Method for producing solid electrolyte material

Abstract

The method for producing a solid electrolyte material according to the present disclosure is a method for producing a solid electrolyte material containing Li, Ti, Al and F, said method comprising: pulverising a mixture containing a solvent and one or more compounds having a composition different from that of the solid electrolyte material and containing Li, Ti, Al and F; and drying the pulverised product of the pulverisation. The one or more compounds include Li2TiF6.

Description

Method for manufacturing solid electrolyte material

[0001] The present disclosure relates to a method for producing a solid electrolyte material.

[0002] Patent Document 1 discloses a method for producing a sulfide solid electrolyte material.

[0003] Patent Document 2 discloses an inorganic solid electrolyte of a compound containing lithium and a halogen, such as LiBF4, as a lithium ion conductive inorganic solid electrolyte.

[0004] JP 2011-129312 A JP 2008-277170 A

[0005] An objective of the present disclosure is to expand the process window in the manufacturing of solid electrolyte materials containing Li, Ti, Al, and F.

[0006] A method for producing a solid electrolyte material according to the present disclosure is a method for producing a solid electrolyte material containing Li, Ti, Al, and F, comprising: pulverizing a mixture containing one or more compounds having a composition different from that of the solid electrolyte material and containing Li, Ti, Al, and F, and a solvent; and drying the pulverized product obtained through the pulverization, wherein the one or more compounds include LiTiF.

[0007] According to the present disclosure, the process window for manufacturing solid electrolyte materials containing Li, Ti, Al, and F can be expanded.

[0008] FIG. 1A is a flowchart showing an example of a method for producing a solid electrolyte material in the first embodiment. FIG. 1B is a flowchart showing another example of a method for producing a solid electrolyte material in the first embodiment. FIG. 2 shows a cross-sectional view of a battery in the second embodiment. FIG. 3 shows a cross-sectional view of a battery in Modification 1. FIG. 4 shows a cross-sectional view of a battery in Modification 2. FIG. 5 shows a schematic diagram of a pressure forming die used to evaluate the ionic conductivity of a solid electrolyte material. FIG. 6 is a graph showing a Cole-Cole plot obtained by impedance measurement of the solid electrolyte material of Example 1. FIG. 7 shows the change in ionic conductivity with change in milling time for the solid electrolyte materials of Examples 1 to 6 and Comparative Examples 1 to 3. FIG. 8 is a graph showing the initial discharge characteristics of the batteries of Example 4 and Comparative Example 4.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The following embodiments are merely examples, and the present disclosure is not limited to the following embodiments.

[0010] First Embodiment FIG. 1A is a flowchart showing an example of a method for producing a solid electrolyte material according to a first embodiment.

[0011] The method for producing a solid electrolyte material in the first embodiment is a method for producing a solid electrolyte material containing Li, Ti, Al, and F. The method includes a pulverization step S11 and a drying step S12. The pulverization step S11 is performed before the drying step S12.

[0012] In the pulverization step S11, a mixture M containing one or more compounds containing Li, Ti, Al, and F and a solvent is pulverized. The one or more compounds have a composition different from that of the solid electrolyte material to be produced.

[0013] In the drying step S12, the pulverized material obtained through the pulverization step S11 is dried, thereby removing the solvent contained in the pulverized material.

[0014] The one or more compounds used in the grinding step S11 include Li2TiF6.

[0015] According to the above configuration, the process window, for example, the range of the optimum grinding time, can be expanded.

[0016] One known method for producing a solid electrolyte material containing Li, Ti, Al, and F is to heat a slurry obtained by grinding raw materials in a solvent. From the perspective of production efficiency, it is desirable to obtain a solid electrolyte material with high ionic conductivity in as short a grinding time as possible. Furthermore, the longer the grinding time, the more the raw materials deteriorate, and the ionic conductivity tends to decrease. This is thought to be due to the fact that as the grinding time increases, the oxygen contained in the raw materials increases, which causes a side reaction between the raw materials and the solvent. From the perspective of production efficiency, it is desirable to suppress the progression of the decrease in ionic conductivity of the solid electrolyte material. In other words, it is desirable to maintain high ionic conductivity for as long a grinding time as possible. Thus, there is a need to expand the process window, e.g., the range of the optimal grinding time, in the method for producing a solid electrolyte material containing Li, Ti, Al, and F. After extensive research, the present inventors have found that using Li2TiF6 as one of the raw materials can expand the range of the optimal grinding time compared to, for example, using TiF4 as one of the raw materials. This is believed to be due to the higher thermal and chemical stability of Li2TiF6 compared to TiF4.

[0017] In this embodiment, the mixture M includes one or more compounds containing Li, Ti, Al, and F and a solvent. The mixture M may consist of one or more compounds containing Li, Ti, Al, and F and a solvent.

[0018] In this embodiment, the one or more compounds include a Ti-containing compound. Examples of the Ti-containing compound include Li2TiF6 and (NH4)2TiF6. The one or more compounds may include Li2TiF6 as the Ti-containing compound. This configuration can expand the process window.

[0019] The one or more compounds may include a Li-containing compound. The Li-containing compound is a compound having a composition different from Li2TiF6. According to the above configuration, the process window can be expanded.

[0020] Examples of the Li-containing compound include LiF, LiOH, and Li2CO3. The one or more compounds may include LiF as the Li-containing compound. According to the above configuration, the process window can be expanded.

[0021] The one or more compounds may include an Al-containing compound. According to the above-described configuration, the process window can be expanded.

[0022] Examples of Al-containing compounds include AlF, (NH)AlF, and LiAlF. One or more of the compounds may contain AlF as the Al-containing compound. This configuration can expand the process window.

[0023] The one or more compounds may include three or more compounds including a Ti-containing compound, a Li-containing compound, and an Al-containing compound. The one or more compounds may be three compounds consisting of a Ti-containing compound, a Li-containing compound, and an Al-containing compound.

[0024] In the pulverization step S11, a mixture M containing Li2TiF6, LiF, and AlF3 and a solvent may be pulverized.

[0025] In this embodiment, the pulverization process in the pulverization step S11 is a wet pulverization process. In the wet pulverization process, the material is mixed with a solvent and then pulverized mainly by shear force and friction force. In the wet pulverization process, the surface of the material particles is scraped off to generate small particles.

[0026] The solvent used in the pulverization step S11 may be an organic solvent or an inorganic solvent such as water, but is preferably an organic solvent.

[0027] The organic solvent may contain a compound having an ester group. In this case, the one or more compounds exhibit excellent dispersibility in the organic solvent. Therefore, the above configuration can improve the ionic conductivity of the solid electrolyte material.

[0028] The organic solvent may include at least one selected from the group consisting of γ-butyrolactone, propylene carbonate, butyl acetate, and tetralin. In this case, the one or more compounds exhibit excellent dispersibility in the organic solvent. Therefore, the above configuration can improve the ionic conductivity of the solid electrolyte material.

[0029] The pulverization method in the pulverization step S11 is not particularly limited. For example, a ball mill, a pot mill, a bead mill, a V-type mixer, a double-cone type mixer, an automatic mortar, or the like may be used. For example, the raw material powder and the solvent may be placed in a mixer such as a planetary ball mill and mixed while being pulverized.

[0030] The pulverization time in the pulverization step S11 can be appropriately set depending on the pulverization method. For example, when a planetary ball mill is used, the ionic conductivity of the solid electrolyte material is reduced to 3×10 after a 10-hour pulverization time. -6 Even if the grinding time exceeds 45 hours, the ionic conductivity of the solid electrolyte is 3×10 -6 It is possible to maintain a resistance of μS / m or more.

[0031] In this embodiment, the BET specific surface area of ​​the solid electrolyte material is 25 m 2 By performing the pulverization step S11 so that the BET specific surface area of ​​the solid electrolyte material is 25 m / g or more, the process window can be easily expanded. 2 The pulverization step S11 may be performed so that the BET specific surface area of ​​the solid electrolyte material obtained by the pulverization step S11 is not particularly limited. The upper limit of the BET specific surface area of ​​the solid electrolyte material is, for example, 100 m 2 / g, and 70m 2 / g, and 50m 2 / g, and 45m 2 / g, and 40m2 / g, and further 35m 2 / g.

[0032] The BET specific surface area of ​​the solid electrolyte material can be determined, for example, by converting data of an adsorption isotherm obtained by a gas adsorption method using nitrogen gas into data by the BET (Brunauer-Emmett-Teller) method.

[0033] In the drying step S12, the pulverized material may be heated in an inert gas atmosphere to remove the solvent from the pulverized material. The heating temperature (atmospheric temperature) is, for example, 50°C or higher and 300°C or lower.

[0034] In this embodiment, in the drying step S12, the solvent may be removed from the pulverized material by 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. In the drying step S12, the solvent may be removed from the pulverized material by vacuum drying. Vacuum drying is a method of removing the solvent from the pulverized material at or below the vapor pressure at a temperature 20°C lower than the boiling point of the solvent. The heating temperature of the pulverized material in reduced pressure drying or vacuum drying is, for example, 50°C or higher and 300°C or lower.

[0035] FIG. 1B is a flowchart showing another example of the method for producing a solid electrolyte material according to the first embodiment.

[0036] 1B, the method for producing a solid electrolyte material in the first embodiment may further include a heating step S10. The heating step S10 is performed before the pulverization step S11.

[0037] In the heating step S10, a mixture M1 containing two or more compounds including TiF and LiF and a solvent is heated to synthesize LiTiF.

[0038] In the pulverization step S11, the mixture M2 containing the composition obtained through the heating step S10 and an Al-containing compound is pulverized. The composition obtained through the heating step S10 contains LiTiF. The Al-containing compound may contain AlF.

[0039] The example shown in FIG. 1B differs from the example shown in FIG. 1A in that Li2TiF6 is synthesized in advance by a heating step S10.

[0040] In the drying step S12, the pulverized material obtained through the pulverization step S11 is dried, thereby removing the solvent contained in the pulverized material.

[0041] The above configuration also makes it possible to expand the process window, for example, the range of the optimum grinding time.

[0042] In this embodiment, the mixture M1 includes two or more compounds including TiF4 and LiF and a solvent. The mixture M1 may consist of two or more compounds including TiF4 and LiF and a solvent.

[0043] In the present embodiment, the mixture M2 includes the composition obtained through the heating step S10 and an Al-containing compound. The mixture M2 may consist of the composition obtained through the heating step S10 and an Al-containing compound.

[0044] The pulverization step S11 and the drying step S12 in the example shown in Fig. 1B correspond to the pulverization step S11 and the drying step S12 in the example shown in Fig. 1A, respectively, and therefore detailed description thereof will be omitted.

[0045] In the example shown in FIG. 1B, a mixture M3 containing three or more compounds including TiF, LiF, and an Al-containing compound and a solvent may be heated in the heating step S10. This may result in LiTiF being synthesized. In this case, in the grinding step S11, the composition obtained through the heating step S10 is ground. The composition obtained through the heating step S10 contains LiTiF and the Al-containing compound. That is, in the example shown in FIG. 1B, the Al-containing compound may be added in the heating step S10.

[0046] The above configuration also makes it possible to expand the process window, for example, the range of the optimum grinding time.

[0047] In this embodiment, the mixture M3 includes three or more compounds including TiF, LiF, and an Al-containing compound, and a solvent. The mixture M3 may consist of three or more compounds including TiF, LiF, and an Al-containing compound, and a solvent.

[0048] Hereinafter, the solid electrolyte material produced by the method for producing a solid electrolyte material in the first embodiment will be referred to as a first solid electrolyte material. The first solid electrolyte material contains Li, Ti, Al, and F. The first solid electrolyte material can have high ionic conductivity.

[0049] The first solid electrolyte material contains F, and therefore can have high oxidation resistance. This is because F has a high oxidation-reduction potential. On the other hand, F has a high electronegativity, and therefore bonds relatively strongly with Li. As a result, solid electrolyte materials containing Li and F usually tend to have low lithium ion conductivity. For example, LiBF4 disclosed in Patent Document 2 has a lithium ion conductivity of 6.67 × 10 -9 On the other hand, the first solid electrolyte material contains Ti and Al in addition to Li and F, and therefore has a low ionic conductivity of, for example, 7×10 -9 It can have a high ionic conductivity of 100 S / cm or more.

[0050] The first 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.

[0051] It is desirable that the first solid electrolyte material does not contain sulfur. A sulfur-free solid electrolyte material does not generate hydrogen sulfide even when exposed to the atmosphere, and therefore is highly safe. The sulfide solid electrolyte disclosed in Patent Document 1 may generate hydrogen sulfide when exposed to the atmosphere.

[0052] The first solid electrolyte material may further contain anions other than F. Examples of such anions are Cl, Br, I, O, and Se. According to the above configuration, the ionic conductivity of the first solid electrolyte material is improved.

[0053] The ratio R of the amount of substance of F to the sum of the amounts of substance of the anions of the first solid electrolyte material may be 0.50 or more. The ratio R may be 0.50 or more and 1.0 or less. According to the above configuration, the oxidation resistance of the first solid electrolyte material is improved.

[0054] The anion constituting the first 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 first solid electrolyte material is further improved.

[0055] The first solid electrolyte material may consist essentially of Li, Ti, Al, and F. Here, "the first solid electrolyte material consists essentially of Li, Ti, Al, and F" means that the ratio of the total amount of substance of Li, Ti, Al, and F to the total amount of substance of all elements constituting the first solid electrolyte material (i.e., molar fraction) is 90% or more. As an example, this ratio (i.e., molar fraction) may be 95% or more. The first solid electrolyte material may consist only of Li, Ti, Al, and F.

[0056] The first solid electrolyte material may contain elements that are inevitably mixed in. Examples of such elements include hydrogen, oxygen, and nitrogen. Such elements may be present in the raw material powder of the first solid electrolyte material or in the atmosphere used for producing or storing the first solid electrolyte material.

[0057] The first solid electrolyte material may be represented by the following formula (1):

[0058] Li 6-(4-x)a (Ti 1-x Al x ) a F6...(1)

[0059] In formula (1), 0<x<1 and 0<a≦1.5 are satisfied. A solid electrolyte material having such a composition has high ionic conductivity.

[0060] In order to increase the ionic conductivity, 0.1≦x≦0.9 may be satisfied in formula (1).

[0061] To further increase the ionic conductivity, 0.1≦x≦0.7 may be satisfied in formula (1).

[0062] The upper and lower limits of the range of x in formula (1) can be defined by any combination selected from the following numerical values: 0.1, 0.3, 0.4, 0.5, 0.6, 0.67, 0.7, 0.8, and 0.9.

[0063] In order to increase the ionic conductivity, 0.8≦a≦1.2 may be satisfied in formula (1).

[0064] The upper and lower limits of the range of a in formula (1) can be defined by any combination selected from the following numerical values: 0.8, 0.9, 0.94, 1.0, 1.06, 1.1, and 1.2.

[0065] The first solid electrolyte material may be represented by the following formula (2): In formula (2), α, β, γ, and δ are each independently a value greater than 0.

[0066] Li α Ti β Al γ F δ ... (2)

[0067] The first solid electrolyte material may be represented by the following formula (3): In formula (3), M is at least one selected from the group consisting of Zr, Ni, Fe, and Cr, m is the valence of M2, and 0.1<x<0.9, 0≦y<0.1, 0≦z<0.1, and 0.8<b≦1.2 are satisfied.

[0068] Li6-(4-x-4y+my)b (Ti 1-x-y Al x M y ) b F 6-2z O z ...(3)

[0069] In addition, in formula (3), when M includes multiple elements, m is the total value of the product of the composition ratio of each element and the valence of the element. For example, when M includes element Me1 and element Me2, and element Me1 has a composition ratio of a1 and a valence of m1, and element Me2 has a composition ratio of a2 and a valence of m2, m is expressed as m1 × a1 + m2 × a2.

[0070] To further enhance ion conductivity, in the solid electrolyte, the ratio of the amount of substance of Li to the total amount of substance of Ti and Al may be 1.12 or more and 5.07 or less.

[0071] The first solid electrolyte material is Li 2.7 Ti 0.3 Al 0.7 It may also be F6.

[0072] The first solid electrolyte material may be crystalline or amorphous.

[0073] The first solid electrolyte material may include a crystalline phase represented by formula (1).

[0074] The shape of the first solid electrolyte material is not limited. Examples of the shape include a needle shape, a sphere shape, or an oval sphere shape. The first solid electrolyte material may be in the form of particles. The first solid electrolyte material may have the shape of a pellet or a plate.

[0075] Next, the first solid electrolyte material is Li 2.7 Ti 0.3 Al 0.7 An example of the manufacturing method in this embodiment when F6 is used will be described below.

[0076] First, one or more compounds containing Li, Ti, Al, and F weighed to have a target composition and having a composition different from that of the first solid electrolyte material are mixed with a solvent in a mixing device while being pulverized.

[0077] As an example, LiF, Li2TiF6, and AlF3 are prepared in a molar ratio of about 2.1:0.3:0.7. The raw material powders may be prepared in a pre-adjusted molar ratio to offset compositional changes that may occur during the synthesis process. The raw material powders and a solvent may be introduced into a mixing device such as a planetary ball mill and mixed while being pulverized. That is, a wet ball mill process may be performed. The raw material powders may be mixed before being introduced into the mixing device.

[0078] After mixing, the balls are separated to obtain a slurry with dispersed particles. The solvent is removed by drying the slurry at a temperature depending on the boiling point of the solvent used. 2.7 Ti 0.3 Al 0.7 A first solid electrolyte material having a composition represented by F6 is obtained. The first solid electrolyte material may be pulverized using a mortar or the like.

[0079] The first solid electrolyte material may be sintered in a vacuum or an inert atmosphere, for example, at a temperature of 100° C. or higher and 300° C. or lower for 1 hour or longer. In order to suppress compositional changes during sintering, the sintering may be performed in a sealed container such as a quartz tube.

[0080] The solvent used in the wet ball mill may contain at least one selected from the group consisting of γ-butyrolactone (GBL), propylene carbonate, butyl acetate, and tetralin. In view of the dielectric constant of the solvent, N-methyl-2-pyrrolidone (NMP) may also be used as the solvent.

[0081] Second Embodiment A second embodiment will be described below, and the matters described in the first embodiment will be omitted as appropriate.

[0082] The battery in the second embodiment includes a positive electrode, a separator member, and a negative electrode. The separator member is located between the positive electrode and the negative electrode.

[0083] At least one selected from the group consisting of the positive electrode, the negative electrode, and the separator contains the first solid electrolyte material. With this configuration, the battery can have excellent charge / discharge characteristics.

[0084] The separator portion may be a solid electrolyte layer, or may be a separator impregnated with an electrolytic solution.

[0085] FIG. 2 shows a cross-sectional view of a battery 100 according to the second embodiment.

[0086] The battery 100 according to the second embodiment includes a positive electrode 21, a solid electrolyte layer 22, and a negative electrode 23. The solid electrolyte layer 22 is located between the positive electrode 21 and the negative electrode 23. In the battery 100, the solid electrolyte layer 22 serves as a separator.

[0087] The positive electrode 21 contains a positive electrode active material 24 and a solid electrolyte 10. The solid electrolyte layer 22 contains an electrolyte material. The negative electrode 23 contains a negative electrode active material 25 and a solid electrolyte 10.

[0088] The solid electrolyte 10 may contain a first solid electrolyte material. The solid electrolyte 10 may be particles containing the first solid electrolyte material as a main component. Particles containing the first solid electrolyte material as a main component refer to particles in which the first solid electrolyte material is the component contained in the largest amount in terms of molar ratio. The solid electrolyte 10 may be particles made of the first solid electrolyte material.

[0089] The positive electrode 21 contains a material capable of absorbing and releasing metal ions (e.g., lithium ions). The material is, for example, a positive electrode active material 24.

[0090] Examples of the positive electrode active material 24 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.

[0091] In the present disclosure, "(A, B, C)" means "at least one selected from the group consisting of A, B, and C."

[0092] The shape of the positive electrode active material 24 is not limited to a specific shape. The positive electrode active material 24 may be particulate. The positive electrode active material 24 may have a median diameter of 0.1 μm or more and 100 μm or less. When the positive electrode active material 24 has a median diameter of 0.1 μm or more, the positive electrode active material 24 and the solid electrolyte 10 can be well dispersed in the positive electrode 21. This improves the charge / discharge characteristics of the battery 100. When the positive electrode active material 24 has a median diameter of 100 μm or less, the lithium diffusion rate within the positive electrode active material 24 improves. This allows the battery 100 to operate at a high output.

[0093] The positive electrode active material 24 may have a larger median diameter than the solid electrolyte 10. This allows the positive electrode active material 24 and the solid electrolyte 10 to be dispersed well in the positive electrode 21.

[0094] In order to improve the energy density and output of the battery 100, in the positive electrode 21, the ratio of the volume of the positive electrode active material 24 to the sum of the volume of the positive electrode active material 24 and the volume of the solid electrolyte 10 may be 0.30 or more and 0.95 or less.

[0095] A coating layer may be formed on at least a portion of the surface of the positive electrode active material 24. The coating layer may be formed on the surface of the positive electrode active material 24, 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, an oxide solid electrolyte, or a halide solid electrolyte. When the solid electrolyte 10 contains a sulfide solid electrolyte, the coating material may contain a first solid electrolyte material to suppress oxidative decomposition of the sulfide solid electrolyte. When the solid electrolyte 10 contains a first solid electrolyte material, the coating material may contain an oxide solid electrolyte to suppress oxidative decomposition of the first solid electrolyte material. Lithium niobate, which has excellent stability at high potentials, may be used as the oxide solid electrolyte. By suppressing oxidative decomposition, an increase in overvoltage of the battery 100 can be suppressed.

[0096] To improve the energy density and output of the battery 100, the positive electrode 21 may have a thickness of 10 μm or more and 500 μm or less.

[0097] The negative electrode 23 contains a material capable of absorbing and releasing metal ions (e.g., lithium ions). The material is, for example, a negative electrode active material 25.

[0098] Examples of the negative electrode active material 25 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.

[0099] The anode active material 25 may be selected taking into consideration the reduction resistance of the solid electrolyte material contained in the anode 23. For example, when the anode 23 contains a first solid electrolyte material, the anode active material 25 may be 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 the above-mentioned negative electrode active material, it is possible to suppress the reductive decomposition of the first solid electrolyte material contained in the negative electrode 23. As a result, it is possible to improve the charge / discharge efficiency of the battery 100.

[0100] The shape of the negative electrode active material 25 is not limited to a specific shape. The negative electrode active material 25 may be particles. The negative electrode active material 25 may have a median diameter of 0.1 μm or more and 100 μm or less. When the negative electrode active material 25 has a median diameter of 0.1 μm or more, the negative electrode active material 25 and the solid electrolyte 10 can be well dispersed in the negative electrode 23. This improves the charge / discharge characteristics of the battery 100. When the negative electrode active material 25 has a median diameter of 100 μm or less, the lithium diffusion rate within the negative electrode active material 25 improves. This allows the battery 100 to operate at a high output.

[0101] The negative electrode active material 25 may have a larger median diameter than the solid electrolyte 10. This allows the negative electrode active material 25 and the solid electrolyte 10 to be dispersed well in the negative electrode 23.

[0102] In order to improve the energy density and output of the battery 100, in the negative electrode 23, the ratio of the volume of the negative electrode active material 25 to the sum of the volume of the negative electrode active material 25 and the volume of the solid electrolyte 10 may be 0.30 or more and 0.95 or less.

[0103] To improve the energy density and output of the battery 100, the negative electrode 23 may have a thickness of 10 μm or more and 500 μm or less.

[0104] The solid electrolyte layer 22 contains an electrolyte material. The electrolyte material is, for example, a solid electrolyte material. The solid electrolyte material may include a first solid electrolyte material. With the above configuration, the battery 100 can operate at high power.

[0105] The solid electrolyte layer 22 may contain 50 mass % or more of the first solid electrolyte material. The solid electrolyte layer 22 may contain 70 mass % or more of the first solid electrolyte material. The solid electrolyte layer 22 may contain 90 mass % or more of the first solid electrolyte material. The solid electrolyte layer 22 may be made of only the first solid electrolyte material.

[0106] At least one selected from the group consisting of the positive electrode 21, the solid electrolyte layer 22, and the negative electrode 23 may contain a second solid electrolyte material having a composition different from that of the first solid electrolyte material, for the purpose of increasing ionic conductivity, chemical stability, and electrochemical stability.

[0107] The solid electrolyte layer 22 may contain a second solid electrolyte material. In the solid electrolyte layer 22, the first solid electrolyte material and the second solid electrolyte material may be uniformly dispersed.

[0108] The solid electrolyte layer 22 may be made of only the second solid electrolyte material.

[0109] The second solid electrolyte material may be a halide solid electrolyte.

[0110] Examples of halide solid electrolytes 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.

[0111] Other examples of halide solid electrolytes include Li a Me b Y c Z6, where 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).

[0112] In order to improve the ionic conductivity of the halide solid electrolyte, 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.

[0113] The halide solid electrolyte may be Li3YCl6 or Li3YBr6.

[0114] The second solid electrolyte material may be a sulfide solid electrolyte.

[0115] Examples of sulfide solid electrolytes 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.

[0116] When the solid electrolyte layer 22 contains the first solid electrolyte material, the anode 23 may contain a sulfide solid electrolyte to suppress reductive decomposition of the solid electrolyte material. The electrochemically stable sulfide solid electrolyte covers the anode active material, thereby preventing the first solid electrolyte material from contacting the anode active material. As a result, the internal resistance of the battery 100 can be reduced.

[0117] The second solid electrolyte material may be an oxide solid electrolyte.

[0118] Examples of oxide solid electrolytes include: (i) NASICON-type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutions; (ii) perovskite-type solid electrolytes such as (LaLi)TiO3; (iii) Li 14 ZnGeO 16 LISICON-type solid electrolytes such as LiSiO, LiGeO or elemental substitutions thereof; (iv) LiLaZrO 12 or an element-substituted product thereof, or (v) a garnet-type solid electrolyte such as Li3PO4 or an N-substituted product thereof.

[0119] The second solid electrolyte material may be an organic polymer solid electrolyte.

[0120] An example of the organic polymer solid electrolyte is a compound of a polymer compound and a lithium salt.

[0121] 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.

[0122] 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.

[0123] At least one selected from the group consisting of the positive electrode 21, the solid electrolyte layer 22, and the negative electrode 23 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 100.

[0124] The non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0125] 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 a combination of two or more non-aqueous solvents selected from these may be used.

[0126] 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 or more and 2 mol / L or less.

[0127] 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.

[0128] 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.

[0129] 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 - is.

[0130] The ionic liquid may contain a lithium salt.

[0131] At least one selected from the group consisting of the positive electrode 21, the solid electrolyte layer 22, and the negative electrode 23 may contain a binder to improve adhesion between particles.

[0132] 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.

[0133] At least one selected from the positive electrode 21 and the negative electrode 23 may contain a conductive additive to improve electronic conductivity.

[0134] 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) above may be used.

[0135] (Modification 1) Fig. 3 shows a cross-sectional view of a battery 101 in Modification 1. The battery 101 has the same structure as the battery 100 shown in Fig. 2 except that the solid electrolyte layer 22 includes a first solid electrolyte layer 221 and a second solid electrolyte layer 222. Elements common to the battery 100 are denoted by the same reference numerals and descriptions thereof will be omitted.

[0136] The first solid electrolyte layer 221 is located between the positive electrode 21 and the second solid electrolyte layer 222. The second solid electrolyte layer 222 is located between the first solid electrolyte layer 221 and the negative electrode 23.

[0137] The solid electrolyte material contained in the first solid electrolyte layer 221 may have a lower reduction potential than the solid electrolyte material contained in the second solid electrolyte layer 222. This allows the solid electrolyte material contained in the second solid electrolyte layer 222 to be used without being reduced. As a result, the charge / discharge efficiency of the battery 101 can be improved. For example, the second solid electrolyte layer 222 may contain a first solid electrolyte material. When the second solid electrolyte layer 222 contains the first solid electrolyte material, the first solid electrolyte layer 221 may contain a sulfide solid electrolyte to suppress reductive decomposition of the solid electrolyte material. This allows the charge / discharge efficiency of the battery 101 to be improved. The first solid electrolyte layer 221 may contain the first solid electrolyte material. The first solid electrolyte material has high oxidation resistance, so that the battery 101 can have excellent charge / discharge characteristics.

[0138] (Variation 2) Fig. 4 shows a cross-sectional view of a battery 200 in Variation 2. The battery 200 has the same structure as the battery 100 shown in Fig. 2, except that the separator portion is a separator impregnated with an electrolyte solution. Elements common to the battery 100 are designated by the same reference numerals and will not be described.

[0139] The separator 26 has lithium ion conductivity. The material of the separator 26 is not particularly limited as long as it allows the passage of lithium ions. Examples of the material of the separator 26 include porous materials. The separator 26 may have the shape of a membrane. When the separator 26 is a porous membrane, examples of the porous membrane include woven fabric, nonwoven fabric, porous membranes made of polyolefin resin, and porous membranes made of glass paper obtained by weaving glass fibers into nonwoven fabric.

[0140] The electrolyte may contain at least one selected from the group consisting of cyclic ethers, glymes, and sulfolane. The electrolyte may also contain an ether. Examples of the ether include cyclic ethers and glycol ethers. Glycol ethers have the formula CH3(OCH2CH2) n The glyme may be represented by OCH3. In the above composition formula, n is an integer of 1 or more. The electrolyte may contain a mixture of a cyclic ether and a glyme, or a cyclic ether as a solvent.

[0141] Examples of cyclic ethers include tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), 2,5-dimethyltetrahydrofuran, 1,3-dioxolane (1,3DO), 4-methyl-1,3-dioxolane (4Me1,3DO), etc. One or a mixture of two or more selected from these can be used.

[0142] Glymes include monoglyme (1,2-dimethoxyethane), diglyme (diethylene glycol dimethyl ether), triglyme (triethylene glycol dimethyl ether), tetraglyme (tetraethylene glycol dimethyl ether), pentaethylene glycol dimethyl ether, polyethylene glycol dimethyl ether, etc. The glyme may be a mixture of tetraglyme and pentaethylene glycol dimethyl ether.

[0143] Sulfolanes include 3-methylsulfolane.

[0144] The electrolyte may contain an electrolyte salt. Examples of the electrolyte salt include lithium salts such as LiPF, LiBF, LiSbF, LiAsF, LiSOCF, LiN(SOCF), LiN(SOCF), LiN(SOCF)(SOCF), LiC(SOCF), LiClO, and lithium bis(oxalate)borate. The electrolyte may contain lithium dissolved therein.

[0145] The separator portion may have a thickness of 1 μm or more and 1000 μm or less. When the separator portion has a thickness of 1 μm or more, the positive electrode 21 and the negative electrode 23 are less likely to short-circuit. When the separator portion has a thickness of 1000 μm or less, the battery can operate at high power.

[0146] Examples of the shape of the battery in the second embodiment include a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, and a laminate type.

[0147] The battery in the second embodiment may be manufactured, for example, by preparing a material for forming a positive electrode, a material for forming a solid electrolyte layer, and a material for forming a negative electrode, and by using a known method to fabricate a laminate in which the positive electrode, the solid electrolyte layer, and the negative electrode are arranged in this order.

[0148] (Other Embodiments) (Additional Notes) The above description of the embodiments discloses the following techniques.

[0149] (Technology 1) A method for producing a solid electrolyte material containing Li, Ti, Al, and F, comprising: pulverizing a mixture containing one or more compounds having a composition different from that of the solid electrolyte material and containing Li, Ti, Al, and F, and a solvent; and drying the pulverized product obtained through the pulverization, wherein the one or more compounds include Li2TiF6.

[0150] According to the method for producing a solid electrolyte material according to Technique 1, the process window, for example, the range of the optimum milling time, can be expanded.

[0151] (Technology 2) The method for producing a solid electrolyte material according to Technology 1, wherein the one or more compounds include a Li-containing compound having a composition different from Li2TiF6. With this configuration, the process window can be expanded.

[0152] (Technology 3) The method for producing a solid electrolyte material according to Technology 2, wherein the Li-containing compound includes LiF. With this configuration, the process window can be expanded.

[0153] (Technology 4) The method for producing a solid electrolyte material according to any one of Technologies 1 to 3, wherein the one or more compounds include an Al-containing compound. With this configuration, the process window can be expanded.

[0154] (Technology 5) The method for producing a solid electrolyte material according to Technology 4, wherein the Al-containing compound includes AlF3. With this configuration, the process window can be expanded.

[0155] (Technology 6) The method for producing a solid electrolyte material according to any one of Technologies 1 to 5, wherein the solvent contains a compound having an ester group. With this configuration, the ionic conductivity of the solid electrolyte material can be improved.

[0156] (Technology 7) The method for producing a solid electrolyte material according to any one of Techniques 1 to 6, wherein the solvent contains at least one selected from the group consisting of γ-butyrolactone, propylene carbonate, butyl acetate, and tetralin. With this configuration, the ionic conductivity of the solid electrolyte material can be improved.

[0157] (Technology 8) The method for producing a solid electrolyte material according to any one of Technologies 1 to 7, wherein a ratio of the amount of substance of F to the sum of the amount of substance of anions of the solid electrolyte material is 0.50 or more. According to this configuration, the oxidation resistance of the solid electrolyte material is improved.

[0158] (Technology 9) The solid electrolyte material is represented by the following formula (1): Li 6-(4-x)a (Ti 1-x Al x ) aF6 (1) wherein 0<x<1 and 0<a≦1.5 are satisfied. With this configuration, the solid electrolyte material has high ionic conductivity.

[0159] (Technology 10) A method for producing a solid electrolyte material containing Li, Ti, Al, and F, comprising: heating a first mixture containing two or more compounds containing TiF4 and LiF and a solvent; pulverizing a second mixture containing a composition obtained through the heating and an Al-containing compound; and drying the pulverized product obtained through the pulverization, wherein the composition contains Li2TiF6.

[0160] According to the method for producing a solid electrolyte material according to the tenth technique, the process window, for example, the range of the optimum milling time, can be expanded.

[0161] (Technology 11) The method for producing a solid electrolyte material according to Technology 10, wherein the Al-containing compound includes AlF3. With this configuration, the process window can be expanded.

[0162] (Technology 12) A method for producing a solid electrolyte material containing Li, Ti, Al, and F, comprising: heating a mixture containing three or more compounds including TiF4, LiF, and an Al-containing compound and a solvent; pulverizing the composition obtained through the heating; and drying the pulverized product obtained through the pulverization, wherein the composition contains Li2TiF6 and the Al-containing compound.

[0163] According to the method for producing a solid electrolyte material according to Technique 12, the process window, for example, the range of the optimum milling time, can be expanded.

[0164] (Technology 13) The method for producing a solid electrolyte material according to Technology 12, wherein the Al-containing compound includes AlF3. With this configuration, the process window can be expanded.

[0165] The present disclosure will be described in more detail below using examples and comparative examples. The following are illustrative and do not limit the present disclosure.

[0166] Example 1 (Preparation of Solid Electrolyte Material) In an argon atmosphere with a dew point of −60°C or less (hereinafter referred to as a “dry argon atmosphere”), raw material powders of LiF, Li2TiF6, and AlF3 were prepared in a molar ratio of LiF:Li2TiF6:AlF3 = 2.1:0.3:0.7. These raw material powders were loaded into a 45 cc planetary ball mill pod along with 25 g of 0.5 mm diameter balls. γ-Butyrolactone (GBL) was added dropwise to the pod to achieve a solid content of 30%. The solid content is calculated as {(mass of input raw materials) / (mass of input raw materials + mass of input solvent)} × 100. Milling was performed using a planetary ball mill at 400 rpm for 2 hours. After milling, the balls were separated to obtain a slurry. The obtained slurry was dried using a mantle heater under nitrogen flow at 200°C for 1 hour. The obtained solid was pulverized in a mortar to obtain a powder of the solid electrolyte material of Example 1. The solid electrolyte material of Example 1 contained Li 2.7 Ti 0.3 Al 0.7 It had the composition F6.

[0167] (Evaluation of Ionic Conductivity) FIG. 5 shows a schematic diagram of a pressure forming die 300 used to evaluate the ionic conductivity of the solid electrolyte material.

[0168] The pressure molding die 300 had an upper punch 301, a frame 302, and a lower punch 303. The frame 302 was made of insulating polycarbonate, and the upper punch 301 and the lower punch 303 were made of electronically conductive stainless steel.

[0169] The ionic conductivity of the solid electrolyte material of Example 1 was evaluated by the following method using the pressure molding die 300 shown in FIG.

[0170] In a dry atmosphere having a dew point of −30° C. or less, the powder 11 of the solid electrolyte material of Example 1 was filled into the inside of the pressure molding die 300. Inside the pressure molding die 300, a pressure of 400 MPa was applied to the powder 11 of the solid electrolyte material using the upper punch 301 and the lower punch 303.

[0171] While the pressure was still applied, the upper punch 301 and the lower punch 303 were connected to a potentiostat (VSP300, manufactured by BioLogic) equipped with a frequency response analyzer. The upper punch 301 was connected to a working electrode and a potential measurement terminal. The lower punch 303 was connected to a counter electrode and a reference electrode. The impedance of the solid electrolyte material powder 11 was measured at room temperature by electrochemical impedance measurement.

[0172] FIG. 6 is a graph showing a Cole-Cole plot obtained by measuring the impedance of the solid electrolyte material of Example 1.

[0173] In Fig. 6, the real value of the impedance at the measurement point where the absolute value of the phase of the complex impedance is smallest was considered to be the resistance value for ion conduction of the solid electrolyte material. SE Using the resistance value, the ionic conductivity σ was calculated based on the following formula (4).

[0174] σ = (R SE × S / t) -1 ...(4)

[0175] In the formula (4), S represents the contact area of ​​the solid electrolyte material with the punch upper portion 301. That is, S is equal to the cross-sectional area of ​​the hollow portion of the frame mold 302 in FIG. SE represents the resistance value of the solid electrolyte material in impedance measurement. t represents the thickness of the solid electrolyte material. That is, t represents the thickness of the layer formed from the powder 11 of the solid electrolyte material in FIG. 5 .

[0176] The ionic conductivity is a value measured at 25°C.

[0177] <Examples 2 to 6> (Preparation of solid electrolyte material) Powders of solid electrolyte materials of Examples 2 to 6 were obtained by the same method as Example 1, except that the grinding time was changed as shown in Table 1. The solid electrolyte materials of Examples 2 to 6 were obtained by the same method as Example 1, except that the grinding time was changed as shown in Table 1. 2.7 Ti 0.3 Al 0.7 It had the composition F6.

[0178] <Comparative Examples 1 to 3> (Preparation of Solid Electrolyte Material) As raw material powders, LiF, TiF4, and AlF3 were prepared in a molar ratio of LiF:TiF4:AlF3 = 2.7:0.3:0.7. The grinding time was changed as shown in Table 1. Except for these, powders of the solid electrolyte materials of Comparative Examples 1 to 3 were obtained by the same method as in Example 1. The solid electrolyte materials of Comparative Examples 1 to 3 were prepared by the same method as in Example 1. 2.7 Ti 0.3 Al 0.7 It had the composition F6.

[0179] (Evaluation of Ionic Conductivity) The ionic conductivity of the solid electrolyte materials of Examples 2 to 6 and Comparative Examples 1 to 4 was measured by the same method as in Example 1. The results are shown in Table 1.

[0180] (Evaluation of BET Specific Surface Area) The BET specific surface area was measured by the above-described method for the solid electrolyte materials of Example 4 and Comparative Example 1. The results are shown in Table 1.

[0181] FIG. 7 shows the change in ionic conductivity with the change in grinding time for the solid electrolyte materials of Examples 1 to 6 and Comparative Examples 1 to 3.

[0182]

[0183] <Discussion> As shown in FIG. 7, in the solid electrolyte material of the example, the ionic conductivity was 3×10 after 10 hours of grinding. -6 On the other hand, the ionic conductivity of the solid electrolyte material of the comparative example was 3×10 -6 7, it took 18 hours of grinding time to reach 3×10 μS / m. -6On the other hand, in the solid electrolyte material of the comparative example, when the grinding time exceeded 43 hours, the ionic conductivity decreased to 3×10 -6 The solubility of the powder was reduced to less than μS / m. That is, the optimum milling time range for the example was 38 hours, from 10 hours to 48 hours, while the optimum milling time range for the comparative example was 25 hours, from 18 hours to 43 hours. Thus, the manufacturing method of the present disclosure was able to expand the process window.

[0184] As shown in Table 1, the grinding time for the solid electrolyte material of Example 4 was 12 hours, which was the same as the grinding time for the solid electrolyte material of Comparative Example 1. However, the solid electrolyte material of Example 4 had a BET specific surface area of ​​25 m 2 / g or more, whereas the solid electrolyte material of Comparative Example 1 has a BET specific surface area of ​​25 m 2 From this result, it was found that the BET specific surface area of ​​the solid electrolyte material was 25 m / g or more. 2 It is believed that by carrying out the pulverization step so that the solubility is 1 / g or more, the process window can be easily expanded.

[0185] The grinding time for the solid electrolyte material of Example 5 was 24 hours, the same as the grinding time for the solid electrolyte material of Comparative Example 2. The ionic conductivity of the solid electrolyte material of Example 5 was slightly lower than that of the solid electrolyte material of Comparative Example 2. However, since the object of the present invention is to expand the process window, this does not pose a problem as long as the ionic conductivity is equal to or higher than a certain value.

[0186] Example 4 (Fabrication of Battery) Using the solid electrolyte material of Example 4, which had the highest ionic conductivity among Examples 1 to 6, a battery was fabricated by the following method.

[0187] In a dry argon atmosphere, the solid electrolyte material of Example 4 and the active material LiCoO2 were prepared in a volume ratio of 30:70. These materials were mixed in an agate mortar. In this way, a positive electrode mixture was obtained.

[0188] Li3PS4 (57.41 mg), the solid electrolyte material of Example 4 (26 mg), and the positive electrode mixture (9.1 mg) were stacked in this order in an insulating tube having an inner diameter of 9.5 mm, and a pressure of 300 MPa was applied. This resulted in a laminate consisting of a first electrolyte layer, a second electrolyte layer, and a positive electrode. That is, the second electrolyte layer contained the solid electrolyte material of Example 4. The thicknesses of the first electrolyte layer and the second electrolyte layer were 450 μm and 150 μm, respectively.

[0189] Next, metallic Li (thickness: 200 μm) was laminated on the first electrolyte layer, and a pressure of 80 MPa was applied to the resulting laminate to form a negative electrode.

[0190] Next, current collectors made of stainless steel were attached to the positive and negative electrodes, and current collecting leads were attached to each current collector.

[0191] Finally, an insulating ferrule was used to isolate the inside of the insulating cylinder from the outside atmosphere, and the inside of the cylinder was sealed. In this way, the battery of Example 4 was produced.

[0192] (Charge / Discharge Test) The initial charge / discharge characteristics of the battery of Example 4 were measured by the following charge / discharge test.

[0193] The battery was placed in a constant temperature bath at 85°C.

[0194] 13.5 μA / cm 2 The battery was charged at a current density of 0.01 C until a voltage of 4.2 V was reached.

[0195] Next, 13.5 μA / cm 2 The cell was discharged at a current density of 0.05 V until a voltage of 2.5 V was reached.

[0196] As a result of the charge-discharge test, the battery of Example 4 had an initial discharge capacity of 867 μAh.

[0197] Comparative Example 4 (Fabrication of Battery) LiBF4 was used as the solid electrolyte material of Comparative Example 4. A battery of Comparative Example 4 was fabricated in the same manner as in Example 4, except that the solid electrolyte material of Comparative Example 4 was used as the solid electrolyte for the positive electrode mixture and the electrolyte layer.

[0198] (Charge-Discharge Test) A charge-discharge test was carried out using the battery of Comparative Example 4 in the same manner as in Example 4.

[0199] The initial discharge capacity of the battery of Comparative Example 4 was 0.01 μAh or less, that is, the battery of Comparative Example 4 was neither charged nor discharged.

[0200] FIG. 8 is a graph showing the initial discharge characteristics of the batteries of Example 4 and Comparative Example 4.

[0201] <Discussion> The battery according to Example 4 was charged and discharged at 85° C. On the other hand, the battery according to Comparative Example 4 was neither charged nor discharged. In other words, the battery according to Example 4 had excellent charge / discharge characteristics.

[0202] As described above, the method for producing a solid electrolyte material according to the present disclosure can expand the process window, for example, the range of the optimal milling time. Furthermore, a battery using the solid electrolyte material produced by this method can have excellent charge / discharge characteristics.

[0203] The solid electrolyte material produced by the method for producing a solid electrolyte material according to the present disclosure can be used, for example, in batteries (for example, solid-state batteries, liquid batteries).

Claims

1. A method for producing a solid electrolyte material containing Li, Ti, Al, and F, A mixture having a different composition from the aforementioned solid electrolyte material and containing one or more compounds containing Li, Ti, Al, and F, and a solvent, is pulverized. The pulverized material obtained after the aforementioned pulverization is dried, Includes, The one or more of the above compounds are Li 2 TiF 6 Includes, The pulverization is carried out such that the BET specific surface area of ​​the solid electrolyte material is 25 m² / g or more. A method for manufacturing solid electrolyte materials.

2. The one or more of the above compounds are Li 2 TiF 6 A Li-containing compound having a different composition, A method for producing a solid electrolyte material according to claim 1.

3. The Li-containing compound contains LiF, A method for producing a solid electrolyte material according to claim 2.

4. The one or more compounds include an Al-containing compound. A method for producing a solid electrolyte material according to claim 1.

5. The Al-containing compound is AlF 3 including, A method for producing a solid electrolyte material according to claim 4.

6. The solvent includes a compound having an ester group. A method for producing a solid electrolyte material according to claim 1.

7. The solvent comprises at least one selected from the group consisting of γ-butyrolactone, propylene carbonate, butyl acetate, and tetralin. A method for producing a solid electrolyte material according to claim 1.

8. The ratio of the amount of substance of F to the total amount of substance of anions in the solid electrolyte material is 0.50 or more. A method for producing a solid electrolyte material according to claim 1.

9. The aforementioned solid electrolyte material is represented by the following formula (1): Li 6-(4-x)a (T) 1-x Al x ) a F 6 ・・・(1) Here, the conditions 0 < x < 1 and 0 < a ≤ 1.5 are satisfied. A method for producing a solid electrolyte material according to claim 1.

10. A method for producing a solid electrolyte material containing Li, Ti, Al, and F, TiF 4 and heating a first mixture containing two or more compounds including LiF and a solvent, The second mixture, which includes the composition obtained after the aforementioned heating and an Al-containing compound, is pulverized. The pulverized material obtained after the aforementioned pulverization is dried, Includes, The composition is Li 2 TiF 6 including, A method for manufacturing solid electrolyte materials.

11. The Al-containing compound is AlF 3 including, A method for producing a solid electrolyte material according to claim 10.

12. A method for producing a solid electrolyte material containing Li, Ti, Al, and F, TiF 4 Heating a mixture containing three or more compounds, including LiF and an Al-containing compound, and a solvent, The composition obtained after the aforementioned heating is pulverized, The pulverized material obtained after the aforementioned pulverization is dried, Includes, The composition is Li 2 TiF 6 and the Al-containing compound, A method for manufacturing solid electrolyte materials.

13. The Al-containing compound is AlF 3 including, A method for producing a solid electrolyte material according to claim 12.