Composite active material, electrode material, battery, and method for manufacturing composite active material

Abstract

A composite active material according to one embodiment of the present disclosure includes an active material containing Li, Ti, and O, and a first solid electrolyte. The active material is a porous material having a plurality of pores, and the first solid electrolyte contains Li, M, and X. M is at least one element selected from the group consisting of a metalloid element and a metal element belonging to period 5 or period 6, and X is at least one element selected from the group consisting of F, Cl, Br, and I. At least a portion of the first solid electrolyte is present inside of the plurality of pores.

Description

Technical Field

[0001] The present disclosure relates to a composite active material, an electrode material, a battery, and a method for producing a composite active material.

Background Art

[0002] Patent Document 1 discloses a battery comprising a negative electrode active material layer containing lithium titanium oxide as a negative electrode active material, wherein the volume of pores in the negative electrode active material layer is adjusted.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] In the conventional art, further improvement in output characteristics is desired.

Means for Solving the Problem

[0005] The composite active material according to one aspect of the present disclosure is: an active material containing Li, Ti, and O; a first solid electrolyte; comprising the foregoing components, wherein the active material is a porous material having a plurality of pores, the first solid electrolyte contains Li, M, and X, M is at least one selected from the group consisting of metallic elements and metalloid elements belonging to the fifth period or the sixth period, X is at least one selected from the group consisting of F, Cl, Br, and I, and at least a part of the first solid electrolyte is present inside the plurality of pores.

Effect of the Invention

[0006] According to this disclosure, the output characteristics of the battery can be improved. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a diagram showing the schematic configuration of the composite active material in Embodiment 1. [Figure 2] Figure 2 is a flowchart showing the method for producing the composite active material in Embodiment 1. [Figure 3] Figure 3 shows a schematic configuration of the electrode material in Embodiment 2. [Figure 4] Figure 4 is a cross-sectional view showing the schematic configuration of the battery in Embodiment 3. [Figure 5] Figure 5 is a schematic diagram of a pressure-molding die used to evaluate the ionic conductivity of solid electrolytes. [Modes for carrying out the invention]

[0008] (Knowledge that forms the basis of this disclosure) Patent Document 1 discloses a lithium secondary battery comprising a negative electrode active material layer containing lithium titanium oxide as the negative electrode active material, in which the volume of pores in the negative electrode active material layer is adjusted from 10 volume% to 50 volume%. Thus, conventional lithium secondary batteries using electrolytes have used porous lithium titanium oxide to improve output characteristics. However, when a solid electrolyte is used as the electrolyte, it is difficult to form an interface between the active material and the solid electrolyte, and the interfacial resistance increases. Therefore, even if porous lithium titanium oxide is used as the negative electrode active material, the output characteristics of the battery cannot be sufficiently improved.

[0009] The inventors diligently researched techniques for improving the output characteristics of batteries. As a result, they conceived the technology described herein.

[0010] (Summary of one aspect of this disclosure) The composite active material relating to the first aspect of this disclosure is Active material containing Li, Ti, and O, The first solid electrolyte, Includes, The active material is a porous material having multiple pores, The first solid electrolyte comprises Li, M, and X. M is at least one element selected from the group consisting of metallic and metalloid elements belonging to the 5th or 6th period. X is at least one selected from the group consisting of F, Cl, Br, and I. At least a portion of the first solid electrolyte is located inside the plurality of pores.

[0011] With the above configuration, the interface formed between the porous active material and the first solid electrolyte increases, thus reducing interfacial resistance. This can improve the output characteristics of the battery.

[0012] In a second aspect of this disclosure, for example, in the composite active material according to the first aspect, the first solid electrolyte may be represented by the following compositional formula (1). Li α M β X γ ...Equation (1) Here, α, β, and γ are each independently greater than 0. With this configuration, the output characteristics of the battery can be further improved.

[0013] In a third aspect of this disclosure, for example, in the composite active material according to the first or second aspect, M in the first solid electrolyte may contain yttrium. With the above configuration, the ionic conductivity of the first solid electrolyte can be further improved.

[0014] In a fourth aspect of this disclosure, for example, in a composite active material according to any one of the first to third aspects, the first solid electrolyte may include at least one selected from the group consisting of Li3YBr3Cl3 and Li3YBr2Cl4. With the above configuration, the output characteristics of the battery can be further improved.

[0015] In the fifth aspect of the present disclosure, for example, in the composite active material according to any one of the first to fourth aspects, let S be the BET specific surface area of the active material AM , and let S be the BET specific surface area of the composite active material AM-SE , the following formula (2) may be satisfied. S AM-SE / S AM < 1 ··· Formula (2) According to the above configuration, the first solid electrolyte tends to easily exist inside the pores of the active material. This can further improve the output characteristics of the battery.

[0016] In the sixth aspect of the present disclosure, for example, in the composite active material according to the fifth aspect, the following formula (3) may be satisfied. S AM-SE / S AM < 0.5 ··· Formula (3) According to the above configuration, the first solid electrolyte tends to more easily exist inside the pores of the active material. This can further improve the output characteristics of the battery.

[0017] In the seventh aspect of the present disclosure, for example, in the composite active material according to any one of the first to sixth aspects, the active material may contain lithium titanium oxide. According to the above configuration, the safety of the battery can be improved while improving the charge-discharge efficiency of the battery.

[0018] In the eighth aspect of the present disclosure, for example, in the composite active material according to the seventh aspect, the lithium titanium oxide is Li4Ti5O 12 may be included. According to the above configuration, the safety of the battery can be improved while improving the charge-discharge efficiency of the battery.

[0019] In the ninth aspect of the present disclosure, for example, in the composite active material according to any one of the first to eighth aspects, the average particle diameter of the active material may be 5 µm or more. According to the above configuration, the output characteristics of the battery can be further improved.

[0020] In the tenth aspect of this disclosure, for example, in the composite active material according to any one of the first to ninth aspects, the first solid electrolyte may not contain sulfur. With the above configuration, the safety of the battery can be improved.

[0021] The electrode material relating to the 11th aspect of this disclosure is A composite active material relating to any one of the first to tenth embodiments, Second solid electrolyte, Includes.

[0022] The above configuration can improve the output characteristics of the battery.

[0023] The battery relating to the 12th aspect of this disclosure is The device comprises a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode. At least one selected from the group consisting of the positive electrode and the negative electrode includes an electrode material according to the 11th embodiment.

[0024] The above configuration can improve the output characteristics of the battery.

[0025] A method for producing a composite active material according to the 13th aspect of this disclosure is: Impregnating the active material with a mixture containing at least one selected from the group consisting of a first solid electrolyte and its raw materials, and a solvent, To remove the solvent contained in the mixture from the active material, Includes, The active material is a porous material containing Li, Ti, and O, and having a plurality of pores. The first solid electrolyte and the raw materials comprise Li, M, and X. M is at least one element selected from the group consisting of metallic and metalloid elements belonging to the 5th or 6th period. X is at least one selected from the group consisting of F, Cl, Br, and I.

[0026] With the above configuration, the first solid electrolyte can be placed inside the pores of the porous active material. This increases the interface formed between the active material and the first solid electrolyte, thus reducing interfacial resistance. Therefore, using the composite active material obtained by the above manufacturing method can improve the output characteristics of the battery.

[0027] In a fourteenth aspect of this disclosure, for example, the method for producing a composite active material according to the thirteenth aspect may further include heating the active material. With the above configuration, the first solid electrolyte can be precipitated.

[0028] In a 15th aspect of this disclosure, for example, in a method for producing a composite active material according to the 13th or 14th aspect, the solvent may include a nitrile-based solvent. With the above configuration, the first solid electrolyte and its raw materials can be appropriately dissolved and dispersed.

[0029] Embodiments of the present disclosure will be described below with reference to the drawings.

[0030] (Embodiment 1) Figure 1 is a diagram showing the schematic configuration of the composite active material in Embodiment 1.

[0031] The composite active material 103 in Embodiment 1 comprises an active material 101 and a first solid electrolyte 102. The active material 101 comprises Li, Ti, and O. The active material 101 is a porous material having a plurality of pores. The first solid electrolyte 102 comprises Li, M, and X. M is at least one selected from the group consisting of metallic and metalloid elements belonging to the 5th or 6th period. X is at least one selected from the group consisting of F, Cl, Br, and I. At least a portion of the first solid electrolyte 102 is present inside the plurality of pores of the active material 101.

[0032] When the first solid electrolyte 102 is present inside the pores of the active material 101, the interface formed between the active material 101 and the first solid electrolyte 102 increases, thus reducing the interfacial resistance. Therefore, by using the composite active material 103, the output characteristics of the battery can be improved.

[0033] In the composite active material 103, the first solid electrolyte 102 may exist in a particle state or in a layer state. The particles of the first solid electrolyte 102 are located inside the pores. The pores may be filled with particles of the first solid electrolyte 102. Multiple particles of the first solid electrolyte 102 may be present in the composite active material 103. The layer of the first solid electrolyte 102 may cover the inner surface of the pores.

[0034] "At least a portion of the first solid electrolyte 102 is present inside multiple pores of the active material 101" means that there are particles of the first solid electrolyte 102 present inside the pores of the active material 101. "At least a portion" may be, for example, 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, or 50% or more of the total mass of the first solid electrolyte 102 contained in the composite active material 103. There is no particular upper limit to "at least a portion". "At least a portion" may be, for example, 95% or less, 90% or less, 80% or less, 50% or less, 30% or less, or 20% or less of the total mass of the first solid electrolyte 102 contained in the composite active material 103. "Present inside pores" means, for example, that some or all of the first solid electrolyte 102 has penetrated into the pores of the active material 101.

[0035] In the example shown in Figure 1, the active material 101 is a secondary particle formed by the aggregation of multiple primary particles. The secondary particle has a porous structure due to the formation of pores between adjacent primary particles. When the active material 101 is a secondary particle, the presence of the first solid electrolyte 102 inside the pores increases the interface formed between the active material 101 and the first solid electrolyte 102, thus reducing the interfacial resistance.

[0036] The BET specific surface area of ​​the active material 101 is S AM Defined as such, the BET specific surface area of ​​the composite active material 103 is S AM-SE This is defined as follows. In this case, the composite active material 103 may satisfy the following equation (2).

[0037] S AM-SE / S AM <1...Equation (2)

[0038] With the above configuration, the particles of the first solid electrolyte 102 are more likely to be present inside the pores of the active material 101. This makes it possible to further improve the output characteristics of the battery.

[0039] BET specific surface area S of active material 101 AM , and the BET specific surface area S of the composite active material 103 AM-SE For example, the specific surface area can be determined by the BET method using a specific surface area measuring device that employs nitrogen gas adsorption. Specifically, molecules with known adsorption occupancy areas are adsorbed onto the surface of particles of each substance at the temperature of liquid nitrogen. The specific surface area of ​​the particles of each substance can then be determined from the amount of adsorption.

[0040] The active material 101 contained in the composite active material 103 can be extracted, for example, by the following method: Dissolve only the first solid electrolyte 102 contained in the composite active material 103 using a solvent. This removes the first solid electrolyte 102 from the composite active material 103, allowing only the active material 101 to be extracted.

[0041] If the composite active material 103 is contained in the electrode layer or electrolyte layer, the composite active material 103 can be extracted, for example, by the following method: Disperse the electrode layer or electrolyte layer containing the composite active material 103 in a solvent in which the first solid electrolyte 102 does not dissolve. By using a centrifugation method on the resulting dispersion medium, only the composite active material 103 can be extracted based on the difference in particle density.

[0042] The composite active material 103 may satisfy the following equation (3).

[0043] SAM-SE / S AM <0.5...Equation (3)

[0044] With the above configuration, the first solid electrolyte 102 is more likely to exist inside the pores of the active material 101. This makes it possible to further improve the output characteristics of the battery. Ratio S AM-SE / S AM There is no particular lower limit to the value of ; for example, it is 0.1.

[0045] The active material 101 may contain lithium titanium oxide. Batteries using lithium titanium oxide are known to exhibit high charge and discharge efficiency. Furthermore, lithium titanium oxide is less prone to the deposition of lithium metal. Therefore, using lithium titanium oxide as the negative electrode can prevent internal short circuits caused by deposited metal penetrating the electrolyte layer and coming into contact with the positive electrode. In addition, lithium titanium oxide has the characteristic of exhibiting little expansion and contraction associated with the insertion and removal of lithium ions. Thus, with the above configuration, it is possible to improve the battery's safety while simultaneously improving the battery's charge and discharge efficiency.

[0046] The active material 101 may contain lithium titanium oxide as its main component. In this disclosure, "main component" means a component that makes up 50% or more by mass.

[0047] The active material 101 may contain 70% or more lithium titanium oxide by mass ratio to the total active material 101.

[0048] The active material 101 may also be lithium titanium oxide.

[0049] Examples of lithium titanium oxide include Li4Ti5O 12 Li7Ti5O 12 Examples include , and LiTi2O4. If the active material 101 contains lithium titanium oxide, the lithium titanium oxide may contain at least one selected from these materials.

[0050] Lithium titanium oxide is Li4Ti5O 12 It may also include [this]. With the above configuration, it is possible to improve the battery's charging and discharging efficiency while also improving the battery's safety.

[0051] Lithium titanium oxide is Li4Ti5O 12 That's fine.

[0052] The first solid electrolyte 102 comprises Li, M, and X. Here, M is at least one selected from the group consisting of metallic and metalloid elements belonging to the fifth or sixth period. X is at least one selected from the group consisting of F, Cl, Br, and I. With this configuration, the ionic conductivity of the first solid electrolyte 102 can be improved. This can improve the output characteristics of the battery.

[0053] In this disclosure, “metalloid elements” refers to B, Si, Ge, As, Sb, and Te. “Metallic elements” refers to all elements in groups 1 through 12 of the periodic table, excluding hydrogen, and all elements in groups 13 through 16 of the periodic table, excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se. In other words, “metalloid elements” or “metallic elements” are the group of elements that can become cations when forming inorganic compounds with halogen elements.

[0054] The first solid electrolyte 102 may consist substantially of Li, M, and X. "Substantially consisting of Li, M, and X" means that in the first solid electrolyte 102, the molar ratio (i.e., mole fraction) of the total amount of substance of Li, M, and X to the total amount of substance of all elements constituting the first solid electrolyte 102 is 90% or more. For example, the molar ratio may be 95% or more.

[0055] The first solid electrolyte 102 may consist only of Li, M, and X. "Consisting only of Li, M, and X" means that in the first solid electrolyte 102, the molar ratio of the total amount of substance of Li, M, and X to the total amount of substance of all elements constituting the first solid electrolyte 102 is 100%.

[0056] The first solid electrolyte 102 may also be represented by the following compositional formula (1).

[0057] Li α M β X γ ...Equation (1)

[0058] In compositional formula (1), α, β, and γ are each independently greater than 0. With this configuration, the ionic conductivity of the first solid electrolyte 102 can be further improved. This allows for a further improvement in the output characteristics of the battery.

[0059] If the first solid electrolyte 102 contains Li, M, and X, then M may be a metallic element belonging to the fifth or sixth period, selected from the group consisting of group 1 elements, group 2 elements, group 3 elements, group 4 elements, and lanthanide elements. With the above configuration, the ionic conductivity of the first solid electrolyte 102 can be further improved.

[0060] Examples of Group 1 elements in M ​​include Rb and Cs. Examples of Group 2 elements in M ​​include Sr and Ba. Examples of Group 3 elements in M ​​include Y. Examples of Group 4 elements in M ​​include Zr and Hf. Examples of lanthanide elements include La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0061] If the first solid electrolyte 102 contains Li, M, and X, then M may be a metallic element belonging to the 5th or 6th period, and may include at least one selected from the group consisting of group 5 elements, group 13 elements, and group 14 elements. With the above configuration, the ionic conductivity of the first solid electrolyte 102 can be further improved.

[0062] Examples of Group 5 elements included in M ​​are Nb and Ta. Examples of Group 13 elements included in M ​​are In. Examples of Group 14 elements included in M ​​are Sn.

[0063] If the first solid electrolyte 102 contains Li, M, and X, then M may contain at least one selected from the group consisting of Sr, Ba, Y, Hf, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. With the above configuration, the ionic conductivity of the first solid electrolyte 102 can be further improved.

[0064] If the first solid electrolyte 102 contains Li, M, and X, then M may contain at least one selected from the group consisting of Sr, Y, Sm, Gd, Dy, and Hf. With the above configuration, the ionic conductivity of the first solid electrolyte 102 can be further improved.

[0065] If the first solid electrolyte 102 contains Li, M, and X, then X may contain at least one selected from the group consisting of Br, Cl, and I. With the above configuration, the ionic conductivity of the first solid electrolyte 102 can be further improved.

[0066] If the first solid electrolyte 102 contains Li, M, and X, then X may also contain Br, Cl, and I. With the above configuration, the ionic conductivity of the first solid electrolyte 102 can be further improved.

[0067] If the first solid electrolyte 102 contains Li, M, and X, then M may also contain Y (=yttrium). That is, the first solid electrolyte 102 may contain Y as a metallic element. With the above configuration, the ionic conductivity of the first solid electrolyte 102 can be further improved.

[0068] If the first solid electrolyte 102 contains Li, M, and X, then M may be Y (= yttrium).

[0069] If the first solid electrolyte 102 contains Y, the first solid electrolyte 102 may be represented by the following compositional formula (2).

[0070] Li3YX6...Formula (2)

[0071] In chemical formula (2), X is at least one selected from the group consisting of F, Cl, Br, and I.

[0072] If the first solid electrolyte 102 contains Y, the first solid electrolyte 102 may be represented by the following compositional formula (3).

[0073] Li3YBr x Cl 6-x ...Equation (3)

[0074] In empirical formula (3), the condition 0 ≤ x ≤ 6 is satisfied.

[0075] If the first solid electrolyte 102 contains Y, the first solid electrolyte 102 may be represented by the following compositional formula (4).

[0076] Li3YBr x Cl y I 6-x-y ...Equation (4)

[0077] In empirical formula (4), the conditions 0 ≤ x ≤ 6 and 0 ≤ y ≤ 6 are satisfied.

[0078] More specifically, the first solid electrolyte 102 may be at least one selected from the group consisting of Li3YBr2Cl4 and Li3YBr3Cl3. With the above configuration, the output characteristics of the battery can be further improved.

[0079] The first solid electrolyte 102 may contain Li3YBr3Cl3. With the above configuration, the ionic conductivity of the first solid electrolyte 102 can be further improved. This can further improve the output characteristics of the battery.

[0080] The first solid electrolyte 102 may contain 70% or more of Li3YBr3Cl3 by mass ratio relative to the total amount of the first solid electrolyte 102.

[0081] The first solid electrolyte 102 may be Li3YBr3Cl3.

[0082] The first solid electrolyte 102 does not necessarily have to contain sulfur. With this configuration, the generation of hydrogen sulfide gas can be suppressed. This improves the safety of the battery.

[0083] The shape of the active material 101 is not limited. The shape of the active material 101 may be, for example, needle-shaped, spherical, or ellipsoidal. The shape of the active material 101 may be, for example, particulate. The active material 101 may be formed as secondary particles formed by the aggregation of multiple primary particles.

[0084] The average particle size of the active material 101 may be 5 μm or larger. With this configuration, the particles of the first solid electrolyte 102 are more likely to be present inside the pores of the active material 101. This makes it possible to further improve the output characteristics of the battery.

[0085] There is no particular upper limit to the average particle size of the active material 101. For example, the average particle size of the active material 101 is 30 μm or less.

[0086] The shape of the first solid electrolyte 102 is not limited. The shape of the first solid electrolyte 102 may be, for example, needle-shaped, spherical, ellipsoidal, or fibrous. The shape of the first solid electrolyte 102 may also be particulate, for example. The first solid electrolyte 102 may be formed to have pellet-like or plate-like shapes.

[0087] The average particle size of the first solid electrolyte 102 may be 0.1 μm or more and 1 μm or less. With the above configuration, the particles of the first solid electrolyte 102 are likely to be located inside the pores of the active material 101.

[0088] The average particle size of the active material 101 and the average particle size of the first solid electrolyte 102 can be determined as median diameters. In this disclosure, "median diameter" means the particle size when the cumulative volume in the volume-based particle size distribution is equal to 50%. The volume-based particle size distribution is measured, for example, by a laser diffraction measuring device or an image analysis device. The first solid electrolyte 102 can be extracted from the composite active material 103 by, for example, the following method: Disperse the composite active material 103 in a solvent in which the first solid electrolyte 102 does not dissolve. By using a centrifugation method on the resulting dispersion medium, only the first solid electrolyte 102 can be extracted from the difference in particle density.

[0089] The average particle size of the active material 101 may be larger than the average particle size of the first solid electrolyte 102. With this configuration, the particles of the first solid electrolyte 102 are more likely to be located inside the pores of the active material 101.

[0090] In the composite active material 103, the ratio of the mass of the first solid electrolyte 102 to the mass of the active material 101 may be 5% or more and 20% or less. That is, the ratio of the total mass of the particles of the first solid electrolyte 102 to the mass of the active material 101 may be 5% or more and 20% or less. With the above configuration, the effect of improving ionic conductivity by the first solid electrolyte 102 can be fully obtained. This makes it possible to further improve the output characteristics of the battery.

[0091] In the composite active material 103, the ratio of the mass of the first solid electrolyte 102 to the mass of the active material 101 may be 5% or more and 15% or less. That is, the ratio of the total mass of the particles of the first solid electrolyte 102 to the mass of the active material 101 may be 5% or more and 15% or less.

[0092] The active material 101 may be coated with a coating material. For example, if the active material 101 is a secondary particle, each of the primary particles of the active material 101 may be coated with a coating material.

[0093] Materials with low electronic conductivity can be used as coating materials. Oxide materials and oxide solid electrolytes can also be used as coating materials.

[0094] Examples of oxide materials that can be used include SiO2, Al2O3, TiO2, B2O3, Nb2O5, WO3, and ZrO2.

[0095] Examples of oxide solid electrolytes that can be used as coating materials include Li-Nb-O compounds such as LiNbO3, Li-BO compounds such as LiBO2 and Li3BO3, Li-Al-O compounds such as LiAlO2, Li-Si-O compounds such as Li4SiO4, Li2SO4, and Li4Ti5O 12 Examples include Li-Ti-O compounds such as Li2ZrO3, Li-ZrO compounds such as Li2MoO3, Li-Mo-O compounds such as LiV2O5, and Li-WO compounds such as Li2WO4.

[0096] The coating material may also be an oxide solid electrolyte.

[0097] Oxide solid electrolytes possess high ionic conductivity and excellent high potential stability. Therefore, using oxide solid electrolytes as a coating material can further improve the charge and discharge efficiency of batteries.

[0098] The coating material may uniformly coat the active material 101. For example, if the active material 101 is a secondary particle, the coating material may uniformly coat each of the primary particles of the active material 101. In this case, direct contact between the active material 101 and other solid electrolytes is suppressed, thereby suppressing side reactions of the other solid electrolytes. This improves the charge and discharge efficiency of the battery. The other solid electrolyte is, for example, the second solid electrolyte 104 described in Embodiment 2.

[0099] The coating material may cover a portion of the active material 101. For example, if the active material 101 is a secondary particle, the coating material may cover a portion of each of the primary particles of the active material 101. Direct contact between multiple primary particles of the active material 101 via the portion without coating material improves the electronic conductivity between the primary particles of the active material 101. This enables the battery to operate at high power.

[0100] <Method for manufacturing complex active materials> Next, a method for producing the composite active material 103 described above will be explained. The composite active material 103 can be produced, for example, by the following method. Figure 2 is a flowchart showing the method for producing the composite active material 103 in Embodiment 1.

[0101] As the active material 101, a porous material containing Li, Ti, and O and having multiple pores is prepared. For example, the active material 101 is porous Li4Ti5O 12 Therefore, the active material 101 may be a secondary particle.

[0102] At least one selected from the group consisting of a first solid electrolyte 102 and its raw materials is prepared.

[0103] The first solid electrolyte 102 comprises Li, M, and X. M is at least one selected from the group consisting of metallic and metalloid elements belonging to the fifth or sixth period. X is at least one selected from the group consisting of F, Cl, Br, and I. Examples of the first solid electrolyte 102 include Li3YBr2Cl4 and Li3YBr3Cl3.

[0104] The raw materials for the first solid electrolyte 102 are raw material powders containing Li, M, and X. The raw material powders containing Li, M, and X may include, for example, raw material powders containing Li and X and raw material powders containing M and X. Examples of raw material powders containing Li and X include LiF, LiCl, LiBr, LiI, and Li3MX6. Examples of raw material powders containing M and X include MF3, MCl3, MBr3, MI3, and Li3MX6.

[0105] A mixture is prepared containing at least one selected from the group consisting of a first solid electrolyte 102 and its raw materials, and a solvent. The mixture is weighed so that the ratio of the mass of the first solid electrolyte 102 or the mass of the raw materials for the first solid electrolyte 102 to the mass of the active material 101 is 5% or more and 20% or less. If both the first solid electrolyte 102 and its raw materials are used, the mixture is weighed so that the ratio of the total mass of the first solid electrolyte 102 and its raw materials to the mass of the active material 101 is 5% or more and 20% or less.

[0106] For example, when using the first solid electrolyte 102, the first solid electrolyte 102 is stirred with a solvent to obtain a mixture. At this time, some or all of the first solid electrolyte 102 is dissolved in the mixture. If some of the first solid electrolyte 102 is dissolved in the mixture, the remainder of the first solid electrolyte 102 is dispersed in the mixture. For example, when using the raw materials for the first solid electrolyte 102, the raw material powders are weighed in stoichiometric ratios and mixed, and the resulting mixed powder is stirred with a solvent to obtain a mixture. At this time, some or all of the mixed powder is dissolved in the mixture. If some of the mixed powder is dissolved in the mixture, the remainder of the mixed powder is dispersed in the mixture. The mixture obtained in this way is then impregnated into the active material 101 (step S1).

[0107] The solvent may include a nitrile-based solvent. Examples of nitrile-based solvents include acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanenitrile, cyclopentanecarbonile, cyclohexanecarbonile, 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, and 4-fluorophenylacetonitrile. The nitrile-based solvent may also be acetonitrile solvent. By using a nitrile-based solvent, the first solid electrolyte 102 and its raw materials can be appropriately dissolved and dispersed.

[0108] The amount of the first solid electrolyte 102 or its raw material added may be 1% or more and 20% by weight relative to the solvent, or 5% or more and 15% or less.

[0109] Next, the solvent contained in the mixture is removed from the active material 101 (step S2). For example, the solvent can be removed by stirring the active material 101 at a temperature of 80°C or higher and 120°C or lower. This yields a composite active material 103 in which at least a portion of the first solid electrolyte 102 is present inside multiple pores. Alternatively, the active material 101 may be separated by filtration or centrifugation, and then the active material 101 may be heated to remove the solvent from the active material 101.

[0110] When using raw materials for the first solid electrolyte 102, the obtained active material 101 may be heated after removing the solvent. Alternatively, the active material 101 may be heated so that the solvent is removed from the active material 101 while the raw materials react with each other to form the first solid electrolyte 102 within the pores of the active material 101. The heat treatment may be carried out under an inert gas atmosphere or vacuum at a temperature of 200°C or higher and 500°C or lower. By performing the heat treatment, the first solid electrolyte 102 can be precipitated.

[0111] (Embodiment 2) Embodiment 2 will be described below. Descriptions that overlap with Embodiment 1 will be omitted as appropriate.

[0112] Figure 3 is a cross-sectional view showing the schematic configuration of the electrode material 1000 in Embodiment 2.

[0113] The electrode material 1000 includes the composite active material 103 and the second solid electrolyte 104 in Embodiment 1.

[0114] In the composite active material 103, at least a portion of the first solid electrolyte 102 is located inside multiple pores of the active material 101. Therefore, the interface formed between the active material 101 and the first solid electrolyte 102 increases, reducing interfacial resistance. Consequently, this configuration can improve the output characteristics of the battery.

[0115] As the second solid electrolyte 104, the material exemplified as the first solid electrolyte 102 in Embodiment 1 can be used. That is, the electrode material 1000 may include a solid electrolyte having the same composition as the first solid electrolyte 102 as the second solid electrolyte 104. With the above configuration, the ionic conductivity of the second solid electrolyte 104 can be further improved. This makes it possible to further improve the output characteristics of the battery.

[0116] The second solid electrolyte 104 may contain a solid electrolyte having a different composition from that of the first solid electrolyte 102.

[0117] The second solid electrolyte 104 may contain two or more solid electrolytes selected from the materials listed as the first solid electrolyte 102.

[0118] The second solid electrolyte 104 may contain only one solid electrolyte selected from the materials listed as the first solid electrolyte 102.

[0119] The second solid electrolyte 104 may contain Li3YBr2Cl4. With the above configuration, the ionic conductivity of the second solid electrolyte 104 can be further improved. This can further improve the output characteristics of the battery.

[0120] The second solid electrolyte 104 may contain 70% or more of Li3YBr2Cl4 by mass ratio relative to the total amount of the second solid electrolyte 104.

[0121] The second solid electrolyte 104 may also be Li3YBr2Cl4.

[0122] The shape of the second solid electrolyte 104 is not limited. The shape of the second solid electrolyte 104 may be, for example, needle-shaped, spherical, ellipsoidal, or fibrous. The shape of the second solid electrolyte 104 may also be particulate, for example. The second solid electrolyte 104 may be formed to have pellet-like or plate-like shapes.

[0123] When the shape of the second solid electrolyte 104 is particulate (for example, spherical), the median diameter of the second solid electrolyte 104 may be 0.1 μm or more and 100 μm or less. With the above configuration, the composite active material 103 and the second solid electrolyte 104 can form a good dispersion state at the electrode. This improves the charge and discharge characteristics of the battery.

[0124] The median diameter of the second solid electrolyte 104 may be 0.5 μm or more and 10 μm or less. With the above configuration, the composite active material 103 and the second solid electrolyte 104 can form a better dispersion state in the electrode.

[0125] The shape of the composite active material 103 is not limited. The shape of the composite active material 103 may be, for example, needle-shaped, spherical, or ellipsoidal. The shape of the composite active material 103 may be, for example, particulate. The composite active material 103 may have the same shape as the active material 101. The composite active material 103 may have the same median diameter as the active material 101.

[0126] In the electrode material 1000, the composite active material 103 and the second solid electrolyte 104 may be in contact with each other.

[0127] The electrode material 1000 may contain particles of a plurality of composite active materials 103 and particles of a plurality of second solid electrolytes 104.

[0128] In the electrode material 1000, the content of the composite active material 103 and the content of the second solid electrolyte 104 may be the same or different.

[0129] <Method for manufacturing electrode materials> The electrode material 1000 can be manufactured, for example, by the following method.

[0130] Electrode material 1000 is obtained by mixing the composite active material 103 and the second solid electrolyte 104. The method of mixing the composite active material 103 and the second solid electrolyte 104 is not particularly limited. For example, the composite active material 103 and the second solid electrolyte 104 may be mixed using an instrument such as a mortar and pestle, or they may be mixed using a mixing device such as a ball mill. The mixing ratio of the composite active material 103 to the second solid electrolyte 104 is not particularly limited.

[0131] The second solid electrolyte 104 can be manufactured, for example, by the following method.

[0132] Prepare raw material powders in a ratio that results in the desired composition. The raw material powders may be, for example, halides. For example, when preparing Li3YBr2Cl4 as the second solid electrolyte 104, LiBr, LiCl, and YCl3 are prepared in a molar ratio of 2.0:1.0:1.0. The raw material powders may be mixed in a pre-adjusted molar ratio to compensate for any compositional changes that may occur during the synthesis process.

[0133] The types of raw material powders are not limited to those listed above. For example, combinations of LiCl and YBr3, and LiBr 0.5 Cl 0.5 A complex anionic compound such as the one shown may be used. A mixture of oxygen-containing raw material powder (e.g., oxide, hydroxide, sulfate, or nitrate) and a halide (e.g., ammonium halide) may also be used.

[0134] The raw material powders are thoroughly mixed using a mortar and pestle, a ball mill, or a mixer to obtain a mixed powder. Then, the mixed powder is pulverized using a mechanochemical milling method. In this way, the raw material powders react to obtain the second solid electrolyte 104. Alternatively, after thoroughly mixing the raw material powders, the mixed powder may be calcined under an inert gas atmosphere or vacuum to obtain the second solid electrolyte 104.

[0135] The firing may be carried out, for example, at a temperature range of 100°C or higher and 650°C or lower for one hour or more. This yields the above-mentioned second solid electrolyte 104 containing the crystalline phase.

[0136] Furthermore, the composition of the crystalline phase (i.e., the crystalline structure) in the second solid electrolyte 104 can be determined by selecting the elements constituting the second solid electrolyte 104 (e.g., M and X), the ratio of the constituent elements of the second solid electrolyte 104, the method of reaction between the raw material powders, and the reaction conditions.

[0137] (Embodiment 3) Embodiment 3 will be described below. Descriptions that overlap with Embodiments 1 and 2 will be omitted as appropriate.

[0138] Figure 4 is a cross-sectional view showing the schematic configuration of the battery 2000 in Embodiment 3.

[0139] The battery 2000 in Embodiment 3 comprises a positive electrode 201, an electrolyte layer 202, and a negative electrode 203. The electrolyte layer 202 is positioned between the positive electrode 201 and the negative electrode 203. At least one selected from the group consisting of the positive electrode 201 and the negative electrode 203 includes the electrode material 1000 in Embodiment 2. Figure 4 illustrates the case where the negative electrode 203 includes the electrode material 1000.

[0140] With the above configuration, the output characteristics of the 2000 battery can be improved.

[0141] Both the positive electrode 201 and the negative electrode 203 may contain the electrode material 1000. Either the positive electrode 201 or the negative electrode 203 may contain the electrode material 1000.

[0142] The negative electrode 203 may contain electrode material 1000. That is, the negative electrode 203 may contain a composite active material 103 as a negative electrode active material and a second solid electrolyte 104 as a solid electrolyte.

[0143] If the positive electrode 201 contains electrode material 1000, the volume ratio "v1:100-v1" of the active material 101 and the first solid electrolyte 102 and second solid electrolyte 104 contained in the positive electrode 201 may satisfy 30 ≤ v1 ≤ 95. Here, v1 represents the volume ratio of the active material 101 when the total volume of the active material 101, the first solid electrolyte 102, and the second solid electrolyte 104 contained in the positive electrode 201 is set to 100. If 30 ≤ v1 is satisfied, a sufficient energy density of the battery 2000 can be secured. If v1 ≤ 95 is satisfied, the battery 2000 can operate at high power.

[0144] If the negative electrode 203 contains electrode material 1000, the volume ratio "v2:100-v2" of the active material 101 and the first solid electrolyte 102 and second solid electrolyte 104 contained in the negative electrode 203 may satisfy 30 ≤ v2 ≤ 95. Here, v2 represents the volume ratio of the active material 101 when the total volume of the active material 101, the first solid electrolyte 102, and the second solid electrolyte 104 contained in the negative electrode 203 is set to 100. If 30 ≤ v2 is satisfied, a sufficient energy density of the battery 2000 can be secured. If v2 ≤ 95 is satisfied, the battery 2000 can operate at high power.

[0145] The thickness of the positive electrode 201 may be 10 μm or more and 500 μm or less. If the thickness of the positive electrode 201 is 10 μm or more, sufficient energy density of the battery 2000 can be ensured. If the thickness of the positive electrode 201 is 500 μm or less, the battery 2000 can operate at high power.

[0146] The thickness of the negative electrode 203 may be 10 μm or more and 500 μm or less. When the thickness of the negative electrode 203 is 10 μm or more, sufficient energy density of the battery 2000 can be ensured. When the thickness of the negative electrode 203 is 500 μm or less, the battery 2000 can operate at high power.

[0147] The electrolyte layer 202 is a layer containing an electrolyte. The electrolyte is, for example, a solid electrolyte. That is, the electrolyte layer 202 may be a solid electrolyte layer.

[0148] The solid electrolyte contained in the electrolyte layer 202 is called the third solid electrolyte. A halogen solid electrolyte, sulfide solid electrolyte, oxide solid electrolyte, polymer solid electrolyte, or complex hydride solid electrolyte may be used as the third solid electrolyte.

[0149] As the halide solid electrolyte, for example, the material exemplified as the first solid electrolyte 102 in Embodiment 1 may be used. That is, the electrolyte layer 202 may contain a solid electrolyte having the same composition as the first solid electrolyte 102. With the above configuration, the ionic conductivity of the third solid electrolyte can be further improved. This makes it possible to further improve the output characteristics of the battery.

[0150] The third solid electrolyte may include a solid electrolyte having a different composition from the first solid electrolyte 102.

[0151] The third solid electrolyte may contain two or more solid electrolytes selected from the materials listed as the first solid electrolyte 102.

[0152] The third solid electrolyte may contain only one solid electrolyte selected from the materials listed as the first solid electrolyte 102.

[0153] The third solid electrolyte may contain Li3YBr2Cl4. With this configuration, the ionic conductivity of the third solid electrolyte can be further improved. This, in turn, can further improve the output characteristics of the battery.

[0154] The third solid electrolyte may contain Li3YBr2Cl4 as its main component.

[0155] The third solid electrolyte may contain 70% or more of Li3YBr2Cl4 by mass ratio to the total third solid electrolyte.

[0156] The third solid electrolyte may be Li3YBr2Cl4.

[0157] 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, Li 10 GeP2S 12These can be used. In addition, LiX, Li2O, MO q Li p MO q The following may be added. Here, X includes at least one selected from the group consisting of F, Cl, Br, and I. Also, M includes at least one selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn. p and q are natural numbers, respectively. One or more sulfide solid electrolytes selected from the above materials may be used.

[0158] Examples of oxide solid electrolytes include NASICON-type solid electrolytes represented by LiTi2(PO4)3 and its elemental substitutions, (LaLi)TiO3-based perovskite-type solid electrolytes, and Li 14 ZnGe4O 16 , LiSICON-type solid electrolytes such as Li4SiO4, LiGeO4 and their elemental substitutions, Li7La3Zr2O 12 Garnet-type solid electrolytes, such as those represented by their elemental substitutions, Li-BO compounds such as Li3N and its H-substituted derivatives, Li3PO4 and its N-substituted derivatives, LiBO2, and Li3BO3, can be used as a base, with Li2SO4, Li2CO3, etc., added as a base, or glass ceramics.

[0159] As a polymeric solid electrolyte, for example, a compound of a polymer compound and a lithium salt can be used. The polymer compound may have an ethylene oxide structure. Polymeric compounds having an ethylene oxide structure can contain a large amount of lithium salt. Therefore, the ionic conductivity can be further increased. Examples of lithium salts that can be used include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), and LiC(SO2CF3)3. One or more lithium salts selected from the above lithium salts can be used.

[0160] Examples of complex hydride solid electrolytes that can be used include LiBH4-LiI and LiBH4-P2S5.

[0161] The electrolyte layer 202 may contain a third solid electrolyte as its main component.

[0162] The electrolyte layer 202 may contain 70% or more of the third solid electrolyte by mass ratio to the total electrolyte layer 202.

[0163] The electrolyte layer 202 may contain only the third solid electrolyte.

[0164] The electrolyte layer 202 may contain two or more of the materials listed as the third solid electrolyte.

[0165] The shape of the third solid electrolyte is not limited. The shape of the third solid electrolyte may be, for example, needle-shaped, spherical, ellipsoidal, or fibrous. The shape of the third solid electrolyte may also be particulate, for example. The third solid electrolyte may be formed to have pellet-like or plate-like shapes.

[0166] When the shape of the third solid electrolyte is particulate (for example, spherical), the median diameter of the third solid electrolyte may be 0.1 μm or more and 100 μm or less. With the above configuration, the ionic conductivity of the third solid electrolyte can be improved. In addition, the third solid electrolyte and other materials can form a good dispersion state in the electrolyte layer 202. As a result, the charge and discharge characteristics of the battery 2000 are improved.

[0167] The median diameter of the third solid electrolyte may be 0.5 μm or more and 10 μm or less. With the above configuration, the ionic conductivity of the third solid electrolyte can be further improved.

[0168] The thickness of the electrolyte layer 202 may be 1 μm or more and 300 μm or less. When the thickness of the electrolyte layer 202 is 1 μm or more, short circuits between the positive electrode 201 and the negative electrode 203 become less likely. When the thickness of the electrolyte layer 202 is 300 μm or less, the battery 2000 can operate at high output.

[0169] The positive electrode 201 may further contain active materials other than the composite active material 103. The positive electrode 201 may contain a positive electrode active material. The positive electrode 201 may contain only a positive electrode active material as its active material. The positive electrode active material may include, for example, a material having the property of intercalating and releasing metal ions such as lithium ions.

[0170] Examples of positive electrode active materials include lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal oxysulfides, and transition metal oxynitrides. Examples of lithium-containing transition metal oxides are Li(Ni,Co,Al)O2, Li(Ni,Co,Mn)O2, and LiCoO2. In particular, when lithium-containing transition metal oxides are used as positive electrode active materials, manufacturing costs can be reduced and the average discharge voltage can be increased. To increase the energy density of the battery 2000, the positive electrode active material may also contain lithium nickel-cobalt manganese oxide. The positive electrode active material may also be, for example, Li(Ni,Co,Mn)O2.

[0171] In this disclosure, the notation "(A,B,C)" in chemical formulas means "at least one selected from the group consisting of A, B, and C." For example, "(Ni,Co,Al)" is synonymous with "at least one selected from the group consisting of Ni, Co, and Al."

[0172] The positive electrode 201 may further contain a solid electrolyte. With the above configuration, the ionic conductivity of the positive electrode 201 can be improved. This can improve the output characteristics of the battery 2000.

[0173] As the solid electrolyte contained in the positive electrode 201, a halide solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, or a complex hydride solid electrolyte may be used.

[0174] As the halogen solid electrolyte, sulfide solid electrolyte, oxide solid electrolyte, polymer solid electrolyte, or complex hydride solid electrolyte, the materials exemplified as the third solid electrolyte contained in the electrolyte layer 202 can be used.

[0175] The negative electrode 203 may further contain active materials other than the composite active material 103. The negative electrode 203 may contain a negative electrode active material. The negative electrode 203 may contain only a negative electrode active material as its active material. The negative electrode active material includes, for example, a material having the property of intercalating and releasing metal ions such as lithium ions.

[0176] Examples of negative electrode active materials include metallic materials, carbon materials, oxides, nitrides, tin compounds, and silicon compounds. Metallic materials may be elemental metals or alloys. Examples of metallic materials include lithium metal and lithium alloys. Examples of carbon materials include natural graphite, coke, carbon in the process of graphitization, carbon fibers, spheroidal carbon, artificial graphite, and amorphous carbon. The capacity density of the Battery 2000 can be improved by using silicon (Si), tin (Sn), silicon compounds, and tin compounds.

[0177] The negative electrode 203 may further contain a solid electrolyte. With the above configuration, the ionic conductivity of the negative electrode 203 can be improved. This can improve the output characteristics of the battery 2000.

[0178] As the solid electrolyte contained in the negative electrode 203, a halide solid electrolyte, sulfide solid electrolyte, oxide solid electrolyte, polymer solid electrolyte, or complex hydride solid electrolyte may be used.

[0179] As the halogen solid electrolyte, sulfide solid electrolyte, oxide solid electrolyte, polymer solid electrolyte, or complex hydride solid electrolyte, the materials exemplified as the third solid electrolyte contained in the electrolyte layer 202 can be used.

[0180] The shape of the solid electrolyte contained in the positive electrode 201 and the negative electrode 203 is not limited. The shape of the solid electrolyte may be, for example, needle-shaped, spherical, ellipsoidal, and fibrous. The shape of the solid electrolyte may be, for example, particulate. The solid electrolyte may be formed to have pellet-like or plate-like forms.

[0181] When the solid electrolyte contained in the positive electrode 201 and the negative electrode 203 is particulate (for example, spherical), the median diameter of the solid electrolyte may be 0.1 μm or more and 100 μm or less. With the above configuration, the positive electrode active material and the solid electrolyte can form a good dispersion state in the positive electrode 201. Also, the negative electrode active material and the solid electrolyte can form a good dispersion state in the negative electrode 203. As a result, the charge and discharge characteristics of the battery 2000 are improved.

[0182] The median diameter of the solid electrolyte contained in the positive electrode 201 and the negative electrode 203 may be 0.5 μm or more and 10 μm or less. With the above configuration, the positive electrode active material and the solid electrolyte can form a better dispersion state in the positive electrode 201. Furthermore, the negative electrode active material and the solid electrolyte can form a better dispersion state in the negative electrode 203.

[0183] The shapes of the positive electrode active material and the negative electrode active material are not limited. The shapes of the positive electrode active material and the negative electrode active material may be, for example, needle-shaped, spherical, or ellipsoidal. The shapes of the positive electrode active material and the negative electrode active material may also be, for example, particulate.

[0184] When the positive electrode active material and negative electrode active material are particulate (e.g., spherical), the median diameter of the positive electrode active material and negative electrode active material may be 0.1 μm or more and 100 μm or less. When the median diameter of the positive electrode active material and negative electrode active material is 0.1 μm or more, the positive electrode active material and solid electrolyte can form a good dispersion state in the positive electrode 201. Furthermore, the negative electrode active material and solid electrolyte can form an even better dispersion state in the negative electrode 203. This improves the charge and discharge characteristics of the battery 2000. When the median diameter of the positive electrode active material and negative electrode active material is 100 μm or less, the diffusion rate of lithium in the positive electrode 201 and negative electrode 203 becomes faster. This allows the battery to operate at high power.

[0185] The median diameters of the positive electrode active material and the negative electrode active material may be larger than the median diameter of the solid electrolyte. With the above configuration, the positive electrode active material and the solid electrolyte can form a good dispersion state at the positive electrode 201. Furthermore, the negative electrode active material and the solid electrolyte can form an even better dispersion state at the negative electrode 203.

[0186] The volume ratio "v3:100-v3" of the positive electrode active material and solid electrolyte contained in the positive electrode 201 may satisfy the condition 30≦v3≦95. Here, v3 represents the volume ratio of the positive electrode active material when the total volume of the positive electrode active material and solid electrolyte contained in the positive electrode 201 is set to 100. If 30≦v3 is satisfied, a sufficient energy density of battery 2000 can be secured. If v3≦95 is satisfied, battery 2000 can operate at high power.

[0187] The volume ratio "v4:100-v4" of the negative electrode active material and solid electrolyte contained in the negative electrode 203 may satisfy the condition 30≦v4≦95. Here, v4 represents the volume ratio of the negative electrode active material when the total volume of the negative electrode active material and solid electrolyte contained in the negative electrode 203 is set to 100. If 30≦v4 is satisfied, a sufficient energy density of battery 2000 can be secured. If v4≦95 is satisfied, battery 2000 can operate at high power.

[0188] At least one selected from the group consisting of a positive electrode 201, an electrolyte layer 202, and a negative electrode 203 may contain a binder for the purpose of improving the adhesion between particles. The binder is used to improve the bonding properties of the materials constituting the electrode. Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl polyacrylate, polyethyl polyacrylate, polyhexyl polyacrylate, polymethacrylic acid, polymethyl polymethacrylate, polyethyl polymethacrylate, polyhexyl polymethacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethylcellulose. Furthermore, 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 can also be used as binders. Alternatively, a mixture of two or more materials selected from the above materials may be used as a binder.

[0189] At least one of the positive electrode 201 and the negative electrode 203 may contain a conductive additive for the purpose of increasing electronic conductivity. Examples of conductive additives include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black and Ketjenblack, conductive fibers such as carbon fibers and metal fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene. When a carbon conductive additive is used as the conductive additive, costs can be reduced.

[0190] The shapes of the 2000 battery include, for example, coin-type, cylindrical, rectangular, sheet-type, button-type, flat, and stacked types.

[0191] <Battery manufacturing method> The battery 2000 can be manufactured, for example, by the method described below. The manufacturing method of the battery 2000 is described below, using the case where the negative electrode 203 includes the electrode material 1000 in Embodiment 2 as an example.

[0192] Electrode materials 1000 are prepared as materials for forming the positive electrode 201, the electrolyte layer 202, and the negative electrode 203. A laminate is fabricated by known methods in which the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 are arranged in this order. This yields a battery 2000.

[0193] The solid electrolyte contained in the positive electrode 201 and the third solid electrolyte contained in the electrolyte layer 202 can be manufactured by the same method as the method for manufacturing the second solid electrolyte 104 described in the manufacturing method of the electrode material 1000 in Embodiment 2. [Examples]

[0194] The details of this disclosure will be explained below using examples and comparative examples. The following examples are illustrative and the disclosure is not limited to these examples.

[0195] Example 1 [Fabrication of composite active materials] Li4Ti5O as the active material 12 Li4Ti5O was used. 12The primary particle was a porous material having multiple pores, and was a secondary particle formed by aggregating primary particles. As raw materials for the first solid electrolyte, LiBr and YCl3, which are raw material powders, were weighed in a molar ratio of 3:1 and mixed. The resulting mixed powder was stirred with acetonitrile solvent to obtain a mixture. Next, the obtained mixture was impregnated into the active material. At this time, the ratio of the mass of the first solid electrolyte to the mass of the active material was weighed to 90:10. The active material impregnated with the mixture was stirred at a temperature of 80°C to remove the solvent. After removing the solvent, the obtained active material was subjected to heat treatment. The heat treatment was carried out under conditions of argon atmosphere, 400°C, and 1 hour. This obtained the composite active material of Example 1.

[0196] X-ray diffraction was used to confirm the formation of a first solid electrolyte inside the pores of the composite active material. Furthermore, scanning electron microscopy (SEM) observation of a cross-section of the composite active material also confirmed the formation of a first solid electrolyte inside the pores of the composite active material.

[0197] [Preparation of the second solid electrolyte] Under an argon atmosphere with a dew point of -60°C or lower (hereinafter referred to as a "dry argon atmosphere"), the raw material powders LiBr, YCl3, LiCl, and YCl3 were weighed in a molar ratio of Li:Y:Br:Cl = 3:1:2:4. The raw material powders were ground and mixed in a mortar to obtain a mixture. The mixture was then milled using a planetary ball mill (Fritsch, P-7 type) at 600 rpm for 25 hours. This yielded the Li3YBr2Cl4 powder as the second solid electrolyte for Example 1.

[0198] [Fabrication of electrode materials] Vapor-phase carbon fiber (VGCF-H, manufactured by Showa Denko Corporation) was used as a conductive additive. Under a dry argon atmosphere, the composite active material, second solid electrolyte, and conductive additive from Example 1 were weighed in a mass ratio of 66.7:28.3:5. These materials were mixed in a mortar. This obtained the electrode material of Example 1. Note that "VGCF" is a registered trademark of Showa Denko Corporation.

[0199] [Battery construction] The obtained electrode material was used as the material for forming the negative electrode. Li3YBr2Cl4, the same as the second solid electrolyte in Example 1, was used as the material for forming the electrolyte layer (third solid electrolyte). 20.8 mg of the electrode material and 80 mg of Li3YBr2Cl4 were weighed out. The electrode material and Li3YBr2Cl4 were stacked in this order inside an electrically insulating outer cylinder and pressure-molded at 360 MPa. This produced a laminate consisting of a negative electrode and an electrolyte layer. Next, a 200 μm thick layer of metallic In, a 300 μm thick layer of metallic Li, and a 200 μm thick layer of metallic In were placed on top of the electrolyte layer of the laminate in this order. This was pressure-molded at a pressure of 80 MPa to produce a three-layer laminate consisting of a negative electrode, an electrolyte layer, and an In-Li-In layer. Next, stainless steel current collectors were placed on both sides of the three-layer laminate, and current collector leads were attached to each current collector. Finally, the battery of Example 1 was fabricated by using an electrically insulating ferrule to isolate and seal the inside of the electrically insulating outer casing from the outside air.

[0200] ≪Comparative Example 1≫ In the fabrication of electrode materials, Li4Ti5O is used as the active material instead of the composite active material. 12 Li4Ti5O was used. 12 This was a porous material having multiple pores, and was a secondary particle formed by aggregating primary particles. In other words, in the electrode material of Comparative Example 1, the first solid electrolyte was not present inside the pores of the active material. Under a dry argon atmosphere, the Li4Ti5O of ​​Example 1 12 The second solid electrolyte and conductive additive were weighed in a mass ratio of 60:35:5. The electrode material and battery of Comparative Example 1 were prepared in the same manner as in Example 1, except for these components.

[0201] (Evaluation of BET specific surface area) Regarding the composite active material of Example 1, the BET specific surface area S of the active material AM , and the BET specific surface area S of the composite active material AM-SEThe specific surface area was determined by the BET method using a nitrogen gas adsorption analyzer (MICROTRAC, BELSORP MINI X). Specifically, 500 mg of each sample was weighed and sealed in a measurement cell, then vacuum-dried at 150°C for 4 hours, and the measurement was performed while cooling with liquid nitrogen.

[0202] (Evaluation of ionic conductivity) Figure 5 is a schematic diagram of a pressure-molding die used to evaluate the ionic conductivity of solid electrolytes.

[0203] The pressure forming die 300 comprised a punch upper section 301, a frame 302, and a punch lower section 303. Both the punch upper section 301 and the punch lower section 303 were formed from electrically conductive stainless steel. The frame 302 was formed from insulating polycarbonate.

[0204] Using a pressure molding die 300, the ionic conductivity of Li3YBr2Cl4, which is the second and third solid electrolyte of Example 1, was evaluated by the following method.

[0205] In a dry argon atmosphere with a dew point of -30°C or lower, Li3YBr2Cl4 powder (i.e., solid electrolyte powder 304 in Figure 5) was filled into the inside of a pressure molding die 300. Inside the pressure molding die 300, a pressure of 300 MPa was applied to the Li3YBr2Cl4 using the upper part of the punch 301 and the lower part of the punch 303.

[0206] With pressure still applied, the upper part 301 and lower part 303 of the punch were connected to a potentiostat (VersaSTAT4, Princeton Applied Research) 305 equipped with a frequency response analyzer. The upper part 301 of the punch was connected to the working electrode and potential measurement terminals. The lower part 303 of the punch was connected to the counter electrode and reference electrode. The impedance of Li3YBr2Cl4 was measured at room temperature using electrochemical impedance measurement.

[0207] The ionic conductivity of Li3YBr2Cl4, the second and third solid electrolytes of Example 1, measured at 22°C, was 1.5 × 10⁻⁶. -3 The value was S / cm.

[0208] (Evaluation of the composition of solid electrolytes) The composition of the second and third solid electrolytes, Li3YBr2Cl4, from Example 1 was evaluated using ICP (Inductively Coupled Plasma) emission spectroscopy. The deviation from the Li / Y charge composition was within 3%. From these results, it can be said that the charge composition using the planetary ball mill and the composition of the obtained solid electrolyte were almost identical.

[0209] (Charge / Discharge Test) Next, charge-discharge tests were conducted using the batteries of Example 1 and Comparative Example 1 under the following conditions.

[0210] The battery was placed in a constant temperature bath at 25°C. The battery was charged with a constant current of 100 μA. Charging was terminated when the potential relative to Li reached 0.38 V. Next, the battery was discharged with a constant current of 100 μA, and discharge was terminated when the potential relative to Li reached 1.9 V. Based on these charge and discharge results, the charge capacity at 100 μA charging and the discharge capacity at 100 μA discharging were obtained. The results are shown in Table 1.

[0211] [Table 1]

[0212] ≪Consideration≫ As shown in Table 1, the battery of Example 1, in which the first solid electrolyte is present inside the pores of the active material in the electrode material, showed increased charge and discharge capacity compared to the battery of Comparative Example 1, in which the first solid electrolyte is not present inside the pores of the active material in the electrode material.

[0213] This is explained below. When the first solid electrolyte is present inside multiple pores of the active material, the interface formed between the active material and the first solid electrolyte increases, and the interfacial resistance decreases. Therefore, in Example 1, the charge and discharge capacity of the battery increased because at least a portion of the first solid electrolyte was present inside multiple pores of the active material.

[0214] BET specific surface area S of the active material AM BET specific surface area S of the composite active material AM-SE The ratio is S AM-SE / S AM In the battery of Example 1, which satisfies <0.5, it is thought that the first solid electrolyte was particularly likely to exist inside the pores of the active material. [Industrial applicability]

[0215] The battery described herein can be used, for example, as an all-solid-state lithium secondary battery. [Explanation of Symbols]

[0216] 1000 electrode materials 101 Active material 102 First solid electrolyte 103 Composite active materials 104 Second solid electrolyte 2000 batteries 201 Positive electrode 202 Electrolyte layer 203 Negative electrode 300 pressure molding dies 301 Punch Top 302 Frame type 303 Punch bottom 304 Solid Electrolyte Powder 305 Potentiostat

Claims

1. An active material which is lithium titanium oxide, The first solid electrolyte and, A composite active material containing, The active material is a porous material having secondary particles formed by the aggregation of a plurality of primary particles, and having a plurality of pores formed between adjacent primary particles. The first solid electrolyte is represented by the following compositional formula (1): Li α M β X γ ... Formula (1), Here, α, β, and γ are each independently greater than 0. M contains yttrium, X is at least one selected from the group consisting of F, Cl, Br, and I. At least a portion of the first solid electrolyte is located inside the plurality of pores, The BET specific surface area of ​​the active material is S AM Defined as such, the BET specific surface area of ​​the composite active material is S AM-SE When defined as, S AM-SE / S AM Satisfying < 0.5, Composite active material.

2. The first solid electrolyte is Li 3 YBr 3 Cl 3 and Li 3 YBr 2 Cl 4 comprises at least one selected from the group consisting of The composite active material according to claim 1.

3. The lithium titanium oxide is Li 4 Ti 5 O 12 including, The composite active material according to claim 1.

4. The average particle size of the active material is 5 μm or larger. The composite active material according to any one of claims 1 to 3.

5. The first solid electrolyte is sulfur-free. The composite active material according to any one of claims 1 to 4.

6. A composite active material according to any one of claims 1 to 5, Second solid electrolyte, including, electrode material.

7. The device comprises a positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode. At least one selected from the group consisting of the positive electrode and the negative electrode includes the electrode material described in claim 6. battery.

8. Impregnating the active material with a mixture containing at least one selected from the group consisting of a first solid electrolyte and its raw materials, and a solvent, To remove the solvent contained in the mixture from the active material, A method for producing a composite active material containing, The active material is lithium titanium oxide and is a porous material having a plurality of pores. The first solid electrolyte is represented by the following compositional formula (1): Li α M β X γ ... Formula (1), Here, α, β, and γ are each independently greater than 0. M contains yttrium, X is at least one selected from the group consisting of F, Cl, Br, and I. By removing the solvent, at least a portion of the first solid electrolyte is present inside the pores. When the BET specific surface area of ​​the active material is defined as SAM and the BET specific surface area of ​​the composite active material is defined as SAM-SE, To obtain the composite active material satisfying S AM-SE / S AM < 0.5, A method for producing a composite active material.

9. The further step includes heating the active material. A method for producing a composite active material according to claim 8.

10. The aforementioned solvent includes a nitrile-based solvent. A method for producing a composite active material according to claim 8 or 9.

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