Solid electrolyte material and battery using the same

Abstract

A solid electrolyte material containing Li, Ti, M, and F, wherein M is at least one selected from Al and Y.

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 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 (also known as lithium-ion electrical conductivity or lithium-ion conductivity).

[0009] Methods for solving problems

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

[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 of the battery 1000 according to the second embodiment is shown.

[0014] Figure 2 A cross-sectional view of the battery 2000 according to the second embodiment is shown.

[0015] Figure 3 A schematic diagram of a pressure forming mold 300 used to evaluate the ionic conductivity of solid electrolyte materials is shown.

[0016] Figure 4 This is a Cole-Cole plot obtained by impedance measurement of the solid electrolyte material of Example 1.

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

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0019] (First Embodiment)

[0020] The solid electrolyte material of the first embodiment contains Li, Ti, M, and F, wherein M is at least one selected from Al and Y. The so-called high lithium-ion conductivity is, for example, 1 × 10⁻⁶. -8 S / cm or higher. That is, the solid electrolyte material of the first embodiment may have, for example, 1×10⁻⁶. -8 Ionic conductivity above S / cm.

[0021] The solid electrolyte material of the first embodiment has high lithium-ion conductivity.

[0022] 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.

[0023] The solid electrolyte material of the first embodiment is preferably 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, however, can produce hydrogen sulfide when exposed to the atmosphere.

[0024] The solid electrolyte material of the first embodiment has high oxidation resistance because it contains F. This is because F has a high redox potential. On the other hand, because F has high electronegativity, it binds strongly to Li. As a result, the lithium-ion conductivity of solid electrolyte materials containing both Li and F is typically reduced. For example, LiBF4 disclosed in Patent Document 2 has a lithium-ion conductivity of 6.67 × 10⁻⁶. -9 The low ionic conductivity (S / cm) is also a concern. Furthermore, LiBF4 is the solid electrolyte material used in Comparative Example 1, described later. In contrast, the solid electrolyte material of the first embodiment, by containing Ti and M in addition to Li and F, can achieve, for example, a conductivity of 1 × 10⁻⁶ S / cm. -8 High ionic conductivity above S / cm.

[0025] 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.

[0026] The solid electrolyte material of the first embodiment may also be substantially made of Li, Ti, M, and F. Here, "the solid electrolyte material of the first embodiment is substantially made of Li, Ti, M, and F" means that the molar ratio (i.e., mole fraction) of the total amount of Li, Ti, M, and F to the total amount of all elements constituting the solid electrolyte material of the first embodiment is 90% or more. As an example, this molar ratio may also be 95% or more. The solid electrolyte material of the first embodiment may also be made solely of Li, Ti, M, and F.

[0027] The solid electrolyte material of the first embodiment may also contain elements that are unavoidably mixed in. Examples of such elements are hydrogen, oxygen, or nitrogen. Such elements may be present in the raw material powder of the solid electrolyte material or in the atmosphere used to manufacture or store the solid electrolyte material.

[0028] To further improve the ionic conductivity of solid electrolyte materials, the ratio of the amount of Li to the total amount of Ti and M can be above 1.7 and below 4.2.

[0029] To further improve the ionic conductivity of solid electrolyte materials, M can also be Al.

[0030] The solid electrolyte material of the first embodiment can also be represented by the following composition formula (1).

[0031] Li 6-(4-x)b (Ti 1-x M x ) b Formula F6 (1)

[0032] In equation (1), 0 < x < 1 and 0 < b ≤ 1.5 are satisfied. Solid electrolyte materials with such a composition have high ionic conductivity.

[0033] To improve the ionic conductivity of solid electrolyte materials, equation (1) can also satisfy the mathematical expression: 0.1≤x≤0.9. When M is Y, to improve the ionic conductivity of solid electrolyte materials, equation (1) can also satisfy the mathematical expression: 0.1≤x≤0.7.

[0034] The upper and lower limits of the range of x in equation (1) can be specified by any combination of the values ​​selected from 0.1, 0.3, 0.4, 0.5, 0.6, 0.67, 0.7, 0.8 and 0.9.

[0035] In order to improve the ionic conductivity of solid electrolyte materials, in equation (1), the mathematical expression can also be satisfied: 0.8≤b≤1.2.

[0036] The upper and lower limits of the range of b in equation (1) can be specified by any combination of the values ​​selected from 0.8, 0.9, 0.94, 1.0, 1.06, 1.1 and 1.2.

[0037] The solid electrolyte material in the first embodiment can be crystalline or amorphous.

[0038] 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 may also be particles. The solid electrolyte material in the first embodiment may also be formed in the form of particles or plates.

[0039] When the solid electrolyte material of the first embodiment is in the shape of particles (e.g., spheres), it may also have a median particle size of 0.1 μm or more and 100 μm or less. The median particle size refers to the particle size in which the cumulative volume of the particle size distribution, based on volume, reaches 50%. The volume-based particle size distribution is measured, for example, by a laser diffraction measuring device or an image analysis device.

[0040] The solid electrolyte material of the first embodiment may also have a median particle size of 0.5 μm or more and 10 μm or less. 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 of the solid electrolyte material of the first embodiment and the other materials becomes excellent.

[0041] <Manufacturing Methods of Solid Electrolyte Materials>

[0042] The solid electrolyte material of the first embodiment can be manufactured, for example, by the method described below.

[0043] The raw material powder is prepared and mixed in a manner that makes it a component for the intended purpose. The raw material powder may, for example, be a halide.

[0044] As an example, when the component for the purpose is Li 2.7 Ti 0.3 Al 0.7 For F6, LiF, TiF4, and AlF3 are mixed in a molar ratio of approximately 2.7:0.3:0.7. Alternatively, the molar ratio of the mixed raw material powders can be pre-adjusted to offset compositional changes that may occur during the synthesis process.

[0045] The raw material powders are mechanically and chemically reacted (i.e., by mechanochemical grinding) in a mixing device such as a planetary ball mill to obtain reactants. The reactants can also be calcined in a vacuum or an inert atmosphere. Alternatively, the reactants can be obtained by calcining a mixture of raw material powders in a vacuum or an inert atmosphere. Calcination is preferably carried out at a temperature of 100°C or higher and 300°C or lower for at least 1 hour. To suppress compositional changes during calcination, it is preferable to calcine the raw material powders in a sealed container such as a quartz tube.

[0046] Through these methods, the solid electrolyte material of the first embodiment is obtained.

[0047] (Second Implementation)

[0048] The second embodiment will be described below. Matters described in the first embodiment will be omitted as appropriate.

[0049] The battery of the second embodiment includes a positive electrode, an electrolyte layer, and a negative electrode. The electrolyte layer is disposed between the positive electrode and the negative electrode.

[0050] The solid electrolyte material of the first embodiment is selected from at least one of the positive electrode, the electrolyte layer and the negative electrode.

[0051] The battery of the second embodiment has excellent charge and discharge characteristics because it contains the solid electrolyte material of the first embodiment.

[0052] Figure 1 A cross-sectional view of the battery 1000 according to the second embodiment is shown.

[0053] 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.

[0054] The positive electrode 201 contains positive electrode active material particles 204 and solid electrolyte particles 100.

[0055] The electrolyte layer 202 contains an electrolyte material (e.g., a solid electrolyte material).

[0056] The negative electrode 203 contains negative electrode active material particles 205 and solid electrolyte particles 100.

[0057] The solid electrolyte particles 100 are particles made of 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" refers to particles in which the solid electrolyte material of the first embodiment is the most abundant component by mass ratio.

[0058] 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 particle 204).

[0059] Examples of positive electrode active materials are lithium-containing transition metal oxides (e.g., Li(NiCoAl)O2 or LiCoO2), transition metal fluorides, polyanions, fluorinated polyanions, transition metal sulfides, transition metal fluorides, transition metal sulfides, or transition metal nitrides.

[0060] The positive electrode active material particles 204 can also have a median particle size of 0.1 μm or more and 100 μm or less. 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 100 μm or less, the lithium diffusion rate within the positive electrode active material particles 204 is increased. As a result, the battery 1000 can operate at high power.

[0061] The positive electrode active material particles 204 can also 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.

[0062] In order to improve the energy density and power of the battery, the ratio of the volume of the positive electrode active material particles 204 to the total volume of the positive electrode active material particles 204 and the solid electrolyte particles 100 in the positive electrode 201 can also be above 0.30 and below 0.95.

[0063] 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 included in the coating layer are sulfide solid electrolytes, oxide solid electrolytes, or halide solid electrolytes. When the solid electrolyte particles 100 contain a sulfide solid electrolyte, the coating material may also 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 an oxide solid electrolyte to suppress the oxidative decomposition of the solid electrolyte material. Lithium niobate, which has excellent stability at high potentials, may also be used as the oxide solid electrolyte. By suppressing the oxidative decomposition of the solid electrolyte, the rise in battery overvoltage can be suppressed.

[0064] To improve the energy density and power of the battery, the cathode 201 can also have a thickness of more than 10 μm and less than 500 μm.

[0065] Electrolyte layer 202 contains an electrolyte material. This electrolyte material is, for example, a solid electrolyte material. Electrolyte layer 202 may also be a solid electrolyte layer.

[0066] The electrolyte layer 202 may also 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. Wherein, X is at least one selected from F, Cl, Br, and I. Furthermore, in this disclosure, when elements in a formula are represented as "(Al, Ga, In)," this notation indicates at least one element selected from the group of elements enclosed in parentheses. That is, "(Al, Ga, In)" is synonymous with "at least one selected from Al, Ga, and In." The same applies to other elements.

[0067] 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.

[0068] 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 may be uniformly dispersed within the electrolyte layer 202. The layers formed from the first and second solid electrolyte materials may also be stacked along the stacking direction of the battery 1000.

[0069] Figure 2 A cross-sectional view of the battery 2000 according to the second embodiment is shown.

[0070] like Figure 2 As shown, the battery 2000 may also include a positive electrode 201, a first electrolyte layer 212, a second electrolyte layer 222, and a negative electrode 203. That is, the electrolyte layer 202 may also 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.

[0071] In the battery 2000, the first electrolyte layer 212 may also contain the solid electrolyte material of the first embodiment. Since the solid electrolyte material of the first embodiment has high oxidation resistance, the solid electrolyte material contained in the second electrolyte layer 222 can be used in a manner that prevents it from oxidizing. As a result, the charge / discharge efficiency of the battery can be improved.

[0072] In the battery 2000, the solid electrolyte material contained in the second electrolyte layer 222 can also have a lower reduction potential than the solid electrolyte material contained in the first electrolyte layer 212. Therefore, the solid electrolyte material contained in the first electrolyte layer 212 can be used in a manner that prevents its reduction. As a result, the charge and discharge efficiency of the battery can be improved. For example, when the first electrolyte layer contains the solid electrolyte material of the first embodiment, the second electrolyte layer may also contain a sulfide solid electrolyte to suppress the reductive decomposition of the solid electrolyte material.

[0073] To improve the energy density and power of the battery, the electrolyte layer 202 can also have a thickness of more than 1 μm and less than 1000 μm.

[0074] 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).

[0075] Examples of negative electrode active materials include metallic materials, carbon materials, oxides, nitrides, tin compounds, or silicon compounds. Metallic materials can be elemental 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.

[0076] The negative electrode active material can also be selected based on its resistance to reduction, considering 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 also 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. 12 LiTi₂O₄ 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.

[0077] The negative electrode active material particles 205 can also have a median particle size of 0.1 μm or larger and 100 μm or smaller. 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 100 μm or smaller, the lithium diffusion rate within the negative electrode active material particles 205 is increased. As a result, the battery can operate at high power.

[0078] The negative electrode active material particles 205 can also have a larger median particle size than 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.

[0079] In order to improve the energy density and power of the battery, the ratio of the volume of the negative electrode active material particles 205 to the total volume of the negative electrode active material particles 205 and the solid electrolyte particles 100 in the negative electrode 203 can also be above 0.30 and below 0.95.

[0080] To improve the energy density and power of the battery, the negative electrode 203 can also have a thickness of more than 10 μm and less than 500 μm.

[0081] At least one of the positive electrode 201, electrolyte layer 202 and negative electrode 203 may also contain a second solid electrolyte material for the purpose of improving ion conductivity, chemical stability and electrochemical stability.

[0082] The second solid electrolyte material can also be a sulfide solid electrolyte.

[0083] 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 .

[0084] 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 coating 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.

[0085] The second solid electrolyte material can also be an oxide solid electrolyte.

[0086] Examples of oxide solid electrolytes are:

[0087] (i) NASICON-type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutes;

[0088] (ii) Perovskite-type solid electrolytes such as (LaLi)TiO3,

[0089] (iii)Li 14 ZnGe4O 16 LISICON-type solid electrolytes such as Li4SiO4, LiGeO4, or their elemental substitutes.

[0090] (iv)Li7La3Zr2O 12 Garnet-type solid electrolytes such as or elemental substitutes thereof, or

[0091] (v)Li3PO4 or its N-substituted derivatives.

[0092] As mentioned above, the second solid electrolyte material can also be a halide solid electrolyte.

[0093] Examples of halide solid electrolytes are Li₂MgX₄, Li₂FeX₄, Li(Al, Ga, In)X₄, Li₃(Al, Ga, In)X₆, or LiI. Wherein, X is selected from at least one of F, Cl, Br, and I.

[0094] Other examples of halide solid electrolyte materials are those using Li a Me b Y c X6 represents a compound that satisfies a + mb + 3c = 6 and c > 0. Me is at least one metallic element and half-metallic element selected from those other than Li and Y. m represents the valence of Me. "Half-metallic elements" are B, Si, Ge, As, Sb, and Te. "Metallic elements" are 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).

[0095] To improve the ionic conductivity of halide solid electrolyte materials, Me can also 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.

[0096] The second solid electrolyte material can also be an organic polymer solid electrolyte.

[0097] Examples of organic polymer solid electrolytes include polymeric compounds and lithium salt compounds.

[0098] Polymers can also possess an ethylene oxide structure. Polymers with an ethylene oxide structure contain a higher proportion of lithium salts, thus further enhancing their ionic conductivity.

[0099] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3. A single lithium salt selected from these can also be used. Alternatively, a mixture of two or more lithium salts selected from these can be used.

[0100] At least one of the positive electrode 201, electrolyte layer 202 and negative electrode 203 may also contain a non-aqueous electrolyte, gel electrolyte or ionic liquid for the purpose of facilitating lithium ion acceptance and improving the power characteristics of the battery.

[0101] The non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0102] 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 butyl carbonate. Examples of chain carbonate solvents include dimethyl carbonate, methyl ethyl carbonate, or diethyl carbonate. Examples of cyclic ether solvents include tetrahydrofuran, 1,4-dioxane, or 1,3-dioxane. 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, methyl ethyl fluorocarbonate, or dimethyl fluorocarbonate. One non-aqueous solvent selected from the above can be used alone. Alternatively, a combination of two or more non-aqueous solvents selected from the above can be used.

[0103] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3. A single lithium salt selected from these can also be used. Alternatively, a mixture 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 or more and 2 mol / L or less.

[0104] As a gel electrolyte, a polymeric material 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.

[0105] Examples of cations contained in ionic liquids include:

[0106] (i) Aliphatic chain quaternary salts (quaternary salts) such as tetraalkylammonium or tetraalkylphosphonium salts;

[0107] (ii) Aliphatic cyclic ammonium compounds such as pyrrolidinemonium, morpholinium, imidazolinemonium, tetrahydropyrimidinemonium, piperazinemonium, or piperidinemonium, or

[0108] (iii) Nitrogen-containing heterocyclic aromatic cations such as pyridinium or imidazoline.

[0109] An example of anion contained in an ionic liquid is PF6. - BF4 - SbF6 - AsF6 - SO3CF3 - N(SO2CF3)2 - N(SO2C2F5)2 - N(SO2CF3)(SO2C4F9) - Or C(SO2CF3)3 - .

[0110] Ionic liquids can also contain lithium salts.

[0111] At least one of the positive electrode 201, electrolyte layer 202 and negative electrode 203 may also contain a binder for the purpose of improving the adhesion between particles.

[0112] Examples of adhesives include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aromatic polyamide resins, polyamides, polyimides, polyamide-imides, 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, 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, trifluorochloroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene. Mixtures of two or more materials selected from the above can also be used as adhesives.

[0113] To reduce resistance, at least one of the positive electrode 201 and the negative electrode 203 may contain a conductive additive.

[0114] Examples of conductive additives are:

[0115] (i) Graphite, such as natural or artificial graphite;

[0116] (ii) Carbon blacks such as acetylene black or Ketjen black;

[0117] (iii) Conductive fibers such as carbon fiber or metal fiber;

[0118] (iv) Fluorocarbon,

[0119] (v) Metal powders such as aluminum

[0120] (vi) Conductive whiskers such as zinc oxide or potassium titanate;

[0121] (vii) Conductive metal oxides such as titanium dioxide, or

[0122] (viii) Conductive polymers such as polyaniline, polypyrrole or polythiophene.

[0123] To reduce costs, the conductive additives described in (i) or (ii) above can also be used.

[0124] Examples of the battery shape in the second embodiment include coin type, cylindrical type, square type, sheet type, button type, flat type, or stacked type.

[0125] The battery of the second embodiment can also be manufactured in the following manner: preparing materials for forming a positive electrode, materials for forming an electrolyte layer, and materials for forming a negative electrode, and fabricating a laminate in which a positive electrode, an electrolyte layer, and a negative electrode are sequentially arranged using a known method.

[0126] Example

[0127] The present disclosure will now be described in more detail with reference to embodiments and comparative examples.

[0128] <Example 1>

[0129] (Preparation of solid electrolyte materials)

[0130] In an argon atmosphere with a dew point below -60°C (hereinafter referred to as "dry argon atmosphere"), LiF, TiF4, and AlF3 were prepared as raw material powders in a molar ratio of LiF:TiF4:AlF3 = 2.7:0.3:0.7. These materials were pulverized and mixed in a mortar. The resulting mixture was then milled using a planetary ball mill at 500 rpm for 12 hours. This process yielded the powder of the solid electrolyte material of Example 1. The solid electrolyte material of Example 1 has the characteristics of using Li... 2.7 Ti 0.3 Al 0.7 F6 represents the composition.

[0131] (Evaluation of ionic conductivity)

[0132] Figure 3 A schematic diagram of a pressure forming mold 300 used to evaluate the ionic conductivity of solid electrolyte materials is shown.

[0133] The pressure forming die 300 includes a punch upper portion 301, a frame die 302, and a punch lower portion 303. The frame die 302 is formed of insulating polycarbonate. The punch upper portion 301 and the punch lower portion 303 are formed of electronically conductive stainless steel.

[0134] use Figure 3 The ionic conductivity of the solid electrolyte material of Example 1 was evaluated using the pressure molding die 300 shown below.

[0135] In a dry 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 forming mold 300. Inside the pressure forming mold 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 the punch.

[0136] The upper part 301 and lower part 303 of the punch were connected to a potentiostat (Princeton Applied Research, Versa STAT4) equipped with a frequency response analyzer under pressure. The upper part 301 of the punch was connected to the working electrode and the potential measurement terminal. The lower part 303 of the punch was connected to the counter electrode and the reference electrode. The impedance of the solid electrolyte material of Example 1 was measured at room temperature by electrochemical impedance spectroscopy.

[0137] Figure 4 This is a Cole-Cole plot showing the solid electrolyte material of Example 1 obtained by impedance measurement.

[0138] Figure 4In this context, the real value of the impedance at the measurement point where the absolute value of the phase of the complex impedance is smallest is considered as the resistance of the solid electrolyte material for ion conduction. For details regarding this real value, please refer to [reference needed]. Figure 4 Arrow R shown in the image SE Using this resistance value, the ionic conductivity was calculated based on the following mathematical formula (2).

[0139] σ=(R SE ×S / t) -1 (2)

[0140] Where σ represents ionic conductivity. S represents the contact area between the solid electrolyte material and the upper part 301 of the punch ( Figure 3 In the middle, the cross-sectional area is equal to that of the hollow part of the frame mold 302. SE This represents the resistance value of the solid electrolyte material during impedance measurement. t represents the thickness of the solid electrolyte material (i.e.,...). Figure 3 (The thickness of the layer formed by the powder 101 of the solid electrolyte material).

[0141] The ionic conductivity of the solid electrolyte material in Example 1, measured at 25°C, was 7.20 × 10⁻⁶. -6 S / cm.

[0142] (Battery manufacturing)

[0143] In a dry argon atmosphere, the solid electrolyte material and active material, LiCoO2, of Example 1 were prepared at a volume ratio of 30:70. These materials were then mixed in an agate mortar. This process yielded a positive electrode mixture.

[0144] Next, LiCl and YCl3 were prepared in a molar ratio of LiCl:YCl3 = 3:1. These materials were pulverized and mixed in a mortar. The resulting mixture was then milled using a planetary ball mill at 500 rpm for 12 hours. This process yielded a halide solid electrolyte (hereinafter referred to as "LYC") with a composition represented by Li3YCl6.

[0145] 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 material 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.

[0146] 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.

[0147] Next, a current collector made of stainless steel is installed on the positive and negative terminals, and the current collector leads are installed on the current collector.

[0148] Finally, an insulating ring is used to isolate the interior of the insulating cylinder from the external atmosphere, thus sealing the interior of the cylinder. This process yields the battery of Example 1.

[0149] (Charge / Discharge Test)

[0150] Figure 5 This is a graph showing the initial discharge characteristics of the battery of Example 1. The initial charge-discharge characteristics were measured by the following method.

[0151] The battery of Example 1 was placed in a constant temperature bath at 85°C.

[0152] The battery of Example 1 was used at 27 μA / cm 2 The current density is used to charge the battery to a voltage of 3.6V. This current density is equivalent to a 0.02C rate.

[0153] Next, the battery from Example 1 was subjected to a current of 27 μA / cm. 2 The current density discharges to a voltage of 1.9V.

[0154] The results of the charge-discharge test showed that the battery in Example 1 had an initial discharge capacity of 903 μAh.

[0155] <Examples 2-18>

[0156] (Preparation of solid electrolyte materials)

[0157] In Examples 2 to 14, LiF, TiF4 and AlF3 were prepared as raw material powders in a molar ratio of LiF:TiF4:AlF3 = {6-(4-x)b}:(1-x)b:xb.

[0158] In Examples 15-18, LiF, TiF4 and YF3 were prepared as raw material powders in a molar ratio of LiF:TiF4:YF3 = {6-(4-x)b}:(1-x)b:xb.

[0159] Except as described above, the solid electrolyte materials of Examples 2 to 18 were obtained by operating in the same manner as in Example 1.

[0160] Regarding the solid electrolyte materials of Examples 2-18, Table 1 shows the values ​​of x, b, and the Li / (Ti+M) molar ratio.

[0161] (Evaluation of ionic conductivity)

[0162] The ionic conductivity of the solid electrolyte materials of Examples 2–18 was measured in the same manner as in Example 1. The results are shown in Table 1.

[0163] (Charge / Discharge Test)

[0164] Batteries of Examples 2-18 were obtained by using the solid electrolyte materials of Examples 2-18 and operating in the same manner as in Example 1.

[0165] For the batteries of Examples 2 to 18, charge-discharge tests were performed in the same manner as in Example 1. The batteries of Examples 2 to 18 were subjected to good charging and discharging in the same manner as in Example 1.

[0166] <Comparative Example 1>

[0167] As a solid electrolyte material, LiBF4 is used to replace Li 2.7 Ti 0.3 Al 0.7 F6.

[0168] The ionic conductivity of LiBF4 was measured using the same procedure as in Example 1. The ionic conductivity measured at 25°C was 6.67 × 10⁻⁶. -9 S / cm.

[0169] Using LiBF4 as the solid electrolyte material, the battery of Comparative Example 1 was obtained by operating in the same manner as in Example 1.

[0170] The battery of Comparative Example 1 was subjected to a charge-discharge test in the same manner as in Example 1. The result was that the battery of Comparative Example 1 had an initial discharge capacity of less than 0.01 μAh. In other words, Comparative Example 1 was neither charged nor discharged.

[0171] Table 1 shows the solid electrolyte materials and evaluation results for Examples 1-18 and Comparative Example 1.

[0172] Table 1

[0173]

[0174] <Inspection>

[0175] The solid electrolyte materials in Examples 1-18 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 conductivity below 1×10⁻⁶. 8 Low ionic conductivity (S / cm).

[0176] By comparing Examples 1 and 6 with Examples 17 and 15, it was found that the ionic conductivity of the solid electrolyte material was further improved when M was Al compared to when M was Y.

[0177] The batteries in Examples 1 through 18 were charged and discharged at 85°C. On the other hand, the battery in Comparative Example 1 was neither charged nor discharged.

[0178] The solid electrolyte materials in Examples 1-18 do not contain sulfur, so no hydrogen sulfide is generated.

[0179] As described above, the solid electrolyte material disclosed herein is suitable for providing batteries with high lithium-ion conductivity and good charge and discharge performance.

[0180] Industrial availability

[0181] The solid electrolyte material disclosed herein can be used, for example, in all-solid-state lithium-ion secondary batteries.

[0182] Symbol Explanation

[0183] 100: Solid electrolyte particles

[0184] 101: Powder of solid electrolyte materials

[0185] 201: Positive electrode

[0186] 202: Electrolyte layer

[0187] 212: First electrolyte layer

[0188] 222: Second electrolyte layer

[0189] 203: Negative electrode

[0190] 204: Positive electrode active material particles

[0191] 205: Negative electrode active material particles

[0192] 300: Pressure forming die

[0193] 301: Upper part of the punch

[0194] 302: Frame mold

[0195] 303: Lower part of the punch

[0196] 1000: Battery

[0197] 2000: Battery

Claims

1. A solid electrolyte material containing Li, Ti, M, and F, wherein, M is selected from at least one of Al and Y. The ratio of the amount of Li to the total amount of Ti and M is 1.7 or more and 4.2 or less. The solid electrolyte material is represented by the following composition formula (1). Li 6-(4-x)b (Ti 1-x M x ) b Type F6 (1) Among them, 0 < x < 1 and 0 < b ≤ 1.5 are satisfied.

2. The solid electrolyte material according to claim 1, wherein, M stands for Al.

3. The solid electrolyte material according to claim 1 or 2, wherein, It satisfies the mathematical formula: 0.1≤x≤0.

9.

4. The solid electrolyte material according to claim 1 or 2, wherein, M is Y, and satisfies the mathematical formula: 0.1≤x≤0.

7.

5. The solid electrolyte material according to claim 1 or 2, wherein, It satisfies the mathematical formula: 0.8≤b≤1.

2.

6. A battery comprising: positive electrode; Negative electrode; and An electrolyte layer disposed between the positive electrode and the negative electrode. in, The material is selected from at least one of the positive electrode, the negative electrode, and the electrolyte layer, and contains any one of the solid electrolyte materials according to claims 1 to 5.

7. The battery according to claim 6, 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. The first electrolyte layer contains the solid electrolyte material.

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