Positive electrode material and battery

Abstract

A positive electrode material according to the present disclosure includes: a positive electrode active material 110; a first solid electrolyte material 111 that covers at least a portion of the surface of the positive electrode active material 110; and a second electrolyte material 100, wherein the second electrolyte material 100 includes at least one element selected from the group consisting of Li, Cl, and Br, the first solid electrolyte material 111 includes Li, Nb, and O, and the positive electrode active material 110 includes a material that is represented by the following compositional formula (1). Formula (1): LiNixMn2-xO4, where x satisfies 0<x<2.

Description

Technical Field

[0001] The present disclosure relates to a positive electrode material and a battery.

Background Art

[0002] Patent Document 1 discloses an all-solid-state battery using a positive electrode material in which at least a part of the surface of a positive electrode active material containing nickel, cobalt, and manganese is coated with lithium niobate (hereinafter also referred to as LiNbO3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The present disclosure provides a positive electrode material that improves the charge and discharge capacity of a battery.

[0005] The positive electrode material of the present disclosure includes a positive electrode active material, a first solid electrolyte material that coats at least a part of the surface of the positive electrode active material, and a second electrolyte material. The second electrolyte material includes Li and at least one selected from the group consisting of Cl and Br. The first solid electrolyte material includes Li, Nb, and O. The positive electrode active material includes a material represented by the following compositional formula (1). LiNi x Mn 2-x O4 ··· Formula (1) Here, x satisfies 0 < x < 2.

[0006] The present disclosure provides a positive electrode material that improves the charge and discharge capacity of a battery.

Brief Description of the Drawings

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of a positive electrode material 1000 in Embodiment 1. [Figure 2] Figure 2 is a cross-sectional view showing the schematic configuration of the battery 2000 in Embodiment 2. [Figure 3] Figure 3 is a cross-sectional view showing the schematic configuration of the battery 3000 in Embodiment 3. [Modes for carrying out the invention]

[0008] (Knowledge that forms the basis of this disclosure) Patent Document 1 discloses an all-solid-state battery using a positive electrode material comprising a positive electrode active material containing nickel, cobalt, and manganese, a coating material that covers at least a portion of the surface of the positive electrode active material, and a halide solid electrolyte material. The coating material that covers the surface of the positive electrode active material is a solid electrolyte material, and this solid electrolyte material is lithium niobate.

[0009] Conventionally, the resistance of halogen solid electrolytes to oxidative decomposition has been studied for cathode materials containing halogen solid electrolytes. Halogen solid electrolytes are materials that contain halogen elements such as fluorine (i.e., F), chlorine (i.e., Cl), bromine (i.e., Br), and iodine (i.e., I) as anions.

[0010] In batteries using a halide solid electrolyte containing at least one element selected from the group consisting of chlorine, bromine, and iodine as the positive electrode material, there is a problem in that the internal resistance of the battery increases during charging because the halide solid electrolyte undergoes oxidative decomposition during charging, and the oxidative decomposition products function as a resistive layer. It is presumed that the cause of this is the oxidation reaction of one element selected from the group consisting of chlorine, bromine, and iodine contained in the halide solid electrolyte. Here, oxidation reaction refers to a side reaction in which, in addition to the normal charging reaction in which lithium and electrons are extracted from the positive electrode active material in the positive electrode material, electrons are also extracted from the halide solid electrolyte containing at least one element selected from the group consisting of chlorine, bromine, and iodine that is in contact with the positive electrode active material. It is thought that this oxidation reaction leads to the formation of an oxidative decomposition layer with poor lithium ion conductivity between the positive electrode active material and the halide solid electrolyte, and that this oxidative decomposition layer functions as a large interfacial resistance in the electrode reaction of the positive electrode. Furthermore, when using a positive electrode active material with a potential relative to Li greater than 3.9V, this problem is more likely to occur than when using a positive electrode active material with a potential relative to Li less than 3.9V, and it is known that decomposition can occur not only with halide solid electrolytes but also, for example, with sulfide solid electrolytes.

[0011] Patent Document 1 discloses a battery having a positive electrode layer comprising a positive electrode active material coated with lithium niobate and a halogenated solid electrolyte. By coating the positive electrode active material with a coating material in this way, the formation of an oxidative decomposition layer by the halogenated solid electrolyte can be suppressed, thereby suppressing the increase in internal resistance and preventing a decrease in the battery's charge and discharge capacity.

[0012] The inventors diligently studied a configuration for a positive electrode material containing a coated positive electrode active material that can further suppress the decrease in the battery's charge and discharge capacity. As a result, the inventors have revealed that when the positive electrode active material contains an oxide composed of Li, Ni, Mn, and O, and the surface of the positive electrode active material is coated with a solid electrolyte material containing Li, Nb, and O, the decrease in the battery's charge and discharge capacity can be further suppressed.

[0013] Based on the above findings, the inventor of the present invention has arrived at the following positive electrode material of the present disclosure.

[0014] The positive electrode material of the present disclosure includes a positive electrode active material, a first solid electrolyte material, and a second electrolyte material. The first solid electrolyte material covers at least a part of the surface of the positive electrode active material and contains Li, Nb, and O. The second electrolyte material contains Li and at least one selected from the group consisting of Cl and Br. The positive electrode active material has a configuration including a material represented by the following compositional formula (1). LiNi x Mn 2-x O4···Formula (1) Here, x satisfies 0 < x < 2.

[0015] With this configuration, the positive electrode material of the present disclosure has improved oxidation resistance and can improve the charge-discharge capacity of the battery.

[0016] (Summary of an aspect according to the present disclosure) The positive electrode material according to the first aspect of the present disclosure includes a positive electrode active material, a first solid electrolyte material that covers at least a part of the surface of the positive electrode active material, and a second electrolyte material. The second electrolyte material contains Li and at least one selected from the group consisting of Cl and Br. The first solid electrolyte material contains Li, Nb, and O. The positive electrode active material has a configuration including a material represented by the following compositional formula (1). LiNi x Mn 2-x O4···Formula (1) Here, x satisfies 0 < x < 2.

[0017] The positive electrode material according to the first aspect has high oxidation resistance in the positive electrode active material whose at least a part of the surface is covered with the first solid electrolyte material. Therefore, it is possible to suppress a decrease in the charge-discharge capacity due to oxidative decomposition of the second electrolyte material in the battery, and improve the charge-discharge capacity of the battery.

[0018] In the second aspect of the present disclosure, for example, in the positive electrode material according to the second aspect, the compositional formula (1) may satisfy 0 < x < 1.

[0019] The positive electrode material according to the second embodiment can improve the charge and discharge capacity of the battery.

[0020] In a third aspect of this disclosure, for example, in the cathode material according to the second aspect, the composition formula (1) may satisfy x = 0.5.

[0021] The positive electrode material according to the third embodiment can improve the charge and discharge capacity of the battery.

[0022] In a fourth aspect of this disclosure, for example, in a cathode material according to any one of the first to third aspects, the first solid electrolyte material may include lithium niobate.

[0023] The positive electrode material according to the fourth embodiment can improve the charge and discharge capacity of the battery.

[0024] In a fifth aspect of this disclosure, for example, in a cathode material according to any one of the first to fourth aspects, the mass ratio of the first solid electrolyte material to the cathode active material may be 0.50% or more.

[0025] The positive electrode material according to the fifth embodiment can improve the charge and discharge capacity of the battery.

[0026] In a sixth aspect of this disclosure, for example, in the cathode material according to the fifth aspect, the mass ratio of the first solid electrolyte material to the cathode active material may be 0.93% or more.

[0027] The positive electrode material according to the sixth embodiment can improve the charge and discharge capacity of the battery.

[0028] In a seventh aspect of this disclosure, for example, in a cathode material according to any one of the first to sixth aspects, the second electrolyte material may further include at least one selected from the group consisting of metal elements and metalloid elements other than Li.

[0029] The positive electrode material according to the seventh embodiment can improve the charge and discharge capacity of the battery.

[0030] In the eighth aspect of the present disclosure, for example, in the positive electrode material according to the seventh aspect, the second electrolyte material may include a material represented by the following compositional formula (2). Li α M β X γ O δ ···Formula (2) Here α, β, and γ are values greater than 0, δ is a value of 0 or more, M is at least one selected from the group consisting of metal elements and metalloid elements other than Li, X is at least one element selected from the group consisting of Cl and Br.

[0031] In the positive electrode material according to the eighth aspect, the ionic conductivity of the second electrolyte material can be further increased. Thereby, the resistance derived from the movement of Li ions in the positive electrode material can be further reduced, and the increase in the internal resistance of the battery during charging can be more effectively suppressed.

[0032] In the ninth aspect of the present disclosure, for example, in the positive electrode material according to the eighth aspect, M may include at least one selected from the group consisting of Y and Ta.

[0033] In the positive electrode material according to the ninth aspect, the ionic conductivity of the second electrolyte material can be further increased. Thereby, the resistance derived from the movement of Li ions in the positive electrode material can be further reduced, and the increase in the internal resistance of the battery during charging can be more effectively suppressed.

[0034] In the tenth aspect of the present disclosure, for example, in the positive electrode material according to the eighth or ninth aspect, the compositional formula (2) is 1 ≦ α ≦ 4, 0 < β ≦ 2, 3 ≦ γ < 7, and 0 ≦ δ ≦ 2 may satisfy.

[0035] In the positive electrode material according to the tenth embodiment, the ionic conductivity of the second electrolyte material can be further increased. This makes it possible to further reduce the resistance caused by the movement of Li ions in the positive electrode material, and to more effectively suppress the increase in the internal resistance of the battery during charging.

[0036] In an eleventh aspect of this disclosure, for example, in a cathode material according to any one of the first to tenth aspects, the second electrolyte material may include a sulfide solid electrolyte.

[0037] In the cathode material according to the eleventh embodiment, the ionic conductivity of the second electrolyte material can be further increased. This makes it possible to further reduce the resistance caused by the movement of Li ions in the cathode material, and to more effectively suppress the increase in the internal resistance of the battery during charging.

[0038] In a twelfth aspect of this disclosure, for example, in a cathode material according to any one of the first to eleventh aspects, the second electrolyte material may include Li6PS5Cl.

[0039] In the positive electrode material according to the twelfth embodiment, the ionic conductivity of the second electrolyte material can be further increased. This makes it possible to further reduce the resistance caused by the movement of Li ions in the positive electrode material, and to more effectively suppress the increase in the internal resistance of the battery during charging.

[0040] In a thirteenth aspect of this disclosure, for example, in a positive electrode material according to any one of the first to twelfth aspects, the first solid electrolyte material may be provided between the positive electrode active material and the second electrolyte material.

[0041] In the positive electrode material according to the 13th embodiment, the first solid electrolyte material having high oxidation resistance is interposed between the positive electrode active material and the second electrolyte material, thereby suppressing the oxidative decomposition of the second electrolyte material and suppressing the increase in the internal resistance of the battery during charging.

[0042] A battery according to a fourteenth aspect of the present disclosure comprises a positive electrode, a negative electrode, and an electrolyte layer located between the positive electrode and the negative electrode, wherein the positive electrode includes a positive electrode material according to any one of the first to thirteenth aspects.

[0043] In the battery according to the 14th embodiment, the decrease in charge and discharge capacity can be suppressed.

[0044] In a 15th aspect of this disclosure, for example, in a battery according to a 14th aspect, the electrolyte layer includes a first electrolyte layer and a second electrolyte layer, The first electrolyte layer may be in contact with the positive electrode, and the second electrolyte layer may be in contact with the negative electrode.

[0045] In a sixteenth aspect of this disclosure, for example, in a battery according to the fifteenth aspect, the first electrolyte layer may include a material having the same composition as the second electrolyte material.

[0046] In the battery according to the 16th embodiment, the charge and discharge capacity is improved.

[0047] In a 17th aspect of this disclosure, for example, in a battery according to the 15th or 16th aspect, the second electrolyte layer may include a material having a different composition from the first solid electrolyte material.

[0048] In the battery according to the 17th embodiment, the charge and discharge capacity is improved.

[0049] Embodiments of the present disclosure will be described below with reference to the drawings.

[0050] (Embodiment 1) FIG. 1 is a cross-sectional view showing a schematic configuration of the positive electrode material 1000 in Embodiment 1. The positive electrode material 1000 includes a positive electrode active material 110, a first solid electrolyte material 111 that coats at least a part of the surface of the positive electrode active material 110, and a second electrolyte material 100. The positive electrode active material 110 includes an oxide composed of Li, Ni, Mn, and O. The second electrolyte material 100 includes Li and at least one selected from the group consisting of Cl and Br. The first solid electrolyte material 111 includes Li, Nb, and O.

[0051] According to the above configuration, the positive electrode material 1000 has improved oxidation resistance. Therefore, the positive electrode material 1000 can suppress an increase in the internal resistance of the battery during charging. Further, the first solid electrolyte material 111 has high ionic conductivity. Therefore, in the positive electrode material 1000, a low interfacial resistance between the first solid electrolyte material 111 and the positive electrode active material 110 can be realized.

[0052] The positive electrode active material 110 includes a material represented by the following compositional formula (1). LiNi x Mn 2-x O4···Formula (1) Here, 0 <x <2 is satisfied.

[0053] In the compositional formula (1), 0 <x <1 may be satisfied.

[0054] In the compositional formula (1), x = 0.5 may be satisfied. That is, the positive electrode active material 110 may include LiNi 0.5 Mn 1.5 O4.

[0055] The oxides represented by these chemical formulas are materials obtained by substituting some of the Mn in LiMn2O4, which has a spinel structure, with Ni, and are suitable for improving the operating voltage of batteries. Oxides composed of Li, Ni, Mn, and O can also have a spinel structure. "Oxides composed of Li, Ni, Mn, and O" means that, excluding unavoidable impurities, no elements other than Li, Ni, Mn, and O are intentionally added. Furthermore, the material represented by compositional formula (1) is inexpensive because it does not contain Co. With the above configuration, a low-cost positive electrode material 1000 that can improve the charge and discharge efficiency of batteries can be realized.

[0056] The positive electrode active material 110 is LiNi 0.5 Mn 1.5 It may consist only of O4.

[0057] With the above configuration, the decrease in the battery's charge and discharge capacity can be suppressed.

[0058] The first solid electrolyte material 111 may contain lithium niobate.

[0059] The first solid electrolyte material 111 may contain lithium niobate as its main component. Here, "main component" refers to the component that is present in the largest amount by mass.

[0060] The first solid electrolyte material 111 may consist solely of lithium niobate.

[0061] With the above configuration, the first solid electrolyte material 111 exhibits higher ionic conductivity. Therefore, in the positive electrode material 1000, a low interfacial resistance can be achieved between the first solid electrolyte material 111 and the positive electrode active material 110.

[0062] The mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 may be 0.50% or more. The mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 may be 0.60% or more, 0.7% or more, or 0.80% or more.

[0063] The mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 may be 0.93% or more.

[0064] The mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 may be 10.0% or less, or 7.0% or less.

[0065] The mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 may be 0.50% or more and 10.0% or less, or 0.50% or more and 7.0% or less. The mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 may be 2.50% or more and 10.0% or less, or 2.50% or more and 7.0% or less.

[0066] The upper and lower limits of the mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 can be defined by any combination selected from the values ​​of 0.93, 2.3, 4.7, and 9.3.

[0067] With the above configuration, the charge and discharge efficiency of a battery using the positive electrode material 1000 can be improved.

[0068] The second electrolyte material 100 may further contain at least one element selected from the group consisting of metal elements and metalloid elements other than Li.

[0069] "Metallic elements" are B, Si, Ge, As, Sb, and Te.

[0070] "Metallic elements" refer to all elements in groups 1 through 12 of the periodic table, excluding hydrogen, as well as all elements in groups 13 through 16, excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se. In other words, they are the elements that can form cations when forming halogen compounds and inorganic compounds.

[0071] The second electrolyte material 100 may include a material represented by the following composition formula (2). Li α M β X γ O δ ...Equation (2) Here, α, β, and γ are values ​​greater than 0, δ is a value greater than or equal to 0, M is at least one element selected from the group consisting of metallic elements and metalloid elements other than Li, and X is at least one element selected from the group consisting of Cl and Br.

[0072] With the above configuration, the ionic conductivity of the second electrolyte material 100 can be further increased. This makes it possible to further reduce the resistance caused by the movement of Li ions in the positive electrode material 1000.

[0073] In compositional formula (2), M may include at least one element selected from the group consisting of Y and Ta. That is, the second electrolyte material 100 may include at least one element selected from the group consisting of Y and Ta as a metallic element.

[0074] With the above configuration, the ionic conductivity of the second electrolyte material 100 can be further increased. This makes it possible to further reduce the resistance caused by the movement of Li ions in the positive electrode material 1000.

[0075] In empirical formula (2), the following conditions may be satisfied: 1 ≤ α ≤ 4, 0 < β ≤ 2, 3 ≤ γ < 7, and 0 ≤ δ ≤ 2.

[0076] With the above configuration, the ionic conductivity of the second electrolyte material 100 can be further increased. This makes it possible to further reduce the resistance caused by the movement of Li ions in the positive electrode material 1000.

[0077] In empirical formula (2), the following conditions may be satisfied: 2.5 ≤ α ≤ 3, 1 ≤ β ≤ 1.1, γ = 6, and δ = 0.

[0078] The second electrolyte material 100 containing Y is, for example, Lia Me b Y c It may be a compound represented by the composition formula of X6. Here, a + m'b + 3c = 6, and c > 0 is satisfied. Me is at least one element selected from the group consisting of metal elements and semi-metal elements excluding Li and Y. Also, m' is the valence of Me.

[0079] As Me, at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, and Nb may be used.

[0080] According to the above configuration, the ionic conductivity of the second electrolyte material 100 can be further increased. Thereby, the resistance derived from the movement of Li ions in the positive electrode material 1000 can be further reduced.

[0081] The second electrolyte material 100 may be a material represented by the following composition formula (A1). Li 6-3d Y d X6 ··· Formula (A1) Here, in the composition formula (A1), X is a halogen element and contains Cl. Also, 0 < d < 2 is satisfied.

[0082] According to the above configuration, the ionic conductivity of the second electrolyte material 100 can be further increased. Thereby, the resistance derived from the movement of Li ions in the positive electrode material 1000 can be further reduced.

[0083] The second electrolyte material 100 may be a material represented by the following composition formula (A2). Li3YX6 ··· Formula (A2) Here, in the composition formula (A2), X is a halogen element and contains Cl.

[0084] According to the above configuration, the ionic conductivity of the second electrolyte material 100 can be further increased. Thereby, the resistance derived from the movement of Li ions in the positive electrode material 1000 can be further reduced.

[0085] The second electrolyte material 100 may be a material represented by the following compositional formula (A3). Li 3-3δ Y 1+δ Cl6 ··· Formula (A3) Here, in the compositional formula (A3), 0 < δ ≦ 0.15 is satisfied.

[0086] According to the above configuration, the ionic conductivity of the second electrolyte material 100 can be further increased. Thereby, the resistance resulting from the movement of Li ions in the positive electrode material 1000 can be further reduced.

[0087] The second electrolyte material 100 may be a material represented by the following compositional formula (A4). Li 3-3δ+a4 Y 1+δ-a4 Me a4 Cl 6-x4 Br x4 ··· Formula (A4) Here, in the compositional formula (A4), Me is at least one element selected from the group consisting of Mg, Ca, Sr, Ba, and Zn. Also, -1 < δ < 2, 0 < a4 < 3, 0 < (3 - 3δ + a4), 0 < (1 + δ - a4), and 0 ≦ x4 < 6 are satisfied.

[0088] According to the above configuration, the ionic conductivity of the second electrolyte material 100 can be further increased. Thereby, the resistance resulting from the movement of Li ions in the positive electrode material 1000 can be further reduced.

[0089] The second electrolyte material 100 may be a material represented by the following compositional formula (A5). Li 3-3δ Y 1+δ-a5 Me a5 Cl 6-x5 Br x5 ··· Formula (A5) Here, in the compositional formula (A5), Me is at least one element selected from the group consisting of Al, Sc, Ga, and Bi. Also, -1 < δ < 1, 0 < a5 < 2, 0 < (1 + δ - a5), and 0 ≤ x5 < 6 are satisfied.

[0090] According to the above configuration, the ionic conductivity of the second electrolyte material 100 can be further increased. As a result, the resistance derived from the movement of Li ions in the positive electrode material 1000 can be further reduced.

[0091] The second electrolyte material 100 may be a material represented by the following compositional formula (A6). Li 3-3δ-a6 Y 1+δ-a6 Me a6 Cl 6-x6 Br x6 ··· Formula (A6) Here, in the compositional formula (A6), Me is at least one element selected from the group consisting of Zr, Hf, and Ti. Also, -1 < δ < 1, 0 < a6 < 1.5, 0 < (3 - 3δ - a6), 0 < (1 + δ - a6), and 0 ≤ x6 < 6 are satisfied.

[0092] The second electrolyte material 100 may be a material represented by the following compositional formula (A7). Li 3-3δ-2a7 Y 1+δ-a7 Me a7 Cl 6-x7 Br x7 ··· Formula (A7) Here, in the compositional formula (A7), Me is at least one element selected from the group consisting of Ta and Nb. Also, -1 < δ < 1, 0 < a7 < 1.2, 0 < (3 - 3δ - 2a7), 0 < (1 + δ - a7), and 0 ≤ x7 < 6 are satisfied.

[0093] As the second electrolyte material 100, for example, Li3YX6, Li2MgX4, Li2FeX4, Li(Al,Ga,In)X4, Li3(Al,Ga,In)X6, etc. can be used. Here, X includes Cl. In this disclosure, when an element in a formula is represented as "(Al,Ga,In)", this notation indicates at least one element selected from the group of elements in parentheses. That is, "(Al,Ga,In)" is synonymous with "at least one element selected from the group consisting of Al, Ga, and In". The same applies to other elements.

[0094] The second electrolyte material 100 may contain Li6PS5Cl.

[0095] The second electrolyte material 100 may further include a sulfide solid electrolyte. Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, Li 3.25 Ge 0.25 P 0.75 S4, Li 10 GeP2S 12 Li6PS5Cl, etc., can be used. In addition, LiX, Li2O, M'O q Li p M'O q The following may be added: Here, X is at least one element selected from the group consisting of F, Cl, Br, and I. M' is at least one element selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn. p and q are each independently natural numbers.

[0096] The sulfide solid electrolyte may contain lithium sulfide and phosphorus sulfide. The sulfide solid electrolyte may also be Li6PS5Cl.

[0097] The second electrolyte material 100 may be a solid electrolyte material.

[0098] The second electrolyte material 100 may contain an electrolyte solution.

[0099] The electrolyte contains water or a non-aqueous solvent and a lithium salt dissolved in the solvent.

[0100] Examples of solvents include water, cyclic carbonate solvents, linear carbonate solvents, cyclic ether solvents, linear ether solvents, cyclic ester solvents, linear ester solvents, or fluorine solvents.

[0101] Examples of cyclic carbonate ester solvents include ethylene carbonate, propylene carbonate, or butylene carbonate.

[0102] Examples of linear carbonate ester solvents include dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate.

[0103] Examples of cyclic ether solvents include tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane.

[0104] Examples of linear ether solvents include 1,2-dimethoxyethane or 1,2-diethoxyethane.

[0105] Examples of cyclic ester solvents include γ-butyrolactone, etc.

[0106] Examples of linear ester solvents include methyl acetate, etc.

[0107] Examples of fluorinated solvents include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, or fluorodimethylene carbonate.

[0108] One solvent selected from these may be used alone, or a combination of two or more solvents selected from these may be used.

[0109] The electrolyte may contain at least one fluorine solvent selected from the group consisting of fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate.

[0110] Lithium salts that can be used include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), LiC(SO2CF3)3, etc. One lithium salt selected from these can be used alone, or a mixture of two or more lithium salts selected from these can be used. The concentration of the lithium salt is, for example, in the range of 0.1 to 15 mol / liter.

[0111] The positive electrode material 1000 may further contain other positive electrode active materials besides the positive electrode active material 110, which consists of Li, N, Mn, and O.

[0112] The positive electrode active material includes a material having the property of intercalating and releasing metal ions (e.g., lithium ions). Other positive electrode active materials besides the positive electrode active material 110 include, for example, lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal oxysulfides, or transition metal oxynitrides. Examples of lithium-containing transition metal oxides include Li(Ni,Co,Al)O2, Li(Ni,Co,Mn)O2, and LiCoO2. In particular, using lithium-containing transition metal oxides can reduce the manufacturing cost of the positive electrode material 1000 and increase the average discharge voltage.

[0113] A first solid electrolyte material 111 may be provided between the positive electrode active material 110 and the second electrolyte material 100.

[0114] With the above configuration, the first solid electrolyte material 111, which has high oxidation resistance, is interposed between the positive electrode active material 110 and the second electrolyte material 100, thereby suppressing the oxidative decomposition of the second electrolyte material 100. Therefore, the decrease in capacity during charging of a battery using the positive electrode material 1000 can be suppressed.

[0115] The thickness of the first solid electrolyte material 111, which covers at least a portion of the surface of the positive electrode active material 110, may be 1 nm or more and 500 nm or less.

[0116] When the thickness of the first solid electrolyte material 111 is 1 nm or more, direct contact between the positive electrode active material 110 and the second electrolyte material 100 is suppressed, and oxidative decomposition of the second electrolyte material 100 can be suppressed. Therefore, the charge and discharge efficiency of the battery using the positive electrode material 1000 can be improved. When the thickness of the first solid electrolyte material 111 is 500 nm or less, the thickness of the first solid electrolyte material 111 does not become too thick. Therefore, the internal resistance of the battery using the positive electrode material 1000 can be sufficiently reduced, and the energy density of the battery can be increased.

[0117] The method for measuring the thickness of the first solid electrolyte material 111 is not particularly limited, but for example, it can be determined by directly observing the thickness of the first solid electrolyte material 111 using a transmission electron microscope.

[0118] The mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 may be 0.01% or more and 30% or less.

[0119] When the mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 is 0.01% or more, direct contact between the positive electrode active material 110 and the second electrolyte material 100 is suppressed, and oxidative decomposition of the second electrolyte material 100 can be suppressed. Therefore, the charge and discharge efficiency of the battery using the positive electrode material 1000 can be improved. When the mass ratio of the first solid electrolyte material 111 to the positive electrode active material 110 is 30% or less, the thickness of the first solid electrolyte material 111 does not become excessive. Therefore, the internal resistance of the battery using the positive electrode material 1000 can be sufficiently reduced, and the energy density of the battery can be increased.

[0120] The first solid electrolyte material 111 may uniformly coat the surface of the positive electrode active material 110. This suppresses direct contact between the positive electrode active material 110 and the second electrolyte material 100, thereby suppressing side reactions of the second electrolyte material 100. As a result, the charge-discharge characteristics of the battery using the positive electrode material 1000 can be further improved, and capacity degradation can be suppressed.

[0121] The first solid electrolyte material 111 may cover a portion of the surface of the positive electrode active material 110. By allowing multiple positive electrode active materials 110 to come into direct contact with each other through the portion without the first solid electrolyte material 111, the electronic conductivity between the multiple positive electrode active materials 110 is improved. This enables high-power operation of the battery using the positive electrode material 1000.

[0122] The first solid electrolyte material 111 may cover 30% or more, 60% or more, or 90% or more of the surface of the positive electrode active material 110. The first solid electrolyte material 111 may substantially cover the entire surface of the positive electrode active material 110.

[0123] The first solid electrolyte material 111 may be in direct contact with the surface of the positive electrode active material 110.

[0124] The positive electrode active material 110 may be covered with at least a portion of its surface by a coating material different from the first solid electrolyte material 111.

[0125] Coating materials include sulfide solid electrolytes, oxide solid electrolytes, and fluoride solid electrolytes. The sulfide solid electrolyte used in the coating material may be the same material as exemplified in the second electrolyte material 100. Oxide solid electrolytes used in the coating material include 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-Zr-O compounds such as Li2MoO3, Li-Mo-O compounds such as LiV2O5, Li-WO compounds such as Li2WO4, and Li-PO compounds such as Li3PO4. Examples of fluoride solid electrolytes used in coating materials include solid electrolytes containing Li, Ti, M1, and F, where M1 is at least one element selected from the group consisting of Ca, Mg, Al, Y, and Zr.

[0126] With the above configuration, the oxidation resistance of the positive electrode material 1000 can be further improved. This makes it possible to suppress the decrease in battery capacity during charging.

[0127] The positive electrode active material 110 and the first solid electrolyte material 111 do not need to be in direct contact with each other, as they are separated by a coating material.

[0128] With the above configuration, the oxidation resistance of the positive electrode material 1000 can be further improved. This makes it possible to suppress the decrease in battery capacity during charging.

[0129] The shape of the second electrolyte material 100 is not particularly limited. If the second electrolyte material 100 is a powder material, its shape may be, for example, needle-shaped, spherical, ellipsoidal, etc. For example, the shape of the second electrolyte material 100 may be particulate.

[0130] For example, if the shape of the second electrolyte material 100 is particulate (e.g., spherical), the median diameter of the second electrolyte material 100 may be 100 μm or less. When the median diameter of the second electrolyte material 100 is 100 μm or less, the positive electrode active material 110 and the second electrolyte material 100 can form a good dispersion state in the positive electrode material 1000. As a result, the charge and discharge characteristics of the battery using the positive electrode material 1000 are improved.

[0131] The median diameter of the second electrolyte material 100 may be 10 μm or less. With the above configuration, the positive electrode active material 110 and the second electrolyte material 100 can form a good dispersion state in the positive electrode material 1000.

[0132] In Embodiment 1, the median diameter of the second electrolyte material 100 may be smaller than the median diameter of the positive electrode active material 110. With the above configuration, the second electrolyte material 100 and the positive electrode active material 110 can form a better dispersion state in the positive electrode.

[0133] The median diameter of the positive electrode active material 110 may be 0.1 μm or more and 100 μm or less.

[0134] When the median diameter of the positive electrode active material 110 is 0.1 μm or more, the positive electrode active material 110 and the second electrolyte material 100 can form a good dispersion state in the positive electrode material 1000. Therefore, the charge and discharge characteristics of the battery using the positive electrode material 1000 are improved. When the median diameter of the positive electrode active material 110 is 100 μm or less, the lithium diffusion rate within the positive electrode active material 110 is improved. Therefore, the battery using the positive electrode material 1000 can operate at high power.

[0135] The median diameter of the positive electrode active material 110 may be larger than the median diameter of the second electrolyte material 100. This allows the positive electrode active material 110 and the second electrolyte material 100 to form a good dispersion state.

[0136] In this disclosure, “median diameter” means the particle size at which the cumulative volume in the volume-based particle size distribution is equal to 50%. The volume-based particle size distribution is measured, for example, by a laser diffraction analyzer or an image analyzer.

[0137] In the positive electrode material 1000, the second electrolyte material 100 and the first solid electrolyte material 111 may be in contact with each other, as shown in Figure 1. In this case, the first solid electrolyte material 111 and the positive electrode active material 110 are in contact with each other.

[0138] The positive electrode material 1000 may include a plurality of second electrolyte materials 100 and a plurality of positive electrode active materials 110.

[0139] The content of the second electrolyte material 100 and the content of the positive electrode active material 110 in the positive electrode material 1000 may be the same or different.

[0140] <Method for manufacturing positive electrode material 1000> The positive electrode material 1000 in Embodiment 1 can be manufactured, for example, by the following method.

[0141] First, as the positive electrode active material 110, for example, LiNi 0.5 Mn 1.5 On the surface of O4, lithium niobate, which is the first solid electrolyte material 111, is formed by the following procedure.

[0142] LiNi 0.5 Mn 1.5 After contacting with O4, a powder is obtained by evaporating ethanol. The obtained powder is then calcined, for example, at 350°C for 3 hours. This yields a positive electrode active material 110 whose surface is coated with the first solid electrolyte material 111.

[0143] The second electrolyte material 100 can be manufactured by the following method.

[0144] As an example, when synthesizing a second electrolyte material 100 consisting of Li, Y, Cl, and Br, LiCl raw material powder, LiBr raw material powder, YBr3 raw material powder, and YCl3 raw material powder are mixed. The raw material powders may be mixed in a pre-adjusted molar ratio to counteract any compositional changes that may occur during the synthesis process. In this way, the second electrolyte material 100 is obtained.

[0145] The positive electrode material 1000 in Embodiment 1 can be manufactured by mixing a positive electrode active material 110 whose surface is coated with a first solid electrolyte material 111 with a second electrolyte material 100.

[0146] (Embodiment 2) Embodiment 2 will be described below. Descriptions that overlap with Embodiment 1 will be omitted as appropriate.

[0147] Figure 2 is a cross-sectional view showing the schematic configuration of the battery 2000 in Embodiment 2.

[0148] The battery 2000 in Embodiment 2 comprises a positive electrode 201, an electrolyte layer 202, and a negative electrode 203. The positive electrode 201 includes the positive electrode material 1000 in Embodiment 1. The electrolyte layer 202 is disposed between the positive electrode 201 and the negative electrode 203.

[0149] With the above configuration, the increase in internal resistance during charging of the 2000 battery can be suppressed, and the charge / discharge capacity can be improved.

[0150] The volume ratio "v1:100-v1" of the positive electrode material 1000 and the second electrolyte material 100 contained in the positive electrode 201 may satisfy the condition 30 ≤ v1 ≤ 98. Here, v1 represents the volume ratio of the positive electrode material 1000 when the total volume of the positive electrode material 1000 and the second electrolyte material 100 contained in the positive electrode 201 is set to 100. If 30 ≤ v1 is satisfied, a sufficient energy density of the battery can be ensured. If v1 ≤ 98 is satisfied, the battery 2000 can operate at high power.

[0151] 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 can be ensured. If the thickness of the positive electrode 201 is 500 μm or less, the battery 2000 can operate at high power.

[0152] The electrolyte layer 202 contains an electrolyte material. This electrolyte material may be, for example, a third solid electrolyte material. That is, the electrolyte layer 202 may be a solid electrolyte layer.

[0153] As the third solid electrolyte material, the same material as the first solid electrolyte material 111 or the second electrolyte material 100 in Embodiment 1 may be used. That is, the electrolyte layer 202 may contain the same material as the first solid electrolyte material 111 or the second electrolyte material 100 in Embodiment 1.

[0154] With the above configuration, the power density and charge / discharge characteristics of the battery 2000 can be further improved.

[0155] As the third solid electrolyte material, the same material as the first solid electrolyte material 111 in Embodiment 1 may be used. That is, the electrolyte layer 202 may contain the same material as the first solid electrolyte material 111 in Embodiment 1.

[0156] With the above configuration, the increase in the internal resistance of the battery 2000 due to oxidation of the electrolyte layer 202 can be suppressed, and the power density and charge / discharge characteristics of the battery 2000 can be further improved.

[0157] As the third solid electrolyte material contained in the electrolyte layer 202, a halogen solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, or a complex hydride solid electrolyte may be used.

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

[0159] As the polymer solid electrolyte for the third solid electrolyte material, for example, a compound of a polymer compound and a lithium salt can be used. The polymer compound may have an ethylene oxide structure. Polymer 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 lithium salt selected from the exemplified lithium salts can be used alone. Alternatively, a mixture of two or more lithium salts selected from the exemplified lithium salts can be used.

[0160] Examples of complex hydride solid electrolytes for the third solid electrolyte material include LiBH4-LiI and LiBH4-P2S5.

[0161] The electrolyte layer 202 may contain a third solid electrolyte material as its main component. That is, the electrolyte layer 202 may contain the third solid electrolyte material in an amount of 50% or more (i.e., 50% by mass or more) of the total mass of the electrolyte layer 202.

[0162] With the above configuration, the charge and discharge characteristics of the battery can be further improved.

[0163] The electrolyte layer 202 may contain a third solid electrolyte material in an amount of 70% or more by mass relative to the total electrolyte layer 202 (i.e., 70% by mass or more).

[0164] With the above configuration, the charge and discharge characteristics of the battery 2000 can be further improved.

[0165] The electrolyte layer 202 mainly contains a third solid electrolyte material, but may also contain unavoidable impurities, or starting materials, by-products, and decomposition products used in the synthesis of the third solid electrolyte material.

[0166] The electrolyte layer 202 may contain a third solid electrolyte material in a mass ratio of 100% (i.e., 100% by mass) of the total electrolyte layer 202, for example, excluding impurities that are unavoidable to be present.

[0167] With the above configuration, the charge and discharge characteristics of the battery 2000 can be further improved.

[0168] The electrolyte layer 202 may be composed solely of the third solid electrolyte material.

[0169] The electrolyte layer 202 may contain two or more of the materials listed as the third solid electrolyte material. For example, the electrolyte layer 202 may contain a halide solid electrolyte and a sulfide solid electrolyte.

[0170] The thickness of the electrolyte layer 202 may be 1 μm or more and 300 μm or less. If 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. If the thickness of the electrolyte layer 202 is 300 μm or less, the battery 2000 can operate at high output.

[0171] The negative electrode 203 includes a material having the property of intercalating and releasing metal ions (e.g., lithium ions). The negative electrode 203 includes, for example, a negative electrode active material.

[0172] The negative electrode active material may be a metallic material, a carbon material, an oxide, a nitride, a tin compound, or a silicon compound. The metallic material may be a pure metal or an alloy. Examples of metallic materials include lithium metal or lithium alloys. Examples of carbon materials include natural graphite, coke, carbon in the process of graphitization, carbon fibers, spheroidal carbon, artificial graphite, or amorphous carbon. From the viewpoint of capacity density, silicon, tin, silicon compounds, or tin compounds may be used.

[0173] The negative electrode 203 may contain a solid electrolyte material. As the solid electrolyte material, the solid electrolyte material exemplified as the material constituting the electrolyte layer 202 may be used. With the above configuration, the lithium-ion conductivity inside the negative electrode 203 is increased, and the battery 2000 can operate at high power.

[0174] The median diameter of the negative electrode active material may be 0.1 μm or more and 100 μm or less. When the median diameter of the negative electrode active material is 0.1 μm or more, the negative electrode active material and the solid electrolyte material can form a good dispersion state in the negative electrode. This improves the charge and discharge characteristics of battery 2000. When the median diameter of the negative electrode active material is 100 μm or less, lithium diffusion within the negative electrode active material becomes faster. Therefore, battery 2000 can operate at high power.

[0175] The median diameter of the negative electrode active material may be larger than the median diameter of the solid electrolyte material contained in the negative electrode 203. This allows for the formation of a good dispersion state between the negative electrode active material and the solid electrolyte material.

[0176] The volume ratio "v2:100-v2" of the negative electrode active material and solid electrolyte material contained in the negative electrode 203 may satisfy the condition 30 ≤ v2 ≤ 95. Here, v2 represents the volume ratio of the negative electrode active material when the total volume of the negative electrode active material and solid electrolyte material contained in the negative electrode 203 is set to 100. If 30 ≤ v2 is satisfied, a sufficient energy density of the battery can be ensured. If v2 ≤ 95 is satisfied, the battery 2000 can operate at high power.

[0177] The thickness of the negative electrode 203 may be 10 μm or more and 500 μm or less. If the thickness of the negative electrode 203 is 10 μm or more, sufficient energy density of the battery 2000 can be ensured. If the thickness of the negative electrode 203 is 500 μm or less, the battery 2000 can operate at high power.

[0178] 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, a copolymer 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 may be used as a binder. Alternatively, a mixture of two or more materials selected from these may be used.

[0179] At least one of the positive electrode 201 and the negative electrode 203 may contain a conductive additive for the purpose of enhancing electronic conductivity. Examples of conductive additives include graphites such as natural graphite or 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.

[0180] Examples of the shapes of the battery 2000 in Embodiment 2 include coin-shaped, cylindrical, rectangular, sheet-shaped, button-shaped, flat, and stacked types.

[0181] The battery 2000 may be manufactured, for example, by preparing a positive electrode material 1000, a material for forming an electrolyte layer, and a material for forming a negative electrode, and then fabricating a laminate in which the positive electrode, electrolyte layer, and negative electrode are arranged in that order using a known method.

[0182] (Embodiment 3) Embodiment 3 will be described below. Descriptions that overlap with Embodiment 1 will be omitted as appropriate.

[0183] Figure 3 is a cross-sectional view showing the schematic configuration of the battery 3000 in Embodiment 3.

[0184] The battery 2000 in Embodiment 2 comprises a positive electrode 201, an electrolyte layer 202, and a negative electrode 203. The positive electrode 201 includes the positive electrode material 1000 in Embodiment 1. The electrolyte layer 202 is disposed between the positive electrode 201 and the negative electrode 203. The electrolyte layer 202 includes a first electrolyte layer 301 and a second electrolyte layer 302, the first electrolyte layer 301 being in contact with the positive electrode 201 and the second electrolyte layer 302 being in contact with the negative electrode 203.

[0185] With the above configuration, the increase in the internal resistance of the battery 3000 during charging can be suppressed.

[0186] The first electrolyte layer 301 may contain the same material as the first solid electrolyte material 111.

[0187] By including the same material as the first solid electrolyte material 111, which has excellent oxidation resistance, in the first electrolyte layer 301 that is in contact with the positive electrode 201, oxidative decomposition of the first electrolyte layer 301 can be suppressed, thereby suppressing the increase in the internal resistance of the battery 3000 during charging.

[0188] The first electrolyte layer 301 may contain the same material as the second electrolyte material 100.

[0189] The second electrolyte layer 302 may contain a material different from the first solid electrolyte material 111.

[0190] The second electrolyte layer 302 may contain the same material as the second electrolyte material 100.

[0191] From the viewpoint of the reduction resistance of the solid electrolyte material, the reduction potential of the solid electrolyte material contained in the first electrolyte layer 301 may be lower than the reduction potential of the solid electrolyte material contained in the second electrolyte layer 302. With the above configuration, the solid electrolyte material contained in the first electrolyte layer 301 can be used without reduction. This makes it possible to improve the charge and discharge efficiency of the battery 3000.

[0192] For example, the second electrolyte layer 302 may contain a sulfide solid electrolyte. Here, the reduction potential of the sulfide solid electrolyte contained in the second electrolyte layer 302 is lower than the reduction potential of the solid electrolyte material contained in the first electrolyte layer 301. With this configuration, the solid electrolyte material contained in the first electrolyte layer 301 can be used without reduction. This makes it possible to improve the charge and discharge efficiency of the battery 3000.

[0193] The thickness of the first electrolyte layer 301 and the second electrolyte layer 302 may be 1 μm or more and 300 μm or less. When the thickness of the first electrolyte layer 301 and the second electrolyte layer 302 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 first electrolyte layer 301 and the second electrolyte layer 302 is 300 μm or less, the battery 3000 can operate at high output. [Examples]

[0194] The present disclosure will be described in more detail below with reference to examples.

[0195] <Example 1> [Fabrication of positive electrode active material with surface coated by first solid electrolyte material] In an argon glove box (hereinafter referred to as "in an argon atmosphere"), 100.1 mg of niobethoxide (Sigma-Aldrich) and 16.4 mg of lithium ethoxide (Sigma-Aldrich) were dissolved in 3 mL of super-dehydrated ethanol (Fujifilm Wako Pure Chemical Industries) to prepare a coating solution.

[0196] Cathode active material LiNi 0.5 Mn 1.5 1.00 g of O4 was placed in a mortar, the entire amount of the prepared coating solution was added and mixed, and then the ethanol was evaporated to obtain a powder. The obtained powder was calcined at 350°C for 3 hours to obtain a positive electrode active material whose surface was coated with LiNbO3, the first solid electrolyte material of Example 1.

[0197] [Preparation of the second electrolyte material] In an argon atmosphere, the raw material powders LiBr, YBr3, LiCl, and YCl3 were weighed in a molar ratio of LiBr:YBr3:LiCl:YCl3 = 1:1:5:1. Then, using a planetary ball mill (Fritsch, P-7 type), the mixture was milled at 600 rpm for 25 hours to obtain Li3YBr2Cl4 powder as the second electrolyte material. In Examples 1 to 4 and Reference Example 1, Li3YBr2Cl4 was used as the second electrolyte material.

[0198] [Fabrication of cathode materials] The cathode material of Example 1 was prepared by weighing the cathode active material, whose surface was coated with LiNbO3 (the first solid electrolyte material of Example 1), the second electrolyte material, and vapor-phase carbon fiber (VGCF (manufactured by Showa Denko K.K.)) as a conductive additive in a mass ratio of 73.7:25.3:1.0, and mixing them in a mortar. The mass ratio of the first solid electrolyte material to the cathode active material in the cathode material of Example 1 is shown in Table 1.

[0199] <Example 2> [Fabrication of positive electrode active material with surface coated by first solid electrolyte material] In an argon atmosphere, 20.0 mg of niobethoxide (Sigma-Aldrich) and 3.3 mg of lithium ethoxide (Sigma-Aldrich) were dissolved in 3 mL of super-dehydrated ethanol (Fujifilm Wako Pure Chemical Industries) to prepare a coating solution.

[0200] Cathode active material LiNi 0.5 Mn 1.5 1.00 g of O4 was placed in a mortar, the entire amount of the prepared coating solution was added and mixed, and then the ethanol was evaporated to obtain a powder. The obtained powder was calcined at 350°C for 3 hours to obtain a positive electrode active material whose surface was coated with LiNbO3, the first solid electrolyte material of Example 2.

[0201] [Fabrication of cathode materials] The positive electrode material of Example 2 was prepared by weighing the positive electrode active material, whose surface was coated with LiNbO3, the first solid electrolyte material of Example 2, the second electrolyte material Li3YBr2Cl4, and the conductive additive VGCF in a mass ratio of 73.0:26.0:1.0, and mixing them in a mortar. The mass ratio of the first solid electrolyte material to the positive electrode active material in the positive electrode material of Example 2 is shown in Table 1.

[0202] <Example 3> [Fabrication of positive electrode active material with surface coated by first solid electrolyte material] In an argon atmosphere, 50.0 mg of niobethoxide (Sigma-Aldrich) and 8.2 mg of lithium ethoxide (Sigma-Aldrich) were dissolved in 3 mL of super-dehydrated ethanol (Fujifilm Wako Pure Chemical Industries) to prepare a coating solution.

[0203] Cathode active material LiNi 0.5 Mn 1.5 1.00 g of O4 was placed in a mortar, the entire amount of the prepared coating solution was added and mixed, and then the ethanol was evaporated to obtain a powder. The obtained powder was calcined at 350 °C for 3 hours to obtain a positive electrode active material whose surface was coated with LiNbO3, the first solid electrolyte material of Example 3.

[0204] [Fabrication of cathode materials] The positive electrode material of Example 3 was prepared by weighing the positive electrode active material, whose surface was coated with LiNbO3, the first solid electrolyte material of Example 3, the second electrolyte material Li3YBr2Cl4, and the conductive additive VGCF in a mass ratio of 73.3:25.8:1.0 and mixing them in a mortar. The mass ratio of the first solid electrolyte material to the positive electrode active material in the positive electrode material of Example 3 is shown in Table 1.

[0205] <Example 4> [Fabrication of positive electrode active material with surface coated by first solid electrolyte material] In an argon atmosphere, 200.2 mg of niobethoxide (Sigma-Aldrich) and 32.7 mg of lithium ethoxide (Sigma-Aldrich) were dissolved in 3 mL of super-dehydrated ethanol (Fujifilm Wako Pure Chemical Industries) to prepare a coating solution.

[0206] Cathode active material LiNi 0.5 Mn 1.5 1.00 g of O4 was placed in a mortar, the entire amount of the prepared coating solution was added and mixed, and then the ethanol was evaporated to obtain a powder. The obtained powder was calcined at 350°C for 3 hours to obtain a positive electrode active material whose surface was coated with LiNbO3, the first solid electrolyte material of Example 4.

[0207] [Fabrication of cathode materials] The positive electrode material of Example 4 was prepared by weighing the positive electrode active material, whose surface was coated with LiNbO3, the first solid electrolyte material of Example 4, the second electrolyte material Li3YBr2Cl4, and the conductive additive VGCF in a mass ratio of 74.5:24.5:0.9, and mixing them in a mortar. The mass ratio of the first solid electrolyte material to the positive electrode active material in the positive electrode material of Example 4 is shown in Table 1.

[0208] <Example 5> [Preparation of the second electrolyte material] In a dry atmosphere with a dew point of -30°C or lower (hereinafter referred to as the "dry atmosphere"), Li2O2 and TaCl5 were prepared as raw material powders in a molar ratio of 1.2:2. These raw material powders were ground and mixed in a mortar to obtain a mixed powder. The obtained mixed powder was milled using a planetary ball mill at 600 rpm for 24 hours. Then, the mixed powder was calcined at 200°C for 6 hours. In this way, the second electrolyte material of Example 5 was obtained.

[0209] The cathode material of Example 5 was prepared in the same manner as in Example 1, except for the second electrolyte material used. The mass ratio of the first solid electrolyte material to the cathode active material in the cathode material of Example 5 is shown in Table 1.

[0210] <Example 6> [Preparation of the second electrolyte material] In an argon glove box with a dew point of -60°C or lower, LiCl and YCl3 were prepared as raw material powders in a molar ratio of 2.7:1.1. Then, using a planetary ball mill (Fritsch, P-5 type), the mixture was milled at 600 rpm for 25 hours to produce the second electrolyte material LiCl. 2.7 Y 1.1 Cl6 powder was obtained.

[0211] As the second electrolyte material, Li 2.7 Y 1.1The cathode material of Example 6 was prepared using the same method as in Example 1, except that Cl6 was used. The mass ratio of the first solid electrolyte material to the cathode active material in the cathode material of Example 6 is shown in Table 1.

[0212] <Example 7> The cathode material of Example 7 was prepared using the same method as in Example 1, except that Li6PS5Cl was used as the second electrolyte material. The mass ratio of the first solid electrolyte material to the cathode active material in the cathode material of Example 7 is shown in Table 1.

[0213] <Reference example 1> [Fabrication of cathode materials] LiNi 0.5 Mn 1.5 The positive electrode material for Reference Example 1 was prepared by weighing O4, the second electrolyte material Li3YBr2Cl4 from Example 1, and the conductive additive VGCF in a mass ratio of 72.8:26.2:1.0 and mixing them in a mortar.

[0214] <Reference example 2> [Fabrication of cathode materials] LiNi 0.5 Mn 1.5 The positive electrode material of Reference Example 2 was prepared by weighing O4, the second electrolyte material of Example 5, and the conductive additive VGCF in a mass ratio of 72.8:26.2:1.0 and mixing them in a mortar.

[0215] <Reference example 3> [Fabrication of cathode materials] LiNi 0.5 Mn 1.5 O4 and the second electrolyte material Li from Example 6. 2.7 Y 1.1 The positive electrode material for Reference Example 3 was prepared by weighing Cl6 and the conductive additive VGCF in a mass ratio of 72.8:26.2:1.0 and mixing them in a mortar.

[0216] <Reference example 4> [Fabrication of cathode materials] LiNi 0.5 Mn1.5 The positive electrode material of Reference Example 4 was prepared by weighing O4, the second electrolyte material Li6PS5Cl from Example 7, and the conductive additive VGCF in a mass ratio of 72.8:26.2:1.0 and mixing them in a mortar.

[0217] [Battery construction] Batteries using the positive electrode materials described in Examples 1 to 7 and Reference Examples 1 to 4 were manufactured by the following process.

[0218] (Example 1) First, 80 mg of Li6PS5Cl was placed inside an insulating outer cylinder and molded under pressure at 2 MPa. Next, 20 mg of the second electrolyte material used as the positive electrode material in Example 1 was placed inside and molded under pressure at 2 MPa. Furthermore, 9.9 mg of the positive electrode material from Example 1 was placed inside and molded under pressure at 720 MPa. This resulted in obtaining a laminate consisting of a positive electrode and a solid electrolyte layer.

[0219] Next, metallic lithium was laminated on the side of the solid electrolyte layer opposite to the side in contact with the positive electrode. A layer of metallic lithium with a thickness of 200 μm was used. By pressurizing this at a pressure of 2 MPa, a laminate consisting of a positive electrode, a solid electrolyte layer, and a negative electrode was fabricated.

[0220] Next, stainless steel current collectors were placed above and below the laminate, and current collection leads were attached to the current collectors.

[0221] Finally, the battery of Example 1 was fabricated by using an insulating ferrule to isolate and seal the inside of the insulating outer casing from the outside air.

[0222] (Examples 2 to 7 and Reference Examples 1 to 4) 80 mg of Li6PS5Cl was placed inside an insulating outer cylinder and molded under pressure at 2 MPa. Next, 20 mg of the second electrolyte material used for the positive electrode material in Examples 2 to 7 or Reference Examples 1 to 4 was placed inside and molded under pressure at 2 MPa. Furthermore, the positive electrode active material LiNi 0.5 Mn 1.5Each of the positive electrode materials from Examples 2 to 7 or Reference Examples 1 to 4 was added to the material so that the O4 content was 7 mg, and this was pressure-molded at a pressure of 720 MPa. The amount of positive electrode material added was 9.7 mg in Example 2, 9.8 mg in Example 3, 10.3 mg in Example 4, 9.9 mg in Examples 5 to 7, and 9.6 mg in Reference Examples 1 to 4. This resulted in obtaining a laminate consisting of a positive electrode and a solid electrolyte layer. Except as described above, batteries from Examples 2 to 7 and Reference Examples 1 to 4 were fabricated in the same manner as in Example 1.

[0223] [Charge / Discharge Test] Charge and discharge tests were conducted using the batteries described in Examples 1 to 7 and Reference Examples 1 to 4 under the following conditions.

[0224] The battery was placed in a constant temperature bath at 25°C.

[0225] Constant current charging was performed at a current value of 42 μA, which corresponds to a 0.05 C rate (20-hour rate) relative to the battery's theoretical capacity. The charging termination voltage was 5.0 V (vs. Li / Li). + Next, the discharge termination voltage was set to 3.5V (vs.Li / Li). + ) and constant current discharge was performed.

[0226] The results of the charge and discharge tests of the batteries in Examples 1 to 7 and Reference Examples 1 to 4 are shown in Table 1.

[0227] [Table 1]

[0228] The coated / uncoated capacity ratios for Examples 1 to 4 in Table 1 represent the ratio of the discharge capacity of Examples 1 to 4 to the discharge capacity of Reference Example 1. The coated / uncoated capacity ratio for Example 5 represents the ratio of the discharge capacity of Example 5 to the discharge capacity of Reference Example 2. The coated / uncoated capacity ratio for Example 6 represents the ratio of the discharge capacity of Example 6 to the discharge capacity of Reference Example 3. The coated / uncoated capacity ratio for Example 7 represents the ratio of the discharge capacity of Example 7 to the discharge capacity of Reference Example 4.

[0229] As shown in Table 1, the charge and discharge capacity is improved when the surface of the positive electrode active material is coated with the first solid electrolyte material.

[0230] According to this disclosure, the charge and discharge capacity will be improved. [Industrial applicability]

[0231] The battery described herein can be used, for example, as an all-solid-state lithium-ion secondary battery. [Explanation of Symbols]

[0232] 1000 Cathode Materials 100 Second Electrolyte Material 110 Cathode active material 111 First solid electrolyte material 2000 batteries 201 Positive electrode 202 Electrolyte layer 203 Negative electrode 3000 batteries 301 1st electrolyte layer 302 Second electrolyte layer

Claims

1. Positive electrode active material and, A first solid electrolyte material that covers at least a portion of the surface of the positive electrode active material, Second electrolyte material, Includes, The aforementioned second electrolyte material includes a material represented by the following compositional formula (2): Li α Ta β X γ O δ ...Formula (2) Here, α, β, and γ are values ​​greater than 0, and δ is a value greater than or equal to 0. X is at least one element selected from the group consisting of Cl and Br. The first solid electrolyte material comprises Li, Nb, and O. The positive electrode active material includes a material represented by the following composition formula (1): LiNi x Mn 2-x O 4 ・・・Form (1) Here, x satisfies 0 < x < 2. Cathode material.

2. The second electrolyte material is a compound containing Li, Ta, Cl, and O. The positive electrode material according to claim 1.

3. The above composition formula (1) satisfies 0 < x < 1, The positive electrode material according to claim 1 or 2.

4. The above compositional formula (1) satisfies x = 0.5, The positive electrode material according to claim 3.

5. The first solid electrolyte material contains lithium niobate. The positive electrode material according to claim 1 or 2.

6. The mass ratio of the first solid electrolyte material to the positive electrode active material is 0.50% or more. The positive electrode material according to claim 1 or 2.

7. The mass ratio of the first solid electrolyte material to the positive electrode active material is 0.93% or more. The positive electrode material according to claim 6.

8. The aforementioned composition formula (2) is, １≦α≦４、 ０＜β≦２、 3 ≤ γ < 7, and 0 ≤ δ ≤ 2 Satisfying The positive electrode material according to claim 1 or 2.

9. The second electrolyte material includes a sulfide solid electrolyte. The positive electrode material according to claim 1.

10. The second electrolyte material is Li 6 PS 5 containing Cl, The positive electrode material according to claim 1.

11. The first solid electrolyte material is provided between the positive electrode active material and the second electrolyte material. The positive electrode material according to claim 1 or 2.

12. Positive electrode and, The negative electrode and, An electrolyte layer located between the positive electrode and the negative electrode, Equipped with, The positive electrode includes the positive electrode material described in claim 1 or 2. battery.

13. The electrolyte layer includes a first electrolyte layer and a second electrolyte layer. The first electrolyte layer is in contact with the positive electrode, and the second electrolyte layer is in contact with the negative electrode. The battery according to claim 12.

14. The first electrolyte layer comprises a material having the same composition as the second electrolyte material. The battery according to claim 13.

15. The second electrolyte layer comprises a material having a different composition from the first solid electrolyte material. The battery according to claim 13.

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