Positive electrode material, battery using the same, and method for charging the battery

Abstract

A cathode material 1000 according to the present disclosure includes a cathode active material 204 and a halide solid electrolyte 100. The halide solid electrolyte 100 contains F. The cathode active material 204 is capable of absorbing and releasing lithium ions at greater than 4.3 V with respect to lithium. A battery according to the present disclosure comprises a cathode, an anode, and an electrolyte layer provided between the cathode and the anode, the cathode containing the cathode material according to the present disclosure.

Description

Technical Field

[0001] The present disclosure relates to a positive electrode material, a battery using the same, and a method for charging the battery.

Background Art

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

[0003] Patent Document 2 discloses an all-solid-state battery using a sulfide solid electrolyte.

Prior Art Documents

Non-Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present disclosure is to provide a positive electrode material suitable for use in a high operating potential range.

Means for Solving the Problems

[0006] The positive electrode material of the present disclosure <� includes a positive electrode active material and a halide solid electrolyte, the halide solid electrolyte contains F, the positive electrode active material can occlude and release lithium ions at a potential exceeding 4.3 V with respect to lithium.

Effects of the Invention

[0007] The present disclosure provides a positive electrode material suitable for use in a high operating potential range.

Brief Description of the Drawings

[0008] [Figure 1] Figure 1 shows a cross-sectional view of the positive electrode material 1000 according to the first embodiment. [Figure 2] Figure 2 shows a cross-sectional view of the battery 1100 according to the first embodiment. [Figure 3] Figure 3 is a graph showing the initial charge and discharge characteristics of batteries according to Examples 1 and 2 and Comparative Examples 1 and 2. [Modes for carrying out the invention]

[0009] Embodiments of the present disclosure will be described below with reference to the drawings.

[0010] (First Embodiment) The positive electrode material according to the first embodiment comprises a positive electrode active material and a halide solid electrolyte. The halide solid electrolyte contains F. The positive electrode active material is capable of intercalating and releasing lithium ions at a voltage greater than 4.3 V relative to lithium.

[0011] With the above configuration, it is possible to provide a positive electrode material suitable for use in a high operating potential range.

[0012] One way to increase the energy density of a battery is to raise the operating potential range of the positive electrode. In other words, the 4.3V vs. Li / Li voltage currently used in batteries with high energy density + This involves operating the battery at a higher potential than the specified voltage.

[0013] Patent Document 1 discloses a halide solid electrolyte. However, halide solid electrolytes containing Cl, Br, or I as the halogen element have a 4.3V vs. Li / Li ratio. + At potentials higher than this, oxidative decomposition occurs. As a result, the battery's charge and discharge characteristics deteriorate.

[0014] Patent document 2 discloses a sulfide solid electrolyte. Because sulfide solid electrolytes have low oxidation resistance, the positive electrode is 4.3V vs. Li / Li +Operating at a higher potential will result in poor charge-discharge characteristics.

[0015] The halogen solid electrolyte contained in the positive electrode material according to the first embodiment may have high oxidation resistance because it contains F. This is because F has a high oxidation-reduction potential. Therefore, if the positive electrode material according to the first embodiment is used, 4.3V vs. Li / Li + Even when operating at a high potential exceeding this value, it is possible to realize a battery with excellent charge and discharge efficiency. The upper limit of the battery's operating potential range is not particularly limited, but for example, 6.0V vs. Li / Li + The following applies:

[0016] As described above, the positive electrode material according to the first embodiment is suitable for use in a high operating potential range, that is, it can increase the operating potential range of the positive electrode. Therefore, the positive electrode material according to the first embodiment can increase the energy density of the battery.

[0017] To enhance the ionic conductivity of the cathode material, the halide solid electrolyte may contain anions other than F. Examples of such anions include Cl, Br, I, O, S, or Se.

[0018] To improve the oxidation resistance of the positive electrode material, the ratio of the amount of F to the total amount of anions constituting the halide solid electrolyte may be 0.50 or more and 1.0 or less.

[0019] To enhance the ionic conductivity of the positive electrode material, the halide solid electrolyte may contain at least one selected from the group consisting of Ti, Zr, and Al, as well as Li and F.

[0020] The halide solid electrolyte may substantially consist of Li, M, Al, and F. Here, M is at least one selected from the group consisting of Ti and Zr. Note that "the halide solid electrolyte substantially consists of Li, M, Al, and F" means that the ratio of the total amount of the substances of Li, M, Al, and F to the total amount of the substances of all the elements constituting the halide solid electrolyte (i.e., the mole fraction) is 90% or more. As an example, the ratio (i.e., the mole fraction) may be 95% or more. The halide solid electrolyte may consist only of Li, M, Al, and F.

[0021] The halide solid electrolyte may contain unavoidably mixed elements. Examples of such elements are hydrogen, oxygen, or nitrogen. Such elements may be present in the raw material powder of the solid electrolyte material or in the atmosphere for manufacturing or storing the solid electrolyte material.

[0022] The halide solid electrolyte may be represented by the following compositional formula (1).

[0023] Li 6-(4-x)b (M 1-x Al x ) b F6···(1) Here, M is at least one selected from the group consisting of Ti and Zr. In formula (1), 0 < x < 1 and 0 < b ≤ 1.5 are satisfied. The halide solid electrolyte represented by such a formula (1) has high ionic conductivity.

[0024] In order to increase the ionic conductivity of the halide solid electrolyte, in formula (1), 0.01 ≤ x ≤ 0.99 may be satisfied, 0.2 ≤ x ≤ 0.95 may be satisfied, 0.6 ≤ x ≤ 0.9 may be satisfied, 0.65 ≤ x ≤ 0.85 may be satisfied, and 0.7 ≤ x ≤ 0.8 may be satisfied.

[0025] The upper and lower limits of the range of x in equation (1) can be defined by any combination selected from the numbers 0.01, 0.2, 0.4, 0.5, 0.5, 0.7, 0.8, 0.95, and 0.99.

[0026] To enhance the ionic conductivity of the halide solid electrolyte, the conditions 0.7 ≤ b ≤ 1.3 and 0.9 ≤ b ≤ 1.04 may be satisfied in equation (1).

[0027] The upper and lower limits of the range of b in equation (1) can be defined by any combination selected from the numbers 0.7, 0.8, 0.9, 0.96, 1, 1.04, 1.1, 1.2, and 1.3.

[0028] In equation (1), M may be Zr.

[0029] In equation (1), M may also be Ti.

[0030] Halide solid electrolytes include Li 2.8 Zr 0.2 Al 0.8 F6, or Li 2.7 Ti 0.3 Al 0.7 F6 is also acceptable.

[0031] The halogenated solid electrolyte may be crystalline or amorphous.

[0032] The halogenated solid electrolyte may contain a crystalline phase represented by formula (1).

[0033] The shape of the halide solid electrolyte is not limited. Examples of such shapes include needle-shaped, spherical, or ellipsoidal. The halide solid electrolyte may be in the form of particles. The halide solid electrolyte may also be in the form of pellets or plates.

[0034] If the shape of the halide solid electrolyte is, for example, particulate (e.g., spherical), the solid electrolyte may have a median diameter of 0.1 μm or more and 100 μm or less, or a median diameter of 0.5 μm or more and 10 μm or less. This allows for good dispersion of the halide solid electrolyte and other materials (e.g., active material). The median diameter refers to the particle size at which the cumulative deposition in the volume-based particle size distribution reaches 50%. The volume-based particle size distribution is measured, for example, by a laser diffraction measuring device or an image analysis device.

[0035] Examples of positive electrode active materials include lithium-containing transition metal oxides, transition metal fluorides, polyanions, fluorinated polyanion materials, transition metal oxyfluorides, 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, or Li(Ni,Mn)O2. Li(Ni,Co,Mn)O2 may also be, for example, LiCoO2. Li(Ni,Mn)O2 may also be, for example, Li(Ni 0.5 Mn 1.5 )O2 is also acceptable.

[0036] In this disclosure, "(A,B,C)" in a chemical formula means "at least one selected from the group consisting of A, B, and C." In a chemical formula, "(A,B)" means "at least one selected from the group consisting of A and B."

[0037] In particular, lithium-containing transition metal oxides or lithium-containing transition metal oxyfluorides may be used as positive electrode active materials that operate at high potentials. Examples of crystal structures of such positive electrode active materials include layered rock salt structure, rock salt structure, or spinel structure.

[0038] The cathode material according to the first embodiment may include at least one selected from the group consisting of lithium-containing transition metal oxides and lithium-containing transition metal oxyfluorides as the cathode active material. In the cathode material according to the first embodiment, the cathode active material may have at least one crystal structure selected from the group consisting of layered rock salt structure, rock salt structure, and spinel structure.

[0039] To increase the battery's operating potential, the positive electrode active material may contain Ni.

[0040] As a positive electrode active material, Li(Ni) has a spinel-type structure. 0.5 Mn 1.5 )O2 may be used.

[0041] Figure 1 is a cross-sectional view showing a positive electrode material 1000 according to the first embodiment.

[0042] The positive electrode material 1000 according to the first embodiment comprises a positive electrode active material 204 and a halogen solid electrolyte 100. The halogen solid electrolyte 100 contains F.

[0043] The shape of the positive electrode active material 204 is not limited to a specific shape. The positive electrode active material 204 may be particles. The positive electrode active material 204 may have a median diameter of 0.1 μm or more and 100 μm or less. When the positive electrode active material 204 has a median diameter of 0.1 μm or more, the positive electrode active material 204 and other materials (e.g., halogen solid electrolyte 100) can be well dispersed. This improves the charge and discharge characteristics of the battery. When the positive electrode active material 204 has a median diameter of 100 μm or less, the lithium diffusion rate within the positive electrode active material 204 is improved. This allows the battery to operate at high power.

[0044] The positive electrode active material 204 may have a larger median diameter than the halide solid electrolyte 100. This allows the positive electrode active material 204 and the halide solid electrolyte 100 to be well dispersed.

[0045] A coating layer may be formed on at least a portion of the surface of the positive electrode active material 204. The coating layer may be formed on the surface of the positive electrode active material 204, for example, before mixing with the conductive additive and binder. Examples of coating materials included in the coating layer are sulfide solid electrolytes or oxide solid electrolytes.

[0046] (Second Embodiment) The second embodiment will now be described. Matters described in the first embodiment will be omitted as appropriate.

[0047] Figure 2 shows a cross-sectional view of the battery 1100 according to the first embodiment.

[0048] The battery 1100 according to the second embodiment comprises a positive electrode 201, an electrolyte layer 202, and a negative electrode 203. The electrolyte layer 202 is provided between the positive electrode 201 and the negative electrode 203.

[0049] The positive electrode 201 contains a positive electrode material according to the first embodiment (for example, positive electrode material 1000).

[0050] With the above configuration, the energy density of the battery can be improved.

[0051] In order for the battery according to the second embodiment to exhibit excellent discharge characteristics, the battery control method (e.g., charging method) according to the second embodiment may be set so that the charging potential of the positive electrode is greater than 4.3V relative to lithium. That is, the battery charging method according to the second embodiment may include, for example, charging the battery such that the charging potential of the positive electrode 201 is greater than 4.3V relative to lithium.

[0052] The positive electrode 201 contains a positive electrode active material 204 and a solid electrolyte 110. The solid electrolyte 110 is, i.e., the halide solid electrolyte described in the first embodiment.

[0053] The electrolyte layer 202 contains an electrolyte material.

[0054] The negative electrode 203 contains a negative electrode active material 205 and a solid electrolyte 110. The solid electrolyte 110 contained in the electrolyte layer 202 may be a halide solid electrolyte as described in the first embodiment.

[0055] In order to improve the energy density and output of the battery 1100, the ratio of the volume of the positive electrode active material 204 to the sum of the volume of the positive electrode active material 204 and the volume of the solid electrolyte 110 in the positive electrode 201 may be 0.30 or more and 0.95 or less.

[0056] To improve the energy density and output of the battery 1100, the positive electrode 201 may have a thickness of 10 μm or more and 500 μm or less.

[0057] The electrolyte layer 202 contains an electrolyte material. This electrolyte material is, for example, a solid electrolyte material. The electrolyte layer 202 may also be a solid electrolyte layer. The solid electrolyte material contained in the electrolyte layer 202 may be a halide solid electrolyte as described in the first embodiment.

[0058] Examples of solid electrolytes included in the positive electrode 201, electrolyte layer 202, and negative electrode 203 include, in addition to the halide solid electrolyte described in the first embodiment, sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, or organic polymer solid electrolytes.

[0059] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, and Li 3.25 Ge 0.25 P 0.75 S4, or Li 10 GeP2S 12 That is the case.

[0060] Examples of oxide solid electrolytes are: (i) NASICON-type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutions, (ii) Perovskite-type solid electrolytes such as (LaLi)TiO3, (iii) Li 14 ZnGe4O 16 , LISICON-type solid electrolytes such as Li4SiO4, LiGeO4 or their elementally substituted counterparts, (iv)Li7La3Zr2O 12 or a garnet-type solid electrolyte such as an elemental substitution thereof, (v) Li3PO4 or its N-substituted derivatives, That is the case.

[0061] Examples of halide solid electrolytes are Li2MgX4, Li2FeX4, Li(Al,Ga,In)X4, Li3(Al,Ga,In)X6, or LiI, where X is at least one selected from the group consisting of F, Cl, Br, and I.

[0062] Other examples of halide solid electrolyte materials include Li a Me b Y c This is a compound represented by Z6. Here, a+mb+3c=6 and c>0 are satisfied. Me is at least one selected from the group consisting of metallic elements other than Li and Y and metalloid elements. Z is at least one selected from the group consisting of F, Cl, Br, and I. m represents the valence of Me. m represents the valence of Me. "Metalloid elements" are B, Si, Ge, As, Sb, and Te. "Metallic elements" are all elements in groups 1 through 12 of the periodic table (except hydrogen), and all elements in groups 13 through 16 of the periodic table (except B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se).

[0063] To improve the ionic conductivity of the halide solid electrolyte, Me may be at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, and Nb.

[0064] The halide solid electrolyte may be Li3YCl6 or Li3YBr6.

[0065] Examples of organic polymer solid electrolytes include polymer compounds and lithium salt compounds.

[0066] Polymer compounds may have an ethylene oxide structure. Polymer compounds having an ethylene oxide structure can contain a large amount of lithium salt, and therefore their ionic conductivity can be further increased.

[0067] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3. One lithium salt selected from these may be used alone, or a mixture of two or more lithium salts selected from these may be used.

[0068] The electrolyte layer 202 may contain two or more solid electrolyte materials. The two or more solid electrolyte materials may be uniformly dispersed in the electrolyte layer 202. The layer made of the first solid electrolyte material and the layer made of the second solid electrolyte material may be stacked along the stacking direction of the battery 1100.

[0069] The battery according to the second embodiment may comprise a positive electrode 201, a second electrolyte layer, a first electrolyte layer, and a negative electrode 203 in this order. Here, the solid electrolyte material contained in the first electrolyte layer may have a lower reduction potential than the solid electrolyte material contained in the second electrolyte layer. This allows the solid electrolyte material contained in the second electrolyte layer to be used without reduction. As a result, the charge and discharge efficiency of the battery can be improved.

[0070] To improve the energy density and output of the battery, the electrolyte layer 202 may have a thickness of 1 μm or more and 1000 μm or less.

[0071] The negative electrode 203 contains a material capable of intercalating and releasing metal ions (e.g., lithium ions). This material is, for example, the negative electrode active material 205.

[0072] Examples of negative electrode active materials 205 are metallic materials, carbon materials, oxides, nitrides, tin compounds, or silicon compounds. Metallic materials may be elemental metals or alloys. Examples of metallic materials are lithium metal or lithium alloys. Examples of carbon materials are natural graphite, coke, carbon in the process of graphitization, carbon fibers, spheroidal carbon, artificial graphite, or amorphous carbon. From the viewpoint of capacity density, preferred examples of negative electrode active materials are silicon (i.e., Si), tin (i.e., Sn), silicon compounds, or tin compounds.

[0073] The shape of the negative electrode active material 205 is not limited to a specific shape. The negative electrode active material 205 may be particles. The negative electrode active material 205 may have a median diameter of 0.1 μm or more and 100 μm or less. When the negative electrode active material 205 has a median diameter of 0.1 μm or more, the negative electrode active material 205 and the solid electrolyte 110 can be well dispersed in the negative electrode 203. This improves the charge and discharge characteristics of the battery 1100. When the negative electrode active material 205 has a median diameter of 100 μm or less, the lithium diffusion rate within the negative electrode active material 205 is improved. This allows the battery 1100 to operate at high power.

[0074] The negative electrode active material 205 may have a larger median diameter than the solid electrolyte 110. This allows the negative electrode active material 205 and the solid electrolyte 110 to be well dispersed in the negative electrode 203.

[0075] In order to improve the energy density and output of the battery 1100, the ratio of the volume of the negative electrode active material 205 to the sum of the volume of the negative electrode active material 205 and the volume of the solid electrolyte 110 in the negative electrode 203 may be 0.30 or more and 0.95 or less.

[0076] To improve the energy density and output of the battery 1100, the negative electrode 203 may have a thickness of 10 μm or more and 500 μm or less.

[0077] At least one selected from the group consisting of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a non-aqueous electrolyte, a gel electrolyte, or an ionic liquid to facilitate the transfer of lithium ions and improve the output characteristics of the battery.

[0078] The non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0079] Examples of non-aqueous solvents include cyclic carbonate solvents, linear carbonate solvents, cyclic ether solvents, linear ether solvents, cyclic ester solvents, linear ester solvents, or fluorinated solvents. Examples of cyclic carbonate solvents are ethylene carbonate, propylene carbonate, or butylene carbonate. Examples of linear carbonate solvents are dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate. Examples of cyclic ether solvents are tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane. Linear ether solvents are 1,2-dimethoxyethane or 1,2-diethoxyethane. An example of a cyclic ester solvent is γ-butyrolactone. An example of a linear ester solvent is methyl acetate. Examples of fluorinated solvents are fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, or fluorodimethylene carbonate. One non-aqueous solvent selected from these may be used alone, or a combination of two or more non-aqueous solvents selected from these may be used.

[0080] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3. One lithium salt selected from these may be used alone, or a mixture of two or more lithium salts selected from these may be used. The concentration of the lithium salt is, for example, in the range of 0.5 mol / L or more and 2 mol / L or less.

[0081] As the gel electrolyte, polymer materials impregnated with a non-aqueous electrolyte can be used. Examples of polymer materials include polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or polymers having ethylene oxide bonds.

[0082] Examples of cations contained in ionic liquids are: (i) aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium, (ii) Aliphatic cyclic ammonium compounds such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperadiniums, or piperidiniums, (iii) Nitrogen-containing heterocyclic aromatic cations such as pyridinium or imidazolium That is the case.

[0083] An example of anion contained in an ionic liquid is PF6. - BF4 - SbF6 - AsF6 - , SO3CF3 - , N(SO2CF3)2 - , N(SO2C2F5)2 - , N(SO2CF3)(SO2C4F9) - , or C(SO2CF3)3 - That is the case.

[0084] The ionic liquid may contain lithium salts.

[0085] 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 to improve the adhesion between particles.

[0086] Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resins, polyamides, polyimides, polyamide-imides, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyethers, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, or carboxymethylcellulose. Copolymers can also be used as binders. Examples of such binders are 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. A mixture of two or more materials selected from these may also be used as a binder.

[0087] At least one of the positive electrode 201 and the negative electrode 203 may contain a conductive additive to improve electronic conductivity.

[0088] Examples of conductive additives are: (i) Graphites such as natural graphite or artificial graphite, (ii) Carbon blacks such as acetylene black or Ketjen black, (iii) Conductive fibers such as carbon fibers or metal fibers, (iv) Carbon fluoride, (v) Metal powders such as aluminum, (vi) Conductive whiskers such as zinc oxide or potassium titanate, (vii) conductive metal oxides such as titanium oxide, or (viii) Conductive polymer compounds such as polyaniline, polypyrrole, or polythiophene, Therefore, to reduce costs, the conductive additives described in (i) or (ii) above may be used.

[0089] Examples of battery shapes according to the second embodiment include coin-shaped, cylindrical, prismatic, sheet-shaped, button-shaped, flat, or stacked types.

[0090] The battery according to the second embodiment may be manufactured, for example, by preparing a material for forming a positive electrode, a material for forming an electrolyte layer, and a material for forming a negative electrode, and then fabricating a laminate in which the positive electrode, electrolyte layer, and negative electrode are arranged in this order by a known method. [Examples]

[0091] The present disclosure will be described in more detail below with reference to examples and comparative examples.

[0092] <Example 1> (Preparation of solid halide electrolytes) In an argon atmosphere with a dew point of -60°C or lower (hereinafter referred to as a "dry argon atmosphere"), LiF, ZrF4, and AlF3 were prepared as raw material powders in a molar ratio of LiF:ZrF4:AlF3 = 2.8:0.2:0.8. These raw material powders were ground and mixed in a mortar. The resulting mixture was placed in a ball mill pod along with γ-butyrolactone as an organic solvent. Next, the mixture was milled at 500 rpm for 12 hours using a planetary ball mill. The solid content ratio at this time was set to 50%, and 1 mmΦ balls were used. The solid content ratio is calculated as {(mass of input raw materials) / (mass of input raw materials + mass of input solvent)} × 100. After milling, the balls were separated to obtain a slurry. The obtained slurry was dried at 200°C for 1 hour under a nitrogen flow using a mantle heater. The obtained solid was ground in a mortar to obtain the halogen solid electrolyte powder of Example 1. The halide solid electrolyte material of Example 1 is Li 2.8 Zr 0.2 Al 0.8 It had a composition represented by F6.

[0093] (Battery construction) In a dry argon atmosphere, the halide solid electrolyte of Example 1 and the active material Li(Ni 0.5 Mn 1.5 O2 was prepared in a volume ratio of 40:60. These materials were mixed in an agate mortar. In this way, the cathode material of Example 1 was obtained.

[0094] In an insulating tube with an inner diameter of 9.5 mm, Li3PS4 (57.41 mg), the halogen solid electrolyte of Example 1 (26 mg), and the positive electrode material of Example 1 (9.9 mg) were laminated in this order. A pressure of 720 MPa was applied to the resulting laminate to form a first electrolyte layer, a second electrolyte layer, and a positive electrode. That is, the second electrolyte layer was sandwiched between the first electrolyte layer and the positive electrode. The thicknesses of the first and second electrolyte layers were 450 μm and 150 μm, respectively.

[0095] Next, metallic Li (thickness: 200 μm) was laminated onto the first electrolyte layer. A pressure of 10 MPa was applied to the resulting laminate to form a negative electrode.

[0096] Next, current collectors made of stainless steel were attached to the positive and negative electrodes, and current collector leads were attached to the current collectors.

[0097] Finally, an insulating ferrule was used to isolate the inside of the insulating cylinder from the outside air, thereby sealing the inside of the cylinder. In this way, the battery according to Example 1 was obtained.

[0098] (Charge / Discharge Test) Figure 3 is a graph showing the initial discharge characteristics of the battery according to Example 1. The initial charge-discharge characteristics were measured by the following method. Note that the voltage on the vertical axis shown in Figure 3 is the voltage relative to lithium, i.e., "electrode potential [V vs. Li / Li + This corresponds to "[]".

[0099] The battery according to Example 1 was placed in a constant temperature bath at 85°C.

[0100] 18 μA / cm 2 The battery according to Example 1 was charged to a voltage of 5.0V at a current density of 0.01C.

[0101] Next, 18 μA / cm 2 The battery according to Example 1 was discharged until it reached a voltage of 3.5V at the given current density.

[0102] The charge-discharge test results showed that the battery according to Example 1 had an initial charge-discharge efficiency of 83.7%.

[0103] <Example 2> (Preparation of solid halide electrolytes) In a dry argon atmosphere, LiF, TiF4, and AlF3 were prepared as raw material powders in a molar ratio of LiF:TiF4:AlF3 = 2.7:0.3:0.7. These raw material powders were ground and mixed in a mortar. The resulting mixture was milled using a planetary ball mill at 500 rpm for 12 hours. In this way, the halogenated solid electrolyte powder of Example 2 was obtained. The halogenated solid electrolyte of Example 2 is Li 2.7 Ti 0.3 Al 0.7 It had a composition represented by F6.

[0104] (Battery construction) In a dry argon atmosphere, the halide solid electrolyte of Example 2 and the active material Li(Ni 0.5 Mn 1.5 O2 was prepared in a volume ratio of 40:60. These materials were mixed in an agate mortar. In this way, the cathode material of Example 2 was obtained.

[0105] Except for the matters mentioned above, the battery of Example 2 was obtained in the same manner as in Example 1.

[0106] (Charge / Discharge Test) A charge-discharge test was performed using the battery from Example 2 in the same manner as in Example 1. The battery from Example 2 charged and discharged well, similar to the battery from Example 1. The battery from Example 2 had an initial charge-discharge efficiency of 81.4%.

[0107] <Comparative Example 1> In Comparative Example 1, a charge-discharge test was performed in the same manner as in Example 1, using Li3PS4 instead of the halogen solid electrolyte. However, the battery was fabricated without using the first electrolyte layer. The thickness of the second electrolyte layer was set to 600 μm. In other words, in the battery of Comparative Example 1, a 600 μm thick Li3PS4 layer was provided as an electrolyte layer between the positive and negative electrodes.

[0108] The charge-discharge test results showed that the initial charge-discharge efficiency of the battery in Comparative Example 1 was 75.6%.

[0109] <Comparative Example 2> Instead of the halogen solid electrolyte in Example 1, Li 2.7 Y 1.1 Cl6 was used.

[0110] In a dry argon atmosphere, LiCl and YCl3 were prepared as raw material powders in a molar ratio of 2.7:1.1. The mixture of raw material powders was calcined at 550°C for 1 hour under an argon atmosphere. In this way, the solid electrolyte Li 2.7 Y 1.1 Cl6 was obtained.

[0111] Instead of the halogen solid electrolyte in Example 1, Li 2.7 Y 1.1 A charge-discharge test was performed using Cl6 in the same manner as in Example 1.

[0112] The charge-discharge test results showed that the initial charge-discharge efficiency of the battery in Comparative Example 2 was 77.2%.

[0113] [Table 1]

[0114] <Consideration> The batteries in Examples 1 and 2 both exhibited high initial charge-discharge efficiency of over 80% at 85°C. In contrast, the batteries in Comparative Examples 1 and 2 had charge-discharge efficiencies of less than 80%.

[0115] As described above, the battery using the positive electrode material according to this disclosure is 4.3V vs. Li / Li + Even in high potential operating ranges exceeding [a certain value], it exhibited excellent charge and discharge characteristics. [Industrial applicability]

[0116] The cathode material of this disclosure can be used, for example, in all-solid-state lithium-ion secondary batteries. [Explanation of Symbols]

[0117] 100 Halide Solid Electrolytes 101 Powder of solid electrolyte material 110 Solid electrolyte 201 Positive electrode 202 Electrolyte layer 203 Negative electrode 204 Cathode active material 205 Anode active material 300 pressure molding dies 301 Punch Top 302 Frame type 303 Punch bottom 1000 Cathode Materials 1100 battery

Claims

1. It comprises a positive electrode active material and a halogen solid electrolyte, The positive electrode active material is capable of intercepting and releasing lithium ions at a voltage greater than 4.3 V relative to lithium. The aforementioned halogen solid electrolyte is represented by the following compositional formula (1): Li 6-(4-x)b (M 1-x Al x ) b F 6 ... (1) Here, M is at least one selected from the group consisting of Ti and Zr. The conditions 0 < x < 1 and 0 < b ≤ 1.5 are satisfied. Cathode material.

2. In the above compositional formula (1), 0.7 ≤ x ≤ 0.8 is satisfied. The positive electrode material according to claim 1.

3. In the above compositional formula (1), M is Ti. The positive electrode material according to claim 1.

4. In the above compositional formula (1), M is Zr. The positive electrode material according to claim 1.

5. The positive electrode active material is at least one selected from the group consisting of lithium-containing transition metal oxides and lithium-containing transition metal oxyfluorides. The positive electrode material according to claim 1.

6. The positive electrode active material has at least one crystal structure selected from the group consisting of layered rock salt structure, rock salt structure, and spinel structure. The positive electrode material according to claim 1.

7. The positive electrode active material contains Ni, The positive electrode material according to claim 1.

8. The positive electrode active material is Li(Ni 0.5 Mn 1.5 ) O 2 including, The positive electrode material according to claim 7.

9. positive electrode, Negative electrode, and An electrolyte layer provided between the positive electrode and the negative electrode, Equipped with, The positive electrode contains the positive electrode material described in any one of claims 1 to 8. battery.

10. A method for charging a battery according to claim 9, The battery is charged such that the charging potential of the positive electrode exceeds 4.3V relative to lithium. Battery charging methods, including [specific details].

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