Battery

Abstract

To provide a battery capable of improving a discharge rate characteristic.SOLUTION: A battery comprises a positive electrode, a solid electrolyte layer, and a negative electrode in this order. In the battery, the negative electrode has a negative electrode current collector and a negative electrode layer in this order in a direction from the negative electrode toward the solid electrolyte layer side. The negative electrode layer includes a Li-Mg-Al alloy layer, and the negative electrode layer includes Li-Al alloy particles in the Li-Mg-Al alloy layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to batteries. [Background technology]

[0002] Various technologies have been proposed for batteries such as those disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-184513 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses a solid-state battery having a Li-Mg alloy as the negative electrode. During discharge of the solid-state battery, Li dissolves preferentially from the Li-Mg alloy near the solid electrolyte (SE) layer, and the Mg concentration near the solid electrolyte layer increases, forming a resistive layer and reducing the discharge capacity.

[0005] The present disclosure has been made in view of the above circumstances, and has as its main object to provide a battery capable of improving discharge rate characteristics. [Means for solving the problem]

[0006] That is, the present disclosure includes the following aspects. <1> A battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode in this order, the negative electrode includes a negative electrode current collector and a negative electrode layer in this order in a direction from the negative electrode toward the solid electrolyte layer, the negative electrode layer includes a Li-Mg-Al alloy layer, The battery, wherein the negative electrode layer contains Li-Al alloy particles in the Li-Mg-Al alloy layer.

[0007] <2> The average particle size of the Li-Al alloy particles is 1 μm or more and 3 μm or less. <1> The battery described in

[0008] <3> The thickness of the negative electrode layer is 1 μm or more and 15 μm or less. <1> or <2> The battery described in

[0009] <4> The solid electrolyte layer includes a sulfide solid electrolyte. <1> ~ <3> 1. A battery according to any one of the preceding claims.

[0010] <5> The negative electrode current collector is a Ni foil. <1> ~ <4> 1. A battery according to any one of the preceding claims. [Effects of the Invention]

[0011] The battery of the present disclosure can improve discharge rate characteristics. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a battery according to the present disclosure before the first charge. [Figure 2] FIG. 2 is a cross-sectional view showing an example of a battery according to the present disclosure after initial charging. [Figure 3] FIG. 3 is a graph showing the relationship between current density and discharge capacity for each cell of Example 1 (Mg, Al), Comparative Example 1 (Mg), and Comparative Example 2 (Al). 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 battery that do not characterize the present disclosure) can be understood as design matters for those 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.

[0014] In this disclosure, a fully charged battery means that the battery's State of Charge (SOC) is 100%. SOC indicates the ratio of the charge capacity to the fully charged capacity of the battery, and the fully charged capacity is SOC 100%. The SOC may be estimated from, for example, the open circuit voltage (OCV) of the battery.

[0015] In the present disclosure, an example of a method for calculating the average particle size is as follows. First, for a given particle, the particle size is calculated when the particle is considered to be spherical in a transmission electron microscope (hereinafter referred to as TEM) image or scanning electron microscope (hereinafter referred to as SEM) image at an appropriate magnification (for example, 50,000 to 1,000,000 times). This calculation of particle size from TEM or SEM observation is performed for 200 to 300 particles of the same type, and the average of these particles is taken as the average particle size.

[0016] The present disclosure provides a battery including a positive electrode, a solid electrolyte layer, and a negative electrode in this order, the negative electrode includes a negative electrode current collector and a negative electrode layer in this order in a direction from the negative electrode toward the solid electrolyte layer, the negative electrode layer includes a Li-Mg-Al alloy layer, The negative electrode layer includes Li-Al alloy particles in the Li-Mg-Al alloy layer.

[0017] In the present disclosure, the inclusion of Li-Al alloy particles in the Li-Mg-Al alloy layer improves the Li diffusion coefficient in the negative electrode layer, thereby supplying Li to the solid electrolyte layer interface, and the supply of Li from the Li-Al alloy particles suppresses an increase in the Mg concentration near the solid electrolyte layer in the negative electrode layer, thereby improving the discharge rate characteristics.

[0018] The battery of the present disclosure comprises a positive electrode, a solid electrolyte layer, and a negative electrode in this order. FIG. 1 is a cross-sectional view showing an example of a battery according to the present disclosure before the first charge. As shown in FIG. 1, a battery 100 before initial charging includes a positive electrode current collector 10, a positive electrode layer 20, a solid electrolyte layer 30, an Al layer 40, an Mg layer 50, and a negative electrode current collector 60, in this order. FIG. 2 is a cross-sectional view showing an example of a battery according to the present disclosure after initial charging. As shown in FIG. 2, the battery 200 after the initial charge includes a positive electrode current collector 10, a positive electrode layer 20, a solid electrolyte layer 30, a Li—Mg—Al alloy layer 41, and a negative electrode current collector 60, in this order. Upon initial charging, the Al layer 40 and the Mg layer 50 become a Li—Mg—Al alloy layer 41. The negative electrode layer contains Li—Al alloy particles 51 in the Li—Mg—Al alloy layer 41. The directions of a three-dimensional Cartesian coordinate system are also shown in Figures 1 and 2. Here, the xy plane is the horizontal plane, the z-axis direction is the vertical direction, and the larger side in the z-axis direction is the top.

[0019] [Negative electrode] The negative electrode has a negative electrode current collector and a negative electrode layer in this order in a direction from the negative electrode toward the solid electrolyte layer.

[0020] The material of the negative electrode current collector may be a material that does not alloy with Li, such as SUS, aluminum, copper, nickel, iron, titanium, and carbon. 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. The negative electrode current collector may have a buffer layer, an elastic layer, or a PTC (Positive Temperature Coefficient) thermistor layer disposed on its surface.

[0021] The negative electrode layer includes a Li—Mg—Al alloy layer. The negative electrode layer contains Li-Al alloy particles in a Li-Mg-Al alloy layer. The aluminum element ratio in the Li-Mg-Al alloy layer may be 0.1 atomic % to 5 atomic %, the magnesium element ratio may be 0.3 atomic % to 54.9 atomic %, and the lithium element ratio may be 45 atomic % to 99.6 atomic %. The ratio of aluminum element in the Li-Al alloy particles may be 0.1 atomic % to 15 atomic %, and the ratio of lithium element may be 85 atomic % to 99.9 atomic %. The Li-Al alloy particles may have an average particle size of 1 μm or more and 3 μm or less. The thickness of the negative electrode layer may be 1 μm or more and 15 μm or less. The thickness of the negative electrode layer may be 10 μm or more and 15 μm or less when the battery is fully charged after the initial charge. The thickness of the negative electrode layer may be 1 μm or more and 4 μm or less when the battery is fully discharged (SOC: 0%) after the first charge.

[0022] Before the initial charge of the battery, the negative electrode layer may include, in order from the solid electrolyte layer side, an Al layer containing elemental Al and an Mg layer containing elemental Mg, which are precursors of the Li-Mg-Al alloy layer. The Mg layer is formed on, for example, the negative electrode current collector. Examples of methods for forming the layer include a method of placing and pressing Mg particles, vapor deposition, sputtering, PVD, and electrolytic plating. Among these, vapor deposition or sputtering may be used. This improves the adhesion of the Mg layer to the negative electrode current collector, thereby suppressing an increase in the resistance of the negative electrode. The Al layer may be formed on the negative electrode current collector side or the solid electrolyte layer side in the same manner as above. In particular, the Al layer may be formed on the solid electrolyte layer side. By forming the Al layer on the solid electrolyte layer side, the adhesion of the Al layer to the solid electrolyte layer is increased.

[0023] The negative electrode layer may include a Li-Mg-Al alloy layer in which elemental Li, an Al layer, and an Mg layer are alloyed together after the initial charge of the battery. The Li-Mg-Al alloy layer may have a Li-Al alloy phase containing Li-Al alloy particles scattered therein. The conditions for charging and discharging a battery in which an Al layer and an Mg layer are disposed between a negative electrode current collector and a solid electrolyte layer to form a Li-Mg-Al alloy layer containing Li-Al alloy particles are not particularly limited. For example, a Li-Mg-Al alloy layer containing Li-Al alloy particles is formed by charging and discharging at a predetermined current density for a predetermined time.

[0024] [Positive electrode] The positive electrode includes a positive electrode layer and, if necessary, a positive electrode current collector. The positive electrode layer contains a positive electrode active material, and may contain a solid electrolyte, a conductive material, a binder, a thickener, and the like, as necessary. The positive electrode layer may be formed by applying a positive electrode slurry to at least one surface of a support such as a positive electrode current collector and drying the coating. The positive electrode slurry contains a positive electrode active material and a solvent, and may also contain a solid electrolyte, a conductive material, a binder, a thickener, a solvent, and the like, as necessary. The method for applying the positive electrode slurry is not particularly limited, and examples thereof include a doctor blade method, a metal mask printing method, an electrostatic coating 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.

[0025] The positive electrode active material may be, for example, an oxide active material. 0.8 Co 0.15 Al 0.05 O2, LiCoO2, LiMnO2, LiNiO2, LiVO2, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiMn2O4, Li(Ni 0.5 Mn 1.5 )O4, LiFePO4, LiMnPO4, LiNiPO4, LiCuPO4, etc. The positive electrode active material may be 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. The content of the positive electrode active material in the positive electrode layer is not particularly limited, and may be 50.00 to 99.00 mass %.

[0026] At least a portion of the surface of the positive electrode active material may be coated with a lithium ion conductive compound. The lithium ion conductive compound may cover at least a part of the surface of the positive electrode active material, or may cover the entire surface of the positive electrode active material. Examples of lithium ion conductive compounds include B2O3, Li2B4O7, LiBPO4, Li3PO4, LiPO3, and LiNbO3. The thickness of the lithium ion conductive compound coating is, for example, 0.1 nm or more, and may be 1 nm or more. On the other hand, the thickness of the lithium ion conductive compound is, for example, 100 nm or less, and may be 20 nm or less. The coverage of the lithium ion conductive compound coating the positive electrode active material is, for example, 70% or more, and may be 90% or more, or even 100%. The method for coating the lithium ion conductive compound is not particularly limited, and any conventionally known method may be used as appropriate.

[0027] The solid electrolyte may be a solid electrolyte contained in a solid electrolyte layer, which will be described later. The content of the solid electrolyte in the positive electrode layer is not particularly limited.

[0028] Examples of conductive materials include carbon materials, metal particles, conductive polymers, etc. Examples of carbon materials include particulate carbon materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as carbon fibers, carbon nanotubes (CNT), and carbon nanofibers (CNF). The content of the conductive material in the positive electrode layer is not particularly limited.

[0029] Examples of binders include acrylonitrile butadiene rubber (ABR), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and styrene-butadiene rubber (SBR). The content of the binder in the positive electrode layer is not particularly limited.

[0030] Examples of thickeners include polysaccharides such as carboxymethyl cellulose (CMC) and methyl cellulose.

[0031] Examples of the solvent include an aqueous solvent and an organic solvent. The aqueous solvent refers to water or a mixed solvent containing water and a polar organic solvent. For example, an appropriate solvent can be selected depending on the types of the positive electrode active material, binder, etc. As the aqueous solvent, water is preferably used because of its ease of handling. Examples of polar organic solvents that can be used in the mixed solvent include alcohols such as methanol, ethanol, and isopropyl alcohol, ketones such as acetone, and ethers such as tetrahydrofuran. Examples of the organic solvent include 1,2,3,4-tetrahydronaphthalene, n-heptane, butyl butyrate, diisobutyl ketone, and N-methyl-2-pyrrolidone (NMP).

[0032] Examples of materials for the positive electrode current collector include metals such as aluminum, copper, SUS, and nickel. The thickness of the positive electrode current collector is, for example, 0.1 μm or more and 100 μm or less. The positive electrode current collector may be in the form of a sheet or the like. The positive electrode current collector may have a buffer layer, an elastic layer, or a PTC (Positive Temperature Coefficient) thermistor layer disposed on its surface.

[0033] [Solid electrolyte layer] The solid electrolyte layer includes at least a solid electrolyte. The thickness of the solid electrolyte layer is not particularly limited, but is usually 0.1 μm or more and 1 mm or less. As the solid electrolyte contained in the solid electrolyte layer, any known solid electrolyte that can be used in solid-state batteries can be appropriately used, and examples thereof include sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, etc. In order to prevent the positive electrode layer and the negative electrode layer from peeling off from the solid electrolyte layer, a relatively soft sulfide solid electrolyte may be used as the solid electrolyte.

[0034] Examples of sulfide solid electrolytes include solid electrolytes containing Li, M (where M is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In), and S. The sulfide solid electrolyte may further contain at least one of O and a halogen element. Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, LiX-Li2S-SiS2, LiX-Li2S-P2S5, LiX-Li2O-Li2S-P2S5, LiX-Li2S-P2O5, LiX-Li3PO4-P2S5, and Li3PS4. The term "Li2S-P2S5" above refers to a material obtained using a raw material composition containing Li2S and P2S5, and the same applies to other terms. Furthermore, the "X" in the LiX represents a halogen element. Examples of halogen elements include F, Cl, Br, and I. The raw material composition containing LiX may contain one or more types of LiX. When two or more types of LiX are contained, the mixing ratio of the two or more types is not particularly limited. 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.

[0035] The sulfide solid electrolyte may be a sulfide glass, a crystallized sulfide glass (glass ceramics), or a crystalline material obtained by a solid-phase reaction treatment of a raw material composition. The crystalline state of the sulfide solid electrolyte can be confirmed, for example, by subjecting the sulfide solid electrolyte to powder X-ray diffraction measurement using CuKα radiation.

[0036] Sulfide glass can be obtained by subjecting a raw material composition (e.g., a mixture of Li2S and P2S5) to amorphous processing, such as mechanical milling.

[0037] Glass ceramics can be obtained, for example, by heat treating sulfide glass. The heat treatment temperature may be any temperature higher than the crystallization temperature (Tc) of the sulfide glass observed by thermal analysis, and is usually 195° C. or higher. On the other hand, there is no particular upper limit to the heat treatment temperature. The crystallization temperature (Tc) of sulfide glass can be measured by differential thermal analysis (DTA). The heat treatment time is not particularly limited as long as it is a time that allows the desired crystallinity of the glass ceramic to be obtained, but is, for example, in the range of 1 minute to 24 hours, and particularly in the range of 1 minute to 10 hours. The heat treatment method is not particularly limited, but for example, a method using a firing furnace can be mentioned.

[0038] Examples of oxide solid electrolytes include substances having a garnet-type crystal structure containing Li, La, A (A is at least one of Zr, Nb, Ta, and Al), 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 PO 4-x Nx (1≦x≦3) etc. may also be used.

[0039] The halide solid electrolyte may be, for example, a solid electrolyte containing Li, M, and X (M represents at least one of Ti, Al, and Y, and X represents F, Cl, or Br).

[0040] The solid electrolyte may be in the form of particles from the viewpoint of ease of handling. The average particle size (D50) of the solid electrolyte particles is not particularly limited and may be from 1 nm to 100 μm.

[0041] The solid electrolyte may be used alone or in combination of two or more. 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 is, for example, 50% by mass or more, and may be in the range of 60% by mass to 100% by mass, 70% by mass to 100% by mass, or even 100% by mass. The solid electrolyte may contain less than 10% by mass of electrolytic solution relative to the total amount of electrolyte. The solid electrolyte may also be a composite solid electrolyte containing an inorganic solid electrolyte and a polymer electrolyte.

[0042] The solid electrolyte layer may contain a binder from the viewpoint of exhibiting plasticity, etc. Examples of such binders include the materials exemplified as the binders used in the positive electrode layer described above. However, in order to facilitate achieving high output, the binder content in the solid electrolyte layer may be 5 mass % or less from the viewpoint of preventing excessive aggregation of the solid electrolyte and enabling the formation of a solid electrolyte layer having a uniformly dispersed solid electrolyte.

[0043] The type of battery is not particularly limited, but examples thereof include a lithium ion battery. The battery may be a primary battery or a secondary battery. The battery may also be a solid-state battery. 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 battery, which is a solid battery containing a solid electrolyte and a liquid-based material, or an all-solid-state battery, which is a solid battery containing no liquid-based material. The shape of the battery is not particularly limited, and may be, for example, a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, or a laminate type. Examples of uses of the 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 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 battery may also be used as a power source for mobile objects other than vehicles (for example, trains, ships, and aircraft), and as a power source for electrical appliances such as information processing devices. [Example]

[0044] Example 1 [Positive electrode production] LiNi as a positive electrode active material 1 / 3 Co 1 / 3 Mn 1 / 3 The positive electrode slurry containing O2, a binder, and a solvent was applied to one side of an Al current collector foil as a positive electrode current collector and dried to obtain a positive electrode having a positive electrode layer on the positive electrode current collector. [Solid electrolyte layer fabrication] A mixture of a Li2S-P2S5-based material containing LiBr and LiI as a sulfide solid electrolyte, a binder, and a solvent was prepared. This mixture was coated onto a release film. The coated mixture was then dried. The release film was peeled off from the dried solid electrolyte thin film to obtain a solid electrolyte layer. [Negative electrode production] An Al material was prepared as a raw material for the modification layer. Using the Al material and a magnetron sputtering device, Al was deposited on one surface of the solid electrolyte layer to form an Al layer (ie, a modification layer) with a thickness of 100 nm. Using an electron beam evaporation apparatus, Mg was deposited on one surface of a Ni foil serving as a negative electrode current collector to form a 1000 nm thick Mg layer. A Ni foil having an Mg layer on one side was placed on the surface of the solid electrolyte layer where the Al layer was placed, so that the Mg layer was in contact with the Ni foil, thereby obtaining a negative electrode having an Mg layer and an Al layer on the negative electrode current collector. [Cell production] A positive electrode was placed on the surface of the solid electrolyte layer opposite to the surface on which the Al layer was placed, so that the solid electrolyte layer and the positive electrode layer were in contact with each other. These were then cold isostatically pressed (CIP) at 4 ton / cm. 2 The solid-state battery had a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, an Al layer, an Mg layer, and a negative electrode current collector in this order.

[0045] [Anode layer of solid-state battery] The solid-state battery was charged at 0.15 mA, and Li was deposited on the anode layer to form the structure during battery operation. The charged solid-state battery was cross-sectionally processed, and the anode layer was observed using a secondary electron microscope (SEM). The thickness of the negative electrode layer was confirmed. The type and concentration of contained metal species, the thickness of the Li-Mg-Al alloy layer, and the particle size of the Li-Al alloy particles were estimated from elemental mapping and spectral analysis of the negative electrode layer using an energy dispersive X-ray analyzer (EDX). This revealed that the negative electrode layer of Example 1 in the charged state contained Li-Al alloy particles in the Li-Mg-Al alloy layer. The cross section of the discharged solid-state battery was also processed in the same way, and the negative electrode layer was observed with a secondary electron microscope (SEM). The thickness of the Li-Mg-Al alloy layer and the particle size of the Li-Al alloy particles were as follows: <Charging status> Li-Mg-Al alloy layer thickness: 12.5 μm Li-Al alloy particle average particle size: 1.5μm <Discharge state> Li-Mg-Al alloy layer thickness: 2 μm Average particle size of Li-Al alloy particles: 1.5 μm (no change)

[0046] (Comparative Example 1) Except for not forming an Al layer in [Negative electrode preparation], a cell was prepared in the same manner as in Example 1. It was found that the negative electrode layer of Comparative Example 1 in the charged state contained a Li—Mg alloy layer.

[0047] (Comparative Example 2) Except for not forming the Mg layer in [Negative electrode preparation], a cell was prepared in the same manner as in Example 1. It was found that the negative electrode layer of Comparative Example 2 in the charged state contained a Li—Al alloy layer.

[0048] <Changes in Mg concentration near the solid electrolyte layer of the negative electrode> For the cells of Example 1 and Comparative Example 1, the change in Mg concentration near the solid electrolyte layer of the negative electrode layer after discharge relative to before discharge was calculated at a discharge capacity of 15% (SOC 77%) 20 minutes after the start of discharge at 25°C and a 0.4C rate. The results are shown in Table 1. "Near the solid electrolyte layer of the negative electrode layer" refers to a region of the negative electrode layer within a predetermined distance from the solid electrolyte layer. "Near the negative electrode current collector of the negative electrode layer" refers to a region of the negative electrode layer within a predetermined distance from the negative electrode current collector. The predetermined distance is less than half the thickness of the negative electrode layer.

[0049] [Table 1]

[0050] As shown in Table 1, in Example 1, the Mg concentration in the vicinity of the solid electrolyte layer of the negative electrode layer after discharge increased by 13.3% compared to before discharge. As shown in Table 1, in Comparative Example 1, the Mg concentration in the vicinity of the solid electrolyte layer of the negative electrode layer after discharge increased by 56.8% compared to before discharge. A partial increase in the Mg concentration near the solid electrolyte layer of the negative electrode layer causes an increase in resistance during discharge, so it is desirable for the Mg concentration to be uniform during discharge. It can be seen that Example 1 is able to suppress the increase in the Mg concentration after discharge more effectively than Comparative Example 1. The SEM images and backscattered electron images of Example 1 revealed that Al was scattered near the solid electrolyte layer of the anode layer and within the anode layer. The slight change in Mg concentration before and after discharge near the solid electrolyte layer of the anode layer is presumably due to the Li-Al alloy particles functioning as a buffer. Furthermore, a comparison of the Mg concentration immediately after discharge was stopped with that during relaxation 90 minutes after discharge was stopped revealed that the change in Mg concentration near the negative electrode current collector during relaxation was minor compared to that immediately after discharge was stopped, which is presumably due to the reduction in the diffusion paths for Mg due to the presence of Al.

[0051] [Discharge evaluation] For each cell of Example 1 and Comparative Examples 1 and 2, the discharge capacity at a high discharge rate (1C) was compared with that at a normal rate (0.2C). Current density of each cell: 0.6mA / cm 2 Discharge capacity at a current density of 3mA / cm when discharged at (0.2C) 2 The percentage of discharge capacity when discharged at (1 C) was calculated. The results are shown in Table 2.

[0052] [Table 2]

[0053] FIG. 3 is a graph showing the relationship between current density and discharge capacity for each cell of Example 1 (Mg, Al), Comparative Example 1 (Mg), and Comparative Example 2 (Al). As shown in FIG. 3 and Table 2, it is clear that Example 1 has a much improved discharge capacity at a high rate (1C) compared to Comparative Examples 1 and 2. In the present disclosure, it is understood that when two types of alloys, Mg and Al, are arranged in the negative electrode layer, the discharge rate characteristics are significantly improved compared to when only one type of alloy is arranged. [Explanation of symbols]

[0054] 10 Positive electrode current collector 20 Positive electrode layer 30 Solid electrolyte layer 40 Al layer 41 Li-Mg-Al alloy layer 50 Mg layer 51 Li-Al alloy particles 60 Negative electrode current collector 100 batteries 200 batteries

Claims

1. A battery comprising a positive electrode, a solid electrolyte layer, and a negative electrode in this order, the negative electrode includes a negative electrode current collector and a negative electrode layer in this order in a direction from the negative electrode toward the solid electrolyte layer, the negative electrode layer includes a Li—Mg—Al alloy layer, The negative electrode layer contains Li—Al alloy particles in the Li—Mg—Al alloy layer.

2. 2. The battery according to claim 1, wherein the Li-Al alloy particles have an average particle size of 1 μm or more and 3 μm or less.

3. The battery according to claim 1 , wherein the thickness of the negative electrode layer is 1 μm or more and 15 μm or less.

4. 10. The battery of claim 1, wherein the solid electrolyte layer comprises a sulfide solid electrolyte.

5. The battery of claim 1 , wherein the negative electrode current collector is a Ni foil.

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