut off discharge at 0.005C. The electrical resistance (Ω) of the all-solid-state battery after the discharge is cut off is measured using the AC four-terminal method (frequency 1 kHz), and the obtained value is measured as the area value (cm²) of the surface perpendicular to the stacking direction of the positive electrode. ２ By dividing by ), the resistance value (Ω / cm) can be calculated. ２ ) to be determined.

[19] A method for manufacturing an all-solid-state battery according to [1] to

[18] , comprising step (A) of kneading the positive electrode active material and the solid electrolyte (A2) to form the composite layer on the particle surface of the positive electrode active material.

[20] A method for manufacturing an all-solid-state battery according to

[19] , wherein in step (A), the positive electrode active material and the solid electrolyte (A2) are kneaded by a ball mill.

[0008] According to the present invention, it is possible to provide an all-solid-state battery that can improve the performance balance between capacity and resistance, and a method for manufacturing an all-solid-state battery that can improve the performance balance between capacity and resistance.

[0009] This is a cross-sectional view showing an example of the structure of an all-solid-state battery according to this embodiment.

[0010] Embodiments of the present invention will be described below with reference to the drawings. In all drawings, similar components are denoted by the same reference numerals, and their descriptions are omitted as appropriate. Also, the drawings are schematic diagrams and do not necessarily correspond to the actual dimensional ratios. In the specification, unless otherwise specified, the notation "A to B" regarding numerical ranges means A or more and B or less. For example, 1 to 5% means 1% or more and 5% or less.

[0011] <All-Solid-State Battery> Figure 1 is a cross-sectional view showing an example of the structure of the all-solid-state battery 10 of this embodiment. The all-solid-state battery 10 of this embodiment comprises a positive electrode having a positive electrode active material layer containing a positive electrode active material, a binder, a solid electrolyte (A1), and a conductive additive, a negative electrode having a solid electrolyte layer 5 and a negative electrode active material layer 2, and the median diameter D of the positive electrode active material in the volume-based particle size distribution measured by laser diffraction scattering particle size distribution measurement method. ５０ The particle size is 0.5 μm or more and 6.0 μm or less, and the particle surface of the positive electrode active material has a composite layer of solid electrolyte (A2) and positive electrode active material, and the solid electrolyte (A2) contains a sulfide-based solid electrolyte. By having the above configuration, the all-solid-state battery of this embodiment can improve the performance balance between capacity and resistance.

[0012] Although the mechanism by which the above effects are obtained with the all-solid-state battery of this embodiment is not clear, it is thought that because the particle size of the positive electrode active material is within the above range, and the particle surface of the positive electrode active material has a composite layer of a solid electrolyte (A2) containing a sulfide-based solid electrolyte and the positive electrode active material, the contact interface between the positive electrode active material and the solid electrolyte (A1) in the positive electrode active material layer is improved, resulting in good ion conduction, which reduces the resistance value of the all-solid-state battery and thus improves the performance balance between the capacity and resistance value of the all-solid-state battery.

[0013] The median diameter D in the volume-based particle size distribution of the positive electrode active material of this embodiment, as measured by laser diffraction scattering particle size distribution analysis. ５０ From the viewpoint of improving the performance balance between capacitance and resistance, the capacitance is 0.5 μm or more and 6.0 μm or less, preferably 1.0 μm or more and 5.5 μm or less, more preferably 1.5 μm or more and 5.0 μm or less, and even more preferably 2.0 μm or more and 4.5 μm or less.

[0014] The discharge capacity of the all-solid-state battery of this embodiment, as measured by the following method 1, is preferably 210 mAh / g or more, more preferably 215 mAh / g or more, even more preferably 220 mAh / g or more, even more preferably 225 mAh / g or more, and even more preferably 230 mAh / g or more. The upper limit of the discharge capacity of the all-solid-state battery of this embodiment by the following method 1 is not particularly limited, but may be, for example, 1000 mAh / g or less, 800 mAh / g or less, or 500 mAh / g or less. (Method 1) At 25°C, the all-solid-state battery of this embodiment is charged with a constant current to 4.25V at a charge rate of 0.05C, then switched to constant voltage charging and cut off charging at 0.005C. Next, it is discharged with a constant current to 2.5V at a discharge rate of 0.05C. The initial discharge capacity (mAh) is calculated by the above charge and discharge process, and the discharge capacity (mAh / g) is determined by dividing the obtained initial discharge capacity (mAh) by the amount (g) of positive electrode active material in the all-solid-state battery.

[0015] The resistance value measured by the following method 2 of the all-solid-state battery of this embodiment is preferably 40 Ω / cm ２ More preferably, 35 Ω / cm ２ More preferably, 30 Ω / cm ２ More preferably, the resistance is 25 Ω / cm. ２ The following applies. The lower limit of the resistance value of the all-solid-state battery according to the following method 2 is not particularly limited, but for example, 1 Ω / cm ２ It may be greater than or equal to 5Ω / cm ２ The above is also acceptable. The resistance value of the all-solid-state battery of this embodiment obtained by the following method 2 is 1 Ω / cm ２ More than 40Ω / cm ２ The following is also acceptable: 1 Ω / cm ２ 35Ω / cm or more ２ The following is also acceptable: 1 Ω / cm ２ More than 30Ω / cm ２ The following is also acceptable: 5Ω / cm ２ 25Ω / cm or more ２The following is also acceptable. (Method 2) At 25°C, the all-solid-state battery of this embodiment is charged with a constant current at a charge rate of 0.05C up to 4.25V, then switched to constant voltage charging and cut off charging at 0.005C. Next, it is discharged with a constant current at a discharge rate of 0.05C up to 3.65V, then switched to constant voltage discharge and cut off discharge at 0.005C. The electrical resistance (Ω) of the all-solid-state battery after the discharge is cut off is measured using the AC four-terminal method (frequency 1kHz), and the obtained value is measured as the area value (cm²) of the surface perpendicular to the stacking direction of the positive electrode of this embodiment. ２ By dividing by ), the resistance value (Ω / cm) can be calculated. ２ )

[0016] (Positive electrode) The positive electrode of this embodiment includes a positive electrode active material layer. The positive electrode active material layer of this embodiment includes a positive electrode active material, a binder, a solid electrolyte (A1), and a conductive additive.

[0017] The positive electrode active material of this embodiment preferably contains a lithium composite oxide.

[0018] The lithium composite oxide preferably comprises one or more composite oxides selected from the group consisting of lithium-nickel composite oxides, lithium-cobalt composite oxides, lithium-manganese composite oxides, lithium-nickel-manganese composite oxides, lithium-nickel-cobalt composite oxides, lithium-nickel-aluminum composite oxides, lithium-nickel-cobalt-aluminum composite oxides, lithium-nickel-manganese-aluminum composite oxides, lithium-nickel-cobalt-manganese-aluminum composite oxides, and lithium-nickel-cobalt-manganese composite oxides. More preferably, it comprises one or more composite oxides selected from the group consisting of lithium-nickel composite oxides, lithium-cobalt composite oxides, lithium-nickel-aluminum composite oxides, and lithium-nickel-cobalt-manganese composite oxides, and even more preferably, it comprises lithium-nickel-cobalt-manganese composite oxides.

[0019] The lithium-nickel-cobalt-manganese composite oxide of this embodiment preferably includes a composite oxide represented by the following formula (1). Li ａ Ni ｂ Co ｃ Mn ｄ M ｅ O ２ (1) (In formula (1) above, M is one or more selected from the group consisting of Al, Mg, Na, Co, K, W, Cu, Fe, Ba, V, Cr, Ti, Zr, Zn, In, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo, and 0.5 ≤ a ≤ 1.5, 0.6 ≤ b < 1.0, 0 < c < 0.2, 0 < d < 0.2, 0 ≤ e < 1.0)

[0020] In the composite oxide of formula (1) above, 0.5 ≤ a ≤ 1.5, preferably 0.6 ≤ a ≤ 1.4, more preferably 0.7 ≤ a ≤ 1.3, even more preferably 0.8 ≤ a ≤ 1.2, even more preferably 0.9 ≤ a ≤ 1.1, and even more preferably a = 1.0.

[0021] Furthermore, in the composite oxide of formula (1), 0.6 ≤ b < 1.0, and from the viewpoint of further improving the capacity of the all-solid-state battery, it is preferably 0.65 ≤ b < 1.0, more preferably 0.7 ≤ b < 1.0, and even more preferably 0.75 ≤ b < 1.0.

[0022] In the composite oxide of formula (1) above, 0 < c < 0.2, preferably 0.01 ≤ c ≤ 0.15, and more preferably 0.02 ≤ c ≤ 0.15.

[0023] In the composite oxide of formula (1) above, 0 < d < 0.2, preferably 0.01 ≤ d ≤ 0.15, and more preferably 0.02 ≤ d ≤ 0.15.

[0024] In the composite oxide of formula (1) above, 0 ≤ e < 1.0, preferably 0 ≤ e ≤ 0.5, more preferably 0 ≤ e ≤ 0.3, even more preferably 0 ≤ e ≤ 0.2, even more preferably 0 ≤ e ≤ 0.1, and even more preferably e = 0.

[0025] When the total amount of metal elements other than lithium contained in the lithium composite oxide of this embodiment is taken as 100 mol%, the nickel content is preferably 75 mol% or more, more preferably 76 mol% or more, even more preferably 77 mol% or more, and even more preferably 79 mol% or more, from the viewpoint of further improving the capacity of the all-solid-state battery. There is no particular upper limit to the nickel content of the lithium composite oxide, but for example it may be 99 mol% or less, 98 mol% or less, 96 mol% or less, or 95 mol% or less.

[0026] In this embodiment, the positive electrode active material has a composite layer on the particle surface of the positive electrode active material, which consists of a solid electrolyte (A2) containing a sulfide-based solid electrolyte and the positive electrode active material, from the viewpoint of reducing the resistance value of the all-solid-state battery.

[0027] A positive electrode active material having a composite layer of a solid electrolyte (A2) and a positive electrode active material on its particle surface can be produced in the method for manufacturing an all-solid-state battery described later, by step (A) of kneading the solid electrolyte (A2) and the positive electrode active material.

[0028] In this embodiment, the content of the positive electrode active material in the positive electrode active material layer is preferably 50 parts by mass or more and 85 parts by mass or less, preferably 55 parts by mass or more and 82 parts by mass or less, more preferably 60 parts by mass or more and 80 parts by mass or less, and even more preferably 65 parts by mass or more and 78 parts by mass or less, when the total amount of the positive electrode active material layer is 100 parts by mass.

[0029] The solid electrolyte (A2) in this embodiment includes a sulfide-based solid electrolyte.

[0030] The sulfide-based solid electrolyte contained in the solid electrolyte (A2) of this embodiment is, for example, Li ２ S-P ２ S ５ Material, Li ２ S-SiS ２ Material, Li ２ S-GeS ２ Material, Li ２ S-Al ２ S ３ Material, Li ２ S-SiS ２ -Li３ PO ４ Materials, Li ２ S-P ２ S ５ -GeS ２ Materials, Li ２ S-Li ２ O-P ２ S ５ -SiS ２ Materials, Li ２ S-GeS ２ -P ２ S ５ -SiS ２ Materials, Li ２ S-SnS ２ -P ２ S ５ -SiS ２ Materials, Li ２ S-P ２ S ５ -Li ３ N materials, Li ２ S ２＋Ｘ -P ４ S ３ Materials, Li ２ S-P ２ S ５ -P ４ S ３ Materials, LiPO ４ -Li ２ S-SiS materials, Li ３ PS ４ Li ３ PO ４ -Li ２ S-Si ２ S material, Li ３ PO ４ -Li ２ S-SiS ２ Materials, LiI-Li ２ S-B ２ S ３ Materials, LiI-Li ２ S-SiS ２ Materials, LiI-Li ２ S-P ２ S ５ Materials, LiI-Li ２ S-P ２ O ５ Materials, LiI-Li ３ PO ４ -P ２ S５ Li ２ S-P ２ S ５ -LiCl material, Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ I ｘ (However, 0 ≤ x ≤ 2), Li １０ GeP ２ S １２ , and Li ３．２５ Ge ０．２５ P ０．７５ S ４ It includes one or more selected from the group consisting of Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (wherein 0 ≤ x ≤ 2) and Li ７－ｘ PS ６－ｘ I ｘ (However, it includes one or more selected from the group consisting of 0 ≤ x ≤ 2.)

[0031] The sulfide-based solid electrolyte (A2) in this embodiment preferably includes an argyrodite-type sulfide-based solid electrolyte, from the viewpoint of further improving the performance balance between the capacity and resistance of the all-solid-state battery. Furthermore, the sulfide-based solid electrolyte (A2) in this embodiment preferably includes a Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (wherein 0 ≤ x ≤ 2) and Li ７－ｘ PS ６－ｘ I ｘ (However, it includes one or more selected from the group consisting of 0 ≤ x ≤ 2, and more preferably Li ６ PS ５Cl, Li ６ PS ５ Br and Li ６ PS ５ It includes one or more selected from the group consisting of I, and more preferably Li ６ PS ５ Contains Cl.

[0032] The median diameter D in the volume-based particle size distribution of the solid electrolyte (A2) of this embodiment, measured by laser diffraction scattering particle size distribution analysis. ５０ Preferably, the particle size is 0.1 μm to 20.0 μm, more preferably 0.2 μm to 10.0 μm, even more preferably 0.3 μm to 5.0 μm, even more preferably 0.4 μm to 2.0 μm, and even more preferably 0.5 μm to 1.5 μm.

[0033] In the positive electrode active material layer of this embodiment, the binder preferably includes a fluorine-based elastomer (B).

[0034] The fluorine-based elastomer (B) preferably contains constituent units derived from vinylidene fluoride (VdF) and more preferably contains constituent units derived from vinylidene fluoride (VdF) and one or more constituent units selected from the group consisting of constituent units derived from hexafluoropropylene (HFP), trifluoropropylene (TFP), tetrafluoroethylene (TFE), 2,3,3,3-tetrafluoropropylene, 1,3,3,3-tetrafluoropropylene, and perfluoroalkyl vinyl ether (PAVE). Furthermore, from the viewpoint of further improving the performance balance between the capacity and resistance of the all-solid-state battery, the fluorine-based elastomer (B) more preferably includes one or more selected from the group consisting of a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), and a copolymer of vinylidene fluoride (VdF) and trifluoropropylene (TFP), and more preferably includes a copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP).

[0035] The content of constituent units derived from vinylidene fluoride (VdF) in the fluorinated elastomer (B) is preferably 20 mol% or more, more preferably 20 mol% to 95 mol%, even more preferably 30 mol% to 90 mol%, even more preferably 40 mol% to 90 mol%, even more preferably 60 mol% to 85 mol%, and even more preferably 70 mol% to 85 mol%.

[0036] The mass-average molecular weight (Mw) of the fluorine-based elastomer (B) is preferably 10,000 to 10,000,000, more preferably 30,000 to 5,000,000, even more preferably 50,000 to 1,000,000, even more preferably 80,000 to 800,000, and even more preferably 100,000 to 500,000.

[0037] In this embodiment, the binder content in the positive electrode active material layer is preferably 0.1 parts by mass or more and 10.0 parts by mass or less, more preferably 0.2 parts by mass or more and 9.0 parts by mass or less, even more preferably 0.3 parts by mass or more and 8.0 parts by mass or less, even more preferably 0.4 parts by mass or more and 6.0 parts by mass or less, even more preferably 0.5 parts by mass or more and 5.0 parts by mass or less, and even more preferably 0.5 parts by mass or more and 4.0 parts by mass or less, when the total positive electrode active material layer is 100 parts by mass.

[0038] The solid electrolyte (A1) in the positive electrode active material layer of this embodiment preferably comprises one or more selected from the group consisting of sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer-based solid electrolytes, and more preferably comprises a sulfide-based solid electrolyte.

[0039] The oxide-based solid electrolyte in this embodiment is, for example, LiTi ２ (PO ４ ) ３ LiZr ２ (PO ４ ) ３ LiGe ２ (PO ４ ) ３ NASICON-type solid electrolyte materials such as (La ０．５＋ｘLi ０．５－３ｘ )TiO ３ Perovskite-type solid electrolyte materials such as Li ２ O-P ２ O ５ Material, Li ２ O-P ２ O ５ -Li ３ It includes one or more materials selected from the group consisting of N materials, etc.

[0040] The polymer-based solid electrolyte of this embodiment includes, for example, one or more selected from the group consisting of polyether-based electrolyte materials such as polyethylene oxide, polypropylene oxide, ethylene oxide-propylene copolymer, and dimethylsiloxane-ethylene oxide copolymer; gel polymer electrolyte materials such as polyacrylonitrile, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene polymer; and polymer solid electrolyte materials using highly branched polymers.

[0041] The sulfide-based solid electrolyte in this embodiment is, for example, Li ２ S-P ２ S ５ Material, Li ２ S-SiS ２ Material, Li ２ S-GeS ２ Material, Li ２ S-Al ２ S ３ Material, Li ２ S-SiS ２ -Li ３ PO ４ Material, Li ２ S-P ２ S ５ -GeS ２ Material, Li ２ S-Li ２ O-P ２ S ５ -SiS ２ Material, Li ２ S-GeS ２ -P ２ S ５ -SiS ２ Material, Li ２ S-SnS ２ -P ２ S ５-SiS ２ Material, Li ２ S-P ２ S ５ -Li ３ N material, Li ２ S ２＋Ｘ -P ４ S ３ Material, Li ２ S-P ２ S ５ -P ４ S ３ Material, LiPO ４ -Li ２ S-SiS material, Li ３ PS ４ Li ３ PO ４ -Li ２ S-Si ２ S material, Li ３ PO ４ -Li ２ S-SiS ２ Material, LiI-Li ２ S-B ２ S ３ Material, LiI-Li ２ S-SiS ２ Material, LiI-Li ２ S-P ２ S ５ Material, LiI-Li ２ S-P ２ O ５ Material, LiI-Li ３ PO ４ -P ２ S ５ Li ２ S-P ２ S ５ -LiCl material, Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ I ｘ (However, 0 ≤ x ≤ 2), Li １０ GeP ２ S １２ , and Li ３．２５ Ge ０．２５ P０．７５ S ４ It includes one or more selected from the group consisting of Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (wherein 0 ≤ x ≤ 2) and Li ７－ｘ PS ６－ｘ I ｘ (However, it includes one or more selected from the group consisting of 0 ≤ x ≤ 2.)

[0042] The median diameter D in the volume-based particle size distribution of the solid electrolyte (A1) in the positive electrode active material layer of this embodiment, as measured by laser diffraction scattering particle size distribution analysis. ５０ Preferably, the particle size is 0.1 μm to 20.0 μm, more preferably 0.2 μm to 10.0 μm, even more preferably 0.3 μm to 5.0 μm, even more preferably 0.4 μm to 2.0 μm, and even more preferably 0.5 μm to 1.5 μm.

[0043] The content of the solid electrolyte (A1) in the positive electrode active material layer of this embodiment is preferably 10.0 parts by mass or more and 40.0 parts by mass or less, more preferably 12.0 parts by mass or more and 35.0 parts by mass or less, even more preferably 13.0 parts by mass or more and 30.0 parts by mass or less, and even more preferably 15.0 parts by mass or more and 28.0 parts by mass or less, when the total amount of the positive electrode active material layer is 100 parts by mass.

[0044] The conductive additive in the positive electrode active material layer of this embodiment preferably comprises one or more selected from the group consisting of carbon black, activated carbon, graphite, mesoporous carbon, fullerenes, carbon nanotubes, carbon nanofibers, and carbon brushes, from the viewpoint of further reducing the resistance value of the all-solid-state battery, and more preferably comprises one or more selected from the group consisting of carbon black and carbon nanotubes, and preferably comprises carbon nanotubes from the viewpoint of further improving the performance balance between the capacity and resistance value of the all-solid-state battery. Examples of carbon black include acetylene black and Ketjen black, and preferably comprises acetylene black.

[0045] The content of the conductive additive in the positive electrode active material layer of this embodiment is preferably 1.0 part by mass or more and 10.0 parts by mass or less, more preferably 1.1 parts by mass or more and 9.0 parts by mass or less, even more preferably 1.2 parts by mass or more and 8.5 parts by mass or less, even more preferably 1.3 parts by mass or more and 7.5 parts by mass or less, and even more preferably 1.4 parts by mass or more and 7.0 parts by mass or less, when the total volume of the positive electrode active material layer is 100 parts by mass, from the viewpoint of further improving the performance balance between the capacity and resistance of the all-solid-state battery.

[0046] The density of the positive electrode active material layer in this embodiment is preferably 1.0 g / cm³. ３ 5.0g / cm or more ３ More preferably, 2.0 g / cm³ ３ 4.0g / cm or more ３ The following applies:

[0047] The thickness of the positive electrode active material layer in this embodiment is not particularly limited, but for example, it is preferably 1 μm to 150 μm, more preferably 5 μm to 100 μm, and even more preferably 10 μm to 80 μm.

[0048] The positive electrode of this embodiment may further include a positive electrode current collector 3. The positive electrode current collector includes, for example, one or more materials selected from the group consisting of aluminum, stainless steel, nickel, titanium, and alloys thereof. The shape of the positive electrode current collector may be, for example, foil, flat plate, or mesh. The thickness of the positive electrode current collector is, for example, 1 μm or more and 50 μm or less.

[0049] (Negative electrode) The negative electrode of this embodiment includes a negative electrode active material layer. The negative electrode active material layer of this embodiment may include, for example, a negative electrode active material and further include one or more selected from the group consisting of a negative electrode binder, a solid electrolyte, and a conductive additive.

[0050] The negative electrode active material in this embodiment is not particularly limited and may include, for example, carbon materials such as graphite, amorphous carbon, diamond-like carbon, fullerene, carbon nanotubes, and carbon nanohorns; lithium-based metallic materials such as metallic lithium and lithium alloys; and Si and SiO ２ SiO ｘ(0 < x ≤ 2), comprising one or more materials selected from the group consisting of Si-based materials such as Si-containing composite materials, and conductive polymers such as polyacene, polyacetylene, and polypyrrole, and more preferably comprising lithium-based metal materials.

[0051] The content of the negative electrode active material in the negative electrode active material layer of this embodiment is preferably 70 parts by mass or more and 100 parts by mass or less, more preferably 80 parts by mass or more and 100 parts by mass or less, and even more preferably 90 parts by mass or more and 100 parts by mass or less, when the total amount of the negative electrode active material layer is 100 parts by mass.

[0052] The negative electrode active material layer of this embodiment may contain one or more binder resins selected from the group consisting of rubber-based binders and acrylic-based binders. Such binder resins may be in emulsion form. When water is used as the solvent, it is preferable to use a water-based binder and a thickener such as CMC (carboxymethylcellulose) in combination.

[0053] The binder resin content in the negative electrode active material layer of this embodiment may be, for example, 1 to 10 parts by mass, or 3 to 6 parts by mass, when the total amount of the negative electrode active material layer is 100 parts by mass.

[0054] The solid electrolyte in the negative electrode active material layer of this embodiment preferably comprises one or more selected from the group consisting of sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer-based solid electrolytes, and more preferably comprises a sulfide-based solid electrolyte.

[0055] Oxide-based solid electrolytes include, for example, LiTi ２ (PO ４ ) ３ LiZr ２ (PO ４ ) ３ LiGe ２ (PO ４ ) ３ NASICON-type solid electrolyte materials such as (La ０．５＋ｘ Li ０．５－３ｘ )TiO ３ Perovskite-type solid electrolyte materials such as Li ２ O-P ２ O ５ Material, Li２ O-P ２ O ５ -Li ３ It includes one or more materials selected from the group consisting of N materials, etc.

[0056] Sulfide-based solid electrolytes include, for example, Li ２ S-P ２ S ５ Material, Li ２ S-SiS ２ Material, Li ２ S-GeS ２ Material, Li ２ S-Al ２ S ３ Material, Li ２ S-SiS ２ -Li ３ PO ４ Material, Li ２ S-P ２ S ５ -GeS ２ Material, Li ２ S-Li ２ O-P ２ S ５ -SiS ２ Material, Li ２ S-GeS ２ -P ２ S ５ -SiS ２ Material, Li ２ S-SnS ２ -P ２ S ５ -SiS ２ Material, Li ２ S-P ２ S ５ -Li ３ N material, Li ２ S ２＋Ｘ -P ４ S ３ Material, Li ２ S-P ２ S ５ -P ４ S ３ Material, LiPO ４ -Li ２ S-SiS material, Li ３ PS ４ Li ３ PO ４ -Li ２ S-Si２ S material, Li ３ PO ４ -Li ２ S-SiS ２ Material, LiI-Li ２ S-B ２ S ３ Material, LiI-Li ２ S-SiS ２ Material, LiI-Li ２ S-P ２ S ５ Material, LiI-Li ２ S-P ２ O ５ Material, LiI-Li ３ PO ４ -P ２ S ５ Li ２ S-P ２ S ５ -LiCl material, Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ I ｘ (However, 0 ≤ x ≤ 2), Li １０ GeP ２ S １２ , and Li ３．２５ Ge ０．２５ P ０．７５ S ４ It includes one or more selected from the group consisting of Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (wherein 0 ≤ x ≤ 2) and Li ７－ｘ PS ６－ｘ I ｘ (wherein 0 ≤ x ≤ 2) it includes one or more selected from the group, and more preferably Li ６ PS ５ Cl, Li ６ PS ５ Br and Li ６ PS５ It includes one or more selected from the group consisting of I, and more preferably Li ６ PS ５ Contains Cl.

[0057] Polymer-based solid electrolytes include, for example, one or more selected from the group consisting of polyether-based electrolyte materials such as polyethylene oxide, polypropylene oxide, ethylene oxide-propylene copolymer, and dimethylsiloxane-ethylene oxide copolymer; gel polymer electrolyte materials such as polyacrylonitrile, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene polymer; and polymer solid electrolyte materials using highly branched polymers.

[0058] The conductive additive in the negative electrode active material layer of this embodiment includes one or more selected from the group consisting of carbon black, activated carbon, graphite, mesoporous carbon, fullerenes, carbon nanotubes, carbon nanofibers, and carbon brushes, and more preferably includes carbon black, from the viewpoint of further reducing the resistance value of the all-solid-state battery.

[0059] In this embodiment, the content of the conductive additive in the negative electrode active material layer is preferably 0.05 parts by mass or more and 10 parts by mass or less, and more preferably 0.5 parts by mass or more and 5.0 parts by mass or less, from the viewpoint of further improving the performance balance between the capacity and resistance of the all-solid-state battery, when the total negative electrode active material layer is 100 parts by mass.

[0060] The negative electrode active material layer can appropriately use electrode additives commonly used for electrode formation, such as thickeners, dispersants, and stabilizers.

[0061] The density of the negative electrode active material layer in this embodiment is preferably 0.5 g / cm³. ３ 3.0g / cm or more ３ More preferably, 1.2 g / cm³ ３ 2.0g / cm or more ３ The following applies:

[0062] The thickness of the negative electrode active material layer in this embodiment is preferably 1 μm to 150 μm, more preferably 5 μm to 100 μm, and even more preferably 10 μm to 80 μm.

[0063] The negative electrode current collector includes, for example, one or more materials selected from the group consisting of copper, stainless steel, nickel, titanium, and alloys thereof. The shape of the negative electrode current collector may be, for example, foil, flat plate, or mesh. The thickness of the negative electrode current collector is, for example, 1 μm to 50 μm.

[0064] (Solid Electrolyte Layer) The solid electrolyte layer of this embodiment contains a solid electrolyte.

[0065] The solid electrolyte in the solid electrolyte layer of this embodiment preferably comprises one or more selected from the group consisting of sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer-based solid electrolytes, and more preferably comprises a sulfide-based solid electrolyte.

[0066] Oxide-based solid electrolytes include, for example, LiTi ２ (PO ４ ) ３ LiZr ２ (PO ４ ) ３ LiGe ２ (PO ４ ) ３ NASICON-type solid electrolyte materials such as (La ０．５＋ｘ Li ０．５－３ｘ )TiO ３ Perovskite-type solid electrolyte materials such as Li ２ O-P ２ O ５ Material, Li ２ O-P ２ O ５ -Li ３ It includes one or more materials selected from the group consisting of N materials, etc.

[0067] Sulfide-based solid electrolytes include, for example, Li ２ S-P ２ S ５ Material, Li ２ S-SiS ２ Material, Li ２ S-GeS ２ Material, Li ２ S-Al ２ S ３ Material, Li ２ S-SiS ２ -Li３ PO ４ Materials, Li ２ S-P ２ S ５ -GeS ２ Materials, Li ２ S-Li ２ O-P ２ S ５ -SiS ２ Materials, Li ２ S-GeS ２ -P ２ S ５ -SiS ２ Materials, Li ２ S-SnS ２ -P ２ S ５ -SiS ２ Materials, Li ２ S-P ２ S ５ -Li ３ N materials, Li ２ S ２＋Ｘ -P ４ S ３ Materials, Li ２ S-P ２ S ５ -P ４ S ３ Materials, LiPO ４ -Li ２ S-SiS materials, Li ３ PS ４ Li ３ PO ４ -Li ２ S-Si ２ S material, Li ３ PO ４ -Li ２ S-SiS ２ Materials, LiI-Li ２ S-B ２ S ３ Materials, LiI-Li ２ S-SiS ２ Materials, LiI-Li ２ S-P ２ S ５ Materials, LiI-Li ２ S-P ２ O ５ Materials, LiI-Li ３ PO ４ -P ２ S５ Li ２ S-P ２ S ５ -LiCl material, Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ I ｘ (However, 0 ≤ x ≤ 2), Li １０ GeP ２ S １２ , and Li ３．２５ Ge ０．２５ P ０．７５ S ４ It includes one or more selected from the group consisting of Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (wherein 0 ≤ x ≤ 2) and Li ７－ｘ PS ６－ｘ I ｘ (wherein 0 ≤ x ≤ 2) it includes one or more selected from the group, and more preferably Li ６ PS ５ Cl, Li ６ PS ５ Br and Li ６ PS ５ It includes one or more selected from the group consisting of I, and more preferably Li ６ PS ５ Contains Cl.

[0068] Polymer-based solid electrolytes include, for example, one or more selected from the group consisting of polyether-based electrolyte materials such as polyethylene oxide, polypropylene oxide, ethylene oxide-propylene copolymer, and dimethylsiloxane-ethylene oxide copolymer; gel polymer electrolyte materials such as polyacrylonitrile, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene polymer; and polymer solid electrolyte materials using highly branched polymers.

[0069] The median diameter D of the volume-based particle size distribution of the solid electrolyte in the solid electrolyte layer of this embodiment, as measured by laser diffraction scattering particle size distribution analysis. ５０ Preferably, the particle size is 0.1 μm to 20.0 μm, more preferably 0.2 μm to 10.0 μm, even more preferably 0.3 μm to 5.0 μm, even more preferably 0.4 μm to 2.0 μm, and even more preferably 0.5 μm to 1.5 μm.

[0070] The solid electrolyte content in the solid electrolyte layer of this embodiment is preferably 80 parts by mass or more and 100 parts by mass or less, and more preferably 90 parts by mass or more and 100 parts by mass or less, when the total amount of the solid electrolyte layer is 100 parts by mass.

[0071] The thickness of the solid electrolyte layer in this embodiment is preferably 1 μm to 150 μm, more preferably 5 μm to 100 μm, and even more preferably 10 μm to 80 μm.

[0072] (Optional configuration of the all-solid-state battery) The all-solid-state battery of this embodiment may further include an outer casing. Examples of the outer casing include an aluminum laminate film, a sturdy aluminum can case, and an aluminum cylindrical outer casing.

[0073] The all-solid-state battery of this embodiment may further include a positive terminal and a negative terminal. Examples of positive terminals include terminals made of aluminum or an aluminum alloy. Examples of negative terminals include terminals made of copper, a copper alloy, or those made of the same material with nickel plating.

[0074] (Method for Manufacturing All-Solid-State Batteries) The method for manufacturing the all-solid-state battery of this embodiment is not particularly limited and known methods can be applied. First, the fabrication of the negative electrode will be described. The negative electrode can be fabricated by known methods. Regardless of the method used to fabricate the negative electrode, it is preferable to fabricate it in a low-moisture environment under dew point control in order to suppress the adsorption of moisture onto the solid electrolyte.

[0075] When using a negative electrode in which a negative electrode active material layer is formed on a negative electrode current collector, a slurry in which the negative electrode active material, solid electrolyte, and binder are dispersed in a dehydrated organic solvent is applied to part or all of the surface of a negative electrode current collector such as copper foil, dried, and a negative electrode precursor sheet is obtained. The obtained negative electrode precursor sheet can be compressed by a press molding method such as a roll press, uniaxial press, rubber press, or isotropic and isobaric press (CIP, WIP) to obtain a negative electrode sheet. The organic solvent preferably includes one or more selected from the group consisting of tertiary amine solvents such as acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, and triethylamine, as well as heptane, hexane, tetrahydrofuran, toluene, N-methylpyrrolidone, ether solvents, thiol solvents, and butyl butyrate, and all of them are preferably dehydrated.

[0076] Furthermore, the negative electrode can be obtained by placing a metallic lithium layer (negative electrode active material layer), such as lithium foil, on part or all of a negative electrode current collector, such as stainless steel foil, and then pressing them together by rolling or other processes.

[0077] Next, a solid electrolyte layer is fabricated on the surface of the negative electrode. When using a sulfide-based solid electrolyte, it is preferable to fabricate it in a low-moisture environment under dew point control in order to suppress the adsorption of moisture.

[0078] A solid electrolyte layer can be created on the surface of the negative electrode by, for example, applying a slurry in which a solid electrolyte is dispersed in an organic solvent to the surface of a negative electrode active material layer fabricated on a negative electrode current collector, and then drying it. The organic solvent preferably includes one or more selected from the group consisting of tertiary amine solvents such as acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, and triethylamine, as well as heptane, hexane, tetrahydrofuran, toluene, N-methylpyrrolidone, ether solvents, thiol solvents, and butyl butyrate, and all of them are preferably dehydrated.

[0079] Next, the laminated negative electrode and solid electrolyte layer are compressed using a press molding method such as a vacuum laminator, roll press, uniaxial press, rubber press, or isotropic and isobaric press (CIP, WIP) to obtain a negative electrode-solid electrolyte layer laminate. When the solid electrolyte layer is laminated together with a base layer such as a polyester sheet and pressed, the base layer is peeled off from the solid electrolyte layer. In this case, it is preferable to use a base layer whose surface is coated with a release agent such as silicone to facilitate the peeling of the base layer from the solid electrolyte layer.

[0080] Next, we will explain how to prepare the positive electrode. Regardless of the method used to prepare the positive electrode, it is preferable to prepare it in a low-moisture environment under dew point control in order to suppress moisture adsorption.

[0081] The positive electrode of this embodiment can be manufactured, for example, by dissolving or dispersing the components constituting the positive electrode active material layer in a solvent to produce a positive electrode slurry, applying the positive electrode slurry to at least one surface of the positive electrode current collector, and then drying and rolling it. Alternatively, the positive electrode of this embodiment can also be manufactured, for example, by applying and drying the positive electrode slurry on a support, peeling it off the support, and then laminating the resulting film onto the positive electrode current collector. The solvent preferably includes one or more selected from the group consisting of, for example, tertiary amine solvents such as acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, and triethylamine, heptane, hexane, tetrahydrofuran, toluene, N-methylpyrrolidone, ether solvents, thiol solvents, and butyl butyrate, and all of them are preferably dehydrated.

[0082] The positive electrode is laminated onto the negative electrode-solid electrolyte layer to obtain an electrode laminate precursor. When a sulfide-based solid electrolyte is used as the solid electrolyte, the ionic conductivity of the solid electrolyte may decrease due to exposure to moisture. Therefore, after obtaining the electrode laminate precursor, it is preferable to compress the electrode laminate precursor using methods such as a vacuum laminator, roll press, uniaxial press, rubber press, or isotropic and isobaric press (CIP, WIP) to obtain the electrode laminate.

[0083] It is preferable to promptly seal the resulting electrode stack inside the outer casing. After attaching one end of a rectangular metal plate that will serve as the negative electrode terminal to the negative electrode current collector and one end of a rectangular metal terminal that will serve as the positive electrode terminal to the positive electrode current collector, the electrode stack is housed in an aluminum outer casing. It is preferable that a resin layer, such as polyolefin, is formed on at least the inner surface of the outer casing that faces the electrode stack. The resin layer is heated to melt the resin, then solidified again, and the electrode stack is sealed with the aluminum outer casing. At this time, the other end of the positive electrode terminal and the other end of the negative electrode terminal are positioned so that they protrude outside the outer casing. A layer of the same or a different type of resin as the resin layer used on the inner surface of the outer casing may be provided in the portions where the positive electrode terminal and the negative electrode terminal contact the resin layer on the inner surface of the outer casing.

[0084] The method for manufacturing an all-solid-state battery of this embodiment preferably includes a step (A) of kneading a positive electrode active material and a solid electrolyte (A2) to form a composite layer of the solid electrolyte (A2) and the positive electrode active material on the particle surface of the positive electrode active material, from the viewpoint of further reducing the resistance value of the all-solid-state battery. Step (A) can preferably be carried out by kneading the positive electrode active material and the solid electrolyte (A2) using a ball mill. By including step (A) in the method for manufacturing an all-solid-state battery of this embodiment, a composite layer of the solid electrolyte (A2) and the positive electrode active material can be formed on the particle surface of the positive electrode active material.

[0085] In step (A), the ball diameter of the ball mill is preferably 15 mm or less, more preferably 12 mm or less, even more preferably 10 mm or less, and even more preferably 8 mm or less. The lower limit of the ball diameter of the ball mill is not particularly limited, but for example it may be 1 mm or more, or 3 mm or more.

[0086] In step (A), the peripheral speed of the ball mill is preferably 1.5 m / s or more and 15.0 m / s or less, more preferably 2.0 m / s or more and 10.0 m / s or less, and even more preferably 2.5 m / s or more and less than 6.0 m / s.

[0087] In addition, in step (A), in order to suppress the adsorption of moisture onto the positive electrode active material and solid electrolyte (A2), the process is preferably carried out in a low-moisture environment under dew point control.

[0088] The embodiments of the present invention have been described above, but these are merely examples, and various other configurations can also be adopted.

[0089] It should be noted that the present invention is not limited to the embodiments described above, and any modifications, improvements, etc., that can achieve the objectives of the present invention are included in the present invention.

[0090] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0091] The raw materials for the all-solid-state batteries in Examples 1-4 and Comparative Examples 1-4 are as follows: <Positive electrode> ・Positive electrode active material (1-1): LiNi ０．８ Co ０．１ Mn ０．１ O ２ (Median diameter D) ５０ : 2.5 μm) - Positive electrode active material (2-1): LiNi ０．８ Co ０．１ Mn ０．１ O ２ (Median diameter D) ５０ : 4.0 μm) - Positive electrode active material (3-1): LiNi ０．８ Co ０．１ Mn ０．１ O ２ (Median diameter D) ５０ : 6.0 μm) - Positive electrode active material (4-1): LiNi ０．８ Co ０．１ Mn ０．１ O ２ (Median diameter D) ５０ :6.5μm) ・Solid electrolyte: Li ６ PS ５ Cl (median diameter D) ５０ : 1.0 μm, manufactured by NEI) • Conductive additive: AB (acetylene black) • Binder: Vdf-HfP (vinylidene fluoride-hexafluoropropylene, mass average molecular weight (Mw): approximately 300,000, polymer composition: VdF is 75 mol% of the total polymer, HFP is 25 mol%) <Solid electrolyte layer> • Solid electrolyte: Li ６ PS ５ Cl (median diameter D) ５０: 1.0 μm, manufactured by NEI Corporation) • Binder: SBR (styrene-butadiene rubber)

[0092] <Method for manufacturing a positive electrode active material having a composite layer> Each positive electrode active material and solid electrolyte (Li ６ PS ５ Each of the two materials (Cl) was weighed in a mass ratio of 95:5 and placed in a zirconia ball mill container of a planetary ball mill along with 5 mm diameter zirconia balls. The materials were then processed for 30 minutes at a peripheral speed of 4.2 m / s and a rotation speed of 400 rpm to produce positive electrode active materials with composite layers. Hereinafter, the positive electrode active materials with composite layers using positive electrode active material (1-1), positive electrode active material (2-1), and positive electrode active material (3-1) will be referred to as positive electrode active material (1-2), positive electrode active material (2-2), and positive electrode active material (3-2), respectively. Weighing and removal of the positive electrode active materials after processing were all carried out in a glove box with a dew point of -50°C, and a ball mill container with a packing was used to prevent the material from coming into contact with the atmosphere.

[0093] <Method for measuring particle size of solid electrolyte and positive electrode active material> The median diameter D of the solid electrolyte and positive electrode active material at which the cumulative volume in the volume-based particle size distribution measured by laser diffraction scattering particle size distribution analysis is 50% ５０ The particle size distribution was measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3000). For the solid electrolyte, the solid electrolyte was suspended in a dispersion medium (butyl butyrate), ultrasonically dispersed, and then measured. For the positive electrode active material, the positive electrode active material was suspended in a dispersion medium (0.1% by mass sodium hexametaphosphate aqueous solution), ultrasonically dispersed, and then measured. Each measurement was performed five times, and the average value was used.

[0094] (Example 1) An all-solid-state battery was fabricated by the following method.

[0095] [I] Fabrication of a laminate of negative electrode and solid electrolyte layer (1) A foil (manufactured by Honjo Metal Co., Ltd.) was prepared as the negative electrode by forming a 20 μm thick metallic lithium layer on the surface of a 10 μm thick stainless steel negative electrode current collector. (2) Li, which is a solid electrolyte, was added to xylene. ６ PS ５A slurry containing dispersed Cl was applied to the surface of a polyester film mainly composed of polyester, and then dried to form a solid electrolyte layer on the polyester film. Next, the solid electrolyte layer was laminated on the negative electrode together with the polyester film so that the obtained solid electrolyte layer was in contact with the surface of the metallic lithium layer of the negative electrode, thereby obtaining a negative electrode-solid electrolyte layer laminate. (3) The negative electrode-solid electrolyte layer laminate obtained in (2) above was vacuum sealed using a vacuum laminator and held at room temperature (25°C) under a pressure of 300 MPa for 1 minute. Next, the negative electrode-solid electrolyte layer laminate was removed from the vacuum laminator and compressed by the isotropic press method (CIP method) to obtain a negative electrode-solid electrolyte layer laminate with a porosity of 7%. The size of the negative electrode-solid electrolyte layer laminate was 50 mm × 70 mm. (4) The polyester film was peeled off from the solid electrolyte layer to obtain a negative electrode-solid electrolyte layer laminate.

[0096] [II] Lamination of positive electrode and negative electrode-solid electrolyte layer laminate (1) The positive electrode active material, solid electrolyte, conductive additive and binder were weighed in the ratio (mass%) shown in Table 1, butyl butyrate was added to achieve a solid content ratio of 65%, and the mixture was mixed for 2 minutes at a rotation speed of 2000 rpm using a rotation-orbit mixer to obtain a slurry. Next, the obtained slurry was coated onto 15 μm thick aluminum foil using a bar coater and dried at 60°C for 10 minutes to form a positive electrode active material layer and obtain a positive electrode. Note that slurry preparation and slurry coating were all carried out in a glove box with a dew point of -50°C. (2) The positive electrode obtained in (1) above was cut to 45 mm × 65 mm, and the positive electrode and negative electrode-solid electrolyte layer laminate was laminated so that the positive electrode active material layer was in contact with the solid electrolyte layer of the negative electrode-solid electrolyte layer laminate prepared in [I] above to obtain an electrode laminate precursor. The stacked structure of the positive electrode and negative electrode-solid electrolyte layer consisted of one layer each.

[0097] [III] Preparation of Electrode Laminate The electrode laminate precursor obtained in [II] above was vacuum sealed using a vacuum laminator and held at room temperature (25°C) under a pressure of 300 MPa for 1 minute. Next, the electrode laminate precursor was removed from the vacuum laminator and compressed by the CIP method to obtain an electrode laminate with a positive electrode active material layer porosity of 5%.

[0098] [IV] Encapsulation into an Outer Shell The electrode stack obtained in [III] above was enclosed in an aluminum outer shell (manufactured by Dai Nippon Printing Co., Ltd.) using the method described in the embodiment, and an all-solid-state battery was obtained in which the positive electrode terminal and the negative electrode terminal were brought out to the outside of the outer shell.

[0099] <Discharge Capacity> The discharge capacity of the obtained all-solid-state battery was measured by charging and discharging at 25°C. The charging and discharging conditions were as follows: First, the all-solid-state battery was charged with a constant current at a charge rate of 0.05C to 4.25V, then switched to constant voltage charging and cut off charging at 0.005C. Next, it was discharged with a constant current at a discharge rate of 0.05C to 2.5V. The initial discharge capacity was calculated from the above charging and discharging, and the discharge capacity (mAh / g) was obtained by dividing the obtained initial discharge capacity (mAh) by the amount of positive electrode active material (g) in the all-solid-state battery. The results are shown in Table 1.

[0100] <Resistance Value> At room temperature of 25°C, the obtained solid-state battery was charged with a constant current at a charge rate of 0.05C to 4.25V, then switched to constant voltage charging and cut off at 0.005C. Next, it was discharged with a constant current at a discharge rate of 0.05C to 3.65V, then switched to constant voltage discharge and cut off at 0.005C. The electrical resistance (Ω) of the discharged solid-state battery was measured using the AC four-terminal method (frequency 1kHz, measuring device name: HIOKI E.E. CORPORATION, 3560 AC milliohm high tester), and the obtained value was measured as the area value (cm²) of the surface perpendicular to the stacking direction of the positive electrode. ２ By dividing by ), the resistance value (Ω / cm) can be calculated. ２ The result was calculated. The results are shown in Table 1.

[0101] (Examples 2-4, Comparative Examples 1-4) All-solid-state batteries were prepared in the same manner as in Example 1, except that the types and ratios (mass%) of the positive electrode active material, solid electrolyte, conductive additive, and binder in the positive electrode active material were changed to those shown in Table 1. The discharge capacity and resistance values ​​were measured for each. The results obtained are shown in Table 1.

[0102]

[0103] This application claims priority based on Japanese Patent Application No. 2025-056538, filed on 28 March 2025, and incorporates all of its disclosures herein.

[0104] 1 Positive electrode active material layer 2 Negative electrode active material layer 3 Positive electrode current collector 4 Negative electrode current collector 5 Solid electrolyte layer 6 Exterior body 7 Exterior body 8 Negative electrode terminal 9 Positive electrode terminal

Claims

1. A positive electrode comprising a positive electrode having a positive electrode active material layer containing a positive electrode active material, a binder, a solid electrolyte (A1), and a conductive additive; a negative electrode having a solid electrolyte layer and a negative electrode active material layer, wherein the median diameter D of the positive electrode active material in the volume-based particle size distribution measured by laser diffraction scattering particle size distribution measurement method. ５０ An all-solid-state battery in which the particle size is 0.5 μm or more and 6.0 μm or less, and the particle surface of the positive electrode active material has a composite layer of a solid electrolyte (A2) and the positive electrode active material, and the solid electrolyte (A2) contains a sulfide-based solid electrolyte.

2. The all-solid-state battery according to claim 1, wherein the sulfide-based solid electrolyte includes an argyrodite-type sulfide-based solid electrolyte.

3. The solid electrolyte (A2) is Li ７－ｘ PS ６－ｘ Cl ｘ (where 0≦x≦2), Li ７－ｘ PS ６－ｘ Br ｘ (where 0≦x≦2) and Li ７－ｘ PS ６－ｘ I ｘ (where 0≦x≦2), the all-solid-state battery according to claim 1 or 2, comprising one or more selected from the group consisting of the above.

4. The all-solid-state battery according to any one of claims 1 to 3, wherein the content of the solid electrolyte (A1) in the positive electrode active material layer is 10.0 parts by mass or more and 40.0 parts by mass or less, when the total amount of the positive electrode active material layer is 100 parts by mass.

5. The all-solid-state battery according to any one of claims 1 to 4, wherein the binder comprises a fluorine-based elastomer (B).

6. The all-solid-state battery according to claim 5, wherein the fluorine-based elastomer (B) comprises a constituent unit derived from vinylidene fluoride (VdF) and one or more constituent units selected from the group consisting of constituent units derived from hexafluoropropylene (HFP), trifluoropropylene (TFP), tetrafluoroethylene (TFE), 2,3,3,3-tetrafluoropropylene, 1,3,3,3-tetrafluoropropylene, and perfluoroalkyl vinyl ether (PAVE).

7. The all-solid-state battery according to claim 5 or 6, wherein the fluorine-based elastomer (B) comprises one or more selected from the group consisting of copolymers of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), and copolymers of vinylidene fluoride (VdF) and trifluoropropylene (TFP).

8. The all-solid-state battery according to any one of claims 5 to 7, wherein the content of constituent units derived from vinylidene fluoride (VdF) in the fluorine-based elastomer (B) is 20 mol% or more.

9. The all-solid-state battery according to any one of claims 5 to 8, wherein the mass-average molecular weight (Mw) of the fluorine-based elastomer (B) is 10,000 or more and 10,000,000 or less.

10. The all-solid-state battery according to any one of claims 1 to 9, wherein the content of the binder in the positive electrode active material layer is 0.1 parts by mass or more and 10.0 parts by mass or less, when the total amount of the positive electrode active material layer is 100 parts by mass.

11. The all-solid-state battery according to any one of claims 1 to 10, wherein the positive electrode active material includes a lithium composite oxide.

12. The all-solid-state battery according to claim 11, wherein the lithium composite oxide comprises one or more composite oxides selected from the group consisting of lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium-manganese composite oxide, lithium-nickel-manganese composite oxide, lithium-nickel-cobalt composite oxide, lithium-nickel-aluminum composite oxide, lithium-nickel-cobalt-aluminum composite oxide, lithium-nickel-manganese-aluminum composite oxide, lithium-nickel-cobalt-manganese-aluminum composite oxide, and lithium-nickel-cobalt-manganese composite oxide.

13. The all-solid-state battery according to claim 11 or 12, wherein the lithium composite oxide comprises a lithium-nickel-cobalt-manganese composite oxide.

14. The all-solid-state battery according to any one of claims 11 to 13, wherein when the total amount of metal elements other than lithium contained in the lithium composite oxide is taken as 100 mol%, the nickel content is 75 mol% or more.

15. The all-solid-state battery according to any one of claims 1 to 14, wherein the conductive additive comprises one or more selected from the group consisting of carbon black and carbon nanotubes.

16. The all-solid-state battery according to any one of claims 1 to 15, wherein the content of the conductive additive in the positive electrode active material layer is 1.0 part by mass or more and 10.0 parts by mass or less, when the total amount of the positive electrode active material layer is 100 parts by mass.

17. A solid-state battery according to any one of claims 1 to 16, wherein the discharge capacity measured by the following method 1 is 210 mAh / g or more. (Method 1) At 25°C, the solid-state battery is charged with a constant current at a charge rate of 0.05C up to 4.25V, then switched to constant voltage charging and cut off at 0.005C. Next, it is discharged with a constant current at a discharge rate of 0.05C up to 2.5V. The initial discharge capacity (mAh) is calculated by the above charge and discharge, and the discharge capacity (mAh / g) is obtained by dividing the initial discharge capacity (mAh) by the content (g) of the positive electrode active material in the solid-state battery.

18. The resistance value measured by Method 2 below is 40 Ω / cm. ２ The all-solid-state battery according to any one of claims 1 to 17, as follows: (Method 2) At 25°C, the all-solid-state battery is charged with a constant current at a charge rate of 0.05C to 4.25V, then switched to constant voltage charging and cut off charging at 0.005C. Next, it is discharged with a constant current at a discharge rate of 0.05C to 3.65V, then switched to constant voltage discharge and cut off discharge at 0.005C. The electrical resistance (Ω) of the all-solid-state battery after the discharge is cut off is measured using the AC four-terminal method (frequency 1 kHz), and the obtained value is measured as the area value (cm²) of the surface perpendicular to the stacking direction of the positive electrode. ２ By dividing by ), the resistance value (Ω / cm) can be calculated. ２ ) 19. A method for manufacturing an all-solid-state battery according to claims 1 to 18, comprising the step (A) of kneading the positive electrode active material and the solid electrolyte (A2) to form the composite layer on the particle surface of the positive electrode active material.

20. The method for manufacturing an all-solid-state battery according to claim 19, wherein in step (A), the positive electrode active material and the solid electrolyte (A2) are kneaded by a ball mill.

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