Cathode Materials and Batteries

Abstract

A positive electrode material 1000 according to the present disclosure contains a material 100 which is represented by composition formula (1) and a carbon material 101 which is capable of adsorbing at least one substance that is selected from the group consisting of elemental halogens and halides.　Formula (1): LiaMbXc In the formula, each of a, b and c represents a number larger than 0; M includes at least one element that is selected from the group consisting of metal elements other than Li and semimetal elements; and X includes a halogen element.

Description

[Technical Field]

[0001] The present disclosure relates to positive electrode materials for batteries and batteries. [Background technology]

[0002] Patent Document 1 discloses a battery using a positive electrode containing a lithium-containing metal oxide and a negative electrode containing a carbon material.

[0003] Patent Document 2 discloses a solid electrolyte material containing lithium, yttrium, and a halogen. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 1989293 [Patent Document 2] International Publication No. 2018 / 025582 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides novel positive electrode materials. [Means for solving the problem]

[0006] In one embodiment of the present disclosure, the positive electrode material is A material represented by the following composition formula (1), a carbon material capable of occluding at least one selected from the group consisting of a halogen element and a halide; Includes. Li a M b X c ...Equation (1) where a, b, and c are each a value greater than 0, M includes at least one selected from the group consisting of metal elements and metalloid elements other than Li, X includes a halogen element. [Effects of the Invention]

[0007] According to the present disclosure, a novel positive electrode material can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of a positive electrode material according to the first embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing a schematic configuration of a battery according to the second embodiment. [Figure 3] FIG. 3 is a graph showing the charge / discharge curves of the batteries of Examples 1, 2 and 3. [Figure 4] FIG. 4 is a graph showing the charge / discharge curves of the batteries of Reference Examples 1 and 2. [Figure 5] FIG. 5 is a graph showing the charge / discharge curves of the batteries of Examples 4, 5, 6 and 7. [Figure 6] FIG. 6 is a graph showing the charge / discharge curves of the batteries of Examples 4, 8 and 9. [Figure 7] FIG. 7 is a graph showing cyclic voltammograms of the batteries of Examples 9 and 10 and Reference Example 2. [Figure 8] FIG. 8 is a graph showing the results of Raman spectroscopy measurements of the positive electrode material of the battery of Example 11 before, after, and after a charge test. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Summary of one aspect of the present disclosure) The positive electrode material according to the first aspect of the present disclosure is A material represented by the following composition formula (1), a carbon material capable of occluding at least one selected from the group consisting of a halogen element and a halide; Includes. Li a M b X c ...Equation (1) where a, b, and c are each a value greater than 0, M includes at least one selected from the group consisting of metal elements and metalloid elements other than Li, X includes a halogen element.

[0010] According to the first aspect, a novel positive electrode material can be provided. In a battery containing this positive electrode material, charge / discharge reactions proceed via a new mechanism. This positive electrode material is suitable for improving the output of the battery.

[0011] In the second aspect of the present disclosure, for example, in the positive electrode material according to the first aspect, in the Raman spectrum of the carbon material, -1 More than 1700cm -1 Intensity of peaks appearing within the range I G For 1300cm -1 More than 1400cm -1 Intensity of peaks appearing within the range I D Ratio of I D / I G may be 0 or more and 2 or less. According to the second embodiment, the carbon material can more easily occlude an elemental halogen or a halide.

[0012] In a third aspect of the present disclosure, for example, in the positive electrode material according to the first or second aspect, the BET specific surface area of ​​the carbon material is 5 m 2 g -1 According to the third aspect, the area where the carbon material and the material represented by composition formula (1) are in contact with each other is large. This allows the current density of a battery containing the positive electrode material to be improved. Furthermore, the carbon material can more easily occlude a halogen atom or a halide.

[0013] In a fourth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to third aspects, the carbon material may include at least one selected from the group consisting of graphite, graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, fullerene, carbon fiber, carbon black, soft carbon, hard carbon, mesoporous carbon, and activated carbon.

[0014] In a fifth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to third aspects, the carbon material may include at least one selected from the group consisting of carbon black, vapor-grown carbon fiber, and graphene.

[0015] In a sixth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to fifth aspects, M may include Y.

[0016] In a seventh aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to fifth aspects, the M may include Y and Zr.

[0017] In an eighth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to seventh aspects, the X may include at least one selected from the group consisting of Cl and Br.

[0018] According to the fourth to eighth aspects, a battery including the positive electrode material has better charge / discharge characteristics.

[0019] A battery according to a ninth aspect of the present disclosure includes: a positive electrode comprising the positive electrode material according to any one of the first to eighth aspects; a negative electrode; an electrolyte layer disposed between the positive electrode and the negative electrode; It is equipped with:

[0020] According to the ninth aspect, in the battery, the charge / discharge reaction proceeds by a new mechanism. The battery tends to have a high output.

[0021] In a tenth aspect of the present disclosure, for example, in the battery according to the ninth aspect, the negative electrode may contain a negative electrode active material capable of absorbing lithium.

[0022] In an eleventh aspect of the present disclosure, for example, in the battery according to the ninth or tenth aspect, the negative electrode may contain at least one selected from the group consisting of metallic lithium, a lithium alloy, metallic indium, an indium alloy, a carbon material, silicon, a silicon alloy, silicon oxide, and lithium titanate.

[0023] According to the tenth or eleventh aspect, the battery has better charge / discharge characteristics.

[0024] In a twelfth aspect of the present disclosure, for example, in the battery according to any one of the ninth to eleventh aspects, the electrolyte layer may contain a solid electrolyte material, and the composition of the solid electrolyte material may be different from the composition of the material represented by composition formula (1).

[0025] In a thirteenth aspect of the present disclosure, for example, in the battery according to any one of the ninth to twelfth aspects, the electrolyte layer may contain a sulfide solid electrolyte.

[0026] According to the twelfth or thirteenth aspect, the battery has better charge / discharge characteristics.

[0027] In a fourteenth aspect of the present disclosure, for example, in the battery according to any one of the ninth to thirteenth aspects, the halogen element contained in the material represented by composition formula (1) may be oxidized during charging to produce at least one selected from the group consisting of a halogen element and a halide, and the halogen element contained in the at least one selected from the group consisting of a halogen element and a halide may be reduced during discharging. According to the fourteenth aspect, in the battery, charge and discharge reactions proceed by a new mechanism.

[0028] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0029] (Embodiment 1) FIG. 1 is a cross-sectional view showing a schematic configuration of a positive electrode material 1000 according to Embodiment 1.

[0030] The positive electrode material 1000 includes a material 100 and a carbon material 101 represented by the following compositional formula (1). The material 100 may be a material known as a halide solid electrolyte. In this specification, the material 100 may be referred to as a "halide material". Li a M b X c ···Formula (1) Here, a, b, and c are each values greater than 0. a, b, and c may satisfy a + b < c. M includes at least one selected from the group consisting of metal elements and metalloid elements other than Li. X includes a halogen element. The halogen element includes at least one selected from the group consisting of, for example, F, Cl, Br, and I.

[0031] In the present disclosure, the "metalloid element" is B, Si, Ge, As, Sb, and Te. The "metal element" is all elements included in Groups 1 to 12 of the periodic table excluding hydrogen, and all elements included in Groups 13 to 16 of the periodic table excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se. That is, the "metalloid element" or "metal element" is a group of elements that can become cations when forming a halogen compound and an inorganic compound.

[0032] The carbon material 101 can occlude at least one element selected from the group consisting of a halogen element and a halide. In this specification, "the carbon material occludes" means that the carbon material 101 takes in an element other than carbon from outside the carbon material 101 and retains the element on the surface or inside the carbon material 101. Furthermore, the carbon material 101 can release at least one element selected from the group consisting of the occluded halogen element and a halide. "The carbon material releases" means that the other element occluded in the carbon material 101 is released from the carbon material 101.

[0033] The above-mentioned configuration allows for the realization of a novel cathode material. Furthermore, this cathode material allows for the realization of a battery in which the charge / discharge reaction proceeds via a mechanism different from that of conventional lithium-ion batteries. Note that the halide material does not need to contain sulfur.

[0034] Patent Document 1 discloses a lithium-ion battery using a positive electrode containing a lithium-containing metal oxide, a negative electrode containing a carbon material, and a nonaqueous organic electrolyte solution as the electrolyte. In the battery of Patent Document 1, lithium ions are desorbed from the lithium-containing positive electrode oxide during charging. These lithium ions are solvated in the electrolyte solution and diffuse into the electrolyte solution. The lithium ions diffused into the electrolyte solution are absorbed into the carbon material.

[0035] Patent Document 2 discloses a solid electrolyte material having a composition represented by Li3YBr6. In this solid electrolyte material, halogens are strongly attracted to yttrium. This allows the solid electrolyte material to exhibit high ionic conductivity. In Patent Document 2, the ionic conductivity of the solid electrolyte material is utilized for charging and discharging a battery.

[0036] As a result of extensive investigation, the present inventors have found that Li a M b X cThe researchers have newly discovered that by using a positive electrode material that combines a material represented by the formula (I) with a carbon material that can occlude at least one element selected from the group consisting of a halogen and a halogen compound, it is possible to fabricate a battery that is capable of reversible charging and discharging using a mechanism different from that of conventional batteries.

[0037] The charge and discharge of a battery containing the positive electrode material of this embodiment is carried out according to the following mechanism. First, when the battery is charged, the halogen element contained in the material 100 is oxidized. At this time, lithium ions are released from the material 100 for charge compensation. The oxidation of the halogen element produces at least one selected from the group consisting of an elemental halogen and a halide. The elemental halogen is, for example, a compound represented by X2. The halide is, for example, MX d Here, d is the same value as the valence of M. The generated halogen or halide is absorbed into the carbon material 101. For example, lithium ions migrate through the electrolyte layer in the battery and are absorbed into the negative electrode. Next, when the battery is discharged, the lithium ions absorbed in the negative electrode are released from the negative electrode. The lithium ions migrate through the electrolyte layer to the positive electrode. At the positive electrode during discharge, the halogen or halide is reduced with the acceptance of electrons. Specifically, the halogen element contained in at least one selected from the group consisting of halogens and halides is reduced. The reduced halogen or halide reacts with the lithium ions migrated from the negative electrode and is released from the carbon material 101. Material 100 represented by composition formula (1) suppresses changes in the internal structure of the positive electrode during battery charge and discharge. For example, the generation of voids inside the positive electrode during battery charge is suppressed. This is presumably what allows reversible charge and discharge reactions to proceed in the battery. In this embodiment, the material 100 and the carbon material 101 can function as a positive electrode active material.

[0038] In lithium-ion batteries, rapid exchange of electrons and lithium ions between the active material and the electrolyte is necessary for lithium desorption or insertion at the positive and negative electrodes. For example, in the positive electrode, electrons and lithium ions are exchanged at a three-phase interface formed by the positive electrode active material, the conductive additive, and the electrolyte. The positive electrode active material is, for example, an oxide that stores lithium ions. The conductive additive, for example, has the function of assisting electron conduction. The electrolyte, for example, is contained in an electrolytic solution or an electrolyte layer and can transport lithium ions. In the positive electrode active material of a lithium-ion battery, electrons are conducted by, for example, hopping conduction through metal-oxygen-metal bonds. In this case, the electron conductivity of the positive electrode active material is significantly affected by the electronic state of the metal ions contained in the positive electrode active material. For example, if the valence of the metal ions is uniform within the positive electrode active material, the electronic conductivity of the positive electrode active material decreases. That is, the electronic conductivity of the positive electrode active material decreases at the end of charging or discharging the battery.

[0039] In a positive electrode containing the positive electrode material of this embodiment, electrons and lithium ions are exchanged at a two-phase interface formed by, for example, a carbon material 101 having high electronic conductivity and a material 100 having high ionic conductivity. That is, charge / discharge reactions proceed using the two-phase interface. Therefore, the positive electrode material of this embodiment is suitable for improving the current density of a battery.

[0040] In the Raman spectrum of carbon material 101, 1500 cm -1 More than 1700cm -1 Intensity of peaks appearing within the range I G For 1300cm -1 More than 1400cm -1 Intensity of peaks appearing within the range I D Ratio of I D / I G is, for example, between 0 and 2.

[0041] According to the above configuration, the carbon material 101 can more easily occlude a simple halogen or a halide.

[0042] The Raman spectrum of the carbon material 101 can be obtained by, for example, laser Raman spectroscopy. -1 More than 1400cm -1 The peaks that appear in the following range are, for example, the sp of carbon. 3 1500cm -1 More than 1700cm -1 The peaks that appear in the following range are, for example, the sp of carbon. 2 Therefore, the ratio I D / I G The lower the ratio I, the more π electrons the carbon material 101 has. When a battery including the positive electrode material 1000 of this embodiment is charged, the generated halogen or halide tends to be attracted to the π electrons of the carbon material 101. D / I G The lower the valence ratio, the easier the carbon material 101 can occlude an elemental halogen or a halide.

[0043] Ratio I D / I G may be 0 or more and 1.6 or less, 0 or more and 1.1 or less, 0 or more and 0.5 or less, or 0 or more and 0.1 or less.

[0044] According to the above configuration, the carbon material 101 can more easily occlude a simple halogen or a halide.

[0045] The BET specific surface area of ​​the carbon material 101 is, for example, 5 m 2 g -1 The BET specific surface area of ​​the carbon material 101 can be determined by, for example, the BET (Brunauer-Emmett-Teller) method using nitrogen gas adsorption. The larger the BET specific surface area of ​​the carbon material 101, the larger the area in which the carbon material 101 and the material 100 are in contact with each other. When the BET specific surface area of ​​the carbon material 101 is 5 m 2 g -1When the BET specific surface area of ​​the carbon material 101 is larger, the current density of a battery containing the positive electrode material 1000 tends to be improved. The larger the BET specific surface area of ​​the carbon material 101, the more easily the carbon material 101 tends to occlude a halogen atom or a halide. Furthermore, the above configuration can realize a battery with better charge / discharge characteristics.

[0046] The BET specific surface area of ​​carbon material 101 is 10m 2 g -1 It can be larger, 14m 2 g -1 It can be larger, up to 40m 2 g -1 It may be more than 100m 2 g -1 The upper limit of the BET specific surface area of ​​the carbon material 101 is not particularly limited, and may be, for example, 1000 m 2 g -1 is.

[0047] The above configuration tends to improve the current density of a battery containing the positive electrode material 1000. Furthermore, the above configuration makes it possible to realize a battery with better charge / discharge characteristics.

[0048] The shape of the carbon material 101 is not particularly limited and may be, for example, particulate. In the present disclosure, "particulate" includes needle-like, scale-like, spherical, and ellipsoidal shapes. When the carbon material 101 is particulate (for example, spherical), the median diameter of the carbon material 101 is not particularly limited and may be 0.001 μm or more and 100 μm or less. When the median diameter of the carbon material 101 is 0.001 μm or more, the carbon material 101 and the material 100 can be well dispersed in the positive electrode material 1000. This can improve the charge / discharge characteristics of a battery including the positive electrode material 1000. When the median diameter of the carbon material 101 is 100 μm or less, the lithium diffusion rate within the carbon material 101 increases. This can enable the battery to operate at high power.

[0049] The median diameter of the carbon material 101 may be smaller than 10 μm, smaller than 8 μm, 5 μm or less, 3 μm or less, or 1 μm or less. The lower limit of the median diameter of the carbon material 101 may be 0.01 μm.

[0050] According to the above configuration, a battery having better charge / discharge characteristics can be realized.

[0051] The median diameter of the carbon material 101 may be larger than the median diameter of the material 100, which will be described later. This allows the carbon material 101 and the material 100 to be well dispersed.

[0052] In this specification, the median diameter means the particle diameter (d50) corresponding to 50% cumulative volume, determined from the particle size distribution measured on a volume basis by a laser diffraction scattering method.

[0053] The carbon material 101 includes, for example, at least one selected from the group consisting of graphite, graphene, graphene oxide, reduced graphene oxide (RGO), carbon nanotubes (CNT), fullerene, carbon fiber, carbon black (CB), soft carbon (easily graphitizable carbon), hard carbon (non-graphitizable carbon), mesoporous carbon, and activated carbon. The graphite may be natural graphite or artificial graphite such as highly oriented pyrolytic graphite (HOPG). The carbon fiber may include, for example, vapor-grown carbon fiber. The carbon black may be acetylene black (AB) or ketjen black (KB). The carbon material may include at least one selected from the group consisting of carbon black, vapor-grown carbon fiber, and graphene.

[0054] According to the above configuration, a battery having better charge / discharge characteristics can be realized.

[0055] The content rate of the carbon material 101 in the positive electrode material 1000 is not particularly limited, and may be 1% by weight or more, 5% by weight or more, 10% by weight or more, or 15% by weight or more. The upper limit value of the content rate of the carbon material 101 is not particularly limited, and is, for example, 40% by weight. The higher the content rate of the carbon material 101, the more likely the battery including the positive electrode material 1000 is to have a large discharge capacity.

[0056] M in the composition formula (1) may contain Y, or may contain Y and Zr.

[0057] According to the above configuration, a battery having better charge-discharge characteristics can be realized.

[0058] X in the composition formula (1) may contain at least one selected from the group consisting of Cl and Br, or may contain both Cl and Br.

[0059] According to the above configuration, a battery having better charge-discharge characteristics can be realized.

[0060] In the composition formula (1), a, b, and c may satisfy 1 ≤ a ≤ 5, 0 < b ≤ 2, and 5.5 ≤ c ≤ 6.5, or may satisfy 1.5 ≤ a ≤ 4.5, 0.5 ≤ b ≤ 1.5, and c = 6. a, b, and c may satisfy the relationship a + mb = c. Here, m is the valence of M. When M contains a plurality of types of elements, mb is the sum of the values obtained by multiplying the composition ratio of each element by the valence of the element. For example, when M contains element M1 and element M2, the composition ratio of element M1 is b1, the valence of element M1 is m1, the composition ratio of element M2 is b2, and the valence of element M2 is m2, then mb = m1b1 + m2b2. When there are multiple possible valences for element M, the above relational expression only needs to be satisfied when those possible valences are used as m.

[0061] The shape of the material 100 is not particularly limited, and may be, for example, particulate. When the material 100 is particulate (for example, spherical), the median diameter of the material 100 may be 100 μm or less. When the median diameter of the material 100 is 100 μm or less, the material 100 and the carbon material 101 can form a well-dispersed state in the positive electrode material 1000. This improves the charge / discharge characteristics of the battery. The median diameter of the material 100 may be 10 μm or less.

[0062] The content of material 100 in positive electrode material 1000 is not particularly limited and may be 30% by weight or more, or 50% by weight or more. The upper limit of the content of material 100 may be 95% by weight, 90% by weight, or 85% by weight.

[0063] The positive electrode material 1000 may further contain other materials in addition to the material 100 and the carbon material 101. Examples of other materials include a positive electrode active material, a binder, and a conductive additive.

[0064] Examples of the positive electrode active material include lithium-containing transition metal oxides, transition metal fluorides, polyanion materials, fluorinated polyanion materials, transition metal sulfides, transition metal oxysulfides, and transition metal oxynitrides. Examples of the lithium-containing transition metal oxides include Li(NiCoAl)O2, Li(NiCoMn)O2, and LiCoO2. In particular, when a lithium-containing transition metal oxide is used as the positive electrode active material, the average discharge voltage of the battery can be improved.

[0065] The positive electrode active material may contain lithium nickel cobalt manganese oxide as the lithium-containing transition metal oxide. For example, the positive electrode active material may be Li(NiCoMn)O2. According to the above configuration, the positive electrode material 1000 can further improve the energy density and charge / discharge efficiency of the battery.

[0066] The binder is used to improve the adhesion between particles and the binding of materials constituting the positive electrode when a positive electrode is produced from the positive electrode material 1000. Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose. Copolymers of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene can also be used as binders. Mixtures of two or more materials selected from these materials can also be used as binders.

[0067] The conductive additive can be used to improve the electronic conductivity of the positive electrode material 1000. Examples of conductive additives that can be used include conductive fibers such as metal fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyacetylene, polyaniline, polypyrrole, and polythiophene. The conductive polymer compounds are suitable for improving the electronic conductivity and plasticity of a positive electrode formed from the positive electrode material 1000.

[0068] The content of other materials in the positive electrode material 1000 is not particularly limited and may be 50% by weight or less, 30% by weight or less, 10% by weight or less, or 5% by weight or less. The positive electrode material 1000 may be substantially free of other materials. In particular, the positive electrode material 1000 may be substantially free of a positive electrode active material as the other material. In other words, the positive electrode material 1000 may consist essentially of the material 100 and the carbon material 101. "Consisting essentially of" means excluding other components that alter the essential characteristics of the referenced material. However, the positive electrode material 1000 may contain impurities in addition to the material 100 and the carbon material 101.

[0069] The cathode material 1000 may include a plurality of particles of material 100, a plurality of particles of carbon material 101, and a plurality of particles of cathode active material.

[0070] <Method for producing the material represented by composition formula (1)> In the first embodiment, the material 100 can be produced, for example, by the following method.

[0071] First, raw material powders of binary halides are prepared in a ratio appropriate for the desired composition. A binary halide is a compound consisting of two elements, including a halogen element. For example, to produce Li3YCl6, raw material powders of LiCl and YCl3 are prepared in a molar ratio of 3:1.

[0072] In this case, the elements "M" and "X" in the above composition formula (1) are determined by the type of raw material powder. The values ​​of "a", "b", and "c" in the above composition formula (1) are determined by the type of raw material powder, the compounding ratio, and the synthesis process.

[0073] After the raw material powders are thoroughly mixed, they are mixed, pulverized, and reacted with each other using a mechanochemical milling method. After the raw material powders are thoroughly mixed, they may be sintered in a vacuum.

[0074] These methods result in a material 100 containing crystalline phases with the compositions described above.

[0075] The constitution of the crystalline phase (crystalline structure) in the material 100 is determined by the reaction method and reaction conditions between the raw material powders.

[0076] (Embodiment 2) The following describes the second embodiment. Explanations that overlap with the first embodiment will be omitted as appropriate.

[0077] FIG. 2 is a cross-sectional view showing a schematic configuration of a battery 2000 according to the second embodiment.

[0078] The battery 2000 includes a positive electrode 201 , an electrolyte layer 202 , and a negative electrode 203 .

[0079] The positive electrode 201 includes the positive electrode material 1000 in the first embodiment described above.

[0080] The electrolyte layer 202 is disposed between the positive electrode 201 and the negative electrode 203 .

[0081] According to the above configuration, the charge / discharge reaction proceeds by a new mechanism in the battery 2000. Furthermore, an increase in the reaction overvoltage of the battery 2000 can be suppressed.

[0082] In the positive electrode 201, the volume ratio "v1:100-v1" of the carbon material 101 to the material 100 may satisfy 5≦v1≦95. v1 represents the volume ratio of the carbon material 101 when the total volume of the carbon material 101 and the material 100 contained in the positive electrode 201 is defined as 100. When v1 satisfies 5≦v1, a sufficient energy density of the battery can be ensured. When v1 satisfies v1≦95, the battery can operate at high output.

[0083] The thickness of the positive electrode 201 may be 5 μm or more and 500 μm or less. When the thickness of the positive electrode 201 is 5 μm or more, a sufficient energy density of the battery can be ensured. When the thickness of the positive electrode 201 is 500 μm or less, the battery can operate at high output.

[0084] The electrolyte layer 202 is a layer containing an electrolyte material. The electrolyte material contained in the electrolyte layer 202 is, for example, a solid electrolyte material. That is, the electrolyte layer 202 may be a solid electrolyte layer.

[0085] Examples of the solid electrolyte material contained in the electrolyte layer 202 include a halide solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte. The electrolyte layer 202 may include a sulfide solid electrolyte.

[0086] The composition of the solid electrolyte material contained in the electrolyte layer 202 may be the same as the composition of the material 100 of the cathode material 1000 in the above-described embodiment 1. That is, the electrolyte layer 202 may contain the material 100 in the above-described embodiment 1 as the solid electrolyte material.

[0087] According to the above configuration, the output density and charge / discharge characteristics of the battery can be further improved.

[0088] The composition of the solid electrolyte material contained in the electrolyte layer 202 may be different from the composition of the material 100 of the cathode material 1000 in the above-described embodiment 1. The electrolyte layer 202 may contain, as the solid electrolyte material, a halide solid electrolyte having a composition different from that of the material 100 in the above-described embodiment 1.

[0089] According to the above configuration, the charge and discharge characteristics of the battery can be further improved.

[0090] Sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, and Li 3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12 These sulfide solid electrolytes include LiX, LiO, MO q , Li p MOq or the like may be added. Here, X is at least one selected from the group consisting of F, Cl, Br, and I. M is at least one selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn. p and q are each a natural number.

[0091] According to the above configuration, the electrolyte layer 202 contains a sulfide solid electrolyte with excellent reduction stability, so low-potential materials such as graphite and metallic lithium can be used as the negative electrode material, thereby improving the energy density of the battery.

[0092] Examples of oxide solid electrolytes include NASICON-type solid electrolytes, such as LiTi2(PO4)3 and its elemental substitution products, (LaLi)TiO3-based perovskite-type solid electrolytes, and Li 14 ZnGeO 16 , Li4SiO4, LiGeO4 and their element-substituted LISICON-type solid electrolytes, Li7La3Zr2O 12 Garnet-type solid electrolytes, such as those typified by LiN and its element substitution products, LiN and its H-substituted products, LiPO and its N-substituted products, and glasses or glass ceramics based on Li-BO compounds such as LiBO and LiBO, to which LiSO, LiCO, etc. are added, can be used.

[0093] As the polymer solid electrolyte, for example, a compound of a polymer compound and a lithium salt can be used. The polymer compound may have an ethylene oxide structure. A polymer compound having an ethylene oxide structure can contain a large amount of lithium salt. Therefore, the ionic conductivity of the electrolyte layer 202 can be further increased. As the lithium salt, LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), LiC(SO2CF3)3, etc. can be used. One lithium salt selected from the exemplified lithium salts can be used alone. A mixture of two or more lithium salts selected from the exemplified lithium salts can also be used.

[0094] As the complex hydride solid electrolyte, for example, LiBH4-LiI and LiBH4-P2S5 can be used.

[0095] The electrolyte layer 202 may contain a solid electrolyte material as a main component, i.e., the electrolyte layer 202 may contain the solid electrolyte material in an amount of, for example, 50 wt % or more based on the weight of the entire electrolyte layer 202.

[0096] According to the above configuration, the charge and discharge characteristics of the battery can be further improved.

[0097] The electrolyte layer 202 may contain a solid electrolyte material in an amount of, for example, 70% by weight or more based on the weight of the entire electrolyte layer 202.

[0098] According to the above configuration, the charge and discharge characteristics of the battery can be further improved.

[0099] The electrolyte layer 202 contains a solid electrolyte material as a main component, and may further contain unavoidable impurities, starting materials used in synthesizing the solid electrolyte material, by-products, decomposition products, and the like.

[0100] The electrolyte layer 202 may contain a solid electrolyte material in an amount of, for example, 100 wt % in terms of weight percentage relative to the entire electrolyte layer 202, excluding unavoidable impurities.

[0101] According to the above configuration, the charge and discharge characteristics of the battery can be further improved.

[0102] As described above, the electrolyte layer 202 may be made substantially of only a solid electrolyte material.

[0103] The electrolyte layer 202 may contain two or more of the materials listed as solid electrolyte materials. For example, the electrolyte layer 202 may contain a halide solid electrolyte and a sulfide solid electrolyte.

[0104] The thickness of the electrolyte layer 202 may be 1 μm or more and 300 μm or less. When the thickness of the electrolyte layer 202 is 1 μm or more, the positive electrode 201 and the negative electrode 203 can be more reliably separated. When the thickness of the electrolyte layer 202 is 300 μm or less, the battery can operate at high power.

[0105] The electrolyte layer 202 may have a multilayer structure in which two or more layers having different compositions are stacked together. For example, the electrolyte layer 202 may have a layer containing a halide solid electrolyte and a layer containing a sulfide solid electrolyte stacked together.

[0106] According to the above configuration, a battery having better charge / discharge characteristics can be realized.

[0107] The negative electrode 203 includes a material capable of absorbing and releasing metal ions (e.g., lithium ions). The negative electrode 203 includes, for example, a negative electrode active material. Specifically, the negative electrode 203 may include a negative electrode active material capable of absorbing lithium. This configuration makes it possible to realize a battery with better charge / discharge characteristics.

[0108] The negative electrode active material may be a metal material, a carbon material, an oxide, a nitride, a tin compound, a silicon compound, or the like. The metal material may be a simple metal. The metal material may be an alloy. Examples of the metal material include metallic lithium and lithium alloys. Examples of the carbon material include natural graphite, coke, partially graphitized carbon, carbon fiber, spherical carbon, artificial graphite, and amorphous carbon. From the viewpoint of the capacity density of the battery, silicon (Si), tin (Sn), silicon compounds, and tin compounds may be used.

[0109] The negative electrode 203 may contain, as a negative electrode active material, at least one selected from the group consisting of metallic lithium, a lithium alloy, metallic indium, an indium alloy, a carbon material, silicon, a silicon alloy, silicon oxide, and lithium titanate.

[0110] According to the above configuration, a battery having better charge / discharge characteristics can be realized.

[0111] The negative electrode 203 may contain a solid electrolyte material. The solid electrolyte material contained in the negative electrode 203 may be any of the solid electrolyte materials exemplified as materials constituting the electrolyte layer 202. With the above configuration, the lithium ion conductivity inside the negative electrode 203 can be improved, and the battery can operate at high power.

[0112] The shape of the negative electrode active material is not particularly limited and may be, for example, particulate. When the negative electrode active material is particulate (for example, spherical), the median diameter of the negative electrode active material may be 0.1 μm or more and 100 μm or less. When the median diameter of the negative electrode active material is 0.1 μm or more, the negative electrode active material and the solid electrolyte material can form a well-dispersed state in the negative electrode 203. This improves the charge / discharge characteristics of the battery. When the median diameter of the negative electrode active material is 100 μm or less, the diffusion rate of lithium in the negative electrode active material increases. This allows the battery to operate at high power.

[0113] The median diameter of the negative electrode active material may be larger than the median diameter of the solid electrolyte material in the negative electrode 203. This allows the negative electrode active material and the solid electrolyte material to be well dispersed.

[0114] In the negative electrode 203, the volume ratio "v2:100-v2" of the negative electrode active material to the solid electrolyte material may satisfy 30≦v2≦95. v2 represents the volume ratio of the negative electrode active material when the total volume of the negative electrode active material and the solid electrolyte material contained in the negative electrode 203 is defined as 100. When v2 satisfies 30≦v2, a sufficient energy density of the battery can be ensured. When v2 satisfies v2≦95, the battery can operate at high output.

[0115] The thickness of the negative electrode 203 may be 10 μm or more and 500 μm or less. When the thickness of the negative electrode 203 is 10 μm or more, a sufficient energy density of the battery can be ensured. When the thickness of the negative electrode 203 is 500 μm or less, the battery can operate at high output.

[0116] At least one selected from the group consisting of the electrolyte layer 202 and the negative electrode 203 may contain a binder to improve adhesion between particles. The binder is used, for example, to improve the binding property of the material constituting the negative electrode 203. As the binder, for example, the binder described above for the positive electrode material 1000 can be used.

[0117] The negative electrode 203 may contain a conductive additive to improve electronic conductivity. Examples of the conductive additive contained in the negative electrode 203 include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black and ketjen black, conductive fibers such as carbon fiber and metal fiber, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene. Using a carbon conductive additive as the conductive additive can reduce costs.

[0118] The shape of the battery 2000 may be coin type, cylindrical type, square type, sheet type, button type, flat type, laminated type, or the like. [Example]

[0119] The present disclosure will be described in detail below using examples, but the present disclosure is not limited to the following examples.

[0120] Example 1 [Preparation of material represented by composition formula (1)] LiCl, YCl3, and YBr3 were weighed as raw material powders in a molar ratio of LiCl:YCl3:YBr3 = 3.000:0.333:0.666 in an argon atmosphere with a dew point below -60°C. These raw material powders were ground and mixed in a mortar. The resulting mixture was then fired at 500°C for 3 hours in an argon atmosphere. An electric furnace was used for firing. The fired product was then pulverized using a pestle and mortar. This yielded a powder of the material represented by composition formula (1). In this specification, the material obtained by the above method may be referred to as LYBC.

[0121] [Preparation of cathode material] In an argon atmosphere with a dew point of -60°C or less, powder of the material represented by composition formula (1) and powder of a carbon material were weighed in a mass ratio of 92.6:7.4. Graphite with a median diameter of 3 μm was used as the carbon material. Next, these materials were mixed in an agate mortar to prepare a positive electrode material.

[0122] [Battery construction] In an insulating outer cylinder, the sulfide solid electrolyte Li6PS5Cl, LYBC powder, and the positive electrode material were layered in this order. The weight of Li6PS5Cl was 60 mg, the weight of LYBC was 20 mg, and the weight of the positive electrode material was 5 mg. Next, a pressure of 720 MPa was applied to these materials to obtain a solid electrolyte layer and a first electrode, which was the positive electrode.

[0123] Next, metal In foil and metal Li foil were laminated on the surface of the solid electrolyte layer opposite to the surface in contact with the first electrode, and a pressure of 80 MPa was applied to these metal foils to produce a laminate consisting of the first electrode, the solid electrolyte layer, and the second electrode (negative electrode).

[0124] Next, a current collector made of stainless steel was placed on each of the positive and negative electrodes, and a current collecting lead was attached to each of the current collectors. Next, an insulating ferrule was used to isolate and seal the inside of the insulating outer cylinder from the outside atmosphere, thereby producing a battery of Example 1.

[0125] [Charge / discharge test] A charge / discharge test was performed on the battery of Example 1 using the following method. First, the battery was placed in a thermostatic chamber set to 25°C. The battery was charged at a constant current of 0.05 mA. Charging was continued until the battery voltage reached 4.0 V. Next, the battery was discharged at a current of 0.05 mA. Discharging was continued until the battery voltage reached 1.9 V.

[0126] Example 2 A battery of Example 2 was fabricated in the same manner as in Example 1, except that the positive electrode material was prepared using a powder of the material represented by composition formula (1) and a powder of a carbon material in a mass ratio of 83.0:17.0. Furthermore, a charge-discharge test was performed on the battery of Example 2 in the same manner as in Example 1.

[0127] Example 3 A battery of Example 3 was fabricated in the same manner as in Example 1, except that the positive electrode material was prepared using a powder of the material represented by composition formula (1) and a powder of a carbon material in a mass ratio of 76.5:23.5. Furthermore, a charge-discharge test was performed on the battery of Example 3 in the same manner as in Example 1.

[0128] Example 4 Except for using acetylene black as the carbon material in the preparation of the positive electrode material, the battery of Example 4 was prepared in the same manner as in Example 1. Furthermore, a charge-discharge test was carried out on the battery of Example 4 in the same manner as in Example 1.

[0129] Example 5 A battery of Example 5 was produced in the same manner as in Example 1, except that carbon black was used as the carbon material in producing the positive electrode material. Furthermore, a charge-discharge test was carried out on the battery of Example 5 in the same manner as in Example 1.

[0130] Example 6 A battery of Example 6 was produced in the same manner as in Example 1, except that vapor grown carbon fiber (VGCF (registered trademark)) was used as the carbon material in producing the positive electrode material. Furthermore, a charge-discharge test was carried out on the battery of Example 6 in the same manner as in Example 1.

[0131] Example 7 Except for using graphene as the carbon material in the preparation of the positive electrode material, the battery of Example 7 was prepared by the same method as in Example 1. Furthermore, a charge-discharge test was performed on the battery of Example 7 by the same method as in Example 1.

[0132] Example 8 The battery of Example 8 was fabricated using the same method as in Example 4, except that Li3YBr6 was used as the material represented by composition formula (1) in the preparation of the positive electrode material. In Example 8, a battery for use in a charge-discharge test and a battery for use in cyclic voltammetry measurements, which will be described later, were prepared. Li3YBr6 was fabricated using the following method. First, LiBr and YBr3 were weighed as raw material powders in an argon glove box with a dew point of −60°C or lower, in a molar ratio of LiBr:YBr3 = 3:1. Next, the mixture of these raw material powders was milled for 25 hours using a planetary ball mill (Fritsch, Model P-7) at a rotational speed of 600 rpm. This resulted in Li3YBr6 powder. In this specification, Li3YBr6 may also be referred to as LYB. Furthermore, a charge-discharge test was performed on the battery of Example 8 using the same method as in Example 1.

[0133] The battery of Example 8 was also subjected to cyclic voltammetry (CV) measurement by the following method. First, the battery was placed in a thermostatic chamber set at 25°C. The battery was connected to a potentiogalvanostat and CV measurement was performed. In the CV measurement, the sweep rate was set to 10 mV / s. The scan range was set from 4.0 V to 1.9 V vs. In-Li.

[0134] Example 9 In the preparation of the positive electrode material, the material represented by the composition formula (1) is Li 2.7 Y 1.1 The battery of Example 9 was fabricated in the same manner as in Example 4, except that Cl6 was used. In Example 9, a battery to be used in a charge-discharge test and a battery to be used in a CV measurement were prepared. 2.7 Y 1.1 Cl6 was produced by the following method. First, in an argon glove box with a dew point of -60°C or less, LiCl and YCl3 were weighed as raw material powders in a molar ratio of LiCl:YCl3 = 2.7:1.1. Next, the mixture of these raw material powders was milled for 25 hours at a rotation speed of 600 rpm using a planetary ball mill (Fritsch, P-7 model). This produced Li 2.7 Y 1.1A powder of LiCl6 was obtained. 2.7 Y 1.1 Cl6 is sometimes referred to as LYC. Furthermore, a charge-discharge test was performed on the battery of Example 9 by the same method as in Example 1. CV measurement was performed on the battery of Example 9 by the same method as in Example 8.

[0135] Example 10 In the preparation of the positive electrode material, the material represented by the composition formula (1) is Li 2.5 Y 0.5 Zr 0.5 The battery of Example 10 was fabricated in the same manner as in Example 4, except that Cl6 was used. 2.5 Y 0.5 Zr 0.5 Cl6 was produced by the following method. First, in an argon glove box with a dew point of -60°C or less, LiCl, YCl3, and ZrCl4 were weighed as raw material powders in a molar ratio of LiCl:YCl3:ZrCl4 = 2.5:0.5:0.5. Next, the mixture of these raw material powders was milled for 25 hours at a rotation speed of 600 rpm using a planetary ball mill (Fritsch, P-7 model). This produced Li 2.5 Y 0.5 Zr 0.5 A powder of LiCl6 was obtained. 2.5 Y 0.5 Zr 0.5 Cl6 is sometimes referred to as LYZC. Furthermore, a charge-discharge test was carried out on the battery of Example 10 in the same manner as in Example 1.

[0136] ≪Reference example 1≫ [Preparation of cathode material] In an argon glove box with a dew point of -60°C or less, LiBr, LiCl, and a carbon material were weighed as raw material powders in a mass ratio of LiBr:LiCl:carbon material = 29:29:42. Graphite with a median diameter of 8 μm was used as the carbon material. Next, these raw material powders were mixed using a planetary ball mill (Fritsch, P-7 model). Mixing using the planetary ball mill was performed at a rotation speed of 200 rpm for 10 minutes, a rotation speed of 400 rpm for 30 minutes, and a rotation speed of 500 rpm for 30 minutes.

[0137] Next, the resulting mixture and the sulfide solid electrolyte Li6PS5Cl were weighed in a mass ratio of 74.8:25.2 in an argon atmosphere with a dew point of -60°C or lower. These materials were then mixed in an agate mortar to produce a positive electrode material.

[0138] [Battery construction] A battery of Reference Example 1 was fabricated in the same manner as in Example 1, except that the above positive electrode material was used.

[0139] [Charge / discharge test] A charge-discharge test was carried out on the battery of Reference Example 1 in the same manner as in Example 1, except that the cutoff voltage was set to 3.6V.

[0140] ≪Reference example 2≫ A battery of Reference Example 2 was fabricated in the same manner as in Example 1, except that in the preparation of the positive electrode material, metal Al powder was used instead of the carbon material, and that the powder of the material represented by composition formula (1) and metal Al powder were used in a mass ratio of 90:10. Furthermore, a charge-discharge test was performed on the battery of Reference Example 2 in the same manner as in Example 1.

[0141] The results of the charge-discharge test of the batteries of the Examples and Reference Examples are shown in Table 1. Table 1 also shows the type of carbon material contained in the positive electrode, the content of the carbon material in the positive electrode, and the ratio I D / I G The median diameter of the carbon material, the BET specific surface area of ​​the carbon material, and the type of material represented by the composition formula (1) are also shown. D / I G As mentioned above, in the Raman spectrum of carbon materials, -1 More than 1700cm -1 Intensity of peaks appearing within the range I G For 1300cm -1 More than 1400cm -1 Intensity of peaks appearing within the range I D It means the ratio of. Ratio I D / I G The median diameter and BET specific surface area were measured on the carbon material before it was used to prepare the positive electrode material. In the charge-discharge test, batteries that quickly reached the cutoff voltage after the start of charging, and batteries that allowed current to flow during charging but quickly reached the cutoff voltage after the start of discharging, were evaluated as unable to charge or discharge.

[0142] [Table 1]

[0143] <Consideration> Figure 3 is a graph showing the initial charge / discharge curves of the batteries of Examples 1, 2 and 3. Figure 3 shows the discharge characteristics of the batteries.

[0144] In the charge-discharge test of Example 1, a constant current was first passed in the forward direction from the negative electrode to the positive electrode until the battery voltage reached the cutoff voltage of 4.0 V vs. In-Li from the open circuit voltage. Next, a constant current was passed in the reverse direction to that during charging until the battery voltage reached the cutoff voltage of 1.9 V vs. In-Li. As shown in Figure 3, a plateau region associated with the charge and discharge of the battery was observed in the charge-discharge test of Example 1. Furthermore, as can be seen from a comparison of Examples 1 to 3, the higher the carbon material content in the positive electrode, the greater the amount of electricity during charge and discharge.

[0145] The observation of a plateau region in the charge-discharge test indicates that the battery of Example 1 behaves differently from a capacitor. In capacitors, voltage tends to increase linearly with current. The observation of a plateau region suggests that an electrochemical redox reaction occurred in the battery of Example 1 during the charge-discharge test. Specifically, a charge reaction proceeded when a current was passed in the forward direction, and a discharge reaction proceeded when a current was passed in the reverse direction. Furthermore, the higher the carbon material content in the positive electrode, the greater the amount of electricity generated during charge and discharge. This suggests that an electrochemical reaction occurred between the carbon material and the material represented by composition formula (1). In Example 1, an In-Li alloy was used as the negative electrode, and a reversible charge-discharge reaction occurred, indicating that the charge carrier was Li ion. Specifically, in the battery of Example 1, Li ions, the charge carriers, migrated from the positive electrode to the negative electrode via the solid electrolyte layer during charging.

[0146] FIG. 4 is a graph showing the initial charge / discharge curves of the batteries of Reference Examples 1 and 2.

[0147] In Reference Example 1, a mixture of LiBr and LiCl was used instead of the material represented by composition formula (1). In the mixture, the molar ratio of Br to Cl was 1:2. This mixture and a carbon material were thoroughly mixed using a ball mill. The resulting mixture was further mixed with a sulfide solid electrolyte having Li ion conductivity to prepare a positive electrode material. In a charge / discharge test of the battery of Reference Example 1, a charge curve indicating the progress of battery charging was confirmed. However, the battery of Reference Example 1 could not be discharged.

[0148] In Reference Example 2, a positive electrode material was prepared by mixing the material represented by composition formula (1) used in Example 1 with metal Al powder. In a charge / discharge test of the battery of Reference Example 2, no current flowed through the battery during either charging or discharging, and the battery voltage reached the cutoff voltage.

[0149] From the above results, it can be seen that in order for the charging reaction to proceed in a battery, it is necessary to combine the material represented by composition formula (1) with a carbon material. Furthermore, it can be seen that in order for the discharging reaction to proceed, the material represented by composition formula (1) needs to contain at least one element selected from the group consisting of metal elements and metalloid elements other than Li.

[0150] Although the detailed mechanism is currently under investigation, it is presumed that contact between a carbon material and a material represented by composition formula (1) promotes the redox reaction of the material represented by composition formula (1). Furthermore, it is known that carbon materials with layered structures, such as graphite, can adsorb various elements within their layered structure. From this, it is presumed that in a positive electrode containing a carbon material and a material represented by composition formula (1), the carbon material occludes the halogen element or halide produced by the redox reaction of the material represented by composition formula (1). It is presumed that this function of the carbon material allows the reversible charge / discharge reaction to proceed in the battery.

[0151] Because the material represented by composition formula (1) contains a metal element or a metalloid element other than Li, halogen gas is unlikely to be generated by oxidation of the halogen element contained in the material during battery charging. Therefore, voids are unlikely to form inside the positive electrode during battery charging. In other words, the internal structure of the positive electrode is unlikely to change. This is presumably why the conduction of electrons and lithium ions is unlikely to be hindered during battery charging and discharging, allowing reversible charge and discharge reactions to proceed. In Reference Example 1, it is presumed that the internal structure of the positive electrode changed during battery charging, which inhibited the conduction of electrons and lithium ions, preventing the discharge reaction from proceeding.

[0152] FIG. 5 is a graph showing the initial charge / discharge curves of the batteries of Examples 4 to 7.

[0153] As can be seen from FIG. 5, even when a carbon material other than graphite was used, a reversible charge-discharge reaction proceeded in the battery. The carbon materials used in Examples 4 to 7 include graphite-like structures, diamond-like structures, and the like. In the batteries of Examples 4 to 7, it is presumed that the charge-discharge reaction proceeded due to the graphite-like structure contained in the carbon material. That is, in the batteries of Examples 4 to 7, it is presumed that the charge-discharge reaction proceeded due to the layer structure contained in the carbon material. As can be seen from a comparison between Example 1 and Examples 4 to 7, carbon black such as acetylene black, vapor-grown carbon fiber, and graphene are more suitable for improving the discharge capacity of a battery than graphite.

[0154] FIG. 6 is a graph showing the initial charge / discharge curves of the batteries of Examples 4, 8 and 9.

[0155] Even when LYB or LYC was used as the material represented by composition formula (1), reversible charge-discharge reactions proceeded in the battery, similar to when LYBC was used. This result indicates that the material represented by composition formula (1) does not need to contain both Br and Cl; it is sufficient if it contains one type of halogen element. In particular, it is presumed that the type of halogen element contained in the material represented by composition formula (1) is not limited to Br or Cl, as long as the battery voltage can be swept to a voltage at which oxidation-reduction of the halogen element occurs.

[0156] FIG. 7 is a graph showing cyclic voltammograms of the batteries of Examples 9 and 10 and Reference Example 2.

[0157] 7, no peaks due to the oxidation-reduction of the material represented by composition formula (1) were observed in the battery of Reference Example 2. This indicates that the combination of metallic Al and the material represented by composition formula (1) hardly causes the oxidation-reduction reaction of the material represented by composition formula (1).

[0158] On the other hand, as can be seen from FIG. 7, in the batteries of Examples 9 and 10, peaks due to the oxidation-reduction of the material represented by composition formula (1) were clearly observed. This shows that even when LYC or LYZC is used as the material represented by composition formula (1), the oxidation-reduction reaction of the material proceeds. In other words, it shows that the oxidation-reduction reaction of the material proceeds regardless of the types of metal elements and metalloid elements other than Li contained in the material represented by composition formula (1). It shows that the halogen element or halide generated from the material is occluded in the carbon material regardless of the types of metal elements and metalloid elements other than Li contained in the material represented by composition formula (1).

[0159] Example 11 [Preparation of material represented by composition formula (1)] By the same method as in Example 1, a powder of LYBC, which is a material represented by composition formula (1), was obtained.

[0160] [Preparation of cathode material] LYBC powder and graphene powder, a carbon material, were weighed in a mass ratio of 92.6:7.4 in an argon atmosphere with a dew point of -60°C or less. Next, these materials were mixed in an agate mortar to prepare a positive electrode material.

[0161] [Battery construction] In an insulating outer cylinder, the sulfide solid electrolyte Li6PS5Cl, LYBC powder, and the positive electrode material were layered in this order. The weight of Li6PS5Cl was 60 mg, the weight of LYBC was 20 mg, and the weight of the positive electrode material was 5 mg. Next, a pressure of 720 MPa was applied to these materials to obtain a solid electrolyte layer and a first electrode, which was the positive electrode.

[0162] Next, a metallic Li foil was laminated on the surface of the solid electrolyte layer opposite to the surface in contact with the first electrode, and a pressure of 80 MPa was applied to this metallic foil to produce a laminate consisting of the first electrode, the solid electrolyte layer, and the second electrode (negative electrode).

[0163] Next, a stainless steel current collector was placed on each of the positive and negative electrodes, and current collecting leads were attached to these current collectors. Next, an insulating ferrule was used to isolate and seal the inside of the insulating outer cylinder from the outside atmosphere, thereby producing a battery of Example 11.

[0164] [Charging test] A charging test was conducted on the battery of Example 11 using the following method. First, the battery was placed in a thermostatic chamber set to 25°C. The battery was subjected to constant current charging at a current value of 0.1 mA. The constant current charging was continued until the battery voltage reached 4.4 V. Next, the battery was subjected to constant voltage charging until the current value decreased to 0.01 mA.

[0165] [Discharge test] The battery was subjected to constant current / constant voltage charging and then constant current discharge at a current value of 0.01 mA until the battery voltage reached 2.5 V. Next, the battery was subjected to constant voltage discharge until the current value decreased to 0.002 mA.

[0166] [Raman spectroscopy] Raman spectroscopy was performed on the positive electrode material of the battery of Example 11 before, after, and after a charge test. The Raman spectroscopy was performed as follows: First, the above-mentioned laminate was removed from the battery. Next, Raman spectroscopy was performed on the laminate sealed in an airtight cell. The Raman spectroscopy was performed using an NRS-5500 manufactured by JASCO Corporation, with an Ar ion laser emitting light with a wavelength of 457 nm. Specifically, the surface of the positive electrode side of the laminate was mapped and measured. The obtained data was subjected to multivariate curve resolution (MCR) to separate peaks derived from carbon. This resulted in a Raman spectrum of the carbon material in the positive electrode material.

[0167] FIG. 8 is a graph showing the results of Raman spectroscopy performed on the positive electrode material of the battery of Example 11 before, after, and after a charge test. The graph in FIG. 8 also shows the results of Raman spectroscopy performed on graphene powder. As can be seen from FIG. 8, the Raman spectrum of the carbon material in the positive electrode material after the charge test shows a larger peak at 1580 cm than the Raman spectrum of the carbon material in the positive electrode material before the charge test. -1 The G band peak, which appears around 1000 kJ / cm2, became broader and shifted to a higher wavenumber. This suggests that the carbon material adsorbed the halogen or halogen compound derived from the material represented by composition formula (1) during the charging test.

[0168] Furthermore, as can be seen from Figure 8, in the Raman spectrum of the carbon material in the positive electrode material after the discharge test, the G band peak was shifted to a lower wavenumber side compared to the Raman spectrum of the carbon material in the positive electrode material after the charge test. From this, it is presumed that the halogen element or halide adsorbed on the carbon material was desorbed from the carbon material by the discharge test. [Industrial Applicability]

[0169] The positive electrode material of the present disclosure can be used, for example, in all-solid-state secondary batteries.

Claims

1. A material represented by the following composition formula (1), a carbon material capable of occluding at least one selected from the group consisting of an elemental halogen and a halide; Including, the carbon material includes at least one selected from the group consisting of carbon black, vapor-grown carbon fiber, and graphene; a halogen element contained in the material represented by the composition formula (1) is oxidized to generate at least one selected from the group consisting of the halogen element and the halide, and the at least one selected from the group consisting of the halogen element and the halide is occluded in the carbon material; a positive electrode material, wherein at least one selected from the group consisting of the halogen element and the halide is reduced, so that the reduced at least one selected from the group consisting of the halogen element and the halide is released from the carbon material. Li a M b X c ... Equation (1) where a, b, and c are each a value greater than 0, M includes Y; X includes a halogen element.

2. In the Raman spectrum of the carbon material, -1 More than 1700cm -1 Intensity I of peaks appearing within the following range G For 1300 cm -1 More than 1400cm -1 Intensity I of peaks appearing within the following range D Ratio I D / I G The positive electrode material according to claim 1 , wherein is 0 or more and 2 or less.

3. The BET specific surface area of ​​the carbon material is 5 m 2 g -1 The positive electrode material according to claim 1 or 2, wherein the positive electrode material has a molecular weight of 1.0 or more.

4. The positive electrode material according to claim 1 , wherein M further comprises Zr.

5. 5. The positive electrode material according to claim 1, wherein X comprises at least one selected from the group consisting of Cl and Br.

6. A positive electrode comprising the positive electrode material according to any one of claims 1 to 5; a negative electrode; an electrolyte layer disposed between the positive electrode and the negative electrode; Equipped with a battery.

7. The battery according to claim 6 , wherein the negative electrode comprises a negative electrode active material capable of absorbing lithium.

8. 8. The battery according to claim 6, wherein the negative electrode comprises at least one selected from the group consisting of metallic lithium, a lithium alloy, metallic indium, an indium alloy, a carbon material, silicon, a silicon alloy, silicon oxide, and lithium titanate.

9. the electrolyte layer includes a solid electrolyte material; The battery according to claim 6 , wherein the composition of the solid electrolyte material is different from the composition of the material represented by the composition formula (1).

10. The battery of claim 6 , wherein the electrolyte layer comprises a sulfide solid electrolyte.

11. a positive electrode including a positive electrode material; a negative electrode; an electrolyte layer disposed between the positive electrode and the negative electrode; A battery comprising: The positive electrode material includes a material represented by the following composition formula (1) and a carbon material capable of occluding at least one element selected from the group consisting of an elemental halogen and a halide, In the battery, During charging, the halogen element contained in the material represented by the composition formula (1) is oxidized to generate at least one selected from the group consisting of a simple halogen and a halide, The battery, wherein the halogen element contained in at least one selected from the group consisting of the simple halogen and the halide is reduced during discharge. Li a M b X c ... Formula (1) where a, b, and c are each a value greater than 0, M includes at least one selected from the group consisting of metal elements and metalloid elements other than Li, X includes a halogen element.

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