Solid electrolyte material and battery using the same

Abstract

The solid electrolyte material of the present disclosure contains Li, Ti, M, and F. Among them, M is at least one selected from Mg and Ca.

Description

Technical Field

[0001] This disclosure relates to solid electrolyte materials and batteries using such solid electrolyte materials. Background Technology

[0002] Patent document 1 discloses an all-solid-state battery using a sulfide solid electrolyte. Patent document 2 discloses LiBF4 as a fluoride solid electrolyte material.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-129312

[0006] Patent Document 2: Japanese Patent Application Publication No. 2008-277170 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] The purpose of this disclosure is to provide a solid electrolyte material with high lithium-ion conductivity.

[0009] Means for solving technical problems

[0010] The solid electrolyte material disclosed herein comprises Li, Ti, M and F, wherein M is selected from at least one of Mg and Ca.

[0011] Invention Effects

[0012] This disclosure provides a solid electrolyte material with high lithium-ion conductivity. Attached Figure Description

[0013] Figure 1 A cross-sectional view showing the battery 1000 of the second embodiment.

[0014] Figure 2 A cross-sectional view showing the battery 2000 of the second embodiment.

[0015] Figure 3 This diagram shows a pressure molding die 300 used to evaluate the ionic conductivity of solid electrolyte materials.

[0016] Figure 4 A graph showing the Cole-Cole curves obtained by impedance measurement of the solid electrolyte material of Example 1.

[0017] Figure 5 A graph showing the initial discharge characteristics of the batteries of Example 1 and Comparative Example 1. Detailed Implementation

[0018] The following is a reference to the appendix. Figure 1 The embodiments of this disclosure will be described below.

[0019] (First Embodiment)

[0020] The solid electrolyte material of the first embodiment comprises Li, Ti, M, and F. M is selected from at least one of Mg and Ca. The solid electrolyte material of the first embodiment has high lithium-ion conductivity. Here, high lithium-ion conductivity, for example, means 1 × 10⁻⁶. -8 S / cm or higher. That is, the solid electrolyte material of the first embodiment may, for example, have a density of 1×10⁻⁶. -8 Ionic conductivity above S / cm.

[0021] The solid electrolyte material of the first embodiment can be used to obtain a battery with excellent charge-discharge characteristics. An example of this battery is an all-solid-state battery. An all-solid-state battery can be a primary battery or a secondary battery.

[0022] The solid electrolyte material of the first embodiment is expected to be sulfur-free. Sulfur-free solid electrolyte materials do not produce hydrogen sulfide even when exposed to the atmosphere, thus exhibiting excellent safety. The sulfide solid electrolyte disclosed in Patent Document 1 produces hydrogen sulfide when exposed to the atmosphere.

[0023] The solid electrolyte material of the first embodiment exhibits high oxidation resistance due to the presence of F. This is because F has a high redox potential. On the other hand, F has high anionicity, resulting in a strong bond with Li. Consequently, the lithium-ion conductivity of solid electrolyte materials typically containing both Li and F is reduced. For example, LiBF4 disclosed in Patent Document 2 has a conductivity of 6.67 × 10⁻⁶. -9 The low ionic conductivity (S / cm) is also present. Furthermore, LiBF4 is the solid electrolyte material used in Comparative Example 1 described later. The solid electrolyte material of the first embodiment, by including Ti and M in addition to Li and F, can have, for example, a conductivity of 1 × 10⁻⁶. -8 High ionic conductivity above S / cm.

[0024] To improve the ionic conductivity of the solid electrolyte material, the solid electrolyte material of the first embodiment may also contain anions other than F. Examples of such anions are Cl, Br, I, O, S, or Se.

[0025] The solid electrolyte material of the first embodiment can also be substantially formed of Li, Ti, M, and F. Here, "the solid electrolyte material of the first embodiment is substantially formed of Li, Ti, M, and F" means that the molar ratio (i.e., mole fraction) of the sum of the amounts of Li, Ti, M, and F is 90% or more relative to the sum of the amounts of all elements constituting the solid electrolyte material of the first embodiment. As an example, this molar ratio can be 95% or more. The solid electrolyte material of the first embodiment can be formed only of Li, Ti, M, and F.

[0026] The solid electrolyte material of the first embodiment may contain unavoidably mixed-in elements. Examples of such elements are hydrogen, oxygen, or nitrogen. Such elements may be present in the raw material powder for manufacturing or storing the solid electrolyte material or in the atmosphere of the solid electrolyte material.

[0027] In order to further improve the ionic conductivity of the solid electrolyte material, in the solid electrolyte material of the first embodiment, the ratio of the amount of Li to the sum of the amounts of Ti and M can be 0.5 to 4.5.

[0028] In order to improve the ionic conductivity of the solid electrolyte material, M can be Mg.

[0029] The solid electrolyte material of the first embodiment can be represented by the following compositional formula (1).

[0030] Li 6-(4-2x)b (Ti 1-x M x ) b F6 Formula (1)

[0031] In formula (1), the mathematical expressions: 0 < x < 1 and 0 < b ≤ 3 are satisfied. The solid electrolyte material having such a composition has a high ionic conductivity.

[0032] In order to improve the ionic conductivity of the solid electrolyte material, the mathematical expression: 0.05 ≤ x ≤ 0.9 can be satisfied in formula (1).

[0033] When M is Mg, in order to improve the ionic conductivity of the solid electrolyte material, the mathematical expression: 0.05 ≤ x ≤ 0.6 can be satisfied in formula (1).

[0034] When M is Ca, in order to improve the ionic conductivity of the solid electrolyte material, the mathematical expression: x = 0 can be satisfied in formula (1).

[0035] The upper and lower limit values of the range of x in formula (1) can be defined by any combination of values selected from 0.05, 0.1, 0.2, 0.4, 0.5, 0.6, and 0.8.

[0036] In order to improve the ionic conductivity of solid electrolyte materials, the mathematical expression in equation (1) can be satisfied: 0.80≤b≤1.71.

[0037] The upper and lower limits of the range of b in equation (1) can be specified by any combination of values ​​selected from 0.8, 0.86, 0.9, 1.0, 1.1, 1.3, 1.5 and 1.71.

[0038] The solid electrolyte material in the first embodiment can be crystalline or amorphous.

[0039] The shape of the solid electrolyte material in the first embodiment is not limited. Examples of this shape include needle-like, spherical, or ellipsoidal. The solid electrolyte material in the first embodiment can be a particle. The solid electrolyte material in the first embodiment can also be formed in a shape having particles or plates.

[0040] When the solid electrolyte material of the first embodiment is in the shape of particles (e.g., spheres), the solid electrolyte material can have a median particle size of 0.1 μm to 100 μm. The median particle size refers to the particle size at which the cumulative volume in the volume standard particle size distribution equals 50%. The volume standard particle size distribution is determined, for example, using a laser diffraction measuring device or an image analysis device.

[0041] The solid electrolyte material of the first embodiment can have a median particle size of 0.5 μm to 10 μm. Therefore, the solid electrolyte material exhibits higher conductivity. Furthermore, when the solid electrolyte material of the first embodiment is mixed with other materials such as active substances, the dispersion state of the solid electrolyte material of the first embodiment and other materials becomes better.

[0042] <Manufacturing Methods of Solid Electrolyte Materials>

[0043] The solid electrolyte material of the first embodiment can be manufactured, for example, by the method described below.

[0044] Prepare raw material powders and mix them according to the desired composition. Raw material powders may be, for example, halides.

[0045] As an example, when the composition of the target is Li 3.0 Ti 0.5 Mg 0.5 In F6, LiF, TiF4, and MgF2 are mixed in a molar ratio of approximately 3.0:0.5:0.5. To compensate for compositional changes that may occur during the synthesis process, the raw material powders can also be mixed in a pre-adjusted molar ratio.

[0046] The raw material powders are mechanically and chemically reacted (i.e., by mechanical and chemical milling) within a mixing apparatus such as a planetary ball mill to obtain reactants. The reactants can be calcined in a vacuum or an inert atmosphere. Alternatively, the mixture of raw material powders can be calcined in a vacuum or an inert atmosphere to obtain reactants. Calcination is preferably performed at 100°C to 300°C for at least 1 hour. To suppress compositional changes during calcination, the raw material powders are preferably calcined in a sealed container such as a quartz tube.

[0047] Through these methods, the solid electrolyte material of the first embodiment is obtained.

[0048] (Second Implementation)

[0049] The second embodiment will be described below. Matters described in the first embodiment may be omitted.

[0050] The battery of the second embodiment includes a positive electrode, a negative electrode, and an electrolyte layer. The electrolyte layer is disposed between the positive electrode and the negative electrode. At least one of the positive electrode, the electrolyte layer, and the negative electrode contains the solid electrolyte material of the first embodiment. Because the battery of the second embodiment contains the solid electrolyte material of the first embodiment, it has excellent charge-discharge characteristics. This battery can also be an all-solid-state battery.

[0051] Figure 1 A cross-sectional view showing the battery 1000 of the second embodiment.

[0052] The battery 1000 of the second embodiment includes a positive electrode 201, an electrolyte layer 202, and a negative electrode 203. The electrolyte layer 202 is disposed between the positive electrode 201 and the negative electrode 203.

[0053] The positive electrode 201 contains positive electrode active material particles 204 and solid electrolyte particles 100.

[0054] Electrolyte layer 202 contains an electrolyte material. The electrolyte material may be, for example, a solid electrolyte material.

[0055] The negative electrode 203 contains negative electrode active material particles 205 and solid electrolyte particles 100.

[0056] The solid electrolyte particles 100 are particles formed from the solid electrolyte material of the first embodiment, or particles containing the solid electrolyte material of the first embodiment as a main component. Here, particles containing the solid electrolyte material of the first embodiment as a main component refer to particles whose main component is the solid electrolyte material of the first embodiment by mass ratio.

[0057] The positive electrode 201 contains a material capable of inserting and deintercalating metal ions (e.g., lithium ions). This material is, for example, a positive electrode active material (e.g., positive electrode active material particles 204).

[0058] Examples of positive electrode active materials include lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal oxysulfides, or transition metal oxynitrides. Examples of lithium-containing transition metal oxides are Li(Ni, Co, Al)O2, Li(Ni, Co, Mn)O2, or LiCoO2. In this disclosure, the expression "(Ni, Co, Al)" in the chemical formula indicates at least one element selected from the group of elements in parentheses. That is, "(Ni, Co, Al)" is synonymous with "at least one element selected from Ni, Co, and Al". The same applies to other elements.

[0059] The positive electrode active material particles 204 can also have a median particle size of 0.1 μm to 100 μm. When the positive electrode active material particles 204 have a median particle size of 0.1 μm or more, the dispersion state of the positive electrode active material particles 204 and the solid electrolyte particles 100 in the positive electrode 201 becomes better. As a result, the charge and discharge characteristics of the battery 1000 are improved. When the positive electrode active material particles 204 have a median particle size of less than 100 μm, the lithium diffusion rate within the positive electrode active material particles 204 is increased. As a result, the battery 1000 can operate at high output power.

[0060] The positive electrode active material particles 204 can have a larger median particle size than the solid electrolyte particles 100. As a result, the dispersion state of the positive electrode active material particles 204 and the solid electrolyte particles 100 in the positive electrode 201 becomes better.

[0061] In order to improve the energy density and output power of the battery, in the positive electrode 201, the ratio of the volume of the positive electrode active material particles 204 to the sum of the volumes of the positive electrode active material particles 204 and the solid electrolyte particles 100 can be 0.30 to 0.95.

[0062] A coating layer may also be formed on at least a portion of the surface of the positive electrode active material particles 204. The coating layer may be formed on the surface of the positive electrode active material particles 204, for example, before being mixed with conductive additives and binders. Examples of coating materials contained in the coating layer are sulfide solid electrolytes, oxide solid electrolytes, or halide solid electrolytes. When the solid electrolyte particles 100 contain sulfide solid electrolytes, the coating material may contain the solid electrolyte material of the first embodiment to suppress the oxidative decomposition of the sulfide solid electrolyte. When the solid electrolyte particles 100 contain the solid electrolyte material of the first embodiment, the coating material may also contain oxide solid electrolytes to suppress the oxidative decomposition of the solid electrolyte material. Lithium niobate, which has excellent stability at high potentials, can be used as the oxide solid electrolyte. By suppressing the oxidative decomposition of the solid electrolyte material, the rise in battery overvoltage can be suppressed.

[0063] To improve the energy density and output power of the battery, the positive electrode 201 can have a thickness of 10μm to 500μm.

[0064] Electrolyte layer 202 contains an electrolyte material. This electrolyte material is, for example, a solid electrolyte material. Electrolyte layer 202 can be a solid electrolyte layer.

[0065] The electrolyte layer 202 may be composed solely of the solid electrolyte material of the first embodiment. Alternatively, it may be composed solely of a solid electrolyte material different from the solid electrolyte material of the first embodiment. Examples of solid electrolyte materials different from the solid electrolyte material of the first embodiment are Li2Mgx4, Li2Fex4, Li(Al, Ga, In)x4, Li3(Al, Ga, In)x6, or LiI. Here, x is at least one selected from F, Cl, Br, and I.

[0066] Hereinafter, the solid electrolyte material of the first embodiment will be referred to as the first solid electrolyte material. Solid electrolyte materials that are different from the solid electrolyte material of the first embodiment will be referred to as the second solid electrolyte material.

[0067] The electrolyte layer 202 may contain not only a first solid electrolyte material but also a second solid electrolyte material. The first and second solid electrolyte materials can be uniformly dispersed in the electrolyte layer 202. The layers formed by the first and second solid electrolyte materials can be stacked along the stacking direction of the battery 1000.

[0068] Figure 2 A cross-sectional view showing the battery 2000 of the second embodiment.

[0069] like Figure 2As shown, the battery 2000 may include a positive electrode 201, a first electrolyte layer 212, a second electrolyte layer 222, and a negative electrode 203. Specifically, the electrolyte layer 202 may include both the first electrolyte layer 212 and the second electrolyte layer 222. The first electrolyte layer 212 is disposed between the positive electrode 201 and the negative electrode 203. The second electrolyte layer 222 is disposed between the first electrolyte layer 212 and the negative electrode 203.

[0070] In the battery 2000, the first electrolyte layer 212 may contain the solid electrolyte material of the first embodiment. Because the solid electrolyte material of the first embodiment has high oxidation resistance, it can be used without oxidizing the solid electrolyte material contained in the second electrolyte layer 222. As a result, the charge / discharge efficiency of the battery can be improved.

[0071] In the battery 2000, the solid electrolyte material contained in the second electrolyte layer 222 can have a lower reduction potential than the solid electrolyte material contained in the first electrolyte layer 212. Therefore, it can be used without reducing the solid electrolyte material contained in the first electrolyte layer 212. As a result, the charge and discharge efficiency of the battery can be improved. For example, when the first electrolyte layer 212 contains the solid electrolyte material of the first embodiment, the second electrolyte layer 222 may also contain a sulfide solid electrolyte to suppress the reduction and decomposition of the solid electrolyte material.

[0072] To improve the energy density and output power of the battery, the electrolyte layer 202 can also have a thickness of 1μm to 1000μm.

[0073] The negative electrode 203 contains a material capable of inserting and deintercalating metal ions (e.g., lithium ions). This material is, for example, a negative electrode active material (e.g., negative electrode active material particles 205).

[0074] Examples of negative electrode active materials include metallic materials, carbon materials, oxides, nitrides, tin compounds, or silicon compounds. Metallic materials can be monomeric metals or alloys. Examples of metallic materials include lithium metal or lithium alloys. Examples of carbon materials include natural graphite, coke, graphitized carbon, carbon fibers, spherical carbon, artificial graphite, or amorphous carbon. From the viewpoint of capacity density, preferred examples of negative electrode active materials are silicon (Si), tin (Sn), silicon compounds, or tin compounds.

[0075] The negative electrode active material can be selected considering the reduction resistance of the solid electrolyte material contained in the negative electrode 203. For example, when the negative electrode 203 contains the solid electrolyte material of the first embodiment, the negative electrode active material can be a material capable of inserting and deintercalating lithium ions at a voltage of 0.27V or higher relative to lithium. Examples of such negative electrode active materials are titanium oxide, indium metal, or lithium alloys. An example of titanium oxide is Li4Ti5O. 12LiTi2O4 or TiO2. By using the above-mentioned negative electrode active material, the reduction and decomposition of the solid electrolyte material of the first embodiment contained in the negative electrode 203 can be suppressed. As a result, the charge and discharge efficiency of the battery can be improved.

[0076] The negative electrode active material particles 205 can have a median particle size of 0.1 μm to 100 μm. When the negative electrode active material particles 205 have a median particle size of 0.1 μm or larger, the dispersion state of the negative electrode active material particles 205 and the solid electrolyte particles 100 in the negative electrode 203 becomes better. As a result, the charge and discharge characteristics of the battery are improved. When the negative electrode active material particles 205 have a median particle size of less than 100 μm, the lithium diffusion rate within the negative electrode active material particles 205 is increased. As a result, the battery can operate at high output power.

[0077] The negative electrode active material particles 205 can have a median particle size larger than that of the solid electrolyte particles 100. As a result, the dispersion state of the negative electrode active material particles 205 and the solid electrolyte particles 100 in the negative electrode 203 becomes better.

[0078] In order to improve the energy density and output power of the battery, the ratio of the volume of the negative electrode active material particles 205 to the sum of the volumes of the negative electrode active material particles 205 and the solid electrolyte particles 100 in the negative electrode 203 can be 0.30 to 0.95.

[0079] To improve the energy density and output power of the battery, the negative electrode 203 can also have a thickness of 10μm to 500μm.

[0080] The material is selected from at least one of the positive electrode 201, the electrolyte layer 202 and the negative electrode 203 for the purpose of improving ion conductivity, chemical stability and electrochemical stability, and may also contain a second solid electrolyte material.

[0081] The second solid electrolyte material can be a sulfide solid electrolyte.

[0082] Examples of sulfide solid electrolytes include Li₂S-P₂S₅, Li₂S-SiS₂, Li₂S-B₂S₃, Li₂S-GeS₂, and Li₂S-P₂S₅. 3.25 Ge 0.25 P 0.75 S4 or Li 10 GeP2S 12 .

[0083] When the electrolyte layer 202 contains the solid electrolyte material of the first embodiment, the negative electrode 203 may also contain a sulfide solid electrolyte to suppress the reductive decomposition of the solid electrolyte material. By covering the negative electrode active material with an electrochemically stable sulfide solid electrolyte, contact between the solid electrolyte material of the first embodiment and the negative electrode active material can be suppressed. As a result, the internal resistance of the battery can be reduced.

[0084] The second solid electrolyte material can be an oxide solid electrolyte.

[0085] Examples of oxide solid electrolytes are

[0086] (i) NASICON-type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutes;

[0087] (ii)Perovskite-type solid electrolytes such as (LaLi)TiO3;

[0088] (iii)Li 14 ZnGe4O 16 LISICON-type solid electrolytes, such as Li4SiO4, LiGeO4, or their elemental substitutes;

[0089] (iv)Li7La3Zr2O 12 Garnet-type solid electrolytes, such as their elemental substitutes;

[0090] Or (v)Li3PO4 or its N-substituted form.

[0091] As mentioned above, the second solid electrolyte material can also be a halide solid electrolyte.

[0092] Examples of halide solid electrolytes are Li₂Mgx₄, Li₂Fex₄, Li(Al,Ga,In)x₄, Li₃(Al,Ga,In)x₆, or LiI. Here, x is selected from at least one of F, Cl, Br, and I.

[0093] Other examples of halide solid electrolyte materials are those made of Li a Me b Y c The compound represented by x6 satisfies a + mb + 3c = 6 and c > 0. Me is at least one metallic and half-metallic element selected from those other than Li and Y. m represents the valence of Me. "Half-metallic element" refers to B, Si, Ge, As, Sb, and Te. "Metallic element" refers to all elements contained in Groups 1 to 12 of the periodic table (except hydrogen) and all elements contained in Groups 13 to 16 of the periodic table (except B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se).

[0094] To improve the ionic conductivity of halide solid electrolyte materials, Me can be selected from at least one of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, and Nb. The halide solid electrolyte can also be Li3YCl6 or Li3YBr6.

[0095] The second solid electrolyte material can be an organic polymer solid electrolyte.

[0096] Examples of organic polymer solid electrolytes are compounds of polymers and lithium salts.

[0097] Polymers can possess an ethylene oxide structure. Polymers with an ethylene oxide structure can contain a greater amount of lithium salt, thus further improving their ionic conductivity.

[0098] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3. One lithium salt selected from these can be used alone. Alternatively, a mixture of two or more lithium salts selected from these can be used.

[0099] In order to facilitate the acceptance and donation of lithium ions and improve the output power characteristics of the battery, at least one of the positive electrode 201, electrolyte layer 202 and negative electrode 203 may also contain a non-aqueous electrolyte, a gel electrolyte or an ionic liquid.

[0100] The non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0101] Examples of non-aqueous solvents include cyclic carbonate solvents, chain carbonate solvents, cyclic ether solvents, chain ether solvents, cyclic ester solvents, chain ester solvents, or fluorinated solvents. Examples of cyclic carbonate solvents include ethylene carbonate, propylene carbonate, or butenyl carbonate. Examples of chain carbonate solvents include dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate. Examples of cyclic ether solvents include tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane. Examples of chain ether solvents include 1,2-dimethoxyethane or 1,2-diethoxyethane. Examples of cyclic ester solvents include γ-butyrolactone. Examples of chain ester solvents include methyl acetate. Examples of fluorinated solvents include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, or fluorodimethyl carbonate. One of these non-aqueous solvents may be used alone. Alternatively, a combination of two or more of these non-aqueous solvents may be used.

[0102] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3. One lithium salt selected from these can be used alone. Alternatively, a combination of two or more lithium salts selected from these can be used. The concentration of the lithium salt is, for example, in the range of 0.5 mol / L to 2 mol / L.

[0103] As a gel electrolyte, polymeric materials impregnated with a non-aqueous electrolyte can be used. Examples of polymeric materials include polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or polymers containing ethylene oxide bonds.

[0104] Examples of cations contained in ionic liquids are:

[0105] (i) Aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphine;

[0106] (ii) aliphatic cyclic ammonium compounds such as pyrrolidines, morpholines, imidazolines, tetrahydropyrimidines, piperazines, or piperidines;

[0107] Or (iii) nitrogen-containing heterocyclic aromatic cations such as pyridine or imidazoline.

[0108] An example of anionic liquids is PF6. - BF4 - SbF6 - AsF6 - SO3CF3 - N(SO2CF3)2 - N(SO2C2F5)2 - N(SO2CF3)(SO2C4F9) - Or C(SO2CF3)3 - .

[0109] Ionic liquids can contain lithium salts.

[0110] The electrode is selected from at least one of the positive electrode 201, electrolyte layer 202 and negative electrode 203 for the purpose of improving the adhesion between particles, and may also contain an adhesive.

[0111] Examples of adhesives include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamide-imide, polyacrylonitrile, polyacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, or carboxymethyl cellulose. Copolymers can also be used as adhesives. Examples of such adhesives are copolymers selected from two or more materials chosen from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, trichlorofluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene. Mixtures selected from two or more of these materials can also be used as adhesives.

[0112] At least one of the positive electrode 201 and the negative electrode 203 may also contain a conductive additive to reduce electronic resistance.

[0113] Examples of conductive additives are

[0114] (i) Graphite, such as natural or artificial graphite;

[0115] (ii) Carbon blacks such as acetylene black or Ketjen black;

[0116] (iii) Conductive fibers such as carbon fiber or metal fiber;

[0117] (iv) Fluorinated carbon;

[0118] (v) Powdered metals such as aluminum;

[0119] (vi) Conductive metal whiskers such as zinc oxide or potassium titanate;

[0120] (vii) Conductive metal oxides such as titanium dioxide;

[0121] Or (viii) conductive polymers such as polyaniline, polypyrrole, or polythiophene. For cost reduction, conductive additives of (i) or (ii) above may also be used.

[0122] Examples of the battery shapes in the second embodiment include coin type, cylindrical type, square type, sheet type, button type, flat type, or stacked type.

[0123] The battery of the second embodiment can be manufactured, for example, by preparing a positive electrode forming material, an electrolyte layer forming material and a negative electrode forming material, and using a known method to manufacture a laminate in which a positive electrode, an electrolyte layer and a negative electrode are arranged in sequence.

[0124] Example

[0125] The present disclosure will now be described in more detail with reference to embodiments and comparative examples.

[0126] <Example 1>

[0127] (Preparation of solid electrolyte materials)

[0128] In an argon atmosphere with a dew point below -60°C (hereinafter referred to as "dry argon atmosphere"), LiF, TiF4, and MgF2 were prepared as raw material powders in a molar ratio of LiF:TiF4:MgF3 = 3.0:0.5:0.5. These materials were pulverized and mixed in a mortar. The resulting mixture was then milled at 500 rpm for 12 hours using a planetary ball mill. This yielded the powder of the solid electrolyte material of Example 1. The solid electrolyte material of Example 1 has Li... 3.0 Ti 0.5 Mg 0.5 F6 represents the composition.

[0129] (Evaluation of ionic conductivity)

[0130] Figure 3 This diagram shows a pressure molding die 300 used to evaluate the ionic conductivity of solid electrolyte materials.

[0131] The pressure forming mold 300 comprises an upper part 301 for punching, a frame 302, and a lower part 303 for punching. The frame 302 is formed of insulating polycarbonate. Both the upper part 301 and the lower part 303 are formed of ion-conductive stainless steel.

[0132] use Figure 3 The ionic conductivity of the solid electrolyte material of Example 1 was evaluated using the pressure molding die 300 shown below.

[0133] In a dry argon atmosphere with a dew point below -30°C, the powder of the solid electrolyte material of Example 1 was filled into the interior of a pressure molding die 300. Inside the pressure molding die 300, a pressure of 400 MPa was applied to the solid electrolyte material of Example 1 using the upper part 301 and the lower part 303 of a punch.

[0134] Under pressure, the upper part 301 and lower part 303 of the punch were connected to a potentiostat (Princeton Applied Research, VersaSTAT4) equipped with a frequency response analyzer. The upper part 301 was connected to the active electrode and the potential measurement terminal. The lower part 303 was connected to the counter electrode and the reference electrode. The impedance of the solid electrolyte material was measured at room temperature using electrochemical impedance spectroscopy.

[0135] Figure 4 A graph showing the Cole-Cole curve obtained by impedance measurement for the solid electrolyte material of Example 1.

[0136] Figure 4 In this method, the real value of the impedance at the measurement point with the smallest absolute phase value of the complex impedance is regarded as the resistance value of the solid electrolyte material relative to ion conduction. Using this resistance value, the ion conductivity is calculated based on the following mathematical formula (2).

[0137] σ=(R SE ×S / t) -1 (2)

[0138] Here, σ represents ionic conductivity. S represents the contact area between the solid electrolyte material and the upper part 301 of the drilling machine (…). Figure 3 (The cross-sectional area is equivalent to that of the hollow section of frame type 302). R SE This represents the resistance value of the solid electrolyte material in the impedance measurement. t represents the thickness of the solid electrolyte material (…). Figure 3 (The thickness of the layer formed by the powder 101 of the solid electrolyte material).

[0139] The ionic conductivity of the solid electrolyte material in Example 1, measured at 25°C, was 2.33 × 10⁻⁶. -6 S / cm.

[0140] (Battery manufacturing)

[0141] In a dry argon atmosphere, the solid electrolyte material of Example 1 and LiCoO2 as the active material were prepared at a volume ratio of 30:70. These materials were then mixed in an agate mortar. This yielded the positive electrode mixture.

[0142] Next, LiCl and YCl3 were prepared to achieve a molar ratio of LiCl:YCl3 = 3:1. These materials were then pulverized and mixed in a mortar. The resulting mixture was milled at 500 rpm for 12 hours using a planetary ball mill. This yielded a halide solid electrolyte (hereinafter referred to as "LYC") with the composition shown in Li3YCl6.

[0143] In an insulating cylinder with an inner diameter of 9.5 mm, LYC (60 mg), the solid electrolyte material of Example 1 (26 mg), and the above-mentioned positive electrode mixture (9.1 mg) were sequentially stacked. A pressure of 300 MPa was applied to the resulting laminate to form a second electrolyte layer, a first electrolyte layer, and a positive electrode. That is, the first electrolyte layer formed from the solid electrolyte layer of Example 1 was sandwiched between the second electrolyte layer and the positive electrode. The thicknesses of the second electrolyte layer and the first electrolyte layer were 450 μm and 150 μm, respectively.

[0144] Next, metallic In (thickness: 200 μm) is laminated on the second electrolyte layer. A pressure of 80 MPa is applied to the resulting laminate to form the negative electrode.

[0145] Next, a current collector made of stainless steel is installed on the positive and negative terminals, and a current collector lead is installed on the current collector.

[0146] Finally, an insulating ring is used to isolate the inside of the insulating cylinder from the external atmosphere, thus sealing the inside of the cylinder. This yields the battery of Example 1.

[0147] (Charge / Discharge Test)

[0148] Figure 5 This is a graph showing the initial discharge characteristics of the battery in Example 1. The initial charge-discharge characteristics were determined using the following method.

[0149] The battery of Example 1 was placed in a constant temperature bath at 85°C.

[0150] At 27μA / cm 2 The battery of Example 1 was charged to a voltage of 3.6V using a current density equivalent to a 0.02C rate.

[0151] Next, at 27 μA / cm 2 The battery of Example 1 was discharged at a current density until it reached a voltage of 1.9V.

[0152] The results of the charge-discharge test showed that the battery in Example 1 had an initial discharge capacity of 900.76 μAh.

[0153] <Examples 2-16>

[0154] (Preparation of solid electrolyte materials)

[0155] In Examples 2 to 15, LiF, TiF4 and MgF2 were prepared as raw material powders in a molar ratio of LiF:TiF4:MgF2 = {6-(4-2x)b}:(1-x)b:xb.

[0156] In Example 16, LiF, TiF4 and CaF2 were prepared as raw material powders in a molar ratio of LiF:TiF4:CaF2 = {6-(4-2x)b}:(1-x)b:xb.

[0157] Apart from the above, the solid electrolyte materials of Examples 2 to 16 were obtained in the same manner as in Example 1.

[0158] For the solid electrolyte materials of Examples 2-16, the values ​​of x, b and Li / (Ti+M) molar ratio are shown in Table 1.

[0159] (Evaluation of ionic conductivity)

[0160] The ionic conductivity of the solid electrolyte materials in Examples 2-16 was measured in the same manner as in Example 1. The results are shown in Table 1.

[0161] (Charge / Discharge Test)

[0162] Using the solid electrolyte materials of Examples 2 to 16, batteries of Examples 2 to 16 were obtained in the same manner as in Example 1.

[0163] For the batteries of Examples 2 to 16, charge-discharge tests were performed in the same manner as in Example 1. The batteries of Examples 2 to 16 were charged and discharged well in the same manner as the batteries of Example 1.

[0164] <Comparative Example 1>

[0165] As a solid electrolyte material, replacing Li 3.0 Ti 0.5 Mg 0.5 F6 uses LiBF4.

[0166] The ionic conductivity of LiBF4 was measured in the same manner as in Example 1. The ionic conductivity measured at 25°C was 6.67 × 10⁻⁶. -9 S / cm.

[0167] Using LiBF4 as the solid electrolyte material, the battery of Comparative Example 1 was obtained in the same manner as in Example 1.

[0168] The battery of Comparative Example 1 was subjected to the same charge-discharge test as in Example 1. As a result, the battery of Comparative Example 1 had an initial discharge capacity of less than 0.01 μAh. That is, the battery of Comparative Example 1 was neither charged nor discharged.

[0169] The solid electrolyte materials of Examples 1-16 and Comparative Example 1 and the evaluation results are shown in Table 1.

[0170] [Table 1]

[0171]

[0172] <Inspection>

[0173] The solid electrolyte materials in Examples 1-16 have a strength of 1×10⁻⁶ at room temperature. -8 High ionic conductivity exceeding S / cm. On the other hand, the solid electrolyte material of the comparative example exhibits a conductivity less than 1 × 10⁻⁶. -8 Low ionic conductivity (S / cm).

[0174] When comparing Examples 1-3 and Examples 11-14 with Examples 4 and 5, it can be seen that when 0.8≤b≤1.3 is satisfied, the ionic conductivity of the solid electrolyte material is further improved.

[0175] When comparing Example 1 with Example 16, it can be seen that when M is Mg, the ionic conductivity of the solid electrolyte material is higher than when M is Ca.

[0176] The batteries in Examples 1-16 were all charged and discharged at 85°C. The battery in Comparative Example 1 was neither charged nor discharged.

[0177] The solid electrolyte materials in Examples 1-16 do not contain sulfur, therefore no hydrogen sulfide is generated.

[0178] As shown above, the solid electrolyte material disclosed herein is suitable for providing batteries with high lithium-ion conductivity and good charging and discharging capabilities.

[0179] Industrial availability

[0180] The solid electrolyte material disclosed herein is used, for example, in all-solid-state lithium-ion secondary batteries.

[0181] Symbol Explanation

[0182] 100 solid electrolyte particles

[0183] 101 Powder of solid electrolyte material

[0184] 201 Positive Electrode

[0185] 202 Electrolyte Layer

[0186] 212 First Electrolyte Layer

[0187] 222 Second Electrolyte Layer

[0188] 203 Negative electrode

[0189] 204 Positive Electrode Active Material Particles

[0190] 205 Negative Electrode Active Material Particles

[0191] 300 pressure molding die

[0192] Upper part of 301 drilling machine

[0193] 302 frame type

[0194] 303 Drilling Machine Lower Part

[0195] 1000 batteries

[0196] 2000 batteries

Claims

1. A solid electrolyte material, substantially composed of Li, Ti, M, and F, wherein, M is at least one selected from Mg and Ca, which is represented by the following compositional formula (1), Li 6-(4-x)b (Ti 1-x M x ) b Type F6 (1) where 0 < x < 1 and 0 < b ≤ 3 are satisfied.

2. A solid electrolyte material comprising Li, Ti, M, and F, in, where M is at least one selected from Mg and Ca, and the ratio of the amount of Li to the sum of the amounts of Ti and M is 0.5 to 4.5, which is represented by the following compositional formula (1), Li 6-(4-x)b (Ti 1-x M x ) b F6 type (1) where 0 < x < 1 and 0 < b ≤ 3 are satisfied.

3. The solid electrolyte material according to claim 1 or 2, which satisfies the mathematical formula: 0.05 ≤ x ≤ 0.

8.

4. The solid electrolyte material according to claim 1 or 2, wherein, M is Mg and satisfies the mathematical formula: 0.05 ≤ x ≤ 0.

6.

5. The solid electrolyte material according to claim 1 or 2, wherein, M is Ca and satisfies the mathematical formula: x = 0.

5.

6. The solid electrolyte material according to claim 1 or 2, which satisfies the mathematical formula: 0.80 ≤ b ≤ 1.

71.

7. A battery comprising a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode, where at least one of the positive electrode, the negative electrode, and the electrolyte layer contains the solid electrolyte material according to any one of claims 1 to 6.

8. The battery according to claim 7, wherein, The electrolyte layer includes a first electrolyte layer and a second electrolyte layer, the first electrolyte layer is disposed between the positive electrode and the negative electrode, the second electrolyte layer is disposed between the first electrolyte layer and the negative electrode, and the first electrolyte layer contains the solid electrolyte material.

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