Solid electrolyte material, positive electrode material, battery, and method for producing solid electrolyte material

Abstract

A solid electrolyte material according to the present disclosure contains Li, Ti, Al, and F, and has a peak in a first range in which the diffraction angle 2θ is 13.7° to 14.7° inclusive in an X-ray diffraction pattern that is obtained by a X-ray diffraction measurement using Cu-Kα rays. In the X-ray diffraction pattern, a peak may be present in at least one range that is selected from the group consisting of a second range in which the diffraction angle 2θ is 20.9° to 21.9° inclusive, a third range in which the diffraction angle 2θ is 41.2° to 42.2° inclusive, and a fourth range in which the diffraction angle 2θ is 53.3° to 54.3° inclusive.

Description

Solid electrolyte material, cathode material, battery, and method for manufacturing solid electrolyte material

[0001] The present disclosure relates to a solid electrolyte material, a positive electrode material, a battery, and a method for producing the solid electrolyte material.

[0002] Patent Document 1 discloses a solid electrolyte material containing Li, Ti, Al, and F.

[0003] International Publication No. 2023 / 042560

[0004] A light-weight solid electrolyte material is desirable from the viewpoint of improving the energy density of a battery. An object of the present disclosure is to provide a solid electrolyte material suitable for reducing the true density.

[0005] The present disclosure provides a solid electrolyte material containing Li, Ti, Al, and F, wherein an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα radiation has a peak in a first range where the diffraction angle 2θ is 13.7° or more and 14.7° or less.

[0006] According to the present disclosure, a solid electrolyte material suitable for reducing true density can be provided.

[0007] Fig. 1 is a flowchart showing an example of a method for producing a solid electrolyte material according to a first embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view showing a battery according to a second embodiment of the present disclosure. Fig. 3 is a graph showing the results of X-ray diffraction measurements of solid electrolyte materials according to examples and comparative examples. Fig. 4 is a schematic diagram showing a pressure forming die used to measure the ionic conductivity of the solid electrolyte material.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

[0009] [First Embodiment] A solid electrolyte material according to a first embodiment contains Li, Ti, Al, and F. In the solid electrolyte material, an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα radiation has a peak in a first range where the diffraction angle 2θ is 13.7° or more and 14.7° or less. Although the peak in the first range is not necessarily clear, it is thought to be a peak derived from a hydrate in the solid electrolyte material.

[0010] According to the above configuration, the true density of the solid electrolyte material can be reduced. The reduction in true density is believed to be due to the presence of hydrates in the solid electrolyte material, which increases the volume of the solid electrolyte material. Furthermore, since the solid electrolyte material contains F, it can have high oxidation resistance. This is because F has a high redox potential. On the other hand, F has high electronegativity, so it bonds relatively strongly with Li. As a result, the lithium ion conductivity of solid electrolyte materials containing Li and F tends to be low. However, by further containing Ti and Al in addition to Li and F, the solid electrolyte material can have a lithium ion conductivity of, for example, 1×10 -6 It can have a high ionic conductivity of 100 S / cm or more.

[0011] The solid electrolyte material can be used, for example, 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 may be a primary battery or a secondary battery.

[0012] The solid electrolyte material may further contain anions other than F. Examples of such anions are Cl, Br, I, and O. According to the above configuration, the ionic conductivity of the solid electrolyte material is improved.

[0013] The ratio R of the amount of substance of F to the sum of the amounts of substances of the anions of the solid electrolyte material may be 0.50 or more and less than 1.0. According to the above configuration, the oxidation resistance of the solid electrolyte material is improved.

[0014] The anion constituting the solid electrolyte material may be only F. That is, the ratio R may be 1.0. According to the above configuration, the oxidation resistance of the solid electrolyte material is further improved.

[0015] The solid electrolyte material may contain substantially only Li, Ti, Al, and F. Here, "the solid electrolyte material contains substantially only Li, Ti, Al, and F" means that the ratio (i.e., molar fraction) of the total amount of substance of Li, Ti, Al, and F to the total amount of substance of all elements constituting the solid electrolyte material is 90% or more. The solid electrolyte material may be composed only of Li, Ti, Al, and F.

[0016] The solid electrolyte material may contain elements that are inevitably mixed in. Examples of such elements are H, O, N, and Zr. In other words, the solid electrolyte material may further contain at least one element selected from the group consisting of H, O, N, and Zr. H, O, and N may be present in the raw material powder of the solid electrolyte material or in the atmosphere used for producing or storing the solid electrolyte material. Furthermore, Zr may be mixed in from the grinding medium used when producing the solid electrolyte material from the raw material powder.

[0017] In this embodiment, as will be described later, the solid electrolyte material can be produced by intentionally absorbing moisture into the solid electrolyte. Therefore, the moisture released when the solid electrolyte material is heated is not an unavoidable component. On the other hand, H and O that remain in the solid electrolyte material without being released when the solid electrolyte material is heated to a predetermined temperature (e.g., 300°C) are considered to be contained in the solid electrolyte material in the form of oxides or hydrides, and are therefore unavoidably contained elements.

[0018] The solid electrolyte material may contain a crystalline material or an amorphous material, or may be composed of only a crystalline material or only an amorphous material.

[0019] The solid electrolyte material may be represented by the following composition formula (1). In composition formula (1), M is at least one selected from the group consisting of Zr, Ni, Fe, and Cr, m is the valence of M, and 0<x<1, 0≦y<0.1, 0≦z<0.1, and 0<a≦1.5 are satisfied. A solid electrolyte having such a composition has high ionic conductivity and can be produced by a method with high industrial productivity. In composition formula (1), 0.1<x<0.9, 0≦y<0.1, 0≦z<0.1, and 0.8<a≦1.2 may be satisfied.

[0020] Li6-(4-x-4y+my)a (Ti 1-x-y Al x M y ) a F 6-2z O z ...(1)

[0021] In the composition formula (1), when M includes multiple elements, m is the sum of the products of the composition ratios of the elements and the valences of the elements. For example, when M includes an element Me1 and an element Me2, and the composition ratio of the element Me1 is a1 and the valence is m1, and the composition ratio of the element Me2 is a2 and the valence is m2, m is expressed as m1 a1 + m2 a2.

[0022] In composition formula (1), y = 0 and z = 0 may be satisfied. In other words, the solid electrolyte material may be represented by the following composition formula (2). In composition formula (2), 0 < x < 1 and 0 < a ≦ 1.5 are satisfied. A solid electrolyte material having such a composition has higher ionic conductivity. In composition formula (2), 0.1 < x < 0.9 may be satisfied, and 0.8 < a ≦ 1.2 may be satisfied.

[0023] Li 6-(4-x)a (Ti 1-x Al x ) a F6 ... (2)

[0024] In composition formula (2), a = 1 may be satisfied. In other words, the solid electrolyte material may be represented by the following composition formula (3). In composition formula (3), 0 < x < 1 is satisfied. A solid electrolyte material having such a composition has higher ionic conductivity. In composition formula (3), 0.1 < x < 0.9 may be satisfied, or 0.6 ≦ x ≦ 0.8 may be satisfied.

[0025] Li 6-(4-x) (Ti 1-x Al x ) F6 ... (3)

[0026] The solid electrolyte material is Li 2.7 Ti 0.3 Al 0.7 It may be represented by the composition formula F6.

[0027] In an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα radiation, the solid electrolyte material may have a peak in at least one range selected from the group consisting of a second range in which the diffraction angle 2θ is 20.9° or more and 21.9° or less, a third range in which the diffraction angle 2θ is 41.2° or more and 42.2° or less, and a fourth range in which the diffraction angle 2θ is 53.3° or more and 54.3° or less, or may have a peak in each of the second range, the third range, and the fourth range. A solid electrolyte material having such a diffraction peak has high ionic conductivity.

[0028] When a peak exists in each of the second range, the third range, and the fourth range, the intensity of the peak in the second range may be higher than the intensity of the peak in the third range and the intensity of the peak in the fourth range. A solid electrolyte material having such diffraction peak intensities has higher ionic conductivity.

[0029] In an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα radiation, the solid electrolyte material may have a peak in at least one range selected from the group consisting of a fifth range in which the diffraction angle 2θ is 25.7° or more and 26.7° or less, a sixth range in which the diffraction angle 2θ is 33.3° or more and 34.3° or less, and a seventh range in which the diffraction angle 2θ is 37.3° or more and 38.3° or less, or may have a peak in each of the fifth range, the sixth range, and the seventh range. A solid electrolyte material having such a diffraction peak has higher ionic conductivity.

[0030] The true density of the solid electrolyte material is 2.65 g / cm 3 2.77g / cm or more 3 may be less than 2.70 g / cm 3 2.75g / cm or more 3 It may be the following:

[0031] The ionic conductivity of the solid electrolyte material is 1×10 -7 S / cm or more, and may be 1×10 -5 It may be S / cm or less.

[0032] As described above, since the solid electrolyte material contains moisture, when the temperature is increased, moisture may be released from the solid electrolyte material. Here, a case where the temperature of the solid electrolyte material is increased from 25°C to 120°C is considered. The MC is the value obtained by dividing the integrated value of the amount of moisture released from the solid electrolyte material during this temperature increase by the total mass of the solid electrolyte material. 120 At this time, the moisture content MC 120 50 ppm≦MC 120 In this disclosure, "ppm" means mass fraction, i.e., wtppm (mass / mass).

[0033] Moisture content MC 120 can be measured by, for example, the Karl Fischer method. 120 can be determined using a Karl Fischer apparatus (Karl Fischer moisture meter) as follows.

[0034] In a dry nitrogen gas atmosphere, the introduction portion of the solid electrolyte material as a measurement sample is pre-baked at 300°C to stabilize the device. "Solid electrolyte material as a measurement sample" refers to a particle group of the solid electrolyte material.

[0035] After the device has stabilized, the temperature of the inlet is set to 120° C. When the temperature of the inlet reaches 120° C., the amount of water released as background (μg / sec) is measured.

[0036] Next, the temperature of the introduction section is set to 25°C. When the temperature of the introduction section reaches 25°C, the measurement sample is introduced into the introduction section. The measurement sample is heated from 25°C to 120°C at a temperature increase rate of 10°C per minute to vaporize the moisture contained in the measurement sample. The vaporized moisture is quantified by coulometric titration until it reaches a value below the background moisture release amount and integrated, thereby determining the integrated value of the moisture amount released from the measurement sample. The integrated value of the moisture amount is divided by the total mass of the measurement sample to determine the moisture amount MC 120 The "total mass of the measurement sample" refers to the total mass of the particle group of the solid electrolyte material before measurement (before water is evaporated).

[0037] Consider the case where the temperature of a solid electrolyte material is increased from 25°C to 300°C. The MC is the value obtained by dividing the integrated value of the amount of water released from the solid electrolyte material during this temperature increase by the total mass of the solid electrolyte material. 300 At this time, the moisture content MC 300 50 ppm≦MC 300 The range of ≦20,000 ppm may be satisfied.

[0038] Moisture content MC 300 can be measured by, for example, the Karl Fischer method. 300 The moisture content MC is measured using a Karl Fischer apparatus (Karl Fischer moisture meter), except that the measurement sample is heated from 25°C to 300°C at a temperature increase rate of 10°C per minute. 120 It can be determined by a method similar to the method for measuring the above.

[0039] The shape of the solid electrolyte material is not particularly limited. The shape of the solid electrolyte material may be, for example, needle-like, spherical, oval-spherical, fibrous, or the like. The solid electrolyte material may have a particulate shape. The solid electrolyte material may have a pellet or plate shape.

[0040] The specific surface area of ​​the solid electrolyte material is 30 m 2 / g or more 70m 2 With this configuration, a solid electrolyte material having high ionic conductivity can be obtained. The specific surface area of ​​the solid electrolyte material can be 35 m 2 / g or more 65m 2 / g or less, 2 / g or more 60m 2 / g or less, 2 / g or more 55m 2 / g or less. With this configuration, a solid electrolyte material having higher ionic conductivity can be obtained.

[0041] The specific surface area of ​​the solid electrolyte material can be determined, for example, by converting data on an adsorption isotherm obtained by a gas adsorption method using nitrogen gas using the Brunauer-Emmett-Teller (BET) method. Hereinafter, the specific surface area calculated using the BET method will be referred to as the "BET specific surface area."

[0042] [Method for Producing Solid Electrolyte Material] The solid electrolyte material can be produced, for example, by the following method: Figure 1 shows an example of a method for producing a solid electrolyte material.

[0043] (Pulverization step S11) First, raw materials for the solid electrolyte material are pulverized to obtain a pulverized product (pulverization step S11 in FIG. 1). In the pulverization step S11, for example, a mixture containing one or more raw materials for the solid electrolyte material containing Li, Ti, Al, and F and a solvent is prepared, and the raw materials in the mixture are pulverized to obtain a pulverized product. The one or more raw materials have a composition different from that of the solid electrolyte material to be produced.

[0044] The raw materials for the solid electrolyte material may include Ti-containing compounds, such as TiF, (NH)TiF, and LiTiF.

[0045] The raw material of the solid electrolyte material may include a Li-containing compound, such as LiF, LiOH, or Li2CO3.

[0046] The raw materials for the solid electrolyte material may include Al-containing compounds, such as AlF, (NH)AlF, and LiAlF.

[0047] The raw materials for the solid electrolyte material may contain three or more compounds including a Ti-containing compound, a Li-containing compound, and an Al-containing compound, for example, two compounds Li2TiF6 and Li3AlF6.

[0048] In the pulverization step S11, the pulverization may be performed in a dry manner or a wet manner. The wet pulverization is a method in which the raw material of the solid electrolyte material is mixed with a solvent and then pulverized mainly by shear force and friction force. In the wet pulverization, the surfaces of the particles of the raw material of the solid electrolyte material are scraped to generate smaller particles.

[0049] The organic solvent used in the wet grinding process may contain a compound having an ester group. In this case, the raw material of the solid electrolyte material exhibits good dispersibility in the organic solvent. Therefore, this configuration can improve the ionic conductivity of the solid electrolyte material.

[0050] The organic solvent used in the wet grinding process may contain at least one selected from the group consisting of γ-butyrolactone, propylene carbonate, butyl acetate, and tetralin. In this case, the raw materials of the solid electrolyte material exhibit good dispersibility in these organic solvents. Therefore, this configuration can improve the ionic conductivity of the solid electrolyte material.

[0051] The pulverization method in the pulverization step S11 is not particularly limited. Examples of the pulverization method include a ball mill, a pot mill, a bead mill, a V-type mixer, a double-cone mixer, and an automatic mortar. In the pulverization step S11, for example, the raw material powder and the solvent may be placed in a mixing device such as a planetary ball mill and mixed while being pulverized by pulverization using a pulverization medium (e.g., balls). When a planetary ball mill is used, examples of the balls used as the pulverization medium include zirconia balls.

[0052] The pulverization time in the pulverization step S11 can be changed as appropriate depending on the pulverization method. For example, in a pulverization method using a planetary ball mill, the ionic conductivity of the solid electrolyte material finally obtained after 10 hours of pulverization is 3×10 -6 It can reach up to 5 S / cm.

[0053] The specific surface area of ​​the crushed material is 30m 2 When the pulverization step S11 is performed so that the specific surface area of ​​the pulverized material is 30 m / g or more, a solid electrolyte material having high ionic conductivity can be obtained. 2 The upper limit of the specific surface area of ​​the pulverized material obtained by the pulverization step S11 is, for example, 70 m 2 The specific surface area of ​​the pulverized material is 40 m 2 / g or more 55m 2 / g or less. With this configuration, the ionic conductivity of the solid electrolyte material is further increased.

[0054] The specific surface area of ​​the pulverized material can be determined, for example, by converting data on an adsorption isotherm obtained by a gas adsorption method using nitrogen gas into data on the BET method.

[0055] (Drying Step S12) Next, the pulverized material is dried to obtain a solid electrolyte (Drying Step S12 in FIG. 1). Through the Drying Step S12, the raw material of the solid electrolyte material can be synthesized into a solid electrolyte. In the Drying Step S12, the solvent can be removed from the pulverized material by normal pressure drying or reduced pressure drying. Reduced pressure drying is a method of removing the solvent from the pulverized material under a pressure atmosphere lower than atmospheric pressure. The pressure atmosphere lower than atmospheric pressure is, for example, 0.01 MPa or less in gauge pressure. The heating temperature of the pulverized material in normal pressure drying or reduced pressure drying can be set according to the boiling point of the solvent used. The heating temperature of the pulverized material is, for example, 50°C or higher and 300°C or lower. In order to increase the specific surface area of ​​the resulting solid electrolyte, the solid electrolyte may be pulverized (re-pulverization step, not shown in FIG. 1).

[0056] In addition, the raw material of the solid electrolyte material may be synthesized mechanochemically (i.e., by a mechanochemical milling method) in the pulverization step S11, or may be synthesized by other methods such as a melt quenching method. In the production of the solid electrolyte material, when a solid electrolyte having the same composition as the solid electrolyte material is used as the raw material of the solid electrolyte material, the pulverization step S11 and the drying step S12 may not be performed. When pulverization by a wet pulverization process is performed in the pulverization step S11, the drying step S12 may not be performed.

[0057] (Moisture absorption step S13) Next, the solid electrolyte is allowed to absorb moisture (moisture absorption step S13 in FIG. 1). In the moisture absorption step S13, for example, the solid electrolyte obtained in the drying step S12 is placed in a container and exposed to a high-humidity atmosphere. The solid electrolyte may be allowed to absorb moisture by being placed in a mixer or the like placed in a high-humidity atmosphere and stirred. The humidity is, for example, 20% or more at 25°C.

[0058] Moisture content after absorption MC 120 For example, MC 120 ≧10,000 ppm.

[0059] (Drying Step (Re-Drying Step) S14) Next, the solid electrolyte is dried (drying step (re-drying step) S14 in FIG. 1). In the drying step (re-drying step) S14, for example, moisture absorbed by the solid electrolyte may be removed by drying at normal pressure or by drying under reduced pressure. The heating temperature in the normal pressure drying or reduced pressure drying can be set to a temperature that can remove the water adsorbed on the surface of the solid electrolyte. The heating temperature is, for example, 50° C. or higher and 200° C. or lower.

[0060] Moisture content after drying MC 120 For example, MC 120 <10,000 ppm. Moisture content after drying MC 120 MC 120 It may be sufficient to satisfy the condition of ≦1000 ppm.

[0061] The drying step (re-drying step) S14 may not be performed, in other words, the solid electrolyte material may be obtained without drying the solid electrolyte.

[0062] Through the above steps, a solid electrolyte material is obtained.

[0063] According to the above method, a solid electrolyte material with a reduced true density can be produced. The reason for the reduction in the true density of the solid electrolyte material is not necessarily clear, but it is thought to be due to the generation of hydrates in the solid electrolyte material in the moisture absorption step S13. The solid electrolyte material produced by such a method has an ionic conductivity equivalent to that of a typical solid electrolyte material produced without undergoing the moisture absorption step S13, but has a lower true density than a typical solid electrolyte material.

[0064] Second Embodiment A second embodiment will be described below, and the matters described in the first embodiment will be omitted as appropriate.

[0065] The battery according to this embodiment includes a positive electrode, an electrolyte layer, and a negative electrode. The electrolyte layer is located between the positive electrode and the negative electrode.

[0066] At least one selected from the group consisting of the positive electrode, the electrolyte layer, and the negative electrode contains the solid electrolyte material according to the first embodiment.

[0067] The battery according to this embodiment has a low density because it contains the solid electrolyte material according to the first embodiment.

[0068] FIG. 2 shows a cross-sectional view of the battery 1000 according to this embodiment.

[0069] The battery 1000 includes a positive electrode 201, an electrolyte layer 202, and a negative electrode 203. The electrolyte layer 202 is located between the positive electrode 201 and the negative electrode 203.

[0070] The positive electrode 201 may contain a positive electrode material including the solid electrolyte material according to the first embodiment. The positive electrode material contained in the positive electrode 201 contains a positive electrode active material 204 and a solid electrolyte 100.

[0071] The electrolyte layer 202 contains an electrolyte material.

[0072] The negative electrode 203 contains a negative electrode active material 205 and a solid electrolyte 100 .

[0073] The solid electrolyte 100 includes, for example, the solid electrolyte material according to the first embodiment. The solid electrolyte 100 may be particles containing the solid electrolyte material according to the first embodiment as a main component. Particles containing the solid electrolyte material according to the first embodiment as a main component refer to particles in which the component contained in the largest amount in terms of molar ratio is the solid electrolyte material according to the first embodiment. The solid electrolyte 100 may be particles made of the solid electrolyte material according to the first embodiment.

[0074] The positive electrode 201 contains a material capable of absorbing and releasing metal ions (e.g., lithium ions). The material is, for example, a positive electrode active material 204.

[0075] Examples of the positive electrode active material 204 include a lithium-containing transition metal oxide, a transition metal fluoride, a polyanion, a fluorinated polyanion material, a transition metal sulfide, a transition metal oxyfluoride, a transition metal oxysulfide, or a transition metal oxynitride. Examples of the lithium-containing transition metal oxide include Li(Ni,Co,Mn)O, Li(Ni,Co,Al)O, or LiCoO.

[0076] In the present disclosure, "(A, B, C)" means "at least one selected from the group consisting of A, B, and C."

[0077] The shape of the positive electrode active material 204 is not limited to a specific shape. The positive electrode active material 204 may be particles. The positive electrode active material 204 may have a median diameter of 0.1 μm or more and 100 μm or less. When the positive electrode active material 204 has a median diameter of 0.1 μm or more, the positive electrode active material 204 and the solid electrolyte 100 can be well dispersed in the positive electrode 201. This improves the charge / discharge characteristics of the battery 1000. When the positive electrode active material 204 has a median diameter of 100 μm or less, the lithium diffusion rate within the positive electrode active material 204 improves. This allows the battery 1000 to operate at a high output.

[0078] The positive electrode active material 204 may have a larger median diameter than the solid electrolyte 100. With this configuration, the positive electrode active material 204 and the solid electrolyte 100 can be dispersed well in the positive electrode 201.

[0079] In order 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 204 to the sum of the volume of the positive electrode active material 204 and the volume of the solid electrolyte 100 may be 0.30 or more and 0.95 or less.

[0080] A coating layer may be formed on at least a portion of the surface of the positive electrode active material 204. The coating layer may be formed on the surface of the positive electrode active material 204, for example, before mixing with the conductive additive and the binder. Examples of coating materials included in the coating layer include a sulfide solid electrolyte material, an oxide solid electrolyte material, or a halide solid electrolyte material. When the solid electrolyte 100 contains a sulfide solid electrolyte material, the coating material may contain the solid electrolyte material according to the first embodiment to suppress oxidative decomposition of the sulfide solid electrolyte material. When the solid electrolyte 100 contains the solid electrolyte material according to the first embodiment, the coating material may contain an oxide solid electrolyte material to suppress oxidative decomposition of the solid electrolyte material. Lithium niobate, which has excellent stability at high potentials, may be used as the oxide solid electrolyte material. By suppressing oxidative decomposition, an increase in overvoltage of the battery 1000 can be suppressed.

[0081] As described above, when the positive electrode 201 includes a positive electrode material including the solid electrolyte material according to the first embodiment, the positive electrode material may include the solid electrolyte material according to the first embodiment as the solid electrolyte 100, or may include the solid electrolyte material according to the first embodiment as a coating material for the coating layer of the positive electrode active material 204.

[0082] To improve 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.

[0083] The electrolyte layer 202 contains an electrolyte material. The electrolyte material is, for example, a solid electrolyte material. The solid electrolyte material may include the solid electrolyte material according to the first embodiment. The electrolyte layer 202 may be a solid electrolyte layer.

[0084] The electrolyte layer 202 may contain 50 mass % or more of the solid electrolyte material according to the first embodiment. The electrolyte layer 202 may contain 70 mass % or more of the solid electrolyte material according to the first embodiment. The electrolyte layer 202 may contain 90 mass % or more of the solid electrolyte material according to the first embodiment. The electrolyte layer 202 may be composed of only the solid electrolyte material according to the first embodiment.

[0085] Hereinafter, the solid electrolyte material according to the first embodiment will be referred to as a first solid electrolyte material, and a solid electrolyte material different from the first solid electrolyte material will be referred to as a second solid electrolyte material.

[0086] 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. A layer made of the first solid electrolyte material and a layer made of the second solid electrolyte material may be stacked along the stacking direction of the battery 1000.

[0087] The battery 1000 may include a positive electrode 201, a second electrolyte layer, a first electrolyte layer, and a negative electrode 203, in this order. Here, the solid electrolyte material contained in the first electrolyte layer may have a lower reduction potential than the solid electrolyte material contained in the second electrolyte layer. This allows the solid electrolyte material contained in the second electrolyte layer to be used without being reduced. As a result, the charge / discharge efficiency of the battery 1000 can be improved. For example, when the second electrolyte layer contains the first solid electrolyte material, the first electrolyte layer may contain a sulfide solid electrolyte material to suppress reductive decomposition of the solid electrolyte material. This allows the charge / discharge efficiency of the battery 1000 to be improved. The second electrolyte layer may contain the first solid electrolyte material. The first solid electrolyte material has high oxidation resistance, so a battery with excellent charge / discharge characteristics can be realized.

[0088] The electrolyte layer 202 may be composed of only the second solid electrolyte material.

[0089] The electrolyte layer 202 may have a thickness of 1 μm or more and 1000 μm or less. When the electrolyte layer 202 has a thickness of 1 μm or more, the cathode 201 and the anode 203 are less likely to short-circuit. When the electrolyte layer 202 has a thickness of 1000 μm or less, the battery 1000 can operate at a high output.

[0090] Examples of the second solid electrolyte material are LiMgX, LiFeX, Li(Al,Ga,In)X, Li(Al,Ga,In)X, or LiI, where X is at least one selected from the group consisting of F, Cl, Br, and I.

[0091] To improve the energy density and power output of the battery 1000, the electrolyte layer 202 may have a thickness of 1 μm or more and 1000 μm or less.

[0092] The negative electrode 203 contains a material capable of absorbing and releasing metal ions (e.g., lithium ions). The material is, for example, a negative electrode active material 205.

[0093] Examples of the negative electrode active material 205 include a metal material, a carbon material, an oxide, a nitride, a tin compound, or a silicon compound. The metal material may be a single metal or an alloy. An example of the metal material is lithium metal or a lithium alloy. Examples of the carbon material are natural graphite, coke, partially graphitized carbon, carbon fiber, spherical carbon, artificial graphite, or amorphous carbon. From the viewpoint of capacity density, suitable examples of the negative electrode active material are silicon (i.e., Si), tin (i.e., Sn), a silicon compound, or a tin compound.

[0094] The anode active material 205 may be selected taking into consideration the reduction resistance of the solid electrolyte material contained in the anode 203. For example, when the anode 203 contains a first solid electrolyte material, the anode active material 205 may be composed of a material capable of absorbing and releasing lithium ions at 0.27 V or more relative to lithium. Examples of such anode active materials include titanium oxide, indium metal, or a lithium alloy. An example of titanium oxide is Li4Ti5O 12 , LiTiO, or TiO. By using these negative electrode active materials, it is possible to suppress the reductive decomposition of the first solid electrolyte material contained in the negative electrode 203. As a result, it is possible to improve the charge / discharge efficiency of the battery 1000.

[0095] The shape of the negative electrode active material 205 is not limited to a specific shape. The negative electrode active material 205 may be particles. The negative electrode active material 205 may have a median diameter of 0.1 μm or more and 100 μm or less. When the negative electrode active material 205 has a median diameter of 0.1 μm or more, the negative electrode active material 205 and the solid electrolyte 100 can be well dispersed in the negative electrode 203. This improves the charge / discharge characteristics of the battery 1000. When the negative electrode active material 205 has a median diameter of 100 μm or less, the lithium diffusion rate within the negative electrode active material 205 improves. This allows the battery 1000 to operate at a high output.

[0096] The negative electrode active material 205 may have a larger median diameter than the solid electrolyte 100. With this configuration, the negative electrode active material 205 and the solid electrolyte 100 can be dispersed well in the negative electrode 203.

[0097] In order 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 205 to the sum of the volume of the negative electrode active material 205 and the volume of the solid electrolyte 100 may be 0.30 or more and 0.95 or less.

[0098] To improve the energy density and power output of the battery 1000, the negative electrode 203 may have a thickness of 10 μm or more and 500 μm or less.

[0099] 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 for the purpose of increasing ionic conductivity, chemical stability, and electrochemical stability.

[0100] The second solid electrolyte material may be a sulfide solid electrolyte material.

[0101] Examples of sulfide solid electrolyte materials include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, and Li 3.25 Ge 0.25 P 0.75 S4 or Li 10 GeP2S 12 is.

[0102] When the electrolyte layer 202 contains the first solid electrolyte material, the anode 203 may contain a sulfide solid electrolyte material to suppress reductive decomposition of the solid electrolyte material. By covering the anode active material with the electrochemically stable sulfide solid electrolyte material, contact between the first solid electrolyte material and the anode active material can be suppressed. As a result, the internal resistance of the battery 1000 can be reduced.

[0103] The second solid electrolyte material may be an oxide solid electrolyte material.

[0104] Examples of oxide solid electrolyte materials include: (i) NASICON-type solid electrolyte materials such as LiTi2(PO4)3 or elemental substitution products thereof; (ii) perovskite-type solid electrolyte materials such as (LaLi)TiO3; (iii) Li 14 ZnGeO 16LISICON-type solid electrolyte materials such as LiSiO, LiGeO, or elemental substitutions thereof; (iv) LiLaZrO 12 or an element-substituted product thereof, or (v) Li3PO4 or an N-substituted product thereof.

[0105] As mentioned above, the second solid electrolyte material may be a halide solid electrolyte material.

[0106] Examples of halide solid electrolyte materials are LiMgX, LiFeX, Li(Al,Ga,In)X, Li(Al,Ga,In)X, or LiI, where X is at least one selected from the group consisting of F, Cl, Br, and I.

[0107] Other examples of halide solid electrolyte materials include Li a Me b Y c Z6. Here, a + mb + 3c = 6 and c > 0 are satisfied. Me is at least one selected from the group consisting of metal elements and metalloid elements other than Li and Y. Z is at least one selected from the group consisting of F, Cl, Br, and I. m represents the valence of Me. "Metalloid elements" are B, Si, Ge, As, Sb, and Te. "Metal elements" are all elements included in Groups 1 to 12 of the periodic table (excluding hydrogen) and all elements included in Groups 13 to 16 of the periodic table (excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se).

[0108] In order to improve the ionic conductivity of the halide solid electrolyte material, Me may be at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, and Nb.

[0109] The halide solid electrolyte material may be Li3YCl6 or Li3YBr6.

[0110] The second solid electrolyte material may be an organic polymer solid electrolyte material.

[0111] An example of the organic polymer solid electrolyte material is a compound of a polymer compound and a lithium salt.

[0112] The polymer compound may have an ethylene oxide structure. A polymer compound having an ethylene oxide structure can contain a large amount of lithium salt, and therefore can further increase ionic conductivity.

[0113] Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiSOF, LiN(SOCF), LiN(SOCF), LiN(SOCF)(SOCF), or LiC(SOCF). 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.

[0114] 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 non-aqueous electrolyte solution, a gel electrolyte, or an ionic liquid to facilitate the exchange of lithium ions and improve the output characteristics of the battery.

[0115] The non-aqueous electrolyte may contain a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0116] Examples of non-aqueous solvents are cyclic carbonate ester solvents, chain carbonate ester solvents, cyclic ether solvents, chain ether solvents, cyclic ester solvents, chain ester solvents, or fluorine-containing solvents. Examples of cyclic carbonate ester solvents are ethylene carbonate, propylene carbonate, or butylene carbonate. Examples of chain carbonate ester solvents are dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate. Examples of cyclic ether solvents are tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane. Examples of chain ether solvents are 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 fluorine-containing solvents are fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, or fluorodimethylene carbonate. One non-aqueous solvent selected from these may be used alone, or two or more non-aqueous solvents selected from these may be used in combination.

[0117] Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiSOCF, LiN(SOCF), LiN(SOCF), LiN(SOCF)(SOCF), or LiC(SOCF). 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.

[0118] The gel electrolyte may be a polymer material impregnated with a non-aqueous electrolyte, such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or a polymer having an ethylene oxide bond.

[0119] Examples of cations contained in the ionic liquid are: (i) aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium; (ii) aliphatic cyclic ammoniums such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperaziniums, or piperidiniums; or (iii) nitrogen-containing heterocyclic aromatic cations such as pyridiniums or imidazoliums.

[0120] An example of an anion contained in the ionic liquid is PF 6- , B.F. 4- , SbF 6- , AsF 6- , SO3CF 3- , N(SO2CF3) 2- , N(SO2C2F5) 2- , N(SO2CF3)(SO2C4F9) - , or C(SO2CF3) 3- is.

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

[0122] 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 to improve adhesion between particles.

[0123] Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl ester of acrylic acid, polyethyl ester of acrylic acid, polyhexyl ester of acrylic acid, polymethacrylic acid, polymethyl ester of methacrylic acid, polyethyl ester of methacrylic acid, polyhexyl ester of methacrylic acid, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose. Copolymers can also be used as binders. Examples of such binders include copolymers of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene. Mixtures of two or more materials selected from these may also be used as binders.

[0124] At least one selected from the positive electrode 201 and the negative electrode 203 may contain a conductive additive to improve electronic conductivity.

[0125] Examples of the conductive additive include: (i) graphites such as natural graphite or artificial graphite, (ii) carbon blacks such as acetylene black or ketjen black, (iii) conductive fibers such as carbon fiber or metal fiber, (iv) carbon fluoride, (v) metal powders such as aluminum, (vi) conductive whiskers such as zinc oxide or potassium titanate, (vii) conductive metal oxides such as titanium oxide, or (viii) conductive polymer compounds such as polyaniline, polypyrrole, or polythiophene. To reduce costs, the conductive additives (i) or (ii) may be used.

[0126] Instead of the electrolyte layer, a separator impregnated with an electrolytic solution may be used, or the exterior housing containing the positive electrode, separator portion, and negative electrode may be filled with the electrolytic solution. The electrolytic solution may be, for example, the nonaqueous electrolytic solution described above.

[0127] Examples of the shape of the battery 1000 include a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, and a laminate type.

[0128] The battery 1000 may be manufactured, for example, by preparing a material for forming a positive electrode, a material for forming an electrolyte layer, and a material for forming a negative electrode, and by using a known method, fabricating a laminate in which the positive electrode, the electrolyte layer, and the negative electrode are arranged in this order.

[0129] [Other Embodiments] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0130] (Technology 1) A solid electrolyte material containing Li, Ti, Al, and F, wherein an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα radiation has a peak in a first range where the diffraction angle 2θ is 13.7° or more and 14.7° or less.

[0131] According to the present disclosure, a solid electrolyte suitable for reducing the true density can be provided.

[0132] (Technology 2) The solid electrolyte material according to Technology 1, wherein in the X-ray diffraction pattern, a peak is present in at least one range selected from the group consisting of a second range in which the diffraction angle 2θ is 20.9° or more and 21.9° or less, a third range in which the diffraction angle 2θ is 41.2° or more and 42.2° or less, and a fourth range in which the diffraction angle 2θ is 53.3° or more and 54.3° or less. With this configuration, a solid electrolyte material having high ionic conductivity can be provided.

[0133] (Technology 3) The solid electrolyte material according to Technology 2, wherein a peak exists in each of the second range, the third range, and the fourth range, and the intensity of the peak in the second range is higher than the intensity of the peak in the third range and the intensity of the peak in the fourth range. With this configuration, a solid electrolyte material having higher ionic conductivity can be provided.

[0134] (Technology 4) The solid electrolyte material has a particulate shape, and the specific surface area of ​​the solid electrolyte material is 30 m 2 / g or more 70m 2 / g or less. This configuration makes it possible to provide a solid electrolyte material having high ionic conductivity.

[0135] (Technology 5) The specific surface area is 40 m 2 / g or more 55m 2 / g or less. According to this configuration, a solid electrolyte material having higher ionic conductivity can be provided.

[0136] (Technology 6) The value obtained by dividing the integrated value of the amount of moisture released from the solid electrolyte material when the temperature of the solid electrolyte material is raised from 25°C to 120°C by the total mass of the solid electrolyte material is MC 120 When defined as above, 50 ppm≦MC 120 6. The solid electrolyte material according to any one of techniques 1 to 5, wherein the content satisfies ≦20,000 ppm. According to this configuration, a suitable solid electrolyte can be provided by reducing the true density.

[0137] (Technology 7) The solid electrolyte material according to any one of Technologies 1 to 6, further comprising at least one element selected from the group consisting of H, O, N, and Zr. With such a configuration, elements that are inevitably mixed in can be tolerated.

[0138] (Technology 8) Represented by the following formula (1): Li6-(4-x-4y+my)a (Ti 1-x-y Al x M y ) a F 6-2z O z ... (1) In the formula (1), M is at least one selected from the group consisting of Zr, Ni, Fe, and Cr, m is the valence of M, and 0<x<1, 0≦y<0.1, 0≦z<0.1, and 0<a≦1.5 are satisfied. A solid electrolyte material having such a composition has high ionic conductivity and can be produced by a method with high industrial productivity.

[0139] (Technology 9) The solid electrolyte material according to Technology 8, wherein in the formula (1), 0.6≦x≦0.8, y = 0, z = 0, and a = 1 are satisfied. With this configuration, a solid electrolyte material having higher ionic conductivity can be provided.

[0140] (Technology 10) A cathode material comprising the solid electrolyte material according to any one of Technologies 1 to 9. According to the present disclosure, a cathode material suitable for reducing true density can be provided.

[0141] (Technology 11) A battery comprising a positive electrode containing the positive electrode material according to Technology 10. According to the present disclosure, the density of the battery can be reduced.

[0142] (Technology 12) A battery comprising a positive electrode, a negative electrode, and an electrolyte layer located between the positive electrode and the negative electrode, wherein 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 Technologies 1 to 9. According to the present disclosure, the density of the battery can be reduced.

[0143] (Technology 13) A method for producing a solid electrolyte material according to any one of Technologies 1 to 9, comprising absorbing moisture into the solid electrolyte. According to the present disclosure, a solid electrolyte material suitable for reducing the true density can be obtained.

[0144] (Technology 14) MC 120 The method for producing a solid electrolyte material according to claim 13, wherein the solid electrolyte is allowed to absorb moisture so as to satisfy a moisture content of 10,000 ppm or more. 120 is a value obtained by dividing the integrated amount of water released from the solid electrolyte when the temperature of the solid electrolyte is raised from 25° C. to 120° C. by the total mass of the solid electrolyte. According to such a method, a solid electrolyte material that is more suitable for reducing the true density can be obtained.

[0145] (Technology 15) The method for producing a solid electrolyte material according to Technology 13 or 14, further comprising drying the solid electrolyte. According to such a method, excess water can be removed from the solid electrolyte material.

[0146] (Technology 16) MC 120 The method for producing a solid electrolyte material according to technique 15, wherein the solid electrolyte is dried so as to satisfy <10,000 ppm of MC. 120 is a value obtained by dividing the integrated value of the amount of water released from the solid electrolyte when the temperature of the solid electrolyte is raised from 25° C. to 120° C. by the total mass of the solid electrolyte. According to such a method, excess water can be further removed from the solid electrolyte material.

[0147] Hereinafter, the present disclosure will be described in detail using examples and comparative examples. Note that the solid electrolyte material, positive electrode material, and battery of the present disclosure are not limited to the following examples.

[0148] Example 1 A solid electrolyte material according to Example 1 was prepared by the following method.

[0149] (Pulverization step) Under an argon atmosphere having a dew point of −20° C. or less (hereinafter referred to as “dry argon atmosphere”), raw material powders of LiF, Li2TiF6, and AlF3 were prepared so that the molar ratio of LiF:Li2TiF6:AlF3 was 2.1:0.3:0.7.

[0150] 45cm 3 The raw material powder was charged into a pod for a planetary ball mill, together with zirconia balls having a diameter of 0.5 mm and a mass of 25 g. γ-Butyrolactone (GBL) was added dropwise to the pod so that the solid content ratio was 30%. The solid content ratio was calculated by {(mass of charged raw materials) / (mass of charged raw materials + mass of charged solvent)}×100.

[0151] The mixture was milled using a planetary ball mill at 400 rpm for 12 hours. After the milling, the zirconia balls were separated to obtain a slurry.

[0152] (Drying Step) The obtained slurry was dried using a mantle heater under nitrogen flow at 250°C for 1 hour. The obtained solid was pulverized in a mortar to obtain a solid electrolyte powder. The solid electrolyte powder contained Li 2.7 Ti 0.3 Al 0.7 It had the composition F6.

[0153] (Moisture absorption step) 5 g of the above solid electrolyte powder was placed in a container and left to stand for 20 days without a lid in an atmosphere at a temperature of 25° C. and a humidity of 40 to 60%. After 20 days, the solid electrolyte material of Example 1 was obtained by lightly mixing the powder in the container.

[0154] [Example 2] A solid electrolyte material of Example 2 was obtained in the same manner as in Example 1, except that after the moisture absorption step in Example 1, the solid electrolyte powder was dried using a hot plate under nitrogen flow at 150°C for 1 hour. In other words, the solid electrolyte material of Example 2 was obtained by adding a drying step (re-drying step) after the moisture absorption step.

[0155] [Comparative Example 1] A solid electrolyte material of Comparative Example 1 was obtained in the same manner as in Example 1, except that the moisture absorption step was not performed in Example 1. In other words, the solid electrolyte material of Comparative Example 1 was obtained by undergoing only the pulverization step and the drying step.

[0156] [Evaluation] The solid electrolyte materials of the examples and comparative examples were evaluated by the following methods.

[0157] (Measurement of X-ray diffraction pattern) The X-ray diffraction patterns of the solid electrolyte materials of the examples and comparative examples were measured using an X-ray diffractometer (RIGAKU Corporation, MiniFlex 600) in a dry environment with a dew point of −20° C. or less. Cu-Kα radiation (wavelengths 1.5405 Å and 1.5444 Å) was used as the X-ray source.

[0158] The X-ray diffraction patterns of the solid electrolyte materials of the Examples and Comparative Examples are shown in FIG. 3, and the peak positions of the X-ray diffraction patterns are shown in Table 1.

[0159]

[0160] (Measurement of ionic conductivity) Fig. 4 is a schematic diagram of a pressure molding die 300 used to evaluate the ionic conductivity of a solid electrolyte material. The pressure molding die 300 included an upper punch 301, a frame 302, and a lower punch 303. The frame 302 was made of insulating polycarbonate. The upper punch 301 and the lower punch 303 were made of electronically conductive stainless steel.

[0161] Using the pressure molding die 300 shown in FIG. 4, the ionic conductivity of the solid electrolyte 100 made of the solid electrolyte material of the examples and comparative examples was evaluated by the following method.

[0162] In a dry atmosphere having a dew point of −30° C. or less, the powder of solid electrolyte 100 of each of the examples and comparative examples was filled into a pressure molding die 300. A pressure of 300 MPa was applied to the powder of solid electrolyte 100 inside the pressure molding die 300 using an upper punch 301 and a lower punch 303.

[0163] With the pressure applied, the upper punch 301 and the lower punch 303 were each connected to a potentiostat (BioLogic, VSP300) equipped with a frequency response analyzer. Specifically, the upper punch 301 was connected to the working electrode and potential measurement terminal of the potentiostat, and the lower punch 303 was connected to the counter electrode and reference electrode. Thereafter, the impedance of the powder of solid electrolyte 100 was measured at a temperature of 25°C by electrochemical impedance measurement.

[0164] The real value of the impedance at the measurement point where the absolute value of the phase of the complex impedance of the measurement result is the smallest is the resistance value R of the ionic conduction of the solid electrolyte material. SE This resistance value R SE Using the above, the ionic conductivity σ of the solid electrolyte material was calculated based on the following formula (4). In formula (4), S is the contact area between the powder of the solid electrolyte 100 and the upper punch 301, and t is the thickness of the solid electrolyte material. S is equal to the cross-sectional area of ​​the hollow portion of the frame mold 302 in FIG. 3 . t is the thickness of the layer formed from the powder of the solid electrolyte 100 in FIG. 4 .

[0165] σ = (R SE × S / t) -1 ...(4)

[0166] The results of the ionic conductivity measurements are shown in Table 2.

[0167] (Measurement of BET Specific Surface Area) The BET specific surface area of ​​the solid electrolyte materials of the Examples and Comparative Examples was measured by the above-mentioned method in a dry environment with a dew point of −20° C. or less. A nitrogen adsorption measuring device (MicrotracBEL, BELSORP MINIX) was used to measure the BET specific surface area.

[0168] The results of the BET specific surface area measurements are shown in Table 2.

[0169] (Measurement of True Density) The true densities of the solid electrolyte materials of the Examples and Comparative Examples were measured using a true density measuring device (Ultrapyc 1200e, manufactured by Anton Paar) in a dry environment with a dew point of −30° C. or less. The true density measurement was performed 10 times.

[0170] The maximum and minimum true density values ​​measured ten times are shown in Table 2.

[0171]

[0172] (Measurement of Moisture Content) In a dry environment with a dew point of −30° C. or less, the moisture content MC 120 and moisture content MC 300 The moisture content MC 120 and moisture content MC 300 The moisture content was measured using a moisture measuring device (HIRANUMA MOICO-A19).

[0173] The results of the moisture content measurements are shown in Table 3.

[0174]

[0175] As shown in Table 1 and Figure 3, in the solid electrolyte materials of the Examples, in the X-ray diffraction patterns obtained by X-ray diffraction measurement using Cu-Kα radiation, a peak was present in the range of diffraction angle 2θ of 13.7° or more and 14.7° or less. As shown in Table 2, the true density of the solid electrolyte materials of the Examples was lower than that of the solid electrolyte materials of the Comparative Examples, and the ionic conductivity was equivalent to that of the solid electrolyte materials of the Comparative Examples. Specifically, the solid electrolyte materials of the Examples had a true density of 2.77 g / cm 3 and the ionic conductivity is less than 1×10 -6 The viscosity was 200 S / cm or more.

[0176] As shown in Table 1 and Figure 3, the solid electrolyte material of the example had a peak at around 14.1° in the X-ray diffraction pattern. The peak at around 14.1° is presumed to be due to a hydrate. The appearance of this peak is thought to be the reason why the solid electrolyte material of the example has both high ionic conductivity and low true density.

[0177] In Example 2, the solid electrolyte material was heated in the re-drying process, but the BET specific surface area was 40 m 2 From this, it is presumed that in the solid electrolyte material of Example 2, the particles do not bond together even when heated, and the small particle size is maintained.

[0178] The solid electrolyte material of the example has a resistance of 1×10 -6 The solid electrolyte materials of the examples maintained an ionic conductivity of 100 S / cm or more. This suggests that the ionic conductivity of the solid electrolyte materials of the examples is less susceptible to the influence of moisture absorption. Therefore, from the viewpoint of ionic conductivity, it is thought that the solid electrolyte materials of the examples do not necessarily need to be stored in a special humidity environment such as a dry room.

[0179] The solid electrolyte material of the present disclosure can be used, for example, as a solid electrolyte material for secondary batteries such as all-solid-state batteries used in various electronic devices or automobiles.

Claims

1. A solid electrolyte material containing Li, Ti, Al, and F, wherein an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα radiation has a peak in a first range where the diffraction angle 2θ is 13.7° or more and 14.7° or less.

2. The solid electrolyte material according to claim 1, wherein the X-ray diffraction pattern has a peak in at least one range selected from the group consisting of a second range in which the diffraction angle 2θ is 20.9° or more and 21.9° or less, a third range in which the diffraction angle 2θ is 41.2° or more and 42.2° or less, and a fourth range in which the diffraction angle 2θ is 53.3° or more and 54.3° or less.

3. The solid electrolyte material according to claim 2, wherein a peak exists in each of the second range, the third range, and the fourth range, and the intensity of the peak in the second range is higher than the intensity of the peak in the third range and the intensity of the peak in the fourth range.

4. The solid electrolyte material has a particulate shape, and the specific surface area of ​​the solid electrolyte material is 30 m 2 / g or more 70m 2 The solid electrolyte material according to claim 1 , wherein the SiO 2 content is 0.15 / g or less.

5. The specific surface area is 40 m 2 / g or more 55m 2 The solid electrolyte material according to claim 4, wherein the SiO2 content is 1 / g or less.

6. The MC value is calculated by dividing the integrated value of the amount of water released from the solid electrolyte material when the temperature of the solid electrolyte material is increased from 25°C to 120°C by the total mass of the solid electrolyte material. 120 When defined as above, 50 ppm≦MC 120 The solid electrolyte material according to claim 1 , wherein the content of SiO 2 satisfies the following condition:≦20,000 ppm.

7. The solid electrolyte material according to claim 1, further comprising at least one element selected from the group consisting of H, O, N, and Zr.

8. Represented by the following formula (1): Li6-(4-x-4y+my)a (Ti 1-x-y Al x M y ) a F 6-2z O z ... (1) In the formula (1), M is at least one selected from the group consisting of Zr, Ni, Fe, and Cr, m is a valence of M, and 0<x<1, 0≦y<0.1, 0≦z<0.1, and 0<a≦1.5 are satisfied. The solid electrolyte material according to claim 1.

9. The solid electrolyte material according to claim 8, wherein in the formula (1), 0.6≦x≦0.8, y=0, z=0, and a=1 are satisfied.

10. A positive electrode material comprising the solid electrolyte material according to any one of claims 1 to 9.

11. A battery comprising a positive electrode containing the positive electrode material of claim 10.

12. A battery comprising: a positive electrode; a negative electrode; and an electrolyte layer located between the positive electrode and the negative electrode, wherein at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer comprises the solid electrolyte material according to claim 1.

13. A method for producing a solid electrolyte material according to claim 1, comprising absorbing moisture into the solid electrolyte.

14. MC 120 The method for producing a solid electrolyte material according to claim 13, wherein the solid electrolyte is allowed to absorb moisture so as to satisfy a moisture content of 10,000 ppm or more. 120 is a value obtained by dividing the integrated value of the amount of water released from the solid electrolyte when the temperature of the solid electrolyte is raised from 25°C to 120°C by the total mass of the solid electrolyte.

15. The method for producing a solid electrolyte material according to claim 13, further comprising drying the solid electrolyte.

16. MC 120 The method for producing a solid electrolyte material according to claim 15, wherein the solid electrolyte is dried so as to satisfy a concentration of MC<10,000 ppm. 120 is a value obtained by dividing the integrated value of the amount of water released from the solid electrolyte when the temperature of the solid electrolyte is raised from 25°C to 120°C by the total mass of the solid electrolyte.

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