Solid electrolyte material and battery using the same

Abstract

The solid electrolyte material disclosed herein contains Li, Zr, and F. The ratio of the amount of substance of Li to the amount of substance of Zr is less than 3.5, and in an X-ray diffraction pattern obtained by X-ray diffraction measurement of the solid electrolyte material using Cu-Kα rays, the ratio of the full width at half maximum of a peak having the highest intensity within a range of a diffraction angle 2θ of 27.5° to 29.5° to the full width at half maximum of a peak corresponding to the (111) plane of Si measured under the same conditions is greater than 1.06.

Description

Technical Field

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

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

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-129312 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] An object of the present disclosure is to provide a solid electrolyte material having high lithium ion conductivity.

[0008] Means for solving problems

[0009] The solid electrolyte material disclosed herein contains Li, Zr, and F, wherein the molar ratio of Li to the molar ratio of Zr is less than 3.5, and in an X-ray diffraction pattern obtained by X-ray diffraction measurement of the solid electrolyte material using Cu-Kα rays, the ratio of the full width at half maximum of a peak having the highest intensity within a range of a diffraction angle 2θ of 27.5° to 29.5° to the full width at half maximum of a peak corresponding to the (111) plane of Si measured under the same conditions is greater than 1.06.

[0010] Effects of the Invention

[0011] The present disclosure provides a solid electrolyte material having high lithium ion conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A cross-sectional view of a battery 1000 according to a second embodiment is shown.

[0013] Figure 2 A cross-sectional view of a battery 2000 according to a second embodiment is shown.

[0014] Figure 3 It is a graph showing X-ray diffraction patterns of the solid electrolyte materials of Examples 1 to 10 and Comparative Example 1.

[0015] Figure 4 Is displayed by Figure 3 This is a graph showing the conversion pattern of the solid electrolyte material of Example 1, in which the horizontal axis of the curve is converted from 2θ to q.

[0016] Figure 5 This is a schematic diagram of a press mold 300 for evaluating the ion conductivity of a solid electrolyte material.

[0017] Figure 6 This is a graph showing a Cole-Cole plot of the solid electrolyte material of Example 1 obtained by impedance measurement.

[0018] Figure 7 It is a graph showing the initial discharge characteristics of the batteries of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0019] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0020] (First embodiment)

[0021] The solid electrolyte material of the first embodiment contains Li, Zr and F, wherein the ratio of the amount of substance of Li to the amount of substance of Zr is less than 3.5. In the X-ray diffraction pattern obtained by X-ray diffraction measurement of the solid electrolyte material of the first embodiment using Cu-Kα rays, the ratio of the value of the half-maximum full width of the peak having the highest intensity within the range of diffraction angle 2θ of 27.5° to 29.5° to the value of the half-maximum full width of the peak corresponding to the (111) plane of Si measured under the same conditions is greater than 1.06. Hereinafter, in the X-ray diffraction pattern obtained by X-ray diffraction measurement of the solid electrolyte material, the half-maximum full width of the peak having the highest intensity within the range of diffraction angle 2θ of 27.5° to 29.5° is referred to as "FWHM". In addition, the half-maximum full width of the peak corresponding to the (111) plane of Si is referred to as "FWHM Si ". Here, as Si measured under the same conditions as those for the X-ray diffraction measurement of the solid electrolyte material of the first embodiment, a Si standard sample is used. As the Si standard sample, for example, standard Si powder manufactured by NIST is used.

[0022] The solid electrolyte material of the first embodiment satisfies the above-mentioned "FWHM and FWHM Si When the ratio is greater than 1.06", the lattice constant of the obtained crystal phase becomes non-uniform. As a result, in the solid electrolyte material of the first embodiment, since a wide lattice region is generated, lithium ions are easily conducted. Therefore, the solid electrolyte material of the first embodiment has high lithium ion conductivity. Here, the so-called high lithium ion conductivity is, for example, 2×10 -11 S / cm or more. That is, the solid electrolyte material of the first embodiment may have, for example, 2×10 -11 S / cm or higher ion conductivity.

[0023] The solid electrolyte material of the first embodiment is not measured by the FWHM value, but by the FWHM and FWHM values. Si Therefore, when determining the solid electrolyte material of the first embodiment, it is not necessary to consider the measurement error caused by the measurement device.

[0024] In the X-ray diffraction pattern of the solid electrolyte material of the first embodiment, the peak with the highest intensity among the single peaks exists in the range of diffraction angle 2θ of 27.5° or more and 29.5° or less. By using such a peak, the value of FWHM can be accurately evaluated. Therefore, the FWHM and FWHM can be accurately evaluated. Si Furthermore, a single peak refers to a peak that does not overlap with other peaks.

[0025] The solid electrolyte material of the first embodiment can be used to obtain a battery with excellent charge-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 substantially no sulfur. The so-called solid electrolyte material of the first embodiment contains substantially no sulfur means that the solid electrolyte material does not contain sulfur as a constituent element except for sulfur that is inevitably mixed in as an impurity. In this case, the sulfur mixed in the solid electrolyte material as an impurity is, for example, 1 mol% or less. From the perspective of safety, the solid electrolyte material of the first embodiment preferably does not contain sulfur. Solid electrolyte materials that do not contain sulfur have excellent safety because they do not generate hydrogen sulfide even when exposed to the atmosphere. The sulfide solid electrolyte disclosed in Patent Document 1 can generate hydrogen sulfide if exposed to the atmosphere.

[0027] The solid electrolyte material of the first embodiment can have high oxidation resistance because it contains F. This is because F has a high redox potential.

[0028] The solid electrolyte material of the first embodiment may be substantially composed of Li, Zr, and F. The phrase "the solid electrolyte material of the first embodiment is substantially composed of Li, Zr, and F" means that the molar ratio (i.e., mole fraction) of the total amount of Li, Zr, 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 (i.e., mole fraction) may be 95% or more. The solid electrolyte material of the first embodiment may be composed only of Li, Zr, and F.

[0029] 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.

[0030] In the converted X-ray diffraction pattern of the solid electrolyte material of the first embodiment, the ratio of the full width at half maximum of the peak having the highest intensity within the range of q of 1.94 to 2.08 to the full width at half maximum of the peak corresponding to the (111) plane of Si measured under the same conditions may be greater than 1.06. Here, q satisfies the mathematical formula: q = 4πsinθ / λ. λ represents the wavelength of the X-ray used in the X-ray diffraction measurement.

[0031] In other words, in the above-mentioned conversion pattern, the ratio of the full width at half maximum of the peak having the highest intensity in the range of q of 1.94 to 2.08 to the full width at half maximum of the peak corresponding to the (111) plane of Si measured under the same conditions has a value greater than 1.06, and the solid electrolyte material containing Li, Zr and F can be regarded as containing Li, Zr and F and satisfying FWHM / FWHM Si >1.06 solid electrolyte material. Therefore, for solid electrolyte materials containing Li, Zr, and F, the measurement results obtained using radiation other than X-rays (e.g., electron beams) can also be transformed using the mathematical formula: q = 4πsinθ / λ' (λ' represents the wavelength of the radiation) to obtain a transformation pattern. In the transformation pattern obtained by operating in this manner, when the condition that "the ratio of the half-maximum value of the peak with the highest intensity in the range of q of 1.94 to 2.08 to the half-maximum value of the peak corresponding to the (111) plane of Si measured under the same conditions is greater than 1.06" is satisfied, the solid electrolyte material can be regarded as the solid electrolyte material of the first embodiment.

[0032] In the solid electrolyte material of the first embodiment, FWHM and FWHM Si The ratio of FWHM to FWHM can also be less than 5.0. Thus, it is possible to maintain a crystal structure with high ion conductivity. In order to improve the ion conductivity of the solid electrolyte material, the FWHM and FWHM Si The ratio may be 1.25 or more and 2.88 or less.

[0033] The solid electrolyte material of the first embodiment may contain a crystal phase represented by the following composition formula (1).

[0034] Li x ZF 4+x Formula (1)

[0035] In formula (1), the mathematical formula is satisfied: 0<x<3.5.

[0036] A solid electrolyte material containing such a crystal phase has high ion conductivity.

[0037] In order to improve the ion conductivity of the solid electrolyte material, the mathematical formula in formula (1) may also be satisfied: 1.0≤x≤3.0.

[0038] The upper limit and lower limit of the range of x in formula (1) can be defined by any combination of numerical values ​​selected from 1.0, 1.5, 1.8, 2.0, 2.2, 2.5, and 3.0.

[0039] 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 the form of pellets or plates.

[0040] 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 accumulation in the volume-based particle size distribution reaches 50%. The volume-based particle size distribution is measured, for example, using a laser diffraction measurement device or an image analyzer.

[0041] 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 allows the solid electrolyte material to have higher conductivity. Furthermore, when the solid electrolyte material of the first embodiment is mixed with other materials such as an active material, the dispersion of the solid electrolyte material of the first embodiment and the other materials becomes better.

[0042] <Method for producing solid electrolyte material>

[0043] The solid electrolyte material of the first embodiment can be produced by, for example, the following method.

[0044] Raw material powders are prepared and mixed so as to obtain the target composition. The raw material powders may be, for example, halides.

[0045] As an example, when the target composition is Li3ZrF7, LiF and ZrF4 are mixed as raw material powders to achieve a molar ratio of LiF:ZrF4 = approximately 3.0:1.0. Alternatively, the raw material powders may be mixed at a molar ratio pre-adjusted to offset compositional variations that may occur during the synthesis process.

[0046] The raw material powders are mechanochemically reacted with each other (i.e., using a mechanochemical grinding method) in a mixing device such as a planetary ball mill to obtain a reactant. The reactants can also be heat-treated in a vacuum or in an inert atmosphere. Alternatively, the mixture of raw material powders can be heat-treated in a vacuum or in an inert atmosphere. The heat treatment can also be performed at a temperature of, for example, 100° C. to 300° C. for more than 1 hour. In order to suppress composition changes during the heat treatment, the raw material powders or reactants are preferably heat-treated in a sealed container such as a quartz tube.

[0047] If the heat treatment temperature is increased or the time is prolonged, the FWHM value of the obtained solid electrolyte material may decrease.

[0048] By these methods, the solid electrolyte material of the first embodiment can be obtained.

[0049] The composition of the solid electrolyte material can be determined, for example, by ICP emission spectroscopy, ion chromatography, inert gas fusion-infrared absorption, or EPMA (Electron Probe Micro Analyzer). For example, the composition of Li and Zr can be determined by ICP emission spectroscopy, and the composition of F can be determined by ion chromatography.

[0050] (Second embodiment)

[0051] The second embodiment will be described below. Matters described in the first embodiment may be omitted.

[0052] The battery of the second embodiment comprises a positive electrode, a negative electrode, and an electrolyte layer. The electrolyte layer is disposed between the positive electrode and the negative electrode. At least one of the positive electrode, the electrolyte layer, and the negative electrode contains the solid electrolyte material of the first embodiment. The battery of the second embodiment, because it contains the solid electrolyte material of the first embodiment, has excellent charge and discharge characteristics. This battery may also be an all-solid-state battery.

[0053] Figure 1 A cross-sectional view of a battery 1000 according to a second embodiment is shown.

[0054] 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 .

[0055] The positive electrode 201 includes positive electrode active material particles 204 and solid electrolyte particles 100 .

[0056] The electrolyte layer 202 contains an electrolyte material. The electrolyte material is, for example, a solid electrolyte material.

[0057] The negative electrode 203 may also include negative electrode active material particles 205 and solid electrolyte particles 100 .

[0058] The solid electrolyte particles 100 are particles containing the solid electrolyte material of the first embodiment. The solid electrolyte particles 100 may be 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. The term "particles containing the solid electrolyte material of the first embodiment as a main component" refers to particles containing the solid electrolyte material of the first embodiment as the largest component by molar ratio.

[0059] 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 ).

[0060] Examples of positive electrode active materials are lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal sulfur oxides or transition metal nitrogen oxides. Examples of lithium-containing transition metal oxides are Li(Ni, Co, Al)O2, Li(Ni, Co, Mn)O2 or LiCoO2. In the present disclosure, the notation "(Ni, Co, Al)" in the chemical formula represents at least one element selected from the group of elements in the brackets. That is, "(Ni, Co, Al)" has the same meaning as "at least one selected from Ni, Co and Al". The same applies to other elements.

[0061] 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 battery's charge and discharge characteristics. 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, enabling the battery to operate at high power.

[0062] 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.

[0063] From the perspective of battery energy density and power, 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.

[0064] 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 the conductive additive and the binder. Examples of the coating material contained in the coating layer include a sulfide solid electrolyte, an oxide solid electrolyte, or a halide solid electrolyte. 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 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 oxidative decomposition of the solid electrolyte material. As the oxide solid electrolyte, lithium niobate, which has excellent stability at high potentials, may also be used. By suppressing oxidative decomposition, the overvoltage increase of the battery can be suppressed.

[0065] From the viewpoint of battery energy density and power, the positive electrode 201 may have a thickness of 10 μm to 500 μm.

[0066] The electrolyte layer 202 contains an electrolyte material. The electrolyte material is, for example, a solid electrolyte material. The electrolyte layer 202 may also be a solid electrolyte layer.

[0067] The electrolyte layer 202 may also contain the solid electrolyte material of the first embodiment. The electrolyte layer 202 may also be composed solely of the solid electrolyte material of the first embodiment. The electrolyte layer 202 may also 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 include Li2MgX4, Li2FeX4, Li(Al, Ga, In)X4, Li3(Al, Ga, In)X6, or LiI. Here, X is at least one selected from F, Cl, Br, and I.

[0068] 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.

[0069] 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 electrolyte layer 202. Layers formed of the first solid electrolyte material and layers formed of the second solid electrolyte material may be stacked along the stacking direction of battery 1000.

[0070] Figure 2 A cross-sectional view of a battery 2000 according to a second embodiment is shown.

[0071] like Figure 2 As shown, 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, electrolyte layer 202 may include a first electrolyte layer 212 and a second electrolyte layer 222. First electrolyte layer 212 is disposed between positive electrode 201 and negative electrode 203. Second electrolyte layer 222 is disposed between first electrolyte layer 212 and negative electrode 203.

[0072] In 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 without being oxidized. As a result, the charge and discharge efficiency of the battery can be improved.

[0073] In battery 2000, the solid electrolyte material contained in the second electrolyte layer 222 may also have a lower reduction potential than the solid electrolyte material contained in the first electrolyte layer 212. This allows the solid electrolyte material contained in the first electrolyte layer 212 to be used without undergoing reduction. As a result, the battery's charge and discharge efficiency can be improved. For example, when the first electrolyte layer 212 contains the solid electrolyte material of the first embodiment, the second electrolyte layer 222 may also contain a sulfide solid electrolyte to suppress the reductive decomposition of the solid electrolyte material.

[0074] From the viewpoint of energy density and power of the battery, the electrolyte layer 202 may have a thickness of 1 μm or more and 1000 μm or less.

[0075] The negative electrode 203 contains a material that can intercalate and deintercalate metal ions (eg, lithium ions), such as a negative electrode active material (eg, negative electrode active material particles 205 ).

[0076] 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.

[0077] The negative electrode active material can be selected in consideration of the reduction resistance of the solid electrolyte material contained in the negative electrode 203. For example, when the negative electrode 203 contains the solid electrolyte material of the first embodiment, the negative electrode active material can also be a material that can intercalate and deintercalate lithium ions at a voltage of 0.27V or more 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 reductive 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.

[0078] 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 battery's charge and discharge characteristics. 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, enabling the battery to operate at high power.

[0079] The negative electrode active material particles 205 may have a larger median diameter than the solid electrolyte particles 100. This improves the dispersion state of the negative electrode active material particles 205 and the solid electrolyte particles 100 in the negative electrode 203.

[0080] From the perspective of battery energy density and power, 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.

[0081] From the viewpoint of the energy density and power of the battery, the negative electrode 203 may have a thickness of 10 μm or more and 500 μm or less.

[0082] At least one selected from the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a second solid electrolyte material for the purpose of improving ion conductivity, chemical stability, and electrochemical stability. Examples of the second solid electrolyte material include a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, or an organic polymer solid electrolyte.

[0083] In this disclosure, the term "sulfide solid electrolyte" refers to a solid electrolyte containing sulfur. The term "oxide solid electrolyte" refers to a solid electrolyte containing oxygen. Oxide solid electrolytes may also contain anions other than oxygen (but excluding sulfur anions and halogen anions). The term "halide solid electrolyte" refers to a solid electrolyte containing a halogen element and not containing sulfur. Halide solid electrolytes may contain not only halogen elements but also oxygen.

[0084] The second solid electrolyte material may be a sulfide solid electrolyte.

[0085] 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 .

[0086] 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 the 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.

[0087] The second solid electrolyte material may also be an oxide solid electrolyte.

[0088] Examples of oxide solid electrolytes are:

[0089] (i) NASICON type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutions,

[0090] (ii) Perovskite-type solid electrolytes such as (LaLi)TiO3,

[0091] (iii)Li 14 ZnGe4O 16 , LISICON type solid electrolytes such as Li4SiO4, LiGeO4 or their elemental substitutions,

[0092] (iv)Li7La3Zr2O 12 or its element-substituted garnet-type solid electrolyte, or

[0093] (v) Li3PO4 or its N-substituted counterparts.

[0094] As described above, the second solid electrolyte material may be a halide solid electrolyte.

[0095] Examples of halide solid electrolytes include 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.

[0096] Other examples of halide solid electrolyte materials are Li a Me b Y c A compound represented by X6. Wherein, a+mb+3c=6 and c>0 are satisfied. Me is at least one selected from metal elements and semi-metal elements other than Li and Y. m represents the valence of Me. The so-called "semi-metal elements" are B, Si, Ge, As, Sb and Te. The so-called "metal elements" are all elements contained in Groups 1 to 12 of the periodic table (excluding hydrogen) and all elements contained in Groups 13 to 16 of the periodic table (excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S and Se).

[0097] In order to improve the ionic conductivity of the halide solid electrolyte material, Me may be at least one selected from Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, and Nb. The halide solid electrolyte may also be Li3YCl6 or Li3YBr6.

[0098] The second solid electrolyte material may also be an organic polymer solid electrolyte.

[0099] Examples of organic polymer solid electrolytes include compounds of polymer compounds and lithium salts.

[0100] The polymer compound may have an ethylene oxide structure. A polymer compound having an ethylene oxide structure can further improve ion conductivity because it contains a large amount of lithium salt.

[0101] 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.

[0102] At least one selected from the positive electrode 201 , the electrolyte layer 202 , and the negative electrode 203 may contain a non-aqueous electrolyte solution, a gel electrolyte, or an ionic liquid for the purpose of facilitating the transfer of lithium ions and improving the power characteristics of the battery.

[0103] The non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0104] 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, ethyl methyl carbonate, or diethyl carbonate. Examples of cyclic ether solvents include tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane. Examples of chain ether solvents include 1,2-dimethoxyethane or 1,2-diethoxyethane. An example of a cyclic ester solvent is γ-butyrolactone. An example of a chain ester solvent is methyl acetate. Examples of fluorinated solvents include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, ethyl fluoromethyl carbonate, or dimethylene fluorocarbonate. 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.

[0105] 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, in the range of 0.5 mol / L to 2 mol / L.

[0106] As the gel electrolyte, a polymer material impregnated with a non-aqueous electrolyte can be used. Examples of the polymer material are polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or a polymer having an ethylene oxide bond.

[0107] Examples of cations contained in ionic liquids are:

[0108] (i) Aliphatic chain quaternary salts (quaternary salts) such as tetraalkylammonium or tetraalkylphosphonium,

[0109] (ii) aliphatic cyclic ammonium such as pyrrolidinium, morpholinium, imidazolinium, tetrahydropyrimidinium, piperazinium or piperidinium, or

[0110] (iii) Nitrogen-containing heterocyclic aromatic cations such as pyridinium and imidazolium cations.

[0111] 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 - .

[0112] The ionic liquid may also contain a lithium salt.

[0113] At least one selected from the positive electrode 201 , the electrolyte layer 202 , and the negative electrode 203 may contain a binder for the purpose of improving adhesion between particles.

[0114] The example of binding agent is polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aromatic polyamide 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.In addition, copolymer also can be used as binding agent.The example of such binding agent is the copolymer of two or more materials selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid and hexadiene.In addition, the mixture selected from two or more materials among above-mentioned these also can be used as binding agent.

[0115] In order to reduce electronic resistance, at least one of the positive electrode 201 and the negative electrode 203 may contain a conductive additive.

[0116] Examples of conductive additives are:

[0117] (i) Graphites such as natural graphite or artificial graphite,

[0118] (ii) Carbon blacks such as acetylene black and Ketjen black,

[0119] (iii) Conductive fibers such as carbon fibers or metal fibers,

[0120] (iv) fluorocarbons,

[0121] (v) Metal powders such as aluminum,

[0122] (vi) Conductive whiskers such as zinc oxide or potassium titanate,

[0123] (vii) conductive metal oxides such as titanium oxide, or

[0124] (viii) Conductive polymer compounds such as polyaniline, polypyrrole, or polythiophene.

[0125] For cost reduction, the conductive auxiliary agent (i) or (ii) mentioned above may be used.

[0126] Examples of the shape of the battery of the second embodiment include a coin shape, a cylindrical shape, a square shape, a sheet shape, a button shape, a flat shape, or a laminated shape.

[0127] The battery 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 producing a stacked body in which the positive electrode, electrolyte layer, and negative electrode are stacked in this order using a known method.

[0128] Example

[0129] Hereinafter, the present disclosure will be described in more detail with reference to Examples and Comparative Examples.

[0130] <Example 1>

[0131] (Fabrication of Solid Electrolyte Materials)

[0132] In an argon atmosphere with a dew point below -60°C (hereinafter referred to as a "dry argon atmosphere"), LiF and ZrF4 were prepared as raw material powders in a molar ratio of LiF:ZrF4 = 3.0:1.0. These raw material powders were crushed and mixed in a mortar. The resulting mixed powder was milled at 500 rpm for 12 hours using a planetary ball mill. This operation yielded a powder of the solid electrolyte material of Example 1. The solid electrolyte material of Example 1 had a composition represented by Li3ZrF7.

[0133] (Evaluation of full width at half maximum)

[0134] Figure 3 This is a graph showing the X-ray diffraction pattern of the solid electrolyte material of Example 1.

[0135] The X-ray diffraction pattern of the solid electrolyte material of Example 1 was measured using an X-ray diffraction device (Rigaku Corporation, MiniFlex600) in a dry environment with a dew point of -50°C or less. Cu-Kα rays (wavelength and ) were measured using the θ-2θ method. The measurement angle interval was 0.01°. The divergence angle of the diverging slit was 0.25°. The slit width of the length-limiting slit was 5 mm.

[0136] The diffraction angle 2θ value of the peak having the highest intensity within the range of diffraction angle 2θ of 27.5° to 29.5° is set as 2θ top , the intensity of this peak is set as I top The intensity at the diffraction angle 2θ of 29.5° is set as I bg That is to say, I bg Indicates the intensity of the baseline. top Half value I htop Set to [(I top -I bg ) / 2+I bg ].

[0137] will be above 27.5° and 2θ top The range of the diffraction angle 2θ below is the closest to I htop The diffraction angle 2θ of the intensity is set as 2θ L . Will be in 2θ top The range of above and below 29.5° is closest to I htop The diffraction angle 2θ of the intensity is set as 2θ H . FWHM is 2θ H and 2θ L The FWHM of the solid electrolyte material of Example 1 is 0.42 degrees.

[0138] Next, the Si crystal powder was subjected to X-ray diffraction measurement under the same conditions as the solid electrolyte material of Example 1. The diffraction angle 2θ value of the peak with the highest intensity within the range of diffraction angle 2θ of 28.0° to 28.6° was set as 2θ top , the intensity of this peak is set as I top The intensity at the diffraction angle 2θ of 28.0° is set as I bg As a result, the FWHM of Si crystal powder Si The Si crystal powder used was Si standard sample "SRM 640d (NIST)".

[0139] (Change of the horizontal axis of the X-ray diffraction pattern)

[0140] Figure 3 The horizontal axis of the X-ray diffraction pattern of the solid electrolyte material of Example 1 shown is transformed from the diffraction angle 2θ to q. Here, the equation q = 4πsinθ / λ is satisfied. λ is the wavelength of the X-rays used in the X-ray diffraction measurement. This results in a transformed pattern of the solid electrolyte material of Example 1. Figure 4 Is displayed by Figure 3 This is a graph showing the conversion pattern of the solid electrolyte material of Example 1, in which the horizontal axis of the curve is converted from 2θ to q.

[0141] (Evaluation of ion conductivity)

[0142] Figure 5 This is a schematic diagram of a press mold 300 for evaluating the ion conductivity of a solid electrolyte material.

[0143] The press mold 300 includes a punch upper portion 301, a frame mold 302, and a punch lower portion 303. The frame mold 302 is formed of insulating polycarbonate. The punch upper portion 301 and the punch lower portion 303 are formed of electronically conductive stainless steel.

[0144] use Figure 5 The press mold 300 shown was used to evaluate the ion conductivity of the solid electrolyte material of Example 1 by the following method.

[0145] In a dry atmosphere with a dew point of -30°C or less, the powder of the solid electrolyte material of Example 1 was filled into the interior of the press mold 300. Inside the press mold 300, a pressure of 400 MPa was applied to the solid electrolyte material of Example 1 using the upper punch 301 and the lower punch 303.

[0146] The upper punch 301 and the lower punch 303 were connected to a potentiostat (Princeton Applied Research, Versa STAT4) equipped with a frequency response analyzer while applying pressure. The upper punch 301 was connected to the working electrode and the potential measurement terminal. The lower punch 303 was connected to the counter electrode and the reference electrode. The impedance of the solid electrolyte material was measured by electrochemical impedance spectroscopy at room temperature.

[0147] Figure 6 This is a graph showing a Cole-Cole diagram of the solid electrolyte material of Example 1 obtained by impedance measurement.

[0148] Figure 6 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 6 The arrow R shown in SE Using this resistance value, the ion conductivity was calculated based on the following mathematical formula (2).

[0149] σ=(R SE ×S / t) -1 (2)

[0150] Wherein, σ represents the ionic conductivity. S represents the contact area between the solid electrolyte material and the upper portion 301 of the punch ( Figure 5The cross-sectional area of ​​the hollow portion of the frame mold 302 is equal to that of the hollow portion of the frame mold 302). SE represents the resistance value of the solid electrolyte material during impedance measurement. t represents the thickness of the solid electrolyte material (i.e., Figure 5 10).

[0151] The ionic conductivity of the solid electrolyte material of Example 1 measured at 25°C was 6.19×10 -8 S / cm.

[0152] (Battery Production)

[0153] In a dry argon atmosphere, the solid electrolyte material of Example 1 and the active material, LiCoO2, were prepared at a volume ratio of 30:70. These materials were mixed in an agate mortar to obtain a positive electrode mixture.

[0154] Next, LiCl and YCl3 were prepared in a molar ratio of LiCl:YCl3=3:1. These materials were crushed and mixed in a mortar. The resulting mixture was milled at 500 rpm for 12 hours using a planetary ball mill. This operation yielded a halide solid electrolyte (hereinafter referred to as "LYC") having a composition represented by Li3YCl6.

[0155] LYC (70 mg), the solid electrolyte material of Example 1 (33 mg), and the aforementioned positive electrode mixture (9.1 mg) were stacked in this order in an insulating cylinder with an inner diameter of 9.5 mm. A pressure of 300 MPa was applied to the resulting stack, forming a second electrolyte layer made of LYC, a first electrolyte layer made of the solid electrolyte material of Example 1, and the positive electrode. In other words, the first electrolyte layer made of the solid electrolyte material of Example 1 was sandwiched between the second electrolyte layer and the positive electrode. The thicknesses of the second and first electrolyte layers were 450 μm and 150 μm, respectively.

[0156] Next, metal In (thickness: 200 μm) was stacked on the second electrolyte layer, and a pressure of 80 MPa was applied to the resulting stack to form a negative electrode.

[0157] Next, current collectors made of stainless steel were attached to the positive electrode and the negative electrode, and current collecting leads were attached to the current collectors.

[0158] Finally, an insulating ferrule was used to isolate the interior of the insulating cylinder from the external atmosphere, thereby sealing the interior of the cylinder.

[0159] (Charge and discharge test)

[0160] Figure 7 This is a graph showing the initial discharge characteristics of the battery of Example 1. The initial discharge characteristics were measured by the following method.

[0161] The battery of Example 1 was placed in a constant temperature chamber at 85°C.

[0162] At 27μA / cm 2 The battery of Example 1 was charged to a voltage of 3.6 V at a current density of 1.5 C. This current density corresponds to a 0.02 C rate.

[0163] Then, at 27 μA / cm 2 The battery of Example 1 was discharged to a voltage of 1.9 V at a current density of 1.5 Å.

[0164] As a result of the charge and discharge test, the battery of Example 1 had an initial discharge capacity of 639 μAh.

[0165] <Examples 2 to 10>

[0166] (Fabrication of Solid Electrolyte Materials)

[0167] In Examples 2 to 7, LiF and ZrF4 were prepared as raw material powders at a molar ratio of LiF:ZrF4 = x:1. The solid electrolyte materials of Examples 2 to 7 were obtained in the same manner as in Example 1 except for the above. Table 1 shows the value of x.

[0168] In Examples 8 to 10, LiF and ZrF₄ were prepared as raw material powders at a molar ratio of LiF:ZrF₄ = x:1. The mixed raw material powders were ground and then heat-treated for 1 hour. The solid electrolyte materials of Examples 8 to 10 were obtained by following the same procedures as in Example 1, except for the above-mentioned matters.

[0169] The value of x in each of Examples 2 to 10 and the heat treatment temperature in each of Examples 8 to 10 are shown in Table 1. In Table 1, "BM" indicates a grinding treatment using a planetary ball mill.

[0170] (Evaluation of full width at half maximum)

[0171] The FWHM of the solid electrolyte materials of Examples 2 to 10 was calculated in the same manner as in Example 1. Table 1 shows the FWHM and FWHM / FWHM Si value.

[0172] (Evaluation of ion conductivity)

[0173] The ion conductivity of the solid electrolyte materials of Examples 2 to 10 was measured in the same manner as in Example 1. Table 1 shows the measurement results.

[0174] (Battery Production)

[0175] Using the solid electrolyte materials of Examples 2 to 10, the same operation as in Example 1 was carried out to obtain batteries of Examples 2 to 10.

[0176] (Charge and discharge test)

[0177] The batteries of Examples 2 to 10 were subjected to charge and discharge tests in the same manner as in Example 1. Similarly to Example 1, the batteries of Examples 2 to 10 were charged and discharged favorably.

[0178] Comparative Example 1

[0179] In a dry argon atmosphere, LiF and ZrF₄ were prepared as raw material powders in a ratio of LiF:ZrF₄ = 2:1. The raw material powders were mixed in a mortar and formed into pellets. The resulting pelletized mixed powder was heat-treated at 450°C for 5 hours. This procedure yielded the solid electrolyte material powder of Comparative Example 1.

[0180] The FWHM of the solid electrolyte material of Comparative Example 1 was calculated in the same manner as in Example 1. Table 1 shows the results.

[0181] The ion conductivity of the solid electrolyte material of Comparative Example 1 was measured in the same manner as in Example 1. Table 1 shows the results.

[0182] Using the solid electrolyte material of Comparative Example 1, the same procedures as in Example 1 were followed to produce a battery of Comparative Example 1. Charge and discharge tests were conducted on the battery of Comparative Example 1 in the same manner as in Example 1. The results showed that the battery of Comparative Example 1 had an initial discharge capacity of 0.01 μAh or less. In other words, the battery of Comparative Example 1 was neither charged nor discharged.

[0183] Table 1

[0184]

[0185] <Investigation>

[0186] The solid electrolyte materials of Examples 1 to 10 have a 2×10 -11 High ion conductivity of S / cm or more.

[0187] The batteries of Examples 1 to 10 were all charged and discharged at 85° C. However, the battery of Comparative Example 1 was neither charged nor discharged.

[0188] Since the solid electrolyte materials of Examples 1 to 10 do not contain sulfur, hydrogen sulfide is not generated.

[0189] As described above, the solid electrolyte material of the present disclosure is suitable for providing a battery having high lithium ion conductivity and capable of good charge and discharge.

[0190] Industrial applicability

[0191] The solid electrolyte material disclosed herein can be used in, for example, all-solid-state lithium-ion secondary batteries.

Claims

1. A solid electrolyte material comprising Li, Zr and F, in, The ratio of the amount of substance of Li to the amount of substance of Zr is less than 3.5, and In an X-ray diffraction pattern obtained by X-ray diffraction measurement of the solid electrolyte material using Cu-Kα radiation, a ratio of a value of the full width at half maximum of a peak having the highest intensity within a range of a diffraction angle 2θ of 27.5° to 29.5° to a value of the full width at half maximum of a peak corresponding to the (111) plane of Si measured under the same conditions is greater than 1.06, The solid electrolyte material contains a crystal phase represented by the following composition formula (1), Li x ZrF 4+x Formula (1) Among them, the mathematical formula is satisfied: 0<x<3.

5.

2. The solid electrolyte material according to claim 1, wherein Satisfies the mathematical formula: 1.0≤x≤3.

0.

3. The solid electrolyte material according to claim 1 or 2, wherein, in a converted pattern obtained by converting the horizontal axis of an X-ray diffraction pattern obtained by X-ray diffraction measurement of the solid electrolyte material using Cu-Kα rays from a diffraction angle 2θ to q, a ratio of a value of the full width at half maximum of a peak having the highest intensity within the range of q of 1.94 to 2.08 to a value of the full width at half maximum of a peak corresponding to the (111) plane of Si measured under the same conditions is greater than 1.06, in, q=4πsinθ / λ, λ represents the wavelength of X-rays used in the above-mentioned X-ray diffraction measurement.

4. A battery comprising: positive electrode; a negative electrode; and an electrolyte layer disposed between the positive electrode and the negative electrode, in, At least one selected from the positive electrode, the negative electrode, and the electrolyte layer contains the solid electrolyte material according to any one of claims 1 to 3.

5. The battery according to claim 4, 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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