Solid electrolyte material and battery using the same

Abstract

The solid electrolyte material disclosed herein comprises Li, M1, M2 and X. M1 is at least one element selected from the group consisting of Group 2 elements and Group 12 elements. M2 is at least three elements selected from the group consisting of rare earth elements and Group 13 elements. X is at least one selected from the group consisting of F, Cl, Br and I. The battery (1000) disclosed herein comprises a positive electrode (201), a negative electrode (203), and an electrolyte layer (202) disposed between the positive electrode (201) and the negative electrode (203). At least one selected from the group consisting of the positive electrode (201), the negative electrode (203) and the electrolyte layer (202) contains the solid electrolyte material disclosed herein.

Description

Technical Field

[0001] The present disclosure relates to a solid electrolyte material and a battery using the same. Background Art

[0002] Patent Document 1 discloses an all-solid-state battery using a sulfide solid electrolyte.

[0003] Patent Document 2 discloses a solid electrolyte material represented by the compositional formula Li

[0017] ,

[0012] , Figure 1 ,

[0010] ,

[0015] ,

[0011] , ,

[0013] , ,

[0014] , , , , , ,

[0016] , , , Figure 2 , Y z X6 (0 < z < 2, X = Cl or Br).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-129312

[0007] Patent Document 2: WO 2018 / 025582

[0008] Non-Patent Documents

[0009] Non-Patent Document 1: R.D. Shannon, Acta Cryst., A32, 751 (1976) Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] An object of the present disclosure is to provide a novel solid electrolyte material having lithium ion conductivity.

[0012] Means for Solving the Problems

[0013] The solid electrolyte material of the present disclosure contains Li, M1, M2, and X, where M1 is at least one element selected from the group consisting of Group 2 elements and Group 12 elements, M2 is at least three elements selected from the group consisting of rare earth elements and Group 13 elements, and X is at least one selected from the group consisting of F, Cl, Br, and I.

[0014] Effects of the Invention

[0015] The present disclosure provides a novel solid electrolyte material having lithium ion conductivity. Brief Description of the Drawings

[0016] Figure 1 A cross-sectional view of the battery 1000 showing the second embodiment.

[0017] Figure 2 A schematic view of the compression molding die 300 used to evaluate the ionic conductivity of the solid electrolyte material.

[0018] Figure 3 This is a graph showing the Cole-Cole curve of the solid electrolyte material of Example 1 obtained by AC impedance measurement.

[0019] Figure 4 This is a graph showing the X-ray diffraction pattern of the solid electrolyte material of Example 1.

[0020] Figure 5 This is a graph showing the initial discharge characteristics of the battery of Example 1. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0022] (First embodiment)

[0023] The solid electrolyte material of the first embodiment includes Li, M1, M2, and X. M1 is at least one element selected from the group consisting of Group 2 elements and Group 12 elements. M2 is at least three elements selected from the group consisting of rare earth elements and Group 13 elements. X is at least one element selected from the group consisting of F, Cl, Br, and I.

[0024] The solid electrolyte material of the first embodiment is a novel solid electrolyte material having lithium ion conductivity. The solid electrolyte material of the first embodiment can have a conductivity of 1.0×10 -3 S / cm or higher ion conductivity.

[0025] The solid electrolyte material of the first embodiment can be used to obtain a battery with excellent charge and discharge characteristics. An example of such a battery is an all-solid-state battery. The all-solid-state battery can be a primary battery or a secondary battery.

[0026] The solid electrolyte material of the first embodiment preferably contains no sulfur. A solid electrolyte material that contains no sulfur does not generate hydrogen sulfide even when exposed to the atmosphere, thus providing excellent safety. The sulfide solid electrolyte disclosed in Patent Document 1 may generate hydrogen sulfide when exposed to the atmosphere.

[0027] In order to improve the ionic conductivity of the solid electrolyte material, the solid electrolyte material of the first embodiment may be substantially composed of Li, M1, M2 and X. Here, the so-called "the solid electrolyte material of the first embodiment is substantially composed of Li, M1, M2 and X" means that the molar ratio (i.e., molar fraction) of the total amount of Li, M1, M2 and X relative to the total amount of all elements constituting the solid electrolyte material of the first embodiment is 90% or more. As an example, the molar ratio may be 95% or more. The solid electrolyte material of the first embodiment may also be composed only of Li, M1, M2 and X.

[0028] The solid electrolyte material of the first embodiment may also contain unavoidable elements. 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.

[0029] The X-ray diffraction pattern of the solid electrolyte material of the first embodiment can be obtained using Cu-Kα rays (wavelength and That is, wavelengths of 0.15405nm and 0.15444nm), obtained by X-ray diffraction measurement using the θ-2θ method. In the obtained X-ray diffraction pattern, there may be at least two peaks within the range of a diffraction angle 2θ of 14.0° or more and 18.0° or less, and at least one peak within the range of a diffraction angle 2θ of 29.0° or more and 32.0° or less. The crystalline phase having these peaks is referred to as the first crystalline phase. In a solid electrolyte material containing the first crystalline phase, a path for lithium ion diffusion is easily formed within the crystal. Therefore, the ionic conductivity of the solid electrolyte material is improved. The solid electrolyte material of the first embodiment may also contain the first crystalline phase.

[0030] The first crystalline phase is trigonal. "Trigonal" in this disclosure refers to a crystalline phase having a crystal structure similar to Li3ErCl6 disclosed in ICSD (Inorganic Crystal Structure Database) Collection Code 50151, and exhibiting an X-ray diffraction pattern unique to that structure. "Having a similar crystal structure" refers to being classified into the same space group and having a similar atomic configuration, and does not limit the lattice constant.

[0031] In order to improve the ionic conductivity of the solid electrolyte material, M1 may be at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn. M2 may be Y, Gd, and Sm. X may be at least one selected from the group consisting of Cl and Br.

[0032] In order to further improve the ionic conductivity of the solid electrolyte material, M1 may also be Ca.

[0033] The solid electrolyte material of the first embodiment may also be a material represented by the following compositional formula (1).

[0034] Li 3-2a M1 a Y 1-b-c Gd b Sm c Br 6-d Cl d (1)

[0035] Among them, the following five mathematical formulas are satisfied:

[0036] 0 < a ≤ 0.2,

[0037] 0 < b,

[0038] 0 < c,

[0039] 0 < b + c < 1, and

[0040] 0 ≤ d ≤ 6.

[0041] According to the material represented by the compositional formula (1), the ionic conductivity of the solid electrolyte material can be further improved.

[0042] In order to further improve the ionic conductivity of the solid electrolyte material, in the compositional formula (1), the mathematical formula: a ≤ 0.15 may also be satisfied.

[0043] In order to further improve the ionic conductivity of the solid electrolyte material, in the compositional formula (1), the mathematical formula: d ≤ 4.5 may also be satisfied.

[0044] In order to further improve the ionic conductivity of the solid electrolyte material, in the compositional formula (1), the mathematical formula: c ≤ 0.325 may also be satisfied.

[0045] The upper limit value and the lower limit value of the range of a in the compositional formula (1) may also be defined by any combination selected from values exceeding 0 (i.e., 0 < a), 0.075, 0.1, 0.15, and 0.2.

[0046] The upper limit value and the lower limit value of the range of b in the compositional formula (1) may also be defined by any combination selected from values exceeding 0 (i.e., 0 < b), 0.1, 0.2, 0.3, 0.38, 0.4, 0.5, 0.55, 0.6, 0.65, 0.7, 0.8, 0.9, and less than 1 (i.e., b < 1).

[0047] The upper and lower limit values of the range of c in the compositional formula (1) can also be defined by any combination selected from values greater than 0 (i.e., 0 < c), 0.02, 0.05, 0.1, 0.125, 0.15, 0.2, 0.225, 0.25, 0.3, 0.325, 0.35, and less than 1 (i.e., c < 1).

[0048] The upper and lower limit values of the range of d in the compositional formula (1) can also be defined by any combination selected from the values of 3, 3.5, 4, 4.5, and 5.

[0049] The weighted average of the ionic radii of Y, Gd, and Sm based on the content ratio of each element is defined as R α . The weighted average of the ionic radii of Cl and Br based on the content ratio of each element is defined as R β . R α is divided by R β and the value obtained is defined as R. At this time, R can also be 0.490 or more and 0.505 or less. When R is within this range, the ionic conductivity of the solid electrolyte material is improved. Preferably, R can also be 0.4965 or more and 0.505 or less. When R is within this range, the ionic conductivity of the solid electrolyte material is further improved. Herein, the "ionic radius" in the present disclosure refers to the 6-coordinate ionic radius described in Non-Patent Document 1 (R.D. Shannon, Acta Cryst., A32, 751 (1976)). Y 3+ , Gd 3+ , Sm 3+ , Cl - and Br - have ionic radii of and

[0050] For example, in the compositional formula (1), R is calculated by the following mathematical formula (1). R α and R β are calculated by the following mathematical formulas (2) and (3), respectively. R Y is the ionic radius of Y, R Gd is the ionic radius of Gd, R Sm is the ionic radius of Sm, R Br is the ionic radius of Br, R Cl is the ionic radius of Cl.

[0051] R = R α / R β (1)

[0052] R α = R Y×(1-bc)+R Gd ×b+R Sm ×c (2)

[0053] R β =(R Br ×(6-d)+R Cl ×d) / 6 (3)

[0054] The solid electrolyte material of the first embodiment may be crystalline or amorphous. In addition, the solid electrolyte material of the first embodiment may be a mixture of crystalline and amorphous. Wherein, the so-called crystalline refers to the presence of a peak in the X-ray diffraction pattern. The so-called amorphous refers to the presence of a wide peak (i.e., a halo) in the X-ray diffraction pattern. When amorphous and crystalline are mixed, there are peaks and halos in the X-ray diffraction pattern.

[0055] The shape of the solid electrolyte material of the first embodiment is not limited. Examples of the shape include needle-shaped, spherical, or ellipsoidal. The solid electrolyte material of the first embodiment may also be particles. The solid electrolyte material of the first embodiment may also be formed in a form having a particle or plate shape.

[0056] When the solid electrolyte material of the first embodiment is in the form of particles (e.g., spheres), the solid electrolyte material may 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 at which the cumulative volume in the volume-based particle size distribution is equal to 50%. The volume-based particle size distribution is measured, for example, using a laser diffraction measurement device or an image analyzer.

[0057] 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. This can further improve the ion conductivity of the solid electrolyte material of the first embodiment. Furthermore, when the solid electrolyte material of the first embodiment is mixed with other materials such as an active material, the dispersion state of the solid electrolyte material of the first embodiment and the other materials becomes better.

[0058] <Method for producing solid electrolyte material>

[0059] The solid electrolyte material of the first embodiment is produced, for example, by the following method.

[0060] Two or more types of halide raw material powders are mixed so as to have a target composition.

[0061] As an example, assuming that the composition of the target solid electrolyte material is Li 2.85 Ca 0.075 Y 0.1 Gd0.8 Sm 0.1 Br3Cl3. In this case, the raw material powders of LiBr, CaBr2, YCl3, GdCl3, and SmCl3 are mixed in a molar ratio of approximately LiBr:CaBr2:YCl3:GdCl3:SmCl3 = 2.85:0.075:0.1:0.8:0.1. The raw material powders may also be mixed in a pre-adjusted molar ratio to compensate for compositional variations that may occur during the synthesis process.

[0062] The mixture of raw material powders is fired in an inert gas atmosphere and reacts with each other to obtain a reactant. Examples of inert gases are helium, nitrogen, or argon. The firing can also be performed in a vacuum. In the firing step, the mixture of raw material powders can also be placed in a container (e.g., a crucible and a vacuum sealed tube) and fired in a heating furnace.

[0063] Alternatively, the raw material powders may be mechanochemically reacted in a mixing device such as a planetary ball mill to obtain a reactant. Specifically, the raw material powders may be mixed and reacted using a mechanochemical grinding method. The reactant obtained in this manner may be further calcined in an inert gas atmosphere or in a vacuum.

[0064] By these methods, the solid electrolyte material of the first embodiment is obtained.

[0065] (Second embodiment)

[0066] The second embodiment will be described below, but matters described in the first embodiment may be omitted.

[0067] In the second embodiment, a battery using the solid electrolyte material of the first embodiment will be described.

[0068] The battery of the second embodiment includes a positive electrode, a negative electrode, and an electrolyte layer. The electrolyte layer is provided between the positive electrode and the negative electrode. At least one selected from the group consisting of the positive electrode, the electrolyte layer, and the negative electrode contains the solid electrolyte material of the first embodiment.

[0069] The battery of the second embodiment has excellent charge and discharge characteristics because it contains the solid electrolyte material of the first embodiment. This battery may also be an all-solid-state battery.

[0070] Figure 1 A cross-sectional view of a battery 1000 according to a second embodiment is shown.

[0071] 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 provided between the positive electrode 201 and the negative electrode 203.

[0072] The positive electrode 201 includes positive electrode active material particles 204 and solid electrolyte particles 100 .

[0073] The electrolyte layer 202 contains an electrolyte material. The electrolyte material is, for example, a solid electrolyte material.

[0074] The negative electrode 203 includes negative electrode active material particles 205 and solid electrolyte particles 100 .

[0075] 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 containing the solid electrolyte material of the first embodiment as the largest component by molar ratio.

[0076] The solid electrolyte particles 100 may have a median diameter of 0.1 μm to 100 μm. In the case of having a median diameter of 0.5 μm to 10 μm, the ion conductivity of the solid electrolyte particles 100 can be further improved.

[0077] The positive electrode 201 contains a material that can intercalate and deintercalate metal ions (eg, lithium ions), such as a positive electrode active material (eg, positive electrode active material particles 204 ).

[0078] 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 oxyfluorides, transition metal oxysulfides, or transition metal oxynitrides. Examples of lithium-containing transition metal oxides include Li(Ni, Co, Al)O2 or LiCoO2.

[0079] In the present disclosure, the expression "(A, B, C)" in a chemical formula means "at least one selected from the group consisting of A, B, and C." For example, "(Ni, Co, Al)" has the same meaning as "at least one selected from the group consisting of Ni, Co, and Al."

[0080] The positive electrode active material particles 204 may also have a median particle size of 0.1 μm or greater and 100 μm or less. When the positive electrode active material particles 204 have a median particle size of 0.1 μm or greater, the dispersion of the positive electrode active material particles 204 and the solid electrolyte particles 100 in the positive electrode 201 is improved. This improves the charge and discharge characteristics of the battery 1000. 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. This enables the battery 1000 to operate at high output power.

[0081] The positive electrode active material particles 204 may have a larger median diameter than the solid electrolyte particles 100. This improves the dispersion state of the positive electrode active material particles 204 and the solid electrolyte particles 100 in the positive electrode 201.

[0082] To improve the energy density and output of the battery 1000 , in the positive electrode 201 , 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 may be 0.30 or more and 0.95 or less.

[0083] In order to increase the energy density and output of the battery 1000 , the positive electrode 201 may have a thickness of 10 μm or more and 500 μm or less.

[0084] The electrolyte layer 202 contains an electrolyte material. This electrolyte material is, for example, the solid electrolyte material of the first embodiment. The electrolyte layer 202 may also be a solid electrolyte layer.

[0085] The electrolyte layer 202 may be composed solely of the solid electrolyte material of the first embodiment. Alternatively, the electrolyte layer 202 may be composed solely of a solid electrolyte material different from the solid electrolyte material of the first embodiment.

[0086] Examples of solid electrolyte materials different from the solid electrolyte material of the first embodiment include Li2MgX'4, Li2FeX'4, Li(Al, Ga, In)X'4, Li3(Al, Ga, In)X'6, or LiI. Here, X' is at least one element selected from the group consisting of F, Cl, Br, and I. As such, a solid electrolyte material different from the solid electrolyte material of the first embodiment may be a solid electrolyte containing a halogen element, that is, a halide solid electrolyte.

[0087] Hereinafter, the solid electrolyte material of the first embodiment is referred to as a first solid electrolyte material. A solid electrolyte material different from the solid electrolyte material of the first embodiment is referred to as a second solid electrolyte material.

[0088] The electrolyte layer 202 may contain not only the first solid electrolyte material but also the second solid electrolyte material. The first solid electrolyte material and the second solid electrolyte material may be uniformly dispersed in the electrolyte layer 202. The layer formed of the first solid electrolyte material and the layer formed of the second solid electrolyte material may be stacked along the stacking direction of the battery 1000.

[0089] Electrolyte layer 202 may have a thickness of 1 μm or greater and 1000 μm or less. When electrolyte layer 202 has a thickness of 1 μm or greater, positive electrode 201 and negative electrode 203 are less likely to short-circuit. When electrolyte layer 202 has a thickness of 1000 μm or less, battery 1000 can operate at high output power.

[0090] The negative electrode 203 contains a material capable of absorbing and releasing metal ions such as lithium ions, such as a negative electrode active material (eg, negative electrode active material particles 205 ).

[0091] Examples of negative electrode active materials include metal materials, carbon materials, oxides, nitrides, tin compounds, or silicon compounds. The metal material may be a single metal or an alloy. Examples of metal 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 perspective of capacity density, preferred examples of negative electrode active materials include silicon (i.e., Si), tin (i.e., Sn), silicon compounds, or tin compounds.

[0092] The negative electrode active material particles 205 may also have a median particle size of 0.1 μm or greater and 100 μm or less. When the negative electrode active material particles 205 have a median particle size of 0.1 μm or greater, the dispersion of the negative electrode active material particles 205 and the solid electrolyte particles 100 in the negative electrode 203 is improved. This improves the charge and discharge characteristics of the battery 1000. When the negative electrode active material particles 205 have a median particle size of 100 μm or less, the lithium diffusion rate within the negative electrode active material particles 205 is increased. This enables the battery 1000 to operate at high output power.

[0093] The negative electrode active material particles 205 may have a larger median diameter than the solid electrolyte particles 100. This improves the dispersion of the negative electrode active material particles 205 and the solid electrolyte particles 100 in the negative electrode 203.

[0094] To improve the energy density and output of the battery 1000 , in the negative electrode 203 , 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 may be 0.30 or more and 0.95 or less.

[0095] In order to increase energy density and output, the negative electrode 203 may have a thickness of 10 μm or more and 500 μm or less.

[0096] For the purpose of improving ion conductivity, chemical stability, and electrochemical stability, at least one selected from the group consisting of the positive electrode 201 , the electrolyte layer 202 , and the negative electrode 203 may contain a second solid electrolyte material.

[0097] As described above, the second solid electrolyte material may be a halide solid electrolyte.

[0098] Examples of halide solid electrolytes include Li2MgX'4, Li2FeX'4, Li(Al, Ga, In)X'4, Li3(Al, Ga, In)X'6, or LiI, wherein X' is at least one selected from the group consisting of F, Cl, Br, and I.

[0099] The second solid electrolyte material may be a sulfide solid electrolyte.

[0100] Examples of sulfide solid electrolytes are Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, Li 3.25 Ge 0.25 P 0.75 S4 or Li 10 GeP2S 12 .

[0101] The second solid electrolyte material may be an oxide solid electrolyte.

[0102] Examples of oxide solid electrolytes are:

[0103] (i) NASICON type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutions,

[0104] (ii) Perovskite-type solid electrolytes such as (LaLi)TiO3,

[0105] (iii)Li 14 ZnGe4O 16 , LISICON type solid electrolytes such as Li4SiO4, LiGeO4 or their elemental substitutions,

[0106] (iv)Li7La3Zr2O 12 or its element-substituted garnet-type solid electrolyte, or

[0107] (v) Li3PO4 or its N-substituted counterparts.

[0108] The second solid electrolyte material may also be an organic polymer solid electrolyte.

[0109] Examples of organic polymer solid electrolytes include compounds of polymers and lithium salts. The polymers may also have an ethylene oxide structure. Polymers with ethylene oxide structures can contain a large amount of lithium salt, thereby further improving ion conductivity.

[0110] 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 may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may be used.

[0111] To facilitate transfer of lithium ions and improve the output characteristics of the battery 1000 , at least one selected from the group consisting of the positive electrode 201 , the electrolyte layer 202 , and the negative electrode 203 may contain a nonaqueous electrolyte solution, a gel electrolyte, or an ionic liquid.

[0112] The non-aqueous electrolyte includes a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0113] 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 butylene carbonate. Examples of chain carbonate solvents include dimethyl carbonate, ethylmethyl 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, fluoroethylmethyl carbonate, or fluorodimethyl carbonate. One non-aqueous solvent selected from these may be used alone. Alternatively, a mixture of two or more non-aqueous solvents selected from these may be used.

[0114] 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 may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may be used. The concentration of the lithium salt is, for example, not less than 0.5 mol / liter and not more than 2 mol / liter.

[0115] As the gel electrolyte, a polymer material impregnated with a non-aqueous electrolyte solution can be used. Examples of the polymer material include polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or a polymer having an ethylene oxide bond.

[0116] Examples of cations contained in ionic liquids are:

[0117] (i) aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium,

[0118] (ii) aliphatic cyclic ammonium such as pyrrolidinium, morpholinium, imidazolinium, tetrahydropyrimidinium, piperazinium, or piperidinium, or

[0119] (iii) Nitrogen-containing heterocyclic aromatic cations such as pyridinium and imidazolium cations.

[0120] An example of an 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 - .

[0121] The ionic liquid may also contain a lithium salt.

[0122] In order to improve the adhesion between particles, at least one selected from the group consisting of the positive electrode 201 , the electrolyte layer 202 , and the negative electrode 203 may contain a binder.

[0123] The example of binding agent is polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamide-imide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinyl pyrrolidone, polyether, polyether sulfone, hexafluoropolypropylene, styrene-butadiene rubber or carboxymethyl cellulose.Copolymer also can be used as binding agent.The example of such binding agent is the copolymer of two or more materials in the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid and hexadiene.Also can use the mixture of two or more materials selected from the above-mentioned material as binding agent.

[0124] In order to improve electron conductivity, at least one selected from the positive electrode 201 and the negative electrode 203 may contain a conductive auxiliary agent.

[0125] Examples of conductive additives are:

[0126] (i) Graphites such as natural graphite or artificial graphite,

[0127] (ii) Carbon blacks such as acetylene black and Ketjen black,

[0128] (iii) Conductive fibers such as carbon fibers or metal fibers,

[0129] (iv) fluorocarbons,

[0130] (v) Metal powders such as aluminum,

[0131] (vi) Conductive whiskers such as zinc oxide or potassium titanate,

[0132] (vii) conductive metal oxides such as titanium oxide, or

[0133] (viii) Conductive polymer compounds such as polyaniline, polypyrrole, or polythiophene.

[0134] For cost reduction, the conductive auxiliary agent (i) or (ii) mentioned above may be used.

[0135] Examples of the shape of the battery 1000 according to the second embodiment include a coin shape, a cylindrical shape, a square shape, a sheet shape, a button shape, a flat shape, or a laminate shape.

[0136] The battery 1000 of the second embodiment can also be manufactured, for example, by preparing materials for forming a positive electrode, materials for forming an electrolyte layer, and materials for forming a negative electrode, and fabricating a stacked body in which the positive electrode, electrolyte layer, and negative electrode are arranged in this order by a known method.

[0137] Example

[0138] Hereinafter, the present disclosure will be described in more detail with reference to Examples and Comparative Examples.

[0139] The solid electrolyte material in the examples is represented by the following composition formula (1).

[0140] Li 3-2a M1 a Y 1-b-c Gd b Sm c Br 6-d Cl d (1)

[0141] <Example 1>

[0142] (Fabrication of Solid Electrolyte Materials)

[0143] In an argon atmosphere with a dew point below -60°C (hereinafter referred to as "dry argon atmosphere"), LiBr, CaBr2, YCl3, GdCl3 and SmCl3 are prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.1:0.8:0.1. These raw material powders are crushed and mixed in an agate mortar. The obtained mixture is placed in an alumina crucible and fired at 500°C for 1 hour in a dry argon atmosphere. The obtained fired product is crushed in an agate mortar. By operating in this way, a powder of the solid electrolyte material of Example 1 is obtained. The solid electrolyte material of Example 1 has a composition consisting of Li 2.85 Ca 0.075 Y 0.1 Gd 0.8 Sm 0.1 The composition represented by Br3Cl3. The value of R in this composition is 0.497. The composition of the solid electrolyte material of Example 1 is shown in Table 1. In addition, the values ​​corresponding to a, b, c and d in composition formula (1), the element species of M1, and the value of R are shown in Table 2.

[0144] (Evaluation of ion conductivity)

[0145] Figure 2 A schematic diagram showing a press-molding die 300 used to evaluate the ion conductivity of a solid electrolyte material.

[0146] The press-forming die 300 includes a punch upper portion 301, a frame 302, and a punch lower portion 303. The punch upper portion 301 and the punch lower portion 303 are both made of electrically conductive stainless steel. The frame 302 is made of insulating polycarbonate.

[0147] use Figure 2 The press-molding die 300 shown in FIG was used to evaluate the ion conductivity of the solid electrolyte material of Example 1 by the following method.

[0148] In a dry argon atmosphere, the solid electrolyte material powder 101 of Example 1 was filled into the press die 300. Inside the press die 300, a pressure of 360 MPa was applied to the solid electrolyte material powder 101 of Example 1 using the punch upper portion 301 and the punch lower portion 303.

[0149] While applying pressure, the upper punch 301 and lower punch 303 were connected to a potentiostat (Princeton Applied Research, Versa STAT4) equipped with a frequency response analyzer. The upper punch 301 was connected to the working electrode and potential measurement terminals. The lower punch 303 was connected to the counter electrode and reference electrode. The impedance of the solid electrolyte material was measured at room temperature using electrochemical impedance spectroscopy.

[0150] Figure 3 This is a graph showing the Cole-Cole curve of the solid electrolyte material of Example 1 obtained by impedance measurement.

[0151] exist Figure 3 The real value of the impedance at the measurement point where the absolute value of the phase of the complex impedance is the smallest is regarded as the resistance value of the solid electrolyte material to ion conduction. Figure 3 The arrow R shown in SE Using this resistance value, the ion conductivity was calculated based on the following mathematical formula (4).

[0152] σ=(R SE ×S / t) -1 (4)

[0153] Wherein, σ represents the ionic conductivity. S represents the contact area between the solid electrolyte material and the punch upper portion 301 ( Figure 2 The cross-sectional area of ​​the hollow portion of the frame 302 is equal to that of the hollow portion of the frame 302). SE represents the resistance value of the solid electrolyte material in the impedance measurement. t represents the thickness of the solid electrolyte material (i.e. Figure 2 , the thickness of the layer formed by the powder 101 of the solid electrolyte material).

[0154] The ionic conductivity of the solid electrolyte material of Example 1 measured at 25°C was 4.21×10 -3 The measurement results are shown in Table 2.

[0155] (X-ray diffraction measurement)

[0156] Figure 4 This is a graph showing the X-ray diffraction pattern of the solid electrolyte material of Example 1.

[0157] The X-ray diffraction pattern of the solid electrolyte material of Example 1 was measured by the θ-2θ method using an X-ray diffractometer (Rigaku Corporation, MiniFlex 600) in a dry environment with a dew point of -50°C or lower. Cu-Kα rays (wavelength and ).

[0158] In the X-ray diffraction pattern of the solid electrolyte material of Example 1, there are one or more peaks within the range of 29.0° to 32.0°, and two peaks within the range of 14.0° to 18.0°. Therefore, the solid electrolyte material of Example 1 contains a crystalline phase belonging to the trigonal crystal.

[0159] (Battery Production)

[0160] In a dry argon atmosphere, the solid electrolyte material of Example 1 and LiCoO 2 were prepared at a volume ratio of 30:70. These materials were mixed in a mortar to obtain a mixture.

[0161] The solid electrolyte material of Example 1 (80 mg) and the above mixture (10 mg) were stacked in this order in an insulating cylinder with an inner diameter of 9.5 mm. A pressure of 720 MPa was applied to the resulting stack, forming a solid electrolyte layer composed of the solid electrolyte material of Example 1 and a first electrode composed of the above mixture. The solid electrolyte layer had a thickness of 400 μm.

[0162] Next, metal In (thickness: 200 μm), metal Li (thickness: 200 μm), and metal In (thickness: 200 μm) were stacked in this order on the solid electrolyte layer. A pressure of 80 MPa was applied to the resulting stack to form a second electrode.

[0163] Next, a current collector made of stainless steel was attached to the first electrode and the second electrode, and a current collecting lead was attached to the current collector.

[0164] Finally, an insulating ferrule was used to block the inside of the insulating tube from the outside atmosphere, thereby hermetically sealing the inside of the tube.

[0165] (Charge and discharge test)

[0166] Figure 5 This is a graph showing the initial discharge characteristics of the battery of Example 1. The initial charge and discharge characteristics were measured by the following method.

[0167] The battery of Example 1 was placed in a constant temperature chamber at 25°C.

[0168] At 75μA / cm 2 The battery of Example 1 was charged at a current density of 1.50 V to a voltage of 3.68 V. This current density is equivalent to a 0.05 C rate.

[0169] Then, at 75 μA / cm 2 The battery of Example 1 was discharged at a current density of 1.88 V.

[0170] As a result of the charge and discharge test, the battery of Example 1 had an initial discharge capacity of 0.96 mAh.

[0171] <Examples 2 to 29>

[0172] (Fabrication of Solid Electrolyte Materials)

[0173] In Example 2, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders so as to have a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.35:0.4:0.25.

[0174] In Example 3, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders so as to have a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.275:0.6:0.125.

[0175] In Example 4, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.375:0.3:0.325.

[0176] In Example 5, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.3:0.5:0.2.

[0177] In Example 6, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders so as to have a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.15:0.7:0.15.

[0178] In Example 7, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.05:0.9:0.05.

[0179] In Example 8, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.1:0.7:0.2.

[0180] In Example 9, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.05:0.8:0.15.

[0181] In Example 10, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.4:0.55:0.05.

[0182] In Example 11, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=2.35:0.5:0.075:0.5:0.2:0.3.

[0183] In Example 12, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=2.35:0.5:0.075:0.475:0.3:0.225.

[0184] In Example 13, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=2.35:0.5:0.075:0.45:0.4:0.15.

[0185] In Example 14, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=2.35:0.5:0.075:0.4:0.5:0.1.

[0186] In Example 15, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=1.85:1:0.075:0.65:0.1:0.25.

[0187] In Example 16, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=1.85:1:0.075:0.6:0.3:0.1.

[0188] In Example 17, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=1.85:1:0.075:0.05:0.8:0.15.

[0189] In Example 18, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=1.3:1.5:0.1:0.6:0.38:0.02.

[0190] In Example 19, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=0.8:2:0.1:0.6:0.38:0.02.

[0191] In Example 20, LiBr, MgBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:MgBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.1:0.8:0.1.

[0192] In Example 21, LiBr, ZnBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:ZnBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.1:0.8:0.1.

[0193] In Example 22, LiBr, SrBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:SrBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.1:0.8:0.1.

[0194] In Example 23, LiBr, BaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:BaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.1:0.8:0.1.

[0195] In Example 24, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.7:0.15:0.05:0.9:0.05.

[0196] In Example 25, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.6:0.2:0.05:0.9:0.05.

[0197] In Example 26, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3:SmCl3=2.35:0.5:0.075:0.55:0.1:0.35.

[0198] In Example 27, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.8:0.1:0.1.

[0199] In Example 28, LiBr, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:CaBr2:YCl3:GdCl3:SmCl3=2.85:0.075:0.6:0.1:0.3.

[0200] In Example 29, LiBr, LiCl, CaBr2, YCl3, GdCl3, and SmCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl, CaBr2:YCl3:GdCl3:SmCl3=1.85:1:0.075:0.05:0.65:0.3.

[0201] Except for the above matters, the solid electrolyte materials of Examples 2 to 29 were obtained in the same manner as in Example 1. The compositions of the solid electrolyte materials of Examples 2 to 29 are shown in Table 1. In addition, the values ​​corresponding to a, b, c, and d in composition formula (1), the element species of M1, and the value of R are shown in Table 2.

[0202] (Evaluation of ion conductivity)

[0203] The ion conductivities of the solid electrolyte materials of Examples 2 to 29 were measured in the same manner as in Example 1. Table 2 shows the measurement results.

[0204] (X-ray diffraction measurement)

[0205] The X-ray diffraction patterns of the solid electrolyte materials of Examples 2 to 29 were measured in the same manner as in Example 1. The solid electrolyte materials of Examples 2 to 29 all contained a crystal phase belonging to a trigonal crystal.

[0206] (Charge and discharge test)

[0207] Using the solid electrolyte materials of Examples 2 to 29, the same procedures as in Example 1 were followed to obtain batteries of Examples 2 to 29. Using the batteries of Examples 2 to 29, charge and discharge tests were conducted in the same manner as in Example 1. The batteries of Examples 2 to 29 were charged and discharged as well as the battery of Example 1.

[0208] <Comparative Examples 1 and 2>

[0209] (Fabrication of Solid Electrolyte Materials)

[0210] In Comparative Example 1, LiBr, CaBr 2 , YCl 3 , and SmCl 3 were prepared as raw material powders so as to have a molar ratio of LiBr:CaBr 2 :YCl 3 :SmCl 3 = 2.8:0.1:0.8:0.2.

[0211] In Comparative Example 2, LiBr, LiCl, CaBr2, YCl3, and GdCl3 were prepared as raw material powders in a molar ratio of LiBr:LiCl:CaBr2:YCl3:GdCl3=1.8:1:0.1:0.6:0.4.

[0212] Solid electrolyte materials of Comparative Examples 1 and 2 were obtained in the same manner as in Example 1 except for the above-mentioned matters.

[0213] The compositions of the solid electrolyte materials of Comparative Examples 1 and 2 are shown in Table 1. Table 2 also shows the values ​​corresponding to a, b, c, and d in the composition formula (1), the element species of M1, and the value of R.

[0214] (Evaluation of ion conductivity)

[0215] The ion conductivity of the solid electrolyte materials of Comparative Examples 1 and 2 was measured in the same manner as in Example 1. The measurement results are shown in Table 2.

[0216] Table 1

[0217] composition Example 1 <![CDATA[Li 2.85 Ca 0.075 Y 0.1 Gd 0.8 Sm 0.1 Br3Cl3]]> Example 2 <![CDATA[Li 2.85 Ca 0.075 Y 0.35 Gd 0.4 Sm 0.25 Br3Cl3]]> Example 3 <![CDATA[Li 2.85 Ca 0.075 Y 0.275 Gd 0.6 Sm 0.125 Br3Cl3]]> Example 4 <![CDATA[Li 2.85 Ca 0.075 Y 0.375 Gd 0.3 Sm 0.325 Br3Cl3]]> Example 5 <![CDATA[Li 2.85 Ca 0.075 Y 0.3 Gd 0.5 Sm 0.2 Br3Cl3]]> Example 6 <![CDATA[Li 2.85 Ca 0.075 Y 0.15 Gd 0.7 Sm 0.15 Br3Cl3]]> Example 7 <![CDATA[Li 2.85 Ca 0.075 Y 0.05 Gd 0.9 Sm 0.05 Br3Cl3]]> Example 8 <![CDATA[Li 2.85 Ca 0.075 Y 0.1 Gd 0.7 Sm 0.2 Br3Cl3]]> Example 9 <![CDATA[Li 2.85 Ca 0.075 Y 0.05 Gd 0.8 Sm 0.15 Br3Cl3]]> Example 10 <![CDATA[Li 2.85 Ca 0.075 Y 0.4 Gd 0.55 Sm 0.05 Br3Cl3]]> Example 11 <![CDATA[Li 2.85 Ca 0.075 Y 0.5 Gd 0.2 Sm 0.3 Br 2.5 Cl 3.5 ]]> Example 12 <![CDATA[Li 2.85 Ca 0.075 Y 0.475 Gd 0.3 Sm 0.225 Br 2.5 Cl 3.5 ]]> Example 13 <![CDATA[Li 2.85 Ca 0.075 Y 0.45 Gd 0.4 Sm 0.15 Br 2.5 Cl 3.5 ]]> Example 14 <![CDATA[Li 2.85 Ca 0.075 Y 0.4 Gd 0.5 Sm 0.1 Br 2.5 Cl 3.5 ]]> Example 15 <![CDATA[Li 2.85 Ca 0.075 Y 0.65 Gd 0.1 Sm 0.25 Br2Cl4]]> Example 16 <![CDATA[Li 2.85 Ca 0.075 Y 0.6 Gd 0.3 Sm 0.1 Br2Cl4]]> Example 17 <![CDATA[Li 2.85 Ca 0.075 Y 0.05 Gd 0.8 Sm 0.15 Br2Cl4]]> Example 18 <![CDATA[Li 2.8 Ca 0.1 Y 0.6 Gd 0.38 Sm 0.02 Br 1.5 Cl 4.5 ]]> Example 19 <![CDATA[Li 2.8 Ca 0.1 Y 0.6 Gd 0.38 Sm 0.02 Br1Cl5]]> Example 20 <![CDATA[Li 2.85 Mg 0.075 Y 0.1 Gd 0.8 Sm 0.1 Br3Cl3]]> Example 21 <![CDATA[Li 2.85 Zn 0.075 Y 0.1 Gd 0.8 Sm 0.1 Br3Cl3]]> Example 22 <![CDATA[Li 2.85 Sr 0.075 Y 0.1 Gd 0.8 Sm 0.1 Br3Cl3]]> Example 23 <![CDATA[Li 2.85 Ba 0.075 Y 0.1 Gd 0.8 Sm 0.1 Br3Cl3]]> Example 24 <![CDATA[Li 2.7 Ca 0.15 Y 0.05 Gd 0.9 Sm 0.05 Br3Cl3]]> Example 25 <![CDATA[Li 2.6 Ca 0.2 Y 0.05 Gd 0.9 Sm 0.05 Br3Cl3<!-- 12 --> ]]> Example 26 <![CDATA[Li 2.85 Ca 0.075 Y 0.55 Gd 0.1 Sm 0.35 Br 2.5 Cl 3.5 ]]> Example 27 <![CDATA[Li 2.85 Ca 0.075 Y 0.8 Gd 0.1 Sm 0.1 Br3Cl3]]> Example 28 <![CDATA[Li 2.85 Ca 0.075 Y 0.6 Gd 0.1 Sm 0.3 Br3Cl3]]> Example 29 <![CDATA[Li 2.85 Ca 0.075 Y 0.05 Gd 0.65 Sm 0.3 Br2Cl4]]> Comparative Example 1 <![CDATA[Li 2.8 Ca 0.1 Y 0.8 Sm 0.2 Br3Cl3]]> Comparative Example 2 <![CDATA[Li 2.8 Ca 0.1 Y 0.6 Gd 0.4 Br1Cl5]]>

[0218] Table 2

[0219]

[0220] <Inspection>

[0221] The solid electrolyte materials of Examples 1 to 29 have a 1.0×10 -3 S / cm or higher lithium ion conductivity.

[0222] The solid electrolyte materials of Examples 1 to 29 have a crystalline phase that is trigonal. Solid electrolyte materials with a crystalline phase that is trigonal easily form pathways for lithium ion diffusion within the crystals. Consequently, the ionic conductivity of the solid electrolyte materials is improved.

[0223] Comparing Examples 1 to 10 and 19 with Comparative Examples 1 and 2 shows the following facts. When the solid electrolyte material is represented by the composition formula (1) and contains both Gd and Sm in addition to Y, the ion conductivity is further improved compared to the case where only one of Gd and Sm is contained in addition to Y. When the solid electrolyte material is represented by the composition formula (1) and contains both Gd and Sm in addition to Y, it becomes easy to form a crystalline phase belonging to the trigonal crystal. Therefore, it is believed that this is because it becomes easy to form a path for lithium ion diffusion in the crystal.

[0224] As shown by comparing Examples 1, 22, and 23 with Examples 20 and 23, the ionic conductivity of the solid electrolyte material is further improved when M1 is Ca, Sr, or Ba. This is believed to be because, compared to when the ionic radius of M1 is smaller than that of Y, Gd, and Sm, the paths for lithium ion diffusion within the crystal become wider, and ionic conductivity is easily improved. The case where M1 has an ionic radius smaller than that of Y, Gd, and Sm refers to the case where M1 is Mg or Zn. The case where M1 has an ionic radius larger than that of Y, Gd, and Sm refers to the case where M1 is Ca, Sr, or Ba. As shown by comparing Example 1 with Examples 22 and 23, the ionic conductivity of the solid electrolyte material is further improved when M1 is Ca. This is believed to be because, when the ionic radius of M1 is close to that of Y, Gd, and Sm, the paths for lithium ion diffusion become appropriately wide, and ionic conductivity is easily improved.

[0225] As shown in Examples 7, 24, and 25, when the value of a is greater than 0 and less than 0.2, the ionic conductivity of the solid electrolyte material increases. This is believed to be because pathways for lithium ion diffusion are easily formed within the crystal. As shown by comparing Examples 7 and 24 with Example 25, when the value of a is greater than 0 and less than 0.15, the ionic conductivity of the solid electrolyte material further increases. This is believed to be because the amount of lithium ions within the crystal is optimized.

[0226] As shown by comparing Examples 1 to 18 with Example 19, the ion conductivity of the solid electrolyte material is further improved when the value of d is 0 or more and 4.5 or less. This is presumably because pathways for lithium ion diffusion are easily formed within the crystal.

[0227] As shown by comparing Examples 11 to 14 with Example 26, the ion conductivity of the solid electrolyte material is further improved when the value of c is greater than 0 and less than 0.325. This is believed to be because the size of the crystal lattice is optimized, making it easier to form paths for lithium ion diffusion.

[0228] As shown by comparing Examples 1 to 18 with Examples 27 to 29, if R is greater than 0.4900 and less than 0.5050, the ion conductivity of the solid electrolyte material is further improved. This is believed to be because it becomes easier to form a diffusion path with a width suitable for lithium ion conduction within the crystal. As shown by comparing Examples 1, 7 to 9 and 17 with Examples 2 to 6, 10 to 16 and 18, when R is greater than 0.4965 and less than 0.5050, the ion conductivity of the solid electrolyte material is further improved. This is believed to be because the size of the crystal lattice is optimized, making it easier to form a path for lithium ion diffusion.

[0229] The batteries of Examples 1 to 29 were all charged and discharged at room temperature.

[0230] Since the solid electrolyte materials of Examples 1 to 29 do not contain sulfur, they do not generate hydrogen sulfide.

[0231] As described above, the solid electrolyte material disclosed herein is a novel solid electrolyte material having lithium ion conductivity. The solid electrolyte material disclosed herein is suitable for providing a battery that can be charged and discharged well.

[0232] Industrial applicability

[0233] The solid electrolyte material disclosed herein is used, for example, in batteries (eg, all-solid-state lithium-ion secondary batteries).

Claims

1. A solid electrolyte material is represented by the following compositional formula (1): Li 3-2a M1 a Y 1-b-c Gd b Sm c Br 6-d Cl d (1) M1 is at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn, in, satisfying the following five mathematical formulas: 0<a≤0.2、 0<b、 0<c、 0 < b + c < 1 and 0≤d≤6。 2. The solid electrolyte material according to claim 1, which contains a crystalline phase belonging to the trigonal crystal system.

3. The solid electrolyte material according to claim 1, wherein M1 is Ca.

4. The solid electrolyte material according to claim 1, wherein In the compositional formula (1), the mathematical formula: a ≤ 0.15 is satisfied.

5. The solid electrolyte material according to claim 1, wherein In the compositional formula (1), the mathematical formula: d ≤ 4.5 is satisfied.

6. The solid electrolyte material according to claim 1, wherein In the compositional formula (1), the mathematical formula: c ≤ 0.325 is satisfied.

7. The solid electrolyte material according to claim 1, wherein The value obtained by dividing the weighted average of the ionic radii of Y, Gd, and Sm based on the content rates of the respective elements by the weighted average of the ionic radii of Cl and Br based on the content rates of the respective elements is 0.4900 or more and 0.5050 or less.

8. A battery comprising: a positive electrode, a negative electrode, and an electrolyte layer provided between the positive electrode and the negative electrode, where at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer contains the solid electrolyte material according to any one of claims 1 to 7.

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