RU2696596C1 - Anode and sulphide solid-state accumulator battery - Google Patents

Abstract

FIELD: electrical engineering.SUBSTANCE: invention relates to anode and sulphide solid-state accumulator battery using sulphide solid electrolyte. According to the invention, the anode comprises: a mixed anode layer and a current-collecting anode layer in contact with the mixed anode layer, wherein mixed anode layer contains active anode material and sulphide solid electrolyte, note here that, at least, surface of current-collector anode layer is made of material containing copper alloy and metal, its inclination to ionisation exceeds corresponding parameter of copper, at that surface is in contact with mixed anode layer.EFFECT: reduced reactivity of the current-collecting anode layer with respect to sulphide solid electrolyte.7 cl, 13 dwg, 8 ex

Description

FIELD OF TECHNOLOGY

[0001] The present invention relates to an anode and a sulfide solid state battery in which a sulfide solid electrolyte is used.

BACKGROUND

[0002] If the anode consists of a current-collecting anode layer made of copper and a mixed anode layer containing a sulfide solid electrolyte in a sulfide solid state battery containing an anode, cathode and solid electrolyte layer, then copper reacts with the sulfide solid electrolyte to form sulfide copper and other compounds, which increases the resistance at the interface between the collector anode layer and the mixed anode layer and leads to an irreversible reaction of copper sulfide with lithium ion with a subsequent decrease HAND battery capacity, which is a problem. Patent Document 1 provides, as one of the means of solving this problem, the formation of a reaction-inhibiting layer containing a predetermined element between the mixed anode layer and the collector anode layer.

[0003] Known technical means disclosed in patent document 2, such as a method for suppressing the reaction of an active material with a sulfide solid electrolyte in a sulfide solid state battery. However, this method is poorly suited to inhibiting the reaction of the current collector anode layer with a sulfide solid electrolyte.

List of links

Patent Literature

[0004] Patent Document 1: JP 2012-049023 A

Patent Document 2: JP 2011-060649 A

SUMMARY OF THE INVENTION

Technical challenge

[0005] A reaction-inhibiting layer must be added between the mixed anode layer and the current collecting anode layer in the technical solution disclosed in Patent Document 1, which raises the problems of the complex steps of manufacturing a battery and low specific energy per unit volume of the battery. Thus, the task is to suppress the reaction of the current collector anode layer with a sulfide solid electrolyte in the mixed anode layer without adding a special reaction inhibiting layer.

Solution to the problem

[0006] In this application, as one of the means for solving this problem, an anode is described comprising: a mixed anode layer and a current-collecting anode layer in contact with the mixed anode layer, wherein the mixed anode layer contains an active anode material and a sulfide solid electrolyte, moreover, at least the surface of the collector anode layer is made of a material containing an alloy of copper and metal, with an increased tendency to ionization compared to copper, and this surface is in contact with mixed node layer.

[0007] In the anode, in accordance with this disclosure, the alloy preferably contains copper and at least one element selected from zinc, beryllium and tin.

[0008] In the anode, in accordance with this disclosure, the alloy preferably contains copper and zinc.

[0009] In the anode, in accordance with this disclosure, the active anode material preferably contains silicon-based active material.

[0010] In the anode, in accordance with this disclosure, the tensile strength of the collector anode layer is preferably not less than 500 MPa.

[0011] In the anode, in accordance with this disclosure, the elongation after ruptures of the current-collecting anode layer of the anode is preferably at least 7.95%.

[0012] In this application, as one means of solving the problem, a sulfide solid state battery is disclosed, comprising: an anode according to the present invention; cathode; and a solid electrolyte layer disposed between the anode and cathode.

Beneficial effects of the invention

[0013] According to the latest experimental data obtained by the authors of the present invention, the electrochemical activity of the alloy of copper with a metal having an increased ionization tendency as compared to copper with respect to a sulfide solid electrolyte will be lower than in the case using copper alone. Even in the case of an electrochemical reaction of such an alloy with a sulfide solid electrolyte, it is believed that a metal with a higher ionization tendency than copper will react with a sulfide solid electrolyte earlier, which will suppress the formation of copper sulfide, which is a disadvantage in the charge / discharge reaction. Thus, the surface of the current collector anode layer is made of a material containing a preselected alloy, similar to the anode according to the present invention, which makes it possible to suppress the reaction of the current collector anode layer with a sulfide solid electrolyte in the mixed anode layer without adding a reaction inhibiting layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is an explanatory diagrammatic view of an embodiment of an anode 100;

In FIG. 2A to 2C are explanatory schematic views of the anode current collector 10;

In FIG. 3 is an explanatory diagrammatic view of the structure of a sulfide solid state battery 1000;

In FIG. 4 is an explanatory diagrammatic view of the structure of the analytical device used in the examples;

In FIG. 5 shows the result of cyclic voltammetry (CV) for comparative example 1;

In FIG. 6 shows the result of cyclic voltammetry (CV) for Example 1;

In FIG. 7 shows the result of cyclic voltammetry (CV) for Example 2;

In FIG. 8 shows the result of cyclic voltammetry (CV) for Example 3;

In FIG. 9 shows the result of cyclic voltammetry (CV) for comparative example 2;

In FIG. 10 is a comparative graph of the tensile strength of various types of copper alloy foil (Examples 1A - 3A and 1B - 3B) and copper foil (Comparative Examples 1A and 1B); and

In FIG. 11 is a comparative graph of elongation after tearing for various types of copper alloy foil (examples 1B to 3B) and copper foil (comparative examples 1A and 1B).

DETAILED DISCLOSURE OF OPTIONS FOR CARRYING OUT THE INVENTION

[0015] 1. Anode 100

The anode 100 comprises a mixed anode layer 20 and a collector anode layer 10 in contact with the mixed anode layer 20, as shown in FIG. 1. The mixed anode layer 20 contains the active anode material 21 and a sulfide solid electrolyte 22, as shown in FIG. 1. By at least, the surface of the current-collecting anode layer 10 in contact with the mixed anode layer 20 is made of a material 11 containing an alloy of copper and metal with an increased tendency to ionize compared to copper, as shown in figures 1 through 2C.

[0016] 1.1. Current Collecting Anode Layer 10

At least the surface of the current-collecting anode layer 10 in contact with the mixed anode layer 20 is made of material 11 containing an alloy of copper and metal with an increased tendency to ionization compared to copper. This makes it possible to suppress the reaction of the current-collecting anode layer 10 with sulfide solid electrolyte 22 in the mixed anode layer 20. It can be easily determined whether the surface of the current-collecting anode layer 10 is made of material 11 by performing an elementary analysis of the surface of the current-collecting anode layer 10, or in another similar way. Bismuth (Bi), antimony (Sb), lead (Pb), tin (Sn), nickel (Ni), cobalt (Co), cadmium (Cd) can be mentioned as a specific example of a metal with an increased tendency to ionize compared with copper. , iron (Fe), chromium (Cr), zinc (Zn), tantalum (Ta), manganese (Mn), zirconium (Zr), titanium (Ti), aluminum (Al), beryllium (Be), thorium (Th) , magnesium (Mg), sodium (Na), calcium (Ca), strontium (Sr), barium (Ba), potassium (K), rubidium (Rb), cesium (Cs) and lithium (Li). Among them, zinc (Zn), beryllium (Be) and tin (Sn) are preferred, and zinc (Zn) is most preferred. Thus, the alloy disclosed above may contain copper and at least one element selected from zinc, beryllium and tin, and may contain copper and zinc. The alloy disclosed above may contain only one metal with an increased tendency to ionize compared to copper, or two or more similar metals.

[0017] Any composition of an alloy of copper and metal with an increased tendency to ionization compared to copper can be used, and this composition can be appropriately determined taking into account the conductivity of the current-collecting anode layer 10, etc. For example, such an alloy preferably contains from 5 atom.% to 99 atom. % copper and from 1atom. % to 95 atom. % metal with a high tendency to ionization compared to copper (total concentration in the presence of two or more such metals in the alloy), more preferably, from 20 atom. % to 96atom. % copper and from 4 atom. % to 80atom. % metal with a high tendency to ionization compared to copper, even more preferably from 50 atom. % to 96 atom. % copper and from 4 atom. % to 50 atom. % metal with a high tendency to ionization compared to copper, particularly preferably from 65 atom. % to 96 atom. % copper and from 4 atom. % to 35 atom. % of a metal with an increased tendency to ionization compared to copper, if the total amount of copper and a metal with an increased tendency to ionization compared to copper is taken to be 100 atoms. % Such an alloy may contain minor impurities. The concentration of non-essential impurities in the alloy is preferably not more than 1 atom. %, if the entire alloy is taken equal to 100 atoms. %

[0018] The material 11 may contain other elements and components other than the alloy, due to contamination and other influence factors, provided that they do not interfere with the solution of the task. For example, a minor oxide film or the like may be formed. on a part of the surface of the current collecting anode layer 10. Thus, the material 11 may contain an insignificant amount of oxide and the like. In addition, the material 11 may contain moisture impurities. The material 11 may partially contain a metal with a lower tendency to ionization compared to copper, provided that this does not interfere with the solution of the problem. Preferably, the material 11 consists essentially of an alloy of copper and metal with an increased tendency to ionize compared with copper, based on the manifestation of a more significant effect.

[0019] At least the surface of the collector anode layer 10 in contact with the mixed anode layer 20 should be made only of material 11, and the collector anode layer 10 can take any form (form). From the material 11, only the surface of the current-collecting anode layer 10, or the surface and all the areas below it, can be made. For example, the current collector anode layer 10 may be a current collector anode layer 10a consisting of a foil or sheet material 11, as shown in FIG. 2A, and may be a current collector anode layer 10b made of a mesh material 11 or perforated metal sheet 11 as shown in figure 2B. The collector anode layers 10a and 10b can be easily obtained, for example, by shaping the material 11. Alternatively, the collector anode layer 10 can be a collector anode layer 10c, made by coating material 11 of the surfaces of the base material 12 made of other than material 11 , material using material 11, as shown in figure 2C. Thus, the surface and the inner part of the collector anode layer 10 can be made of various materials. The current collecting anode layer 10c can be easily obtained, for example, by applying a thin layer of material 11 by electrodeposition, sputtering, or another similar method to the surface of the base material 12. The base material 12 must provide mechanical strength and durability as a current collecting anode layer 10c. For example, the base material 12 may consist of a metal different from the material 11, or a material different from the metal (in particular resin).

[0020] The thickness of the current-collecting anode layer 10 is not limited and may correspond to the thickness of the current-collecting anode layer of a conventional anode, that is, it is preferably, for example, from 0.1 μm to 1 mm, more preferably from 1 μm to 100 μm. According to the experimental data obtained by the authors of the present invention, at least the surface of the current collector anode layer 10 in contact with the mixed anode layer 20 is made of material 11, which makes it possible to suppress the reaction of the current collector anode layer 10 with sulfide solid electrolyte 22 in the mixed anode layer 20 regardless of the thickness of the collector anode layer 10. At least a portion of the surface of the collector anode layer 10 in contact with the sulfide solid electrolyte 22 can be made of m Material 11.

[0021] A variant is possible in which the mixed anode layer 20 is rolled with a high-pressure roll together with the current collector anode layer 10 in order to increase the fill factor of the mixed anode layer 20 in the manufacture of the anode 100. Moreover, ruptures of the current collector anode layer 10 in the roller press are preferably suppressed from the point of view of productivity, etc. For example, to prevent ruptures of the current collector anode layer in a roller press, the option of thickening the current collector anode layer is effective. In this case, however, the thickened current collector anode layer 10 of the anode 100 reduces the specific energy per unit volume of the battery. Therefore, ruptures of the current collector anode layer 10 in the roller press are preferably prevented by the smallest possible thickening of the current collector anode layer 10 of the anode.

[0022] According to new experimental data obtained by the authors of the present invention, the collector anode layer 10, having a given mechanical strength, can prevent tearing of this layer on the anode 100 in a roller press. In particular, the tensile strength of the collector anode layer 10 is preferably not less than 500 MPa. Alternatively, the current-collecting anode layer 10 is more preferably made of a metal foil, the tensile strength of which is at least 500 MPa. The lower limit of the ultimate tensile strength is more preferably not less than 600 MPa, most preferably not less than 800 MPa. The upper limit of the ultimate strength has not been specifically established. The collector anode layer 10 having such a tensile strength can be easily obtained, for example, by selecting the alloy composition for the collector anode layer 10 or strain hardening the collector anode layer 10. If the collector anode layer, which has undergone strain hardening, will be subjected to additional heat treatment, for example , annealing, the tensile strength of the collector anode layer will decrease.

The term "tensile strength of the current-collecting anode layer" in the framework of the present invention is understood to mean the tensile strength measured according to JIS Z 2241: 2011, using the current-collecting anode layer (for example, metal foil) as a prototype.

[0023] According to new experimental data obtained by the authors of the present invention, ruptures of the collector anode layer 10 on the anode 100 in the roller press can be avoided if the elongation after ruptures (in percent) of the collector anode layer 10 is not lower than a predetermined value. In particular, the elongation after ruptures of the collector anode layer 10 is preferably at least 7.95%. In an alternative embodiment, the collector anode layer 10, more preferably, is made of metal foil, the elongation of which after breaking is at least 7.95%. In a more preferred embodiment, the lower limit of elongation after breaks is at least 14%. The current collector anode layer 10 with similar elongation after breaks can be easily obtained, for example, by selecting the alloy composition for the current collector anode layer 10.

By “elongation after ruptures of the current collector anode layer”, as used herein, is meant elongation after rupture, measured according to JIS Z 2241: 2011, using the current collector anode layer (eg, metal foil) as a prototype.

[0024] 1.2. Mixed anode layer 20

The mixed anode layer 20 contains an active anode material 21 and a sulfide solid electrolyte 22, as shown in FIG. 1. The mixed anode layer 20 contains a sulfide solid electrolyte 22, which leads to contact between a portion of the surface of the collector anode layer 10 in contact with the mixed anode layer 20, and a sulfide solid electrolyte 22. The mixed anode layer 20 may further comprise a conductive additive, a binder, and other additives (e.g., a thickener).

[0025] Any material known as an anode active material for a sulfide solid state battery can be used as an anode active material 21 contained in a mixed anode layer 20. Among the known active materials, a material having a lower anode material can be used. charging and discharging potential compared to the active cathode material 41. As an example, silicon-based active materials, for example, Si, Si alloys, and silicon oxide, can be mentioned. tions; carbon based active materials, for example graphite and solid carbon; various oxide-based active materials, for example lithium titanate; lithium metal and lithium alloys. One conductive additive can be used alone, or two or more conductive additives can be mixed to be used as the active anode material 21. The shape of the active anode material 21 is not limited and preferably corresponds, for example, to the shape of particles or a thin film. The content of the active anode material 21 in the mixed anode layer 20 is not limited and may correspond to the content in a conventional mixed anode layer.

[0026] There is a risk of the reaction of copper with a sulfide solid electrolyte during OCV (open circuit voltage) of a silicon-based active material in a conventional anode if, for the manufacture of the anode, a mixed anode layer containing silicon-based active material and a sulfide solid electrolyte is deposited on the surface current collector anode layer made of copper. Thus, there is a risk of the reaction of the current collector anode layer with a sulfide solid electrolyte in the mixed anode layer immediately after the formation of the mixed anode layer on the surface of the current collector anode layer. In contrast, the anode 100 according to the present invention allows to suppress the reaction of the current-collecting anode layer 10 with a sulfide solid electrolyte 22 in the mixed anode layer 20 even if a mixed anode layer 20 containing silicon-based active material is applied to form the anode 100, and sulfide solid electrolyte, since the surface of the collector anode layer 10 in contact with the mixed anode layer 20 is made of material 11. That is, a favorable effect can be achieved in ano de 100 according to the present invention, even if the active anode material 21 contains an active material based on silicon.

[0027] Any known sulfide used to make a solid electrolyte of a sulfide solid state battery can be used to produce a sulfide solid electrolyte 22 contained in the mixed anode layer 20. As an example, solid electrolytes containing Li, P and S as constituents can be mentioned. elements. Particular examples of the above include: Li ₂ SP ₂ S ₅ , Li ₂ S-SiS ₂ , LiI-Li ₂ S-SiS ₂ , LiI-Si ₂ SP ₂ S ₅ , LiI-LiBr-Li ₂ SP ₂ S ₅ , LiI- Li ₂ SP ₂ S ₅ , LiI-Li ₂ O-Li ₂ SP ₂ S ₅ , LiI-Li ₂ SP ₂ O ₅ , LiI-Li ₃ PO ₄ -P ₂ S ₅ and Li ₂ SP ₂ S ₅ -GeS ₂ . In particular, in a more preferred embodiment, a sulfide solid electrolyte containing Li ₂ SP ₂ S _{5 is used} . As the sulfide solid electrolyte 22, one of these components or a mixture of two or more of these components can be used. The form of the sulfide solid electrolyte 22 is not particularly limited and, for example, may be in the form of particles. The content of sulfide solid electrolyte 22 in the mixed anode layer 20 is not particularly limited and may correspond to the content in a conventional mixed anode layer.

[0028] The mixed anode layer 20, in addition to the sulfide solid electrolyte 22, may contain an inorganic solid electrolyte other than sulfide solid electrolyte 22, provided that it does not interfere with the desired effect. As an example, oxide solid electrolytes can be mentioned.

[0029] Any known conductive additive used in sulfide solid state batteries can be used for the conductive additive contained in the mixed anode layer 20 as an additional component. Examples of such additives include carbon materials, in particular acetylene carbon black (AC), Ketjenblack carbon black (KB), vapor-grown carbon fiber (UVPF), carbon nanotubes (CNTs), carbon nanofibers (CNFs) and graphite; and metallic materials, in particular nickel, aluminum and stainless steel. Carbon materials are particularly preferred. One conductive additive may be used alone, or two or more conductive additives may be mixed for use as a conductive additive. The shape of the conductive additive is not particularly limited and preferably corresponds, for example, to the shape of particles or fibers. The content of the conductive additive in the mixed anode layer 20 is not particularly limited and may correspond to the content in a conventional mixed anode layer.

[0030] Any known binder used in sulfide solid state batteries can be used to produce a binder contained in the mixed anode layer 20 as an additional component. Styrene-butadiene rubber (SBC), carboxymethyl cellulose (CMC), acrylonitrile butadiene rubber (ANB), butadiene rubber (BK), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE) and polytetrafluoroethylene are examples of examples. You can use one binder separately, or two or more binders in a mixture. The content of the binder in the mixed anode layer 20 is not limited and may correspond to the content in a conventional mixed anode layer.

[0031] An anode 100 having the structure disclosed above can be easily obtained by performing processes such as depositing and mixing the active anode material 21, a solid sulfide electrolyte 22, a conductive additive, a binder, and other optional additives in a non-aqueous solvent to obtain the electrode composition in the form of a suspension, and the subsequent application of the obtained electrode composition to the surface of the collector anode layer 10, drying the surface and, optionally, pressing the collector anode layer 1 0. The anode 100 can be made not only in a similar wet manner, but also, for example, by compression molding in a dry process. After the above formation of the mixed anode layer 20 in the form of a sheet on the surface of the collector anode layer 10, the thickness of the mixed anode layer 20 is, for example, preferably from 0.1 μm to 1 mm, more preferably from 1 μm to 100 μm.

[0032] 2. Sulphide solid state battery 1000

3 schematically shows the structure of a sulfide solid state battery 1000. The sulfide solid state battery 1000 comprises an anode 100 according to the present invention, a cathode 200 and a solid electrolyte layer 300 disposed between the anode 100 and the cathode 200. The solid electrolyte layer 300 is in contact with the mixed anode layer 20 100 and the mixed cathode layer 40 of the cathode 200. The terminals, battery compartment, etc. are not shown in FIG. 3. Although the structure of the cathode 200 and the solid electrolyte layer 300 in the sulfide solid state battery 1000 is obvious, below will be given one example of it.

[0033] 2.1. Cathode 200

The cathode 200 comprises a mixed cathode layer 40 and a collector cathode layer 30 in contact with the mixed cathode layer 40, as shown in FIG. 3.

[0034] 2.1.1. Current Collecting Cathode Layer 30

The collector cathode layer 30 may consist of a metal foil, a metal mesh and other, in a particularly preferred embodiment, a metal foil. As an example of the metal from which the current collector cathode layer 30 can be composed, stainless steel, nickel, chromium, gold, platinum, aluminum, iron, titanium and zinc can be mentioned. The collector cathode layer 30 may be a metal foil or base material, the surface of which is coated with a metal, as disclosed above, or on the surface of which a metal is deposited, as described above. The thickness of the current collecting cathode layer 30 is not particularly limited and is, for example, preferably from 0.1 μm to 1 mm, more preferably from 1 μm to 100 μm.

[0035] 2.1.2. Current Collecting Cathode Layer 40

The collector cathode layer 40 contains the active cathode material 41, as shown in FIG. 3. The mixed cathode layer 40 may further comprise a solid electrolyte 42, a conductive additive, a binder, and other additives (for example, a thickener).

[0036] Any known cathode active material for use in a sulfide solid state battery can be used as cathode active material 41 contained in the mixed cathode layer 40. Among the known active materials, a material having a higher noble charge and discharge potential can be used. in comparison with the active anode material 21. As an example of the active cathode material 41, lithium-containing oxides, in particular lithium cobaltate, nickel lithium elate, Li (Ni, Mn, Co) O ₂ (Li _{1 + b} Ni _1/3 Mn _1/3 Co _1/3 O ₂ ), lithium manganate, spinel and lithium oxide composite, lithium titanate and lithium phosphate (LiMPO ₄ , where M is at least one substance selected from the group consisting of Fe, Mn, Co and Ni). You can use one conductive additive alone or two or more conductive additives in the mixture as the cathode active material 41. The surface of the active cathode material 41 may be coated with lithium niobate, lithium titanate, lithium phosphate or the like. The shape of the active cathode material 41 is not specifically limited and preferably corresponds, for example, to the shape of particles or a thin film. The content of the active cathode material 41 in the mixed cathode layer 40 is not limited and may correspond to the content in a conventional mixed cathode layer.

[0037] Any known sulfide solid electrolyte of a sulfide solid state battery can be used as solid electrolyte 42 contained in the mixed cathode layer 40 as an additional component. For example, in a preferred embodiment, a sulfide solid electrolyte is used, as disclosed above. An inorganic solid electrolyte other than a sulfide solid electrolyte may be contained in addition to a sulfide solid electrolyte if the desired effect is achieved. The form of solid electrolyte 42 is essentially not limited and may be, for example, in the form of particles. The content of solid electrolyte 42 in the mixed cathode layer 40 is not particularly limited and may correspond to the content in a conventional mixed cathode layer.

[0038] Any known conductive additive used in sulfide solid state batteries can be used to produce the conductive additive contained in the mixed cathode layer 40 as an additional component. Examples of such additives include carbon materials, in particular acetylene carbon black (AC), Ketjenblack carbon black (KB), vapor-grown carbon fiber (UVPF), carbon nanotubes (CNTs), carbon nanofibers (CNFs) and graphite; and metallic materials, in particular nickel, aluminum and stainless steel. Carbon materials are particularly preferred. One conductive additive may be used alone, or two or more conductive additives may be mixed for use as a conductive additive. The shape of the conductive additive is not limited, and preferably corresponds, for example, to the shape of the particles. The content of the conductive additive in the mixed cathode layer 40 is not limited and may correspond to the content in a conventional mixed cathode layer.

[0039] Any known binder used in sulfide solid state batteries can be used to produce a binder contained in the mixed cathode layer 40 as an additional component. Examples include styrene-butadiene rubber (SBK), carboxymethyl cellulose (CMC), acrylonitrile butadiene rubber (ANB), butadiene rubber (BC), polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). You can use one binder separately, or two or more binders in a mixture. The binder content in the mixed cathode layer 40 is not specifically limited and may correspond to the content in a conventional mixed cathode layer.

[0040] A cathode 200 having the structure described above can be easily manufactured by performing processes such as depositing and mixing the cathode active material 41, solid electrolyte 42, a binder, a conductive additive, and other optional additives in a non-aqueous solvent to obtain the composition of the electrode in the form of a suspension, and subsequent application of the obtained electrode composition to the surface of the current collector cathode layer 30, drying the surface and, possibly, pressing the current collector cathode layer 30. The cathode 200 It is made to be not similar only wet but also, for example, by press molding under a dry method. After forming the mixed cathode layer 40 in the form of a sheet on the surface of the collector cathode layer 30 described above, the thickness of the mixed cathode layer 40 is, for example, preferably from 0.1 μm to 1 mm, more preferably from 1 μm to 100 μm.

[0041] 2.2. Layer 300 solid electrolyte

The solid electrolyte layer 300 is designed to isolate the anode 100 from the cathode 200 and conduct lithium ion between the anode 100 and the cathode 200. The solid electrolyte layer 300 contains at least solid electrolyte 51. Preferably, the solid electrolyte layer 300 contains a binder.

[0042] 2.2.1. Solid electrolyte

The solid electrolyte 51 contained in the solid electrolyte layer 300 can be appropriately selected from a number of solid electrolytes that can be contained in the mixed anode layer 20 and the mixed cathode layer 40. In particular, a sulfide solid electrolyte is preferred, a sulfide solid electrolyte containing Li is more preferred. ₂ SP ₂ S ₅ . You can use one separately, or two or more in a mixture can be used as solid electrolyte 51. Solid electrolyte 51 can have a normal shape, that is, the shape of particles. The content of solid electrolyte 51 in the solid electrolyte layer 300 is not particularly limited and can be appropriately determined in accordance with the required battery capacity. For example, the solid electrolyte content is preferably not less than 90 wt.%, More preferably not less than 95 wt.%, If the entire solid electrolyte layer 300 is taken to be 100 wt.%.

[0043] 2.2.2. Binder

Preferably, the solid electrolyte layer 300 contains a binder. A binder, which may be included in the solid electrolyte layer 300, is well known. For example, the binder can be appropriately selected from a number of binders that can be included in the mixed anode layer 20 and the mixed cathode layer 40 of the cathode.

[0044] A solid electrolyte layer 300 having the structure described above can be easily made by performing processes such as introducing and mixing the solid electrolyte 51, optionally containing a binder and other additives, into a non-aqueous solvent to obtain a suspension of the electrolyte and then applying this electrolyte composition to the surface of the base material (or to the surface of the mixed anode layer 20 or to the surface of the mixed cathode layer 40), drying the surfaces and, alternatively , Pressing the base material. The solid electrolyte layer 300 can be made not only in a similar wet manner, but also, for example, by compression molding in a dry process. The thickness of the solid electrolyte layer 300 is, for example, preferably from 0.1 μm to 1 mm, more preferably from 1 μm to 100 μm, when the solid electrolyte layer 300 is formed as a sheet as described above.

[0045] 2.3. Other components

All components of a sulfide solid state battery 1000 need not be solids. The sulfide solid state battery 1000 may partially contain liquids, for example, an electrolyte solution, provided that this does not reduce the battery performance.

[0046] For example, a sulfide solid state battery 1000 having the structure disclosed above can be manufactured as follows: that is, a method for manufacturing a sulfide solid state battery 1000 comprises a step of manufacturing an anode 100, a cathode 200 and a solid electrolyte layer 300 according to the methods described above, as well as a layering step an anode 100, a cathode 200, and a solid electrolyte layer 300. Sulphide solid state battery 1000 can be made, for example, by layering the anode 100, the solid electrolyte layer 300 and the cathode 200, as described above, to form laminate and seal the laminate in the battery case after attaching appropriate terminals and other elements.

Examples

[0047] 1. Assessment of the reactivity of the current collector anode layer with respect to a sulfide solid electrolyte

As shown in FIG. 4, a layer made of a sulfide solid electrolyte (with the main component Li ₂ SP ₂ S ₅ ) (thickness: 450 μm) is sandwiched between pre-selected metal foil and In-Li foil (thickness: 80 μm), and the metal foil and the In-Li foil are connected to a power source to evaluate the reactivity of the metal foil with respect to the sulfide solid electrolyte using cyclic voltammetry (CV). In the examples and comparative examples, the following types of metal foil were used.

[0048] Comparative Example 1 ... 10 μm thick copper (Cu) foil

Example 1 ... a foil of a copper-beryllium alloy (CuBe) with a thickness of 10 μm, copper: beryllium = 88 atom.%: 12 atom. %

Example 2 ... a foil of copper-zinc alloy (CuZn) with a thickness of 10 μm, copper: zinc = 65 atom.%: 35 atom.%

Example 3 ... a foil of copper-tin alloy (CuSn) (with traces of phosphorus (P) as an impurity) 10 μm thick, copper: tin = 96 atom.%: 3 atom.%

Comparative example 2 ... a foil of copper-silver alloy (CuAg) with a thickness of 50 μm, copper: silver = 81 atom.%: 19 atom.%.

[0049] Figures 5 to 9 show the results of cyclic voltammetry (CV) for examples and comparative examples. FIG. 5 corresponds to comparative example 1, FIG. 6 corresponds to example 1, FIG. 7 corresponds to example 2, FIG. 8 corresponds to example 3 and FIG. 9 corresponds to comparative example 2. Values plotted on the vertical axis according to FIG. 5 are 100 times higher than those in FIG. 6-8. It can be said that the electrochemical reaction activity with respect to the sulfide solid electrolyte was high, since the current density (vertical axis) in FIG. 5 - 9 varies widely.

[0050] As is evident from the results shown in FIG. 5, in comparative example 1 using copper foil as a metal foil, it was found that the current density in cyclic voltammetry (CV) varied widely, and the electrochemical reaction activity of the copper foil with respect to to sulfide solid electrolyte was high.

[0051] On the contrary, as is evident from the results shown in figures 6-8, for examples 1-3 using a foil of an alloy of copper and metal with an increased tendency to ionization compared to copper (beryllium, zinc or tin), it was found that current density in cyclic voltammetry (CV) varied within narrow limits, and the electrochemical reaction activity of the alloy foil with respect to the sulfide solid electrolyte was low (about a thousandth of the level of comparative example 1). In particular, it turned out that the electrochemical reactivity of the alloy foil with respect to the sulfide solid electrolyte in Example 2 (a copper and zinc alloy foil) was further reduced.

[0052] In addition, from the results shown in figures 6-8, it follows that the reaction of the alloy foil with a sulfide solid electrolyte proceeded difficult, even in the case of repeating cyclic voltammetry (CV) in examples 1-3. That is, it is assumed that although the alloy reacted with the sulfide solid electrolyte on the surface of the alloy foil in contact with the sulfide solid electrolyte, it was difficult to move the reaction of the alloy with the sulfide solid electrolyte deeper into the alloy foil. Thus, it is believed that at least the surface of the foil in contact with the sulfide solid electrolyte is made of a material containing a preselected alloy, which ensures a sufficient effect regardless of the thickness of the foil.

[0053] As is apparent from the results shown in FIG. 9, it was found that the reaction of the alloy foil with a sulfide solid electrolyte cannot be suppressed in comparative example 2 using a copper-metal alloy foil with a reduced tendency to ionize compared to copper (silver), in contrast to examples 1 to 3.

[0054] Beryllium, zinc and tin are indicated in examples 1-3 as metals with an increased tendency to ionization compared to copper. It is believed that the present invention will give the same effect if another metal is used as a metal with an increased tendency to ionize compared to copper. Examples of metals other than beryllium, zinc and tin include bismuth (Bi), antimony (Sb), lead (Pb), nickel (Ni), cobalt (Co), cadmium (Cd), iron (Fe), chromium (Cr), tantalum (Ta), manganese (Mn), zirconium (Zr), titanium (Ti), aluminum (Al), thorium (Th), magnesium (Mg), sodium (Na), calcium (Ca), strontium (Sr), barium (Ba), potassium (K), rubidium (Rb), cesium (Cs) and lithium (Li).

[0055] Copper-based alloys having predetermined compositions are disclosed in Examples 1-3. The composition of the copper-based alloy of the present invention is not particularly limited. Such a composition can be appropriately determined in accordance with the characteristics of the battery that must be provided, taking into account the reactivity with respect to the sulfide solid electrolyte, the electrical conductivity as the current collector layer of the anode, etc.

[0056] 2. Assessment of the mechanical strength of the collector layer of the anode

2.1. Tensile strength

A solution of butyl butyrate and 5 wt.% PVDF-based binder (manufactured by Kureha Corporation), silicone (manufactured by Kojundo Chemical Laboratory Co., Ltd., average particle diameter of 5 μm (D ₅₀ )) as an anode active material, and a sulfide solid electrolyte placed in a vessel made of polypropylene, and mixed with an ultrasonic dispersion device (UH-50, manufactured by SMT Corporation) for 30 seconds. After that, the vessel was shaken in a mixer (TTM-1 manufactured by Sibata Scientific Technology Ltd.) for 30 minutes, and its contents were again mixed with an ultrasonic dispersion device for 30 seconds. The vessel was then shaken in a mixer for 3 minutes to obtain a suspension of the anode mixture. Sheets of metal foil, characterized by different tensile strengths, were coated with the resulting suspension of the anode mixture using an applicator in accordance with the blade method. After air drying, the metal foil was dried on a hot plate at 100 ° C for 30 minutes to form a mixed anode layer on the metal foil. After that, the solid electrolyte layer and the mixed cathode layer formed by coating were layered on the mixed anode layer by transfer, then rolled by rolling at maximum linear pressure (linear pressure: 5 t / cm) at a feed rate of 0.5 m / min s the purpose of increasing the fill factor of the electrode housing obtained by transfer (mixed anode layer + solid electrolyte layer + mixed cathode layer), and obtain the required battery properties.

[0057] In this case, the presence or absence of tears in the rolled metal foil was confirmed. It was found that the anode can be made without gaps in the metal foil, regardless of the composition of the metal foil, if a metal foil was used having a tensile strength of at least 500 MPa, which was measured in accordance with JIS Z 2241: 2011.

[0058] Tensile tests were performed on various types of copper alloy foil and copper foil in accordance with JIS Z 2241: 2011 with a measurement of tensile strength as follows. The results are shown in FIG. ten.

[0059] Comparative Example 1A ... Rolled Copper (Cu) Foil 10 μm Thick

 Comparative Example 1B ... High Strength Copper (Cu) Foil (SEED, Manufactured by Nippon Denkai, Ltd.) About 10 μm Thick, Fine Grained to Increase Metal Strength

Example 1A ... foil of copper-beryllium alloy (CuBe) 10 μm thick, copper: beryllium = 88 atom.%: 12 atom.%, Strain hardened, without hardening after strain hardening

Example 1B ... a foil of a copper-beryllium alloy (CuBe) 10 μm thick, copper: beryllium = 88 atom.%: 12 atom.%, Strain hardened, quenched after strain hardening

Example 2A ... copper-zinc alloy (CuZn) foil with a thickness of 10 μm, copper: zinc = 65 atom%: 35 atom%, strain hardened, without hardening after strain hardening

Example 2B ... copper-zinc alloy (CuZn) foil 10 μm thick, copper: zinc = 65 atom%: 35 atom%, strain hardened, quenched after strain hardening

Example 3A ... a copper-tin alloy (CuSn) foil (with traces of phosphorus (P) as an impurity) 10 μm thick, copper: tin = 96 atom%: 3 atom%, strain hardened, without quenching after strain hardening

Example 3B ... copper-tin alloy (CuSn) foil (with traces of phosphorus (P) as an impurity) 10 μm thick, copper: tin = 96 atom%: 3 atom%, strain hardened, quenched after strain hardening

[0060] The tensile strength of a metal foil, even having the same composition and the same thickness, may vary depending on whether the foil was subjected to mechanical or thermal treatment (annealing), as shown in FIG. 10. It was found that the copper alloy foil in accordance with Examples 1-3 was a material having such a potential that its tensile strength significantly exceeds 500 MPa, as shown in FIG. 10, and it is able to adequately withstand roller pressing in the manufacture of the anode. Thus, it can be said that the alloy constituting the current collecting anode layer preferably contains copper and at least one element selected from zinc, beryllium and tin.

[0061] 2.2. Elongation after breaks

The mixed anode layer is formed on the surface of the metal foil in the same way as in the analysis of the tensile strength, after which it was subjected to roller pressing at a maximum linear pressure (5 t / cm) and a feed rate of 0.5 m / min, which allows to increase the coefficient filling the mixed anode layer while maintaining the material properties of the mixed anode layer.

[0062] In this case, the presence or absence of tears in the rolled metal foil was confirmed. It was found that the anode can be manufactured without tearing the metal foil, regardless of the composition of the metal foil, even if the tensile strength of the metal foil was below 500 MPa, even if the roller pressing was carried out at a linear pressure of 5 t / cm and speed feed 0.5 m / min, and the metal foil with an elongation after breaks of at least 7.95% was measured in accordance with JIS Z 2241: 2011.

[0063] The values of elongation after tearing on the same copper alloy foil as in examples 1B and 3B, and the same copper foil as in comparative examples 1A and 1B, were measured in accordance with JIS Z 2241: 2011. Results presented in FIG. 11. It was found that the elongation after tearing of the copper alloy foil described by Examples 1B and 3B significantly exceeded 7.95%, while the tensile strength was below 500 MPa, as shown in Figures 10 and 11, and the foil from the copper alloy according to examples 1B and 3B was sufficiently able to withstand the pressure of the roller press during the manufacture of the anode.

[0064] As described above, it has been found that the current collector anode layer preferably satisfies at least one of the following requirements (1) and (2), which makes it possible to prevent tearing of the current collector anode layer in the roller press in the manufacture of the anode:

(1) the tensile strength of the current-collecting anode layer is at least 500 MPa; and

(2) the elongation after ruptures of the collector anode layer is at least 7.95%.

Industrial applicability

[0065] The sulfide solid state battery containing the anode according to the present invention is preferably suitable for use as a power source in a wide range, in particular as a compact power source for portable devices and a large on-board power source.

List of Reference Items

[0066] 100 anode

10 current collector anode layer

20 mixed anode layer

200 cathode

30 current collector cathode layer

40 mixed cathode layer

300 layer solid electrolyte

1000 sulfide solid state battery

Claims (14)

1. Anode containing: mixed anode layer; and current collecting anode layer in contact with the mixed anode layer, wherein the mixed anode layer contains an active anode material and a sulfide solid electrolyte, and at least the surface of the current-collecting anode layer is made of a material containing an alloy of copper and metal with an increased tendency to ionize compared to copper, wherein said surface is in contact with the mixed anode layer. 2. The anode according to claim 1, in which the alloy contains copper and at least one element selected from zinc, beryllium and tin. 3. The anode of claim 1, wherein the alloy contains copper and zinc. 4. The anode according to any one of paragraphs. 1-3, in which the active anode material contains an active material based on silicon. 5. The anode according to any one of paragraphs. 1-3, in which the tensile strength of the slip ring anode layer is at least 500 MPa. 6. The anode according to any one of paragraphs. 1-3, in which the elongation after ruptures of the collector anode layer is at least 7.95%. 7. Sulfide solid state battery containing: the anode according to any one of paragraphs. 1-3; cathode; and a layer of solid electrolyte located between the anode and cathode.

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