Composition, method for producing coated active material, method for producing battery, and battery

Abstract

A composition according to the present disclosure contains a solvent, an organic material, and an active material, wherein the hydrogen bond term δh of the HSP value of the solvent is greater than 14.0 MPa1 / 2 and less than 26.0 MPa1 / 2, the solubility of the organic material in the solvent is greater than 10 g / L, and the active material includes elemental V.

Description

Composition, method for producing coated active material, method for producing battery, and battery

[0001] The present disclosure relates to compositions, methods for making coated active materials, batteries, and methods for making batteries.

[0002] Patent Document 1 discloses a method for producing a carbon-coated active material.

[0003] International Publication No. 2021 / 118026

[0004] In the prior art, there is a need for the development of an active material that has high electronic conductivity and can improve battery characteristics. The present disclosure provides a technology for realizing an active material that can improve the charge capacity of a battery.

[0005] A composition according to one embodiment of the present disclosure includes a solvent, an organic substance, and an active material, wherein the hydrogen bond term δh in the Hansen solubility parameters of the solvent is 14.0 MPa. 1 / 2 Larger than 26.0 MPa 1 / 2 the solubility of the organic substance in the solvent is greater than 10 g / L; and the active material contains a V element.

[0006] The present disclosure provides a technology for realizing an active material that can improve the charge capacity of a battery.

[0007] Fig. 1 is a cross-sectional view showing a schematic configuration of a battery 1000 according to embodiment 4. Fig. 2 is a schematic diagram of a pressure molding die 300 used to evaluate the electronic conductivity of the active material. Fig. 3 is a graph showing the initial charge-discharge characteristics of the battery of example 1.

[0008] <Inventor's Point of View> Conventionally, in the field of secondary batteries, where high energy density and large capacity are required, the mainstream has been to use an organic electrolyte solution in which an electrolyte salt is dissolved in an organic solvent. It has been pointed out that secondary batteries using an organic electrolyte solution (hereinafter referred to as "liquid battery") have concerns about leakage and the possibility of large heat generation in the event of a short circuit or the like.

[0009] Meanwhile, all-solid-state secondary batteries, which use inorganic solid electrolytes instead of organic electrolytes, are gaining attention. All-solid-state secondary batteries do not leak. Because inorganic solid electrolytes are non-flammable, they are expected to suppress heat generation in the event of a short circuit.

[0010] In both liquid batteries and all-solid-state secondary batteries, the use of electrode materials with high energy density has been investigated to further improve charge / discharge capacity. However, many of these electrode materials experience volume expansion and contraction during charge / discharge, which can lead to deterioration of durability, particularly in all-solid-state secondary batteries.

[0011] Lithium oxide materials are examples of active materials with small volume expansion and contraction, but these materials generally have low electronic conductivity, which poses a problem of reduced charge and discharge capacity.

[0012] Therefore, the inventors have investigated methods for increasing the electronic conductivity of materials with low electronic conductivity and improving the charge / discharge capacity of batteries. As a result, they have found that coating the surface of an active material containing V element with a solution in which a specific organic substance is dissolved in a specific solvent can increase the electronic conductivity of the active material and improve the charge capacity of batteries. From these points of view, the configuration of the present disclosure has been obtained.

[0013] (Embodiment 1) A composition according to embodiment 1 includes a solvent, an organic substance, and an active material. The hydrogen bond term δh in the Hansen solubility parameter of the solvent is 14.0 MPa. 1 / 2 Larger than 26.0 MPa 1 / 2 The solubility of the organic substance in the above solvent is greater than 10 g / L. The active material contains V (vanadium).

[0014] In the present disclosure, "the solubility of the organic substance in the solvent is greater than 10 g / L" means that the amount of solvent required to dissolve 10 g of the organic substance at 25°C is less than 1 L. Here, "solubility" means that both the solution obtained when dissolving the solute in the solvent in a container is not cloudy and no precipitate is observed on the bottom of the container after the solution is left standing for 24 hours. When the solvent contained in the composition is a mixed solvent, "the solubility of the organic substance in the solvent" means the solubility in the mixed solvent. The solubility of the organic substance in the solvent at 25°C may be 100 g / L or more.

[0015] The composition may be in the form of a paste or a dispersion. The active material may be, for example, in the form of particles. In the composition, the particles of the active material are mixed with, for example, a solvent. The viscosity of the composition may be adjusted as appropriate. For example, if the viscosity of the composition is relatively low, the solvent may be removed by drying the composition using a method such as a spray method. If the viscosity of the composition is relatively high, the solvent may be removed by drying the composition using a method such as heat drying.

[0016] The Hansen solubility parameter (HSP) is a parameter that represents the solubility characteristics between substances. In this disclosure, HSP refers to a vector parameter obtained by decomposing the Hildebrand solubility parameter into three cohesive energy components: London dispersion force, dipole-dipole force, and hydrogen bond. In this disclosure, the component of HSP corresponding to hydrogen bond is referred to as the hydrogen bond term δh. The HSP value of a solvent can be obtained, for example, by referencing a database. For solvents whose HSP values ​​are not registered in a database, the HSP value can be calculated from the chemical structure of the solvent using computer software such as Hansen Solubility Parameters in Practice (HSPiP). When the solvent contained in a composition is a mixed solvent, the "hydrogen bond term δh in the HSP of the solvent" refers to the hydrogen bond term δh in the HSP of the mixed solvent. The HSP value of a mixed solvent can be determined, for example, from the HSP values ​​and volume ratios of the individual solvents that make up the mixed solvent. For example, in a mixed solvent consisting of solvent 1 and solvent 2, when the hydrogen bond term of the HSP in solvent 1 is δh1, the hydrogen bond term of the HSP in solvent 2 is δh2, the volume ratio of solvent 1 is a, and the volume ratio of solvent 2 is b, the hydrogen bond term δh of the HSP in the mixed solvent is expressed by the formula: δh = (aδh1 + bδh2) / a + b.

[0017] The hydrogen bond term δh in the HSP of the solvent is 16.0 MPa. 1 / 2 or more and 23.0 MPa 1 / 2 It may be 16.0 MPa or less, 1 / 2 or more and 20.0 MPa 1 / 2 It may be 16.4 MPa or less, 1 / 2 or more and 22.3 MPa 1 / 2 This allows the organic material to be easily dissolved in the solvent in the composition, and the active material to be stably dispersed in the solvent.

[0018] The polar term δp, which is a component corresponding to the dipole-dipole force of the HSP of the solvent, and the dispersion term δd, which is a component corresponding to the London dispersion force of the HSP, are not limited to specific values.

[0019] The solvent may comprise an organic solvent.

[0020] In a preferred embodiment of the present disclosure, the solvent may contain a compound having a linear structure. By using a compound having a linear structure, a composition having excellent suspension stability of the active material can be obtained.

[0021] The number of carbon atoms in the compound contained in the solvent is not particularly limited and may be 8 or less. When the solvent is a mixed solvent, the number of carbon atoms in each compound constituting the mixed solvent may be 8 or less. As described above, the solvent is easily volatilized, and therefore the solvent can be easily removed by drying the composition.

[0022] In another preferred embodiment of the present disclosure, the solvent may contain a compound having a ring structure. The solvent may have an aromatic ring. The ring structure may be an alicyclic hydrocarbon or an aromatic hydrocarbon. The ring structure may be monocyclic or polycyclic. By having a ring structure, the active material can be easily dispersed in the compound. From the viewpoint of increasing the suspension stability of the active material in the composition, the solvent may contain an aromatic compound.

[0023] The solvent may have only a hydroxyl group as a functional group. By using such a solvent, the active material can be easily dispersed in the composition. Therefore, a composition with excellent suspension stability of the active material can be obtained.

[0024] The solvent may include a monohydric alcohol.

[0025] The monohydric alcohol may be composed only of carbon and hydrogen other than the hydroxy group, i.e., the monohydric alcohol may be a compound in which one of the hydrogen atoms contained in a hydrocarbon is substituted with a hydroxy group.

[0026] The monohydric alcohol may have a structure in which one hydrogen atom of a hydrocarbon having a straight-chain structure is substituted with a hydroxy group, or may have a structure in which one hydrogen atom at the terminal of a hydrocarbon having a straight-chain structure is substituted with a hydroxy group.

[0027] The number of carbon atoms contained in the monohydric alcohol is not particularly limited and may be 8 or less. As a result, since the monohydric alcohol is easily volatilized, the composition can be easily dried to remove the monohydric alcohol. The number of carbon atoms contained in the monohydric alcohol may be 1 or more, or 2 or more.

[0028] The monohydric alcohol may not contain heteroatoms other than the hydroxyl group. This configuration allows the active material to be easily dispersed in the compound. Examples of heteroatoms include N, P, O, and S.

[0029] The solvent may include at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, and water.

[0030] The solvent may include at least one selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol.

[0031] The solvent may include ethanol.

[0032] According to the above-mentioned configuration, the active material can be easily dispersed in the composition. Furthermore, the composition can be easily dried to remove the solvent. The use of ethanol particularly makes it easy to dry the composition to remove the solvent.

[0033] The solvent may be a mixed solvent of two or more solvents selected from the above solvents.

[0034] The solvent may include water, or may be a mixed solvent of water and another solvent.

[0035] Solvents may include solvents composed only of carbon and hydrogen, i.e., hydrocarbons.

[0036] The boiling point of the solvent is not particularly limited and may be 60°C or higher and 200°C or lower. The solvent may be liquid at 25°C. Such a solvent is unlikely to volatilize at room temperature, allowing the active material to be stably dispersed. This also allows the solvent to be easily removed. The solvent may be any liquid that can disperse the active material, and the active material does not dissolve in the solvent.

[0037] According to the above configuration, a composition capable of improving the charge / discharge capacity of a battery can be provided. The composition of the present disclosure has high electronic conductivity and is suitable for producing an active material member capable of improving the charge / discharge capacity. For example, when the composition of the present disclosure is dried to remove the solvent, an active material member having high electronic conductivity can be obtained. The active material member can be a coated active material in which the surfaces of active material particles are coated with a conductive material. Alternatively, the active material member can be an active material film containing an active material and a conductive material.

[0038] The organic substance may have a hydroxy group. The organic substance may not have a carboxy group. The organic substance may have a hydroxy group and not have a carboxy group.

[0039] The organic substance may include a sugar. Since a sugar has many hydroxy groups in its structure, it can be selectively adsorbed onto the surface of the active material to form a good coating state. In the present disclosure, the sugar also includes a sugar alcohol.

[0040] The sugar may be at least one selected from the group consisting of monosaccharides and sugar alcohols. Examples of monosaccharides include mannose and fructose. Examples of sugar alcohols include sorbitol and xylitol.

[0041] The sugar may be a monosaccharide.

[0042] The sugar may comprise at least one selected from the group consisting of fructose, mannose, sorbitol, and xylitol.

[0043] The sugar may include fructose, which can increase the amount of organic matter dissolved in the solvent.

[0044] According to the above-mentioned configuration, it is possible to provide an active material having high electronic conductivity and a composition capable of improving the charge / discharge capacity of a battery.

[0045] The organic matter may include a polymer compound, such as a polysaccharide or a polyphenol.

[0046] The polymer compound may be at least one selected from the group consisting of ethyl cellulose and polyphenol. The polymer compound may be ethyl cellulose. Ethyl cellulose has many hydroxy groups in its structure, so it can be selectively adsorbed onto the surface of the active material, forming a good coating state.

[0047] According to the above-mentioned configuration, it is possible to provide an active material having high electronic conductivity and a composition capable of improving the charge / discharge capacity of a battery.

[0048] In the composition according to the first embodiment, the content of the organic substance may be 0.2% by mass or more and 15.0% by mass or less.

[0049] The active material contains V element. When coating the surface of the active material to improve the electronic conductivity of the V element-containing active material, there is a problem that V-containing active materials such as vanadium oxide are easily dissolved and decomposed in solvents, particularly water. This is thought to be because, in solvents with a large value of the hydrogen bond term δh in the HSP, water molecules derived from hydroxy groups contained in the solvent coordinate to V to form, for example, a hexacoordinated complex. The composition of the present disclosure has a hydrogen bond term in the HSP value of the solvent of 14.0 MPa. 1 / 2 Larger than 26.0 MPa 1 / 2 When the content is less than 100%, dissolution and decomposition of the active material containing V can be suppressed, and the electronic conductivity of the active material and the charge / discharge capacity of the battery can be improved.

[0050] The ratio of the mass of the active material to the total mass of the active material and the mass of the solvent is not particularly limited, and may be 10 mass% or less. With this configuration, a composition that can be easily dried using, for example, a spray method can be obtained.

[0051] The active material includes a material that has the property of absorbing and releasing metal ions (e.g., lithium ions). The active material may be either a negative electrode active material or a positive electrode active material.

[0052] The active material may be a negative electrode active material. In this case, the composition of the present disclosure can provide a negative electrode active material that has high electronic conductivity and can improve charge / discharge capacity.

[0053] The active material may be a composite oxide containing lithium and vanadium.

[0054] The active material may be a compound represented by the following composition formula (1): Li 3+x+a V 1-x M x O 4+a / 2 ...Formula (1) Here, M is at least one selected from the group consisting of tetravalent metal elements and tetravalent metalloid elements, and composition formula (1) satisfies 0≦a<1 and 0≦x<1.

[0055] The composition formula (1) may satisfy 0≦x≦0.15, which can improve the charge / discharge capacity of the battery.

[0056] The composition formula (1) may satisfy the relationship 0<x≦0.15, which can improve the charge / discharge capacity of the battery.

[0057] Examples of tetravalent metal elements and tetravalent metalloid elements include Ti, Zr, Si, Ge, Sn, etc. In composition formula (1), M may contain at least one element selected from the group consisting of Ti, Zr, Si, Ge, and Sn, thereby improving the charge / discharge capacity of the battery.

[0058] In the composition formula (1), M may contain Ti, which can improve the charge / discharge capacity of the battery.

[0059] The shape of the active material is not limited. Examples of the shape include an acicular shape, a spherical shape, and an oval spherical shape. The active material according to embodiment 1 may be in the form of particles. The active material may be formed into a pellet or plate shape.

[0060] When the active material has a particulate (e.g., spherical) shape, the active material may have a median diameter of 0.1 μm or more and 100 μm or less, preferably 0.5 μm or more and 10 μm or less. This allows the composition of embodiment 1 to provide an active material with higher lithium diffusibility. Furthermore, when the active material is mixed with other materials such as solid electrolytes, the active material and the other materials are better dispersed. The median diameter refers to 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, using a laser diffraction measurement device or an image analysis device.

[0061] The active material may not be soluble in the solvent. The solubility of the active material in 100 mL of the solvent in the composition according to embodiment 1 at 25°C may be, for example, less than 0.1 g. That is, more than 100 mL of the solvent may be required to dissolve 0.1 g of the active material at 25°C. This makes it possible to suppress decomposition and structural collapse of the active material. When the solvent contained in the composition is a mixed solvent, the solubility of the active material refers to the solubility in the mixed solvent.

[0062] The composition according to embodiment 1 may further contain other substances in addition to those described above. For example, the composition may contain a binder.

[0063] By including a binder, the adhesiveness between particles can be improved when the composition is dried as described below.

[0064] Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl ester of acrylic acid, polyethyl ester of acrylic acid, polyhexyl ester of acrylic acid, polymethacrylic acid, polymethyl ester of methacrylic acid, polyethyl ester of methacrylic acid, polyhexyl ester of methacrylic acid, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose. Copolymers can also be used as binders. Examples of such binders include copolymers of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene. Mixtures of two or more of the above materials may also be used as binders.

[0065] (Embodiment 2) Hereinafter, embodiment 2 will be described. The same description as in embodiment 1 will be omitted as appropriate.

[0066] The method for producing a coated active material according to the second embodiment includes: (A) drying the composition according to the first embodiment.

[0067] By removing the solvent by drying the composition, for example, a coated active material that is uniformly coated with an organic substance can be produced. As a result, the coated active material has high electronic conductivity. Such a coated active material can be used to obtain a battery with excellent charge / discharge characteristics. The coated active material produced by the production method according to embodiment 2 is suitable for improving battery capacity, for example. An example of the battery is an all-solid-state battery. The all-solid-state battery may be a primary battery or a secondary battery.

[0068] (A) is carried out, for example, by heating the composition. The heating temperature may be, for example, 50°C or higher and 200°C or lower. The heating time may be, for example, 30 minutes or longer and 24 hours or shorter. Drying may be carried out under atmospheric pressure or under reduced pressure. That is, the solvent may be removed by drying under reduced pressure.

[0069] "Drying under reduced pressure" refers to drying a composition in a pressure atmosphere lower than atmospheric pressure. The pressure atmosphere lower than atmospheric pressure may be, for example, -0.01 MPa or lower in gauge pressure. During drying under reduced pressure, the composition may be heated to, for example, 50°C or higher and 200°C or lower.

[0070] The solvent may be removed by vacuum drying, which refers to removing the compound by drying the composition at a temperature equal to or lower than the vapor pressure of the compound at a temperature 20° C. lower than the boiling point of the compound, for example.

[0071] Removal of the solvent can be confirmed by, for example, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), gas chromatography (GC), or gas chromatography mass spectrometry (GC / MS). In the present disclosure, "removing the solvent" means performing a process to remove the solvent, such as drying the composition, but does not mean completely removing all of the solvent. In other words, it is sufficient that the coated active material obtained after drying has electronic conductivity, and the solvent does not have to be completely removed from the composition.

[0072] The method for producing a coated active material according to the second embodiment may further include: (B) carbonizing the organic material by heat treatment.

[0073] By carbonizing the organic material, active material particles that are uniformly coated with conductive carbon can be produced.

[0074] The temperature of the heat treatment is not particularly limited as long as it is a temperature at which the organic material is carbonized, and may be, for example, 500°C or higher and 900°C or lower. The heat treatment may be performed for 3 hours or longer and 72 hours or shorter. The heat treatment may be performed in a vacuum atmosphere or an inert atmosphere. The inert atmosphere may be, for example, a nitrogen atmosphere or an argon atmosphere.

[0075] In the method for producing a coated active material according to the second embodiment, (B) may be performed after (A). That is, the composition may be dried and then heat-treated to carbonize the organic matter. (A) and (B) may be performed consecutively, or a separate treatment may be performed between (A) and (B). For example, the dried composition may be crushed after (A) and before (B).

[0076] (A) and (B) may be carried out simultaneously. By firing the composition according to embodiment 1, the composition may be dried and the organic matter may be carbonized.

[0077] In (A), the composition may be converted into coated particles in which a solution containing a solvent and an organic substance (hereinafter referred to as the "solution portion of the composition") coats at least a portion of the surface of the active material particles, and then the coated particles may be dried to remove the solvent. For example, by filtering the composition according to embodiment 1, the coated particles in which an appropriate amount of the solution portion of the composition coats at least a portion of the surface of the active material particles can be separated by filtration.

[0078] That is, the method for producing the coated active material according to the second embodiment may include: (A1) filtering the composition according to the first embodiment to obtain coated particles in which the solution portion of the composition coats at least a portion of the surface of the active material particles; (A2) drying the coated particles; and (B) carbonizing the organic material by heat treatment.

[0079] According to the above, a coated active material can be produced in which the surface of the active material is uniformly coated with an appropriate amount of organic material. This allows the production of an active material that has high electronic conductivity and can further improve the charge / discharge capacity of the battery. Furthermore, by removing the excess monohydric alcohol in advance, the subsequent removal of the monohydric alcohol by drying can be facilitated.

[0080] (A1) and (A2) may be performed consecutively, or a separate treatment may be performed between each step. (A2) and (B) may be performed consecutively, or a separate treatment may be performed between each step. For example, the dried coated particles may be crushed after (A2) and before (B). Alternatively, (A2) and (B) may be performed simultaneously.

[0081] (Embodiment 3) A method for manufacturing a battery according to Embodiment 3 is a method for manufacturing a battery including a first electrode, a second electrode, and an electrolyte layer disposed between the first electrode and the second electrode. In the method for manufacturing a battery according to Embodiment 3, the formation of the first electrode includes: (A) drying the composition according to Embodiment 1; and (B) carbonizing the organic matter by heat treatment.

[0082] As described above, a battery including a coated active material having high electronic conductivity can be manufactured. Therefore, the battery manufacturing method according to the third embodiment can manufacture a battery having excellent charge / discharge characteristics.

[0083] When the active material in the composition is a negative electrode active material, the first electrode becomes a negative electrode. When the active material in the composition is a positive electrode active material, the first electrode becomes a positive electrode.

[0084] The method for producing a battery according to the third embodiment may include obtaining a coated active material by steps including the above-described steps (A) and (B), and preparing an electrode material including the coated active material.

[0085] In the battery manufacturing method according to the third embodiment, the first electrode may be formed by laminating the electrode material on a current collector. Alternatively, in the battery manufacturing method according to the third embodiment, the first electrode may be formed by forming an electrolyte layer and then laminating the electrode material on the electrolyte layer. The electrolyte layer may be formed by laminating a solid electrolyte material.

[0086] The electrode material may be prepared by mixing the coated active material with a solid electrolyte material, such as a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, or an organic polymer solid electrolyte.

[0087] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, and Li 3.25 Ge 0.25 P 0.75 S4, or Li 10 GeP2S 12 is.

[0088] Examples of oxide solid electrolytes include: (i) NASICON-type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutions; (ii) perovskite-type solid electrolytes such as (LaLi)TiO3; (iii) Li 14 ZnGeO 16 LISICON-type solid electrolytes such as LiSiO, LiGeO or elemental substitutions thereof; (iv) LiLaZrO 12 or an element-substituted product thereof, or (v) a garnet-type solid electrolyte such as Li3PO4 or an N-substituted product thereof.

[0089] Examples of halide solid electrolytes are Li2MgX'4, Li2FeX'4, Li(Al,Ga,In)X'4, Li3(Al,Ga,In)X'6, or LiX'.

[0090] Other examples of halide solid electrolytes include Li p Me qYZ6, where p + m'q + 3r = 6 and r > 0 are satisfied. Me is at least one element selected from the group consisting of metal elements and metalloid elements other than Li and Y. The value of m' represents the valence of Me. Z is at least one element selected from the group consisting of F, Cl, Br, and I. "Metalloid elements" are B, Si, Ge, As, Sb, and Te. "Metal elements" are all elements included in Groups 1 to 12 of the periodic table (excluding hydrogen) and all elements included in Groups 13 to 16 of the periodic table (excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se). In order to increase 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.

[0091] Examples of organic polymer solid electrolytes are compounds of polymer compounds and lithium salts.

[0092] The polymer compound may have an ethylene oxide structure. A polymer compound having an ethylene oxide structure can contain a large amount of lithium salt, thereby increasing ionic conductivity.

[0093] Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiSOCF, LiN(SOCF), LiN(SOCF), LiN(SOCF)(SOCF), or LiC(SOCF). One lithium salt selected from these may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may be used.

[0094] The electrode material may contain, in addition to the coated active material, a material capable of absorbing and releasing metal ions (e.g., lithium ions). When the active material in the composition is a negative electrode active material, the electrode material may further contain another negative electrode active material.

[0095] Examples of the negative electrode active material include the materials described in embodiment 1, as well as metal materials, carbon materials, oxides, nitrides, tin compounds, and silicon compounds. The metal material may be a simple metal material or an alloy. An example of the metal material is lithium metal or a lithium alloy. Examples of the carbon material are natural graphite, coke, partially graphitized carbon, carbon fiber, spherical carbon, artificial graphite, and amorphous carbon. From the viewpoint of capacity density, suitable examples of the negative electrode active material are silicon (i.e., Si), tin (i.e., Sn), silicon compounds, and tin compounds. Using an active material with a low average discharge voltage, such as graphite, as the negative electrode active material can improve the energy density of the battery.

[0096] The electrode material may further contain a conductive additive to enhance electronic conductivity.

[0097] Examples of the conductive additive include: (i) graphites such as natural graphite or artificial graphite, (ii) carbon blacks such as acetylene black or ketjen black, (iii) conductive fibers such as carbon fiber or metal fiber, (iv) carbon fluoride, (v) metal powders such as aluminum, (vi) conductive whiskers such as zinc oxide or potassium titanate, (vii) conductive metal oxides such as titanium oxide, or (viii) conductive polymer compounds such as polyaniline, polypyrrole, or polythiophene. For cost reduction, the conductive additives (i) or (ii) above may be used.

[0098] For the purpose of facilitating the transfer of lithium ions and improving the output characteristics of the battery, the electrode material may contain a non-aqueous electrolyte, a gel electrolyte, or an ionic liquid.

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

[0100] Examples of non-aqueous solvents are cyclic carbonate ester solvents, chain carbonate ester solvents, cyclic ether solvents, chain ether solvents, cyclic ester solvents, chain ester solvents, or fluorine-containing solvents. Examples of cyclic carbonate ester solvents are ethylene carbonate, propylene carbonate, or butylene carbonate. Examples of chain carbonate ester solvents are dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate. Examples of cyclic ether solvents are tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane. Examples of chain ether solvents are 1,2-dimethoxyethane or 1,2-diethoxyethane. An example of a cyclic ester solvent is γ-butyrolactone. An example of a chain ester solvent is methyl acetate. Examples of fluorine-containing solvents are fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, or fluorodimethylene carbonate. One non-aqueous solvent selected from these may be used alone, or a mixture of two or more non-aqueous solvents selected from these may be used.

[0101] Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiSOCF, LiN(SOCF), LiN(SOCF), LiN(SOCF)(SOCF), and LiC(SOCF). One lithium salt selected from these may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may be used.

[0102] The concentration of the lithium salt may be, for example, 0.5 mol / liter or more and 2 mol / liter or less.

[0103] The gel electrolyte may be a polymer material impregnated with a non-aqueous electrolyte, such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or a polymer having an ethylene oxide bond.

[0104] Examples of cations contained in the ionic liquid are: (i) aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium; (ii) aliphatic cyclic ammoniums such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiums, piperaziniums, or piperidiniums; or (iii) nitrogen-containing heterocyclic aromatic cations such as pyridiniums or imidazoliums.

[0105] An example of an anion contained in an ionic liquid is PF6 - , BF4 - , SbF6 - , AsF6 - , SO3CF3 - , N(SO2CF3)2 - , N(SO2C2F5)2 - , N(SO2CF3)(SO2C4F9) - , or C(SO2CF3)3 - is.

[0106] The ionic liquid may contain a lithium salt.

[0107] The electrode material may contain a binder to enhance adhesion between particles. The binder may be the material described above in the first embodiment.

[0108] Fourth Embodiment Hereinafter, a fourth embodiment of the present disclosure will be described. Matters described in the first to third embodiments will be omitted as appropriate.

[0109] The battery according to embodiment 4 includes a first electrode, a second electrode, and an electrolyte layer. The electrolyte layer is disposed between the first electrode and the second electrode. The first electrode contains the composition according to embodiment 1. That is, the battery according to embodiment 4 has a hydrogen bond term δh of HSP of 14.0 MPa. 1 / 2 Larger than 26.0 MPa 1 / 2 The battery according to the fourth embodiment includes a solvent having a solubility of less than 10 g / L, an organic substance having a solubility in the solvent of more than 10 g / L, and an active material containing element V. The battery according to the fourth embodiment has excellent charge-discharge characteristics.

[0110] When the composition contained in the first electrode includes a negative electrode active material, the first electrode is a negative electrode and the second electrode is a positive electrode. When the composition contained in the first electrode includes a positive electrode active material, the first electrode is a positive electrode and the second electrode is a negative electrode.

[0111] The second electrode may or may not contain the composition according to embodiment 1. When the first electrode is a negative electrode and the second electrode is a positive electrode, the first electrode may contain the composition according to embodiment 1 including a negative electrode active material, and the second electrode may contain the composition according to embodiment 1 including a positive electrode active material.

[0112] The first electrode may further include a conductive additive.

[0113] The battery according to the fourth embodiment can be manufactured by, for example, the method for manufacturing the battery according to the third embodiment.

[0114] A specific example of a battery will be described below, in which the first electrode is a negative electrode and the second electrode is a positive electrode.

[0115] FIG. 1 shows a cross-sectional view of a battery 1000 according to a fourth embodiment.

[0116] The battery 1000 includes a positive electrode 201 , an electrolyte layer 202 , and a negative electrode 203 .

[0117] The positive electrode 201 contains positive electrode active material particles 204 and solid electrolyte particles 100 .

[0118] The electrolyte layer 202 is disposed between the positive electrode 201 and the negative electrode 203 .

[0119] The electrolyte layer 202 contains an electrolyte material (for example, a solid electrolyte material).

[0120] The negative electrode 203 includes the composition according to embodiment 1. For example, the negative electrode 203 includes negative electrode active material particles 205, a solvent (not shown), an organic substance (not shown), and solid electrolyte particles 100, and the negative electrode active material particles 205 include a coated active material. The hydrogen bond term δh in the HSP of the solvent is 14.0 MPa. 1 / 2 Larger than 26.0 MPa 1 / 2The organic substance has a solubility in the solvent of greater than 10 g / L. The coated active material includes a negative electrode active material and a coating material that coats at least a portion of the surface of the negative electrode active material.

[0121] The coated active material is, for example, a coated active material manufactured by the manufacturing method according to the second embodiment.

[0122] As the negative electrode active material, the active material described above in the first embodiment can be used.

[0123] The coating material may include, for example, a conductive material. The conductive material may be obtained by carbonizing the organic material. The coating material may include the organic material in addition to the conductive material.

[0124] The negative electrode active material particles 205 may be particles containing the coated active material as a main component. Particles containing the coated active material as a main component refer to particles in which the coated active material is the component contained in the largest amount by mass. The negative electrode active material particles 205 may be particles consisting only of the coated active material.

[0125] The positive electrode 201 contains a material capable of absorbing and releasing metal ions (e.g., lithium ions). The material is, for example, a positive electrode active material (e.g., positive electrode active material particles 204).

[0126] Examples of positive electrode active materials include lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal oxyfluorides, transition metal oxysulfides, and transition metal oxynitrides. Examples of lithium-containing transition metal oxides include Li(Ni,Co,Al)O2, LiCoO2, and Li(Ni,Co,Mn)O2. From the viewpoint of battery energy density, a suitable example of the positive electrode active material is Li(Ni,Co,Mn)O2. Li(Ni,Co,Mn)O2 can be charged and discharged at a potential of 4 V or higher. In this disclosure, "(A,B,C)" means "at least one selected from the group consisting of A, B, and C." Here, A, B, and C all represent elements.

[0127] The positive electrode active material particles 204 may have a median diameter of 0.1 μm or more and 100 μm or less. When the positive electrode active material particles 204 have a median diameter of 0.1 μm or more, the positive electrode active material particles 204 and the solid electrolyte particles 100 can be well dispersed in the positive electrode 201. This improves the charge / discharge characteristics of the battery. When the positive electrode active material particles 204 have a median diameter of 100 μm or less, the lithium diffusion rate within the positive electrode active material particles 204 improves. This allows the battery to operate at high power.

[0128] The positive electrode active material particles 204 may have a larger median diameter than the solid electrolyte particles 100. This allows the positive electrode active material particles 204 and the solid electrolyte particles 100 to be dispersed well.

[0129] In order to increase the energy density and output of the battery, in the positive electrode 201, the ratio of the volume of the positive electrode active material particles 204 to the sum of the volume of the positive electrode active material particles 204 and the volume of the solid electrolyte particles 100 may be 0.30 or more and 0.95 or less.

[0130] To increase the energy density and power output of the battery, the positive electrode 201 may have a thickness of 10 μm or more and 500 μm or less.

[0131] The electrolyte layer 202 contains an electrolyte material. The electrolyte material is, for example, a solid electrolyte material. The electrolyte layer 202 may be a solid electrolyte layer.

[0132] The electrolyte layer 202 may be made of only a solid electrolyte material, such as the materials described above in the third embodiment.

[0133] The electrolyte layer 202 may have a thickness of 1 μm or more and 100 μm or less. When the electrolyte layer 202 has a thickness of 1 μm or more, the cathode 201 and the anode 203 are less likely to short-circuit. When the electrolyte layer 202 has a thickness of 100 μm or less, the battery can operate at high power.

[0134] The negative electrode 203 may contain, in addition to the above-mentioned coated active material, a material capable of absorbing and releasing metal ions (e.g., lithium ions). The material is, for example, a negative electrode active material.

[0135] As the negative electrode active material, for example, the negative electrode active material described above in the third embodiment can be used.

[0136] The negative electrode active material particles 205 may have a median diameter of 0.1 μm or more and 100 μm or less. When the negative electrode active material particles 205 have a median diameter of 0.1 μm or more, the negative electrode active material particles 205 and the solid electrolyte particles 100 are well dispersed in the negative electrode 203. This improves the charge / discharge characteristics of the battery. When the negative electrode active material particles 205 have a median diameter of 100 μm or less, the lithium diffusion rate within the negative electrode active material particles 205 is improved. This allows the battery to operate at high power.

[0137] The negative electrode active material particles 205 may have a larger median diameter than the solid electrolyte particles 100. This improves the dispersion state of the negative electrode active material particles 205 and the solid electrolyte particles 100 in the negative electrode 203.

[0138] In order to increase the energy density and output of the battery, in the negative electrode 203, the ratio of the volume of the negative electrode active material particles 205 to the sum of the volume of the negative electrode active material particles 205 and the volume of the solid electrolyte particles 100 may be 0.30 or more and 0.95 or less.

[0139] To increase the energy density and power output of the battery, the negative electrode 203 may have a thickness of 10 μm or more and 500 μm or less.

[0140] For the solid electrolyte particles 100, for example, the solid electrolyte material described above in the third embodiment can be used.

[0141] 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 nonaqueous electrolyte solution, a gel electrolyte, or an ionic liquid for the purpose of facilitating the transfer of lithium ions and improving the output characteristics of the battery. For the nonaqueous electrolyte solution, the gel electrolyte, or the ionic liquid, for example, the materials described in embodiment 3 can be used.

[0142] At least one selected from the group consisting of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a binder to enhance adhesion between particles. For example, the binder described in embodiment 3 can be used as the binder.

[0143] Examples of the shape of the battery according to the fourth embodiment include a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, and a laminate type.

[0144] The battery according to the fourth 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 an anode, and fabricating a laminate in which the positive electrode, the electrolyte layer, and the anode are arranged in this order by a known method. In this case, at least one selected from the group consisting of the material for forming the positive electrode and the material for forming the anode contains the composition according to the first embodiment.

[0145] (Other Embodiments) (Additional Notes) The above description of the embodiments discloses the following techniques.

[0146] (Technology 1) A method for manufacturing a semiconductor device comprising: a solvent; an organic substance; and an active material, wherein the hydrogen bond term δh in the Hansen solubility parameter of the solvent is 14.0 MPa. 1 / 2 Larger than 26.0 MPa 1 / 2 the solubility of the organic substance in the solvent is greater than 10 g / L; and the active material contains a V element.

[0147] This configuration makes it possible to realize an active material that can improve the charge / discharge capacity of a battery.

[0148] (Technology 2) The hydrogen bond parameter δh is 16.0 MPa 1 / 2 or more and 23.0 MPa 1 / 2 The composition according to Technology 1, which is as follows: According to this configuration, an active material capable of improving the charge / discharge capacity of a battery can be realized.

[0149] (Technology 3) The hydrogen bond parameter δh is 16.0 MPa 1 / 2 or more and 20.0 MPa 1 / 2 The composition according to Technology 1 or 2, which is as follows: According to such a configuration, an active material capable of improving the charge / discharge capacity of a battery can be realized.

[0150] (Technology 4) The composition according to any one of Technologies 1 to 3, wherein the solvent includes at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, and water. With this configuration, an active material that can improve the charge / discharge capacity of a battery can be realized.

[0151] (Technology 5) The composition according to Technology 4, wherein the solvent contains ethanol. With this configuration, an active material that can improve the charge / discharge capacity of a battery can be realized.

[0152] (Technology 6) The composition according to any one of Technologies 1 to 5, wherein the organic material has a hydroxy group but does not have a carboxy group. With this configuration, an active material that can improve the charge / discharge capacity of a battery can be realized.

[0153] (Technology 7) The composition according to any one of Technologies 1 to 6, wherein the organic material contains sugar. With this configuration, an active material that can improve the charge / discharge capacity of a battery can be realized.

[0154] (Technology 8) The composition according to any one of Technologies 1 to 7, wherein the sugar comprises at least one selected from the group consisting of fructose, mannose, sorbitol, and xylitol. With this configuration, an active material that can improve the charge / discharge capacity of a battery can be realized.

[0155] (Technology 9) The composition according to Technology 8, wherein the sugar includes fructose. With this configuration, an active material that can improve the charge / discharge capacity of a battery can be realized.

[0156] (Technology 10) The composition according to any one of Technologies 1 to 9, wherein the organic material includes a polymer compound. With this configuration, an active material that can improve the charge / discharge capacity of a battery can be realized.

[0157] (Technology 11) The active material is a compound represented by composition formula (1), Li 3+x+a V 1-x M x O 4+a / 2...Formula (1) wherein M is at least one selected from the group consisting of tetravalent metal elements and tetravalent metalloid elements, and composition formula (1) satisfies 0≦a<1 and 0≦x<1. The composition according to any one of techniques 1 to 10, wherein the compound represented by composition formula (1) is suitable for improving the charge / discharge characteristics of a battery. Therefore, this configuration can further improve the charge / discharge capacity of the battery.

[0158] (Technology 12) The composition according to Technology 11, wherein the composition formula (1) satisfies 0≦x≦0.15. With this configuration, the charge / discharge capacity of the battery can be further improved.

[0159] (Technology 13) The composition according to Technology 11 or 12, wherein M contains Ti. With this configuration, the charge / discharge capacity of the battery can be further improved.

[0160] (Technology 14) A method for producing a coated active material, comprising: (A) drying the composition according to any one of Technologies 1 to 13.

[0161] According to this configuration, it is possible to provide a coated active material that can improve the charge / discharge capacity of a battery.

[0162] (Technology 15) The method for producing a coated active material according to Technology 14, further comprising: (B) carbonizing the organic material by heat treatment. According to this configuration, a coated active material capable of improving the charge / discharge capacity of a battery can be provided.

[0163] (Technology 16) A method for manufacturing a battery including a first electrode, a second electrode, and an electrolyte layer disposed between the first electrode and the second electrode, wherein the method includes, in forming the first electrode, (A) drying the composition according to any one of Technologies 1 to 13, and (B) carbonizing the organic material by heat treatment.

[0164] With this configuration, a battery having excellent charge / discharge characteristics can be provided.

[0165] (Technology 17) A battery comprising: a first electrode; a second electrode; and an electrolyte layer disposed between the first electrode and the second electrode, wherein the first electrode comprises the composition according to any one of claims 1 to 13.

[0166] With this configuration, excellent charge / discharge characteristics can be achieved.

[0167] (Technology 18) The battery according to Technology 17, wherein the first electrode further contains a conductive additive. With this configuration, the first electrode has high electronic conductivity, and as a result, the battery has excellent charge / discharge characteristics.

[0168] Hereinafter, the present disclosure will be described in detail using examples and comparative examples.

[0169] Example 1 Preparation of Coated Active Material A 0.070 mol / L solution was prepared by dissolving 1.0 g of fructose in 80 mL of 2-propanol (IPA). Table 1 shows the hydrogen bond parameter δh in the HSP of 2-propanol. At 25°C, fructose was completely dissolved. A slurry was obtained by immersing 1 g of powder of the negative electrode active material Li3VO4 (hereinafter referred to as LVO) in the solution. The slurry was stirred for approximately 30 minutes and then filtered using a membrane filter with a mesh size of 1 μm. Filtration yielded LVO powder with the solution adhered to its surface. The obtained LVO powder was dried at 80°C under atmospheric pressure for 2 hours and then crushed. The crushed LVO powder was then calcined at 600°C for 24 hours in a vacuum atmosphere of 0.2 Pa or less, carbonizing the fructose present on the surface of the LVO powder. The fired product was crushed in a mortar to obtain a coated active material as an active material sample of Example 1.

[0170] [Measurement of Electronic Conductivity] FIG. 2 shows a schematic diagram of a pressure molding die 300 used to evaluate the electronic conductivity of the active material.

[0171] The pressure molding die 300 had an upper punch 301, a frame 302, and a lower punch 303. The frame 302 was made of insulating polycarbonate, and the upper punch 301 and the lower punch 303 were made of electronically conductive stainless steel.

[0172] The electronic conductivity of the coated active material of Example 1 was measured by the following method using the pressure molding die 300 shown in FIG.

[0173] In a dry argon atmosphere, the coated active material of Example 1 (i.e., sample 101 in FIG. 2 ) was filled into the inside of the pressure molding die 300. Inside the pressure molding die 300, a pressure of 720 MPa was applied to the coated active material of Example 1 using the upper punch 301 and the lower punch 303.

[0174] While pressure was still applied, the upper punch 301 and the lower punch 303 were connected to a potentiostat (Biologic, VSP-300) equipped with a frequency response analyzer. The upper punch 301 was connected to a working electrode and a potential measurement terminal. The lower punch 303 was connected to a counter electrode and a reference electrode. The electronic conductivity was measured by a direct current measurement method at room temperature.

[0175] Using the resistance value, the electronic conductivity was calculated based on the following formula (2): σ=(R E × S / t) -1 ...(2) where σ represents the electronic conductivity, and S represents the contact area of ​​the sample 101 with the punch upper portion 301 (equal to the cross-sectional area of ​​the hollow portion of the frame mold 302 in FIG. 2). E represents the resistance value of the coated active material in a DC measurement method, and t represents the thickness of the coated active material to which pressure is applied (equal to the thickness of the layer formed from sample 101 in FIG. 2).

[0176] The electronic conductivity of the coated active material of Example 1 measured at 25°C was 1.05 × 10 -1 The viscosity was S / cm.

[0177] [Preparation of Sulfide Solid Electrolyte] In an argon glove box with a dew point of -60°C or less, raw material powders LiS and PS were weighed out to a molar ratio of LiS:PS = 0.750:0.250. These raw material powders were pulverized and mixed in an agate mortar. A mixture was thus obtained. The mixture was then milled for 12 hours at 500 rpm using a planetary ball mill (Fritsch, Model P-7). This resulted in a glassy solid electrolyte. Next, in a glove box with a dew point of -60°C or less, the glassy solid electrolyte was fired at 270°C for 2 hours using a firing furnace. In this way, a powder of LiS-PS (hereinafter referred to as LPS), a glass-ceramic solid electrolyte, was obtained as a sulfide solid electrolyte.

[0178] [Preparation of Negative Electrode Material] In an argon glove box with a dew point of −60° C. or less, the coated active material of Example 1 and LPS were weighed out so that the volume ratio of LVO to LPS was 0.650:0.350. These were mixed in an agate mortar to prepare the negative electrode material of Example 1.

[0179] [Fabrication of Secondary Battery] LPS (94.0 mg) was placed in an insulating cylinder having an inner diameter of 9.50 mm, and a pressure of 80 MPa was applied to form a solid electrolyte layer.

[0180] Next, the negative electrode material (6.27 mg) of Example 1 was laminated on the solid electrolyte layer formed from LPS to obtain a laminate. A pressure of 720 MPa was applied to this laminate to form a negative electrode.

[0181] Next, a metal Li foil (thickness: 300 μm) was laminated on the solid electrolyte layer formed from LPS to obtain a laminate. A pressure of 80.0 MPa was applied to this laminate to form a positive electrode.

[0182] Current collectors made of stainless steel were placed on the positive and negative electrodes, and current collecting leads were attached to the current collectors.

[0183] Finally, the inside of the insulating cylinder was isolated from the outside atmosphere using an insulating ferrule, and the inside of the cylinder was sealed. In this way, the battery of Example 1 was obtained.

[0184] Example 2 Preparation of Coated Active Material A coated active material of Example 2 was obtained in the same manner as in Example 1, except that 80 mL of 1-propanol (NPA) was used instead of 80 mL of 2-propanol. The value of the hydrogen bond parameter δh in the HSP of 1-propanol is shown in Table 1. Note that fructose was completely dissolved at 25°C.

[0185] [Measurement of Electronic Conductivity] The electronic conductivity of the coated active material of Example 2 was measured in the same manner as in Example 1. The electronic conductivity of the coated active material of Example 2 measured at 25°C was 1.02 × 10 -1 The viscosity was S / cm.

[0186] [Preparation of Negative Electrode Material] The negative electrode material of Example 2 was obtained in the same manner as in Example 1, except that the coated active material of Example 2 was used.

[0187] [Fabrication of Secondary Battery] A battery of Example 2 was obtained in the same manner as in Example 1, except that the negative electrode material of Example 2 was used.

[0188] Example 3 A coated active material of Example 3 was obtained in the same manner as in Example 1, except that 80 mL of a mixed solvent prepared by mixing ethanol (EtOH), 2-propanol, and 1-propanol in a volume ratio of 69.5:3.9:6.6 was used instead of 80 mL of 2-propanol. The value of the hydrogen bond parameter δh in the HSP of the mixed solvent is shown in Table 1. Note that fructose was completely dissolved at 25°C.

[0189] [Measurement of Electronic Conductivity] The electronic conductivity of the coated active material of Example 3 was measured in the same manner as in Example 1. The electronic conductivity of the coated active material of Example 3 measured at 25°C was 1.07 × 10 -1 The viscosity was S / cm.

[0190] [Preparation of Negative Electrode Material] The negative electrode material of Example 3 was obtained in the same manner as in Example 1, except that the coated active material of Example 3 was used.

[0191] [Fabrication of Secondary Battery] A battery of Example 3 was obtained in the same manner as in Example 1, except that the negative electrode material of Example 3 was used.

[0192] Example 4 A coated active material of Example 4 was obtained in the same manner as in Example 1, except that 80 mL of ethanol was used instead of 80 mL of 2-propanol. The value of the hydrogen bond parameter δh in the HSP of ethanol is shown in Table 1. Note that fructose was completely dissolved at 25°C.

[0193] [Measurement of Electronic Conductivity] The electronic conductivity of the coated active material of Example 4 was measured in the same manner as in Example 1. The electronic conductivity of the coated active material of Example 4 measured at 25°C was 2.83 × 10 -3 The viscosity was S / cm.

[0194] [Preparation of Negative Electrode Material] The negative electrode material of Example 4 was obtained in the same manner as in Example 1, except that the coated active material of Example 4 was used.

[0195] [Fabrication of Secondary Battery] A battery of Example 4 was obtained in the same manner as in Example 1, except that the negative electrode material of Example 4 was used.

[0196] Example 5 A coated active material of Example 5 was obtained in the same manner as in Example 1, except that 80 mL of a mixed solvent prepared by mixing ethanol and water in a volume ratio of 78.4:1.6 was used instead of 80 mL of 2-propanol. The value of the hydrogen bond parameter δh in the HSP of the mixed solvent is shown in Table 1. Note that fructose was completely dissolved at 25°C.

[0197] [Measurement of Electronic Conductivity] The electronic conductivity of the coated active material of Example 5 was measured in the same manner as in Example 1. The electronic conductivity of the coated active material of Example 5 measured at 25°C was 1.14 × 10 -1 The viscosity was S / cm.

[0198] [Preparation of Negative Electrode Material] The negative electrode material of Example 5 was obtained in the same manner as in Example 1, except that the coated active material of Example 5 was used.

[0199] [Fabrication of Secondary Battery] A battery of Example 5 was obtained in the same manner as in Example 1, except that the negative electrode material of Example 5 was used.

[0200] Example 6 A coated active material of Example 6 was obtained in the same manner as in Example 1, except that 80 mL of a mixed solvent prepared by mixing methanol (MeOH) and ethanol in a volume ratio of 32:48 was used instead of 80 mL of 2-propanol. The value of the hydrogen bond parameter δh in the HSP of the mixed solvent is shown in Table 1. Note that fructose was completely dissolved at 25°C.

[0201] [Measurement of Electronic Conductivity] The electronic conductivity of the coated active material of Example 6 was measured in the same manner as in Example 1. The electronic conductivity of the coated active material of Example 6 measured at 25°C was 1.17 × 10 -1 The viscosity was S / cm.

[0202] [Preparation of Negative Electrode Material] The negative electrode material of Example 6 was obtained in the same manner as in Example 1, except that the coated active material of Example 6 was used.

[0203] [Fabrication of Secondary Battery] A battery of Example 6 was obtained in the same manner as in Example 1, except that the negative electrode material of Example 6 was used.

[0204] Example 7 A coated active material of Example 7 was obtained in the same manner as in Example 1, except that 80 mL of methanol was used instead of 80 mL of 2-propanol. The value of the hydrogen bond parameter δh in the HSP of methanol is shown in Table 1. Note that fructose was completely dissolved at 25°C.

[0205] [Measurement of Electronic Conductivity] The electronic conductivity of the coated active material of Example 7 was measured in the same manner as in Example 1. The electronic conductivity of the coated active material of Example 7 measured at 25°C was 1.01 × 10 -1 The viscosity was S / cm.

[0206] [Preparation of Negative Electrode Material] The negative electrode material of Example 7 was obtained in the same manner as in Example 1, except that the coated active material of Example 7 was used.

[0207] [Fabrication of Secondary Battery] A battery of Example 7 was obtained in the same manner as in Example 1, except that the negative electrode material of Example 7 was used.

[0208] Comparative Example 1: 1.0 g of fructose was dissolved in 80 mL of ethylene glycol (EG) to prepare a 0.070 mol / L solution. The value of the hydrogen bond parameter δh in the HSP of ethylene glycol is shown in Table 1. 1 g of LVO powder was immersed in the solution to obtain a slurry. After stirring the slurry for approximately 30 minutes, the solution was filtered using a membrane filter with 1 μm openings. However, since the LVO was almost completely dissolved, the LVO powder could not be filtered out, and a coated active material could not be obtained.

[0209] Comparative Example 2: 1.0 g of fructose was dissolved in 80 mL of a mixed solvent of ethanol and water in a 40:40 volume ratio to prepare a 0.070 mol / L solution. The hydrogen bond parameter δh value in the HSP of this mixed solvent is shown in Table 1. 1 g of LVO powder was immersed in this solution to obtain a slurry. After stirring the slurry for approximately 30 minutes, the solution was filtered using a membrane filter with 1 μm openings. However, since the LVO was almost completely dissolved, the LVO powder could not be filtered out, and a coated active material could not be obtained.

[0210] Comparative Example 3: 1.0 g of fructose was dissolved in 80 mL of water to prepare a 0.070 mol / L solution. The value of the hydrogen bond parameter δh in the HSP of water is shown in Table 1. 1 g of LVO powder was immersed in the solution to obtain a slurry. After stirring the slurry for approximately 30 minutes, the solution was filtered using a membrane filter with 1 μm openings. However, since almost all of the LVO had dissolved in the water, the LVO powder could not be filtered out, and a coated active material could not be obtained.

[0211] Comparative Example 4: A mixture was obtained by adding 1.0 g of fructose to 80 mL of acetonitrile (MeCN). The value of the hydrogen bond parameter δh in the HSP of acetonitrile is shown in Table 1. When the mixture was stirred for about 30 minutes, fructose did not dissolve in acetonitrile and precipitated. Therefore, a fructose solution could not be obtained, and therefore the LVO powder surface could not be coated.

[0212] Comparative Example 5: A mixture was obtained by adding 1.0 g of fructose to 80 mL of acetone (MeCO). The value of the hydrogen bond parameter δh in the HSP of acetone is shown in Table 1. When the mixture was stirred for about 30 minutes, the fructose did not dissolve in the acetone and precipitated. Therefore, a fructose solution could not be obtained, and therefore the LVO powder surface could not be coated.

[0213] Comparative Example 6: 1 g of LVO powder was immersed in 80 mL of ethanol to obtain a slurry. The slurry was stirred for approximately 30 minutes and then filtered using a membrane filter with 1 μm mesh size to obtain an LVO powder. The obtained LVO powder was dried at 80°C under atmospheric pressure for 2 hours and then crushed. The crushed LVO powder was then fired at 600°C for 24 hours in a vacuum atmosphere of 0.2 Pa or less. The fired product was crushed in a mortar to obtain an active material sample of Comparative Example 6.

[0214] Comparative Example 7 A solution was prepared by adding 1.0 g of glucose to 80 mL of ethanol. The glucose did not dissolve in the ethanol but precipitated. The solubility of glucose in 100 mL of ethanol at 25°C is less than 0.1 g. An active material sample of Comparative Example 7 was obtained by the same procedure as in Example 1, except that a slurry was obtained by immersing 1 g of LVO powder in the solution containing the precipitated glucose. The active material sample of Comparative Example 7 was a mixed powder of LVO and conductive carbon. No coated active material was obtained in Comparative Example 7.

[0215] Comparative Example 8 A solution was prepared by adding 1.0 g of sucrose to 80 mL of ethanol. The sucrose did not dissolve in the ethanol but precipitated. The solubility of sucrose in 100 mL of ethanol at 25°C is less than 0.1 g. An active material sample of Comparative Example 8 was obtained by the same procedure as in Example 1, except that a slurry was obtained by immersing 1 g of LVO powder in the solution containing the precipitated sucrose. The active material sample of Comparative Example 8 was a mixed powder of LVO and conductive carbon. In Comparative Example 8, no coated active material was obtained.

[0216] [Measurement of Electronic Conductivity] The electronic conductivity of the active material sample of Comparative Example 6 was measured in the same manner as in Example 1. The electronic conductivity of the active material sample of Comparative Example 6 was 1.0 × 10 -10 The viscosity was below 100 S / cm and was therefore unmeasurable.

[0217] [Preparation of Negative Electrode Material] Negative electrode materials of Comparative Examples 6 to 8 were obtained in the same manner as in Example 1, except that the active material samples of Comparative Examples 6 to 8 were used.

[0218] [Fabrication of Secondary Battery] A battery of Comparative Example 6 was obtained in the same manner as in Example 1, except that the negative electrode materials of Comparative Examples 6 to 8 were used.

[0219] [Charge / Discharge Measurement] The initial charge / discharge characteristics of the batteries of Examples 1 to 7 and Comparative Examples 6 to 8 were measured by the following method. The produced batteries were cells for charge / discharge tests and corresponded to half-cells of the negative electrode. Therefore, in the examples, charging refers to a state in which current flows in the direction in which lithium ions move from metallic Li (i.e., the above-mentioned positive electrode) to the negative electrode, and discharging refers to a state in which current flows in the direction in which lithium ions move from the negative electrode to metallic Li (i.e., the above-mentioned positive electrode). In other words, the direction in which the potential of the half-cell decreases is called charging, and the direction in which the potential increases is called discharging.

[0220] The battery was placed in a thermostatic chamber at 25°C.

[0221] 78 μA / cm 2 The battery was charged until the negative electrode reached a voltage of 0.30 V relative to the positive electrode at a current density of 0.05 C (20-hour rate) relative to the theoretical capacity of the battery.

[0222] Next, 78 μA / cm 2 The battery was discharged until the negative electrode reached a voltage of 2.50 V relative to the positive electrode at a current density of 0.05 C (20-hour rate) relative to the theoretical capacity of the battery.

[0223] As a result of the charge / discharge measurement, the battery according to Example 1 had an initial charge capacity of 1.37 mAh. Figure 3 is a graph showing the initial charge / discharge characteristics of the battery according to Example 1.

[0224] The battery according to Example 2 had an initial charge capacity of 1.13 mAh.

[0225] The battery according to Example 3 had an initial charge capacity of 1.21 mAh.

[0226] The battery according to Example 4 had an initial charge capacity of 1.14 mAh.

[0227] The battery according to Example 5 had an initial charge capacity of 1.25 mAh.

[0228] The battery according to Example 6 had an initial charge capacity of 1.00 mAh.

[0229] The battery according to Example 7 had an initial charge capacity of 1.08 mAh.

[0230] The battery according to Comparative Example 6 had an initial charge capacity of 0.100 mAh.

[0231] The battery according to Comparative Example 7 had an initial charge capacity of 0.130 mAh.

[0232] The battery according to Comparative Example 8 had an initial charge capacity of 0.160 mAh.

[0233]

[0234] <<Discussion>> In Examples 1 to 7, coated active materials with high electronic conductivity and batteries with improved charge capacities were obtained. The batteries of Examples 1 to 7 exhibited higher charge capacities than the batteries of Comparative Examples 6 to 8.

[0235] In the preparation of the coated active material, the hydrogen bond term δh of HSP is 26 MPa 1 / 2 In Comparative Examples 1 to 3, which used the above solvents, LVO dissolved in the solvent, and a coated active material could not be produced. This is thought to be because hydroxy groups bonded to vanadium in LVO to form a complex, causing LVO to dissolve in the solvent and decompose, making it impossible to maintain its structure.

[0236] From Examples 3, 5, and 6 and Comparative Example 2, when a mixed solvent containing a solvent with a large hydrogen bond parameter δh of HSP was used, the value of the hydrogen bond parameter δh of the mixed solvent was 26 MPa. 1 / 2It was found that when the temperature is less than 100°C, good carbon coating can be achieved without dissolving LVO, and a coated active material with high electronic conductivity and a battery with improved charge capacity can be obtained. This is thought to be because the solvents are miscible with each other and the entire mixed solvent exhibits uniform polarity.

[0237] In the preparation of the coated active material, the hydrogen bond term δh of HSP is 14.0 MPa. 1 / 2 In Comparative Examples 4 and 5, in which the following solvents were used, fructose did not dissolve in the solvent, and a solution for coating LVO could not be obtained. This is thought to be because the polarity of the solvent was insufficient, and the fructose molecules were not solvated.

[0238] In Comparative Examples 7 and 8, in which glucose and sucrose were used as organic substances in the preparation of the coated active material, the organic substances did not dissolve in the solvent, resulting in a decrease in charge capacity. This is thought to be because the organic substances could not be adsorbed onto the LVO surface, preventing the formation of a coated active material, and because a large amount of the organic substances was carbonized to form carbon residues, which were then included in the active material sample, increasing the electrode resistance.

[0239] The battery of the present disclosure can be used, for example, as an all-solid-state lithium secondary battery.

[0240] REFERENCE SIGNS LIST 100 Solid electrolyte particles 201 Positive electrode 202 Electrolyte layer 203 Negative electrode 204 Positive electrode active material particles 205 Negative electrode active material particles 1000 Battery 300 Pressure molding die 301 Upper punch 302 Frame 303 Lower punch 101 Sample

Claims

1. A method for producing a liquid crystal display comprising the steps of: a solvent; an organic substance; and an active material; wherein the hydrogen bond term δh in the Hansen solubility parameter of the solvent is 14.0 MPa. 1 / 2 Larger than 26.0MPa 1 / 2 a solubility of the organic matter in the solvent is greater than 10 g / L; the active material includes a V element; and the organic matter includes at least one selected from the group consisting of fructose, mannose, sorbitol, and xylitol.

2. The hydrogen bond term δh is 16.0 MPa. 1 / 2 More than 23.0 MPa 1 / 2 2. The composition of claim 1, wherein:

3. The hydrogen bond term δh is 16.0 MPa. 1 / 2 More than 20.0 MPa 1 / 2 2. The composition of claim 1, wherein:

4. The composition of claim 1, wherein the solvent comprises at least one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, and water.

5. The composition of claim 4, wherein the solvent comprises ethanol.

6. The composition according to claim 1, wherein the organic material has a hydroxy group and no carboxy group.

7. The composition of claim 1, wherein the organic matter comprises fructose.

8. The composition according to claim 1, wherein the organic material comprises a polymer compound.

9. The active material is a compound represented by the composition formula (1), Li 3+x+a V 1-x M x O 4+a / 2 2. The composition according to claim 1 , wherein M is at least one selected from the group consisting of tetravalent metal elements and tetravalent metalloid elements, and wherein the composition formula (1) satisfies 0≦a<1 and 0≦x<1.

10. The composition according to claim 9, wherein the composition formula (1) satisfies 0≦x≦0.

15.

11. The composition of claim 9, wherein M comprises Ti.

12. A method for producing a coated active material, comprising: (A) drying the composition according to any one of claims 1 to 11.

13. The method for producing a coated active material according to claim 12, further comprising: (B) carbonizing the organic material by heat treatment.

14. A method for manufacturing a battery comprising: a first electrode; a second electrode; and an electrolyte layer disposed between the first electrode and the second electrode, the method comprising, in forming the first electrode, (A) drying a composition according to any one of claims 1 to 11; and (B) carbonizing the organic matter by heat treatment.

15. A battery comprising: a first electrode; a second electrode; and an electrolyte layer disposed between the first electrode and the second electrode, wherein the first electrode comprises the composition of any one of claims 1 to 11.

16. The battery according to claim 15, wherein the first electrode further comprises a conductive additive.

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