Method for manufacturing electrode material and electrode material

Abstract

The present invention provides a method for manufacturing electrode materials that allows for the efficient and safe production of granular active material using a suspension in which the active material is dispersed in an organic solvent, while suppressing hydrogen generation, and also provides an electrode material that can be produced in this manner. [Solution] A method for producing an electrode material for a non-aqueous electrolyte secondary battery, comprising the step of heating a mixture obtained by mixing an aqueous solution of an inorganic binder containing an inorganic binder as a component and a suspension in which an active material is dispersed in an organic solvent, thereby vaporizing the water in the mixture and obtaining granules containing the inorganic binder and the active material, wherein the solid content concentration of the aqueous solution of the inorganic binder is 1% by mass or more and 30% by mass or less.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing electrode materials and electrode materials, and more particularly to a method for manufacturing materials for non-aqueous electrolyte secondary batteries and electrode materials for non-aqueous electrolyte secondary batteries. [Background technology]

[0002] Conventionally, in electrode materials for non-aqueous secondary batteries such as lithium-ion batteries, a technique has been known in which active material particles such as Si particles are compounded with a binder to form granules, with the aim of increasing capacity and improving cycle characteristics (for example, Patent Document 1). In addition, a wet grinding method is known as a method for micronizing Si particles, in which a suspension in which Si particles are dispersed is ground using a bead mill (for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2013-235682 [Patent Document 2] Japanese Patent Publication No. 2020-17389 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] When forming granules from active material particles such as Si particles using a wet grinding method, the active material particles are dispersed to form a suspension. The dispersion medium used in this suspension can be a liquid such as water or an organic solvent, or any other fluid material. When the dispersion medium is water and the active material is an alloying material or a material that may react with water, hydrogen generation may occur as the active material disperses in the dispersion medium. A similar problem can occur when the binder uses water as a solvent or dispersion medium. Therefore, when using a binder that uses water as a solvent or dispersion medium (aqueous binder) with alloying materials, the water decomposes and generates hydrogen gas, making it very difficult to handle and resulting in difficulties in obtaining uniform electrodes. In addition, simultaneously with hydrogen generation, an oxide film is easily formed on the surface of the alloying material, causing a decrease in capacity and an increase in internal resistance. Hydrogen generation and oxide film formation occur, for example, according to Equation 1 below. Si+2H2O→SiO2+2H2↑···Formula 1

[0005] To suppress hydrogen generation, organic solvents are sometimes selected as dispersion media. While a wide variety of solvents exist, including hydrocarbons, alcohols, ketones, esters, glycols, glycol ethers, halogens, and nitrogen-based solvents, alcohols are preferred because they suppress the alteration of the active material and hydrogen generation, have minimal impact on human health and the environment, and are inexpensive.

[0006] As a specific example of a method for preparing an electrode active material consisting of Si particles using an alcohol-based solvent as a dispersion medium, the median diameter (D 50 A mixture of 5μm Si powder and ethanol is placed in a bead mill (zirconia beads φ20μm) and processed for 10 minutes to obtain the median diameter (D 50 A suspension containing 300 nm silicon can be easily prepared. In this case, corresponding to the use of ethanol as the dispersion medium, no hydrogen generation from the suspension was observed, suggesting that the oxidation reaction of Si as shown in Equation 1 did not proceed. If ethanol were replaced with water, although the Si could be pulverized, a large amount of hydrogen generation would be observed from the suspension.

[0007] Granules consisting of an active material and a granulation binder can be produced by mixing the active material powder, obtained by removing ethanol as a dispersion medium from the suspension containing ethanol and Si particles obtained above, with the granulation binder, and then drying the mixture. However, this method requires a step to produce the active material powder by removing the dispersion medium from the suspension before the granulation process, thus increasing the number of manufacturing steps.

[0008] If granulation binders could be added directly to the above suspension to produce granules, it would be efficient because the process of removing the organic solvent used as a dispersion medium would be eliminated. However, in that case, the granulation binder used must not only not generate hydrogen, but also retain its fluidity and binder function even when in contact with the organic solvent contained in the suspension.

[0009] In view of the above, the problem that the present invention aims to solve is to provide a method for producing an electrode material that can efficiently and safely produce granules of an active material using a suspension in which an active material is dispersed in an organic solvent, while suppressing hydrogen generation, and to provide an electrode material that can be produced in this manner. [Means for solving the problem]

[0010] To solve the above problems, the method for manufacturing an electrode material and the electrode material of the present invention have the following configuration.

[0011] [1] The present invention relates to a method for producing an electrode material for a non-aqueous electrolyte secondary battery, comprising the steps of heating a mixture obtained by mixing an aqueous solution of an inorganic binder containing an inorganic binder as a component and a suspension in which an active material is dispersed in an organic solvent, thereby vaporizing the water in the mixture and obtaining granules containing the inorganic binder and the active material, wherein the solid content concentration of the aqueous solution of the inorganic binder is 1% by mass or more and 30% by mass or less.

[0012] [2] In the aspect of [1] above, it is preferable that the phosphate contains aluminum phosphate represented by the empirical formula Al2O3·nP2O5·mH2O (0.5 ≦ n ≦ 4, 0 ≦ m ≦ 8).

[0013] [3] In the aspect of [1] or [2] above, the solid content concentration of the suspension is preferably 1% by mass or more and 30% by mass or less, the suspension further contains water, and in the suspension, the concentration of water with respect to the organic solvent is preferably 10% by mass or more.

[0014] [4] In any of the aspects from [1] to [3] above, the organic solvent is preferably a water-soluble organic solvent.

[0015] [5] In the aspect of [4] above, the water-soluble organic solvent is preferably alcohol-based.

[0016] [6] In any of the aspects from [1] to [5] above, the heat treatment is preferably a step of heating under the conditions of 100°C or more and 500°C or less.

[0017] [7] In any of the aspects from [1] to [6] above, the active material preferably consists of single particles with a median diameter (D 50 ) of 10 nm or more and 1 μm or less.

[0018] [8] In any of the aspects from [1] to [7] above, the active material preferably contains a material capable of forming an alloy phase with an alkali metal.

[0019] [9] In the aspect of [8] above, the material capable of forming an alloy phase with the alkali metal is preferably a Si-based material.

[0020]

[10] In any of the aspects from [1] to [9] above, the mixed solution preferably further contains carbon.

[0021]

[11] In any of the aspects from [1] to

[10] above, the method for manufacturing the electrode material has a median diameter (D 50It is preferable to obtain the aforementioned granules in the shape of 0.5 μm to 50 μm.

[0022]

[12] In any of the embodiments described in [1] to

[11] above, the heat treatment may include a step by spray drying.

[0023]

[13] The electrode material of the present invention is an electrode material for a non-aqueous electrolyte secondary battery, wherein the electrode material is a granule containing an inorganic binder having a phosphate component and an active material, and the inorganic binder is contained in an amount of 1% by mass or more and 30% by mass or less.

[0024]

[14] In the embodiment described in

[13] above, the phosphate may contain aluminum phosphate represented by the structural formula Al2O3·nP2O5·mH2O (0.5≦n≦4, 0≦m≦8).

[0025]

[15] In the embodiments of

[13] or

[14] above, the active material may include a Si-based material.

[0026]

[16] In the embodiment described in

[15] above, the Si-based material may include Si particles and SiX compound particles, where X is at least one element selected from Fe, Co, Ni, Zr, Ti, Cr, V, and Nb.

[0027]

[17] In the embodiment of

[16] above, it is preferable that the mass ratio of the Si particles in the active material is 10% or more and 90% or less, and the mass ratio of the SiX compound particles is 5% or more and 90% or less.

[0028]

[18] In the embodiment of

[17] above, it is preferable that the mass ratio of the Si particles in the active material is 20% or more and 50% or less, and the mass ratio of the SiX compound particles is 30% or more and 85% or less.

[0029]

[19] In any of the embodiments described in

[16] to

[18] above, the Si-based material may further contain YCu compound particles. [Effects of the Invention]

[0030] In the method for manufacturing the electrode material of the present invention having the configuration described in [1] above, an aqueous solution containing an inorganic binder and a suspension in which an active material is dispersed in an organic solvent are directly mixed, and a granule containing the inorganic binder and the active material is obtained by heat treatment of the mixture. Since there is no need to remove the organic solvent constituting the suspension, the electrode material can be manufactured efficiently. By using an inorganic binder containing phosphate, oxidation of the active material and hydrogen generation during the manufacturing process of the electrode material can be suppressed. Therefore, the manufacturing of the granule can be carried out safely. By setting the solid content concentration in the aqueous inorganic binder solution to 1% by mass or more, a high effect can be obtained in suppressing hydrogen generation and improving the mechanical strength of the manufactured granule. Furthermore, by setting the concentration to 30% by mass or less, aggregation and precipitation of phosphate in the aqueous inorganic binder solution are less likely to occur, making it easier to manufacture a homogeneous granule. In addition, the electrode material obtained by this manufacturing method is given the characteristics of excellent flame resistance and low hydrogen generation upon contact with water. Furthermore, a non-aqueous electrolyte secondary battery using this electrode material has excellent cycle characteristics, can operate stably in high-temperature environments, and has low electrode resistance. In addition, it reduces the likelihood of battery overheating, thus improving safety.

[0031] In the embodiment described in [2] above, the phosphate contains aluminum phosphate represented by the structural formula Al2O3·nP2O5·mH2O, which contains predetermined m and n. In this case, a granular material with high mechanical strength is obtained, and its flame resistance is also enhanced.

[0032] In the embodiment described in [3] above, the solid content concentration of the suspension is 1% by mass or more and 30% by mass or less, the suspension further contains water, and the concentration of water relative to the organic solvent in the suspension is 10% by mass or more. By including water within the above range in addition to the organic solvent, the suspension is made easier to mix with the aqueous solution of the inorganic binder, and aggregation and precipitation of the inorganic binder are less likely to occur.

[0033] In the embodiment described in [4] above, the organic solvent is a water-soluble organic solvent. In this case, the suspension and the aqueous solution of the inorganic binder become less likely to separate. Furthermore, in the embodiment described in [5] above, the water-soluble organic solvent is an alcohol-based solvent. In this case, the volatility of the solvent is within an appropriate range, and the impact on the environment and human health is kept to a minimum.

[0034] In the embodiment described in [6] above, the heat treatment is carried out at a temperature of 100°C to 500°C. In this case, the mechanical strength of the granules is effectively improved by hardening due to drying of the phosphate, and dephosphorylation due to excessive heating is suppressed.

[0035] In the embodiment described in [7] above, the active material has a median diameter (D 50 It is composed of single particles between 10 nm and 1 μm in size. In this case, it is easier to obtain excellent cycle characteristics and output characteristics in a battery constructed using the electrode material of the present invention.

[0036] In the embodiment described in [8] above, the active material includes a material capable of forming an alloy phase with an alkali metal. Furthermore, in the embodiment described in [9] above, a Si-based material is used as the material capable of forming an alloy phase with an alkali metal. In these cases, a large theoretical capacity can be obtained in a non-aqueous electrolyte secondary battery constructed using the manufactured electrode material.

[0037] In the embodiment described in

[10] above, the mixture further contains carbon. In this case, the resulting granules contain carbon, which functions as a conductive additive, in addition to the active material and inorganic binder, thereby improving the conductivity of the granules.

[0038] In the embodiment described in

[11] above, the median diameter (D 50) Obtain spherical granules with a particle size of 0.5 μm to 50 μm. In this case, making the granules spherical makes it easier to increase density when forming electrodes from the electrode material, and also makes it easier to avoid uneven charging and discharging. Furthermore, by making the granules with the above particle size, the handling of the granule powder is improved, and it becomes easier to manufacture uniform electrodes.

[0039] In the embodiment described in

[12] above, the heat treatment includes a spray-drying step. In this case, spherical granules are easily obtained, and the particle size of the granules can be easily controlled.

[0040] The electrode material of the present invention having the configuration described in

[13] above is composed of granules containing an inorganic binder with phosphate as a component and an active material, and the inorganic binder content is 1% by mass or more and 30% by mass or less. This electrode material can be suitably manufactured by any of the manufacturing methods described in [1] to

[12] above. Therefore, the electrode material of the present invention can be efficiently manufactured using a suspension in which the active material is dispersed in an organic solvent, and oxidation of the active material and hydrogen generation are suppressed during the manufacturing process. Furthermore, this electrode material has excellent flame resistance and is less likely to generate hydrogen when in contact with water. Moreover, a non-aqueous electrolyte secondary battery using this electrode material has excellent cycle characteristics, can operate stably in high-temperature environments, and has low electrode resistance. In addition, thermal runaway of the battery is less likely to occur, and safety is also enhanced.

[0041] In the embodiment described in

[14] above, the phosphate contained in the granules contains aluminum phosphate represented by the structural formula Al2O3·nP2O5·mH2O, which contains predetermined m and n elements, thereby increasing the mechanical strength and flame resistance of the granules.

[0042] In the embodiment described in

[15] above, a large theoretical capacity can be obtained in a non-aqueous electrolyte secondary battery constructed using electrode materials, because the active material contains a Si-based material.

[0043] Furthermore, in the embodiment described in

[16] above, the Si-based material contains Si particles and SiX compound particles, thereby providing high cycle characteristics in a non-aqueous electrolyte secondary battery constructed using the electrode material. In particular, in the embodiments described in

[17] and

[18] above, by setting the mass ratio of Si particles and SiX compound particles in the active material to a predetermined range, high cycle characteristics and high discharge characteristics can be obtained.

[0044] In the embodiment described above

[19] , the effect of improving cycle characteristics is particularly enhanced when the Si-based material further contains YCu compound particles. [Brief explanation of the drawing]

[0045] [Figure 1] This is a schematic diagram illustrating a method for manufacturing an electrode material according to one embodiment of the present invention. The area within the dashed lines is an enlarged view of the granulated material. [Figure 2] This is a scanning electron microscope (SEM) image of the electrode composite layer in Example 1. [Figure 3] This is a surface SEM image of the electrode composite layer in Example 2. [Figure 4] This is a surface SEM image of the electrode composite layer in Example 3. [Figure 5] This is a surface SEM image of the electrode composite layer in Example 4. [Figure 6] This is a surface SEM image of the electrode composite layer in Example 5. [Figure 7] This is a surface SEM image of the electrode composite layer in Example 6. [Figure 8] This is a surface SEM image of the electrode composite layer of Comparative Example 1. [Figure 9] This is a surface SEM image of the electrode composite layer in Comparative Example 2. [Figure 10] This is the differential scanning calorimetry (DSC) curve for Example 1. [Figure 11] This is the DSC curve for Example 2. [Figure 12] This is the DSC curve for Example 3. [Figure 13] This is the DSC curve for Example 4. [Figure 14] This is the DSC curve for Example 5. [Figure 15] This is the DSC curve for Example 6. [Figure 16] This is the DSC curve for Comparative Example 1. [Figure 17] This is the DSC curve for Comparative Example 2. [Modes for carrying out the invention]

[0046] A method for manufacturing an electrode material according to one embodiment of the present invention, and an electrode material according to one embodiment, will be described in detail below.

[0047] [1] Method for manufacturing electrode material and outline of electrode material A method for manufacturing an electrode material according to one embodiment of the present invention is a method for manufacturing an electrode material for a non-aqueous electrolyte secondary battery. Furthermore, the electrode material according to the embodiment of the present invention is an electrode material for a non-aqueous electrolyte secondary battery and can be manufactured by the above manufacturing method. According to the method for manufacturing an electrode material according to one embodiment of the present invention described below, an electrode material consisting of a granule containing an active material can be efficiently manufactured, and oxidation of the active material and hydrogen generation during the manufacturing process of the electrode material can be suppressed.

[0048] In this specification, "granulated material" refers to secondary particles formed by using a granulation binder to create composite particles that are larger than the raw active material (single particle). "Active material" refers to electrode active material, which is a substance that can undergo reversible chemical changes through charging and discharging, and is capable of adsorbing or releasing carriers. "Granulation binder" is a material that binds the active materials together and improves the mechanical strength of the granulated material.

[0049] In the method for manufacturing the electrode material of this embodiment, as schematically shown in Figure 1, as a granulation step, an aqueous solution 4 of an inorganic binder containing an inorganic binder 1 having phosphate (for example, Al2O3·3P2O5) as a component is mixed with a suspension 6 in which an active material 2 is dispersed in an organic solvent 5. Then, as an example, the mixture 7 is subjected to heat treatment using a spray dryer. Through heat treatment, a granule 3 is produced that contains the inorganic binder 1 containing phosphate as a component, the active material 2, and optionally a conductive additive. The specific raw materials and other details will be described in order below. The manufacturing method according to this embodiment does not include a step of removing the organic solvent 5 from the suspension 6 before preparing the mixture 7.

[0050] [2] Suspension containing the active material In this manufacturing method, as described above, a suspension in which the active material is dispersed in an organic solvent as a dispersion medium is used as the raw material for manufacturing the electrode material. The dispersion medium used in this suspension is an organic solvent. This is because using an organic solvent makes it less likely for the surface of the active material to oxidize, thus reducing the likelihood of deterioration of the active material. Then, by mixing this suspension containing the organic solvent and the active material with an aqueous solution of an inorganic binder containing phosphate, and then drying it, the active material and the inorganic binder are compounded, and a granulated material can be obtained. By using an organic solvent, it is possible to prevent a decrease in reversible capacity and an increase in resistance due to deterioration of the active material in electrodes using the manufactured electrode material, and it is also possible to suppress hydrogen generation in the manufacturing process of the electrode material. The suspension can be suitably prepared by a wet grinding method using a bead mill or the like.

[0051] The active material contained in the suspension is not particularly limited as long as it is an active material used in non-aqueous electrolyte secondary batteries. For example, in the case of lithium-ion batteries, it is not particularly limited as long as it is an active material that can intercept and release the lithium ions used. Examples of such active materials include known active materials such as alkali metal / transition metal composite oxide systems, vanadium systems, sulfur systems, solid solution systems (lithium-rich, sodium-rich, potassium-rich), carbon systems, organic systems, graphite, hard carbon, soft carbon, lithium titanate, alloying materials, and conversion materials. In addition to these, one type of active material may be used, or two or more types may be used. From the viewpoint of high theoretical capacity, it is preferable to use materials that can form an alloy phase with alkali metals, in particular alloying materials such as tin (Sn), silicon (Si), aluminum (Al), germanium (Ge), and silver (Ag). Among these, Si and SiO are particularly preferable due to their high capacity. x (x is a real number between 0.3 and 1.4), preferably a Si-based material such as a Si-M alloy. In other words, it is preferable that the active material contains particles containing Si. The Si-M alloy may be any of the following: a fully solid-solution alloy, a eutectic alloy, a hypoeutectic alloy, a hypereutectic alloy, or a peritectic alloy, where M is a metallic element and examples include iron (Fe), nickel (Ni), cobalt (Co), chromium (Cr), yttrium (Y), aluminum (Al), vanadium (V), tin (Sn), manganese (Mn), zirconium (Zr), titanium (Ti), copper (Cu), niobium (Nb), and molybdenum (Mo). The surface of the active material particles may be coated with a material with excellent electronic conductivity such as carbon or ceramics.

[0052] As a preferred example of the Si-based material constituting the active material, which includes a Si-M alloy, a Si-based material can be described as one in which the Si-based material includes Si particles and SiX compound particles. Here, element X is at least one element selected from Fe, Co, Ni, Zr, Ti, Cr, V, and Nb. All of element X are elements capable of forming compounds (silicides) with Si. Preferably, element X contains at least Fe. The Si particles are mainly composed of Si only, excluding unavoidable impurities, or an alloy in which element X is solid-solved in Si. Preferably, Si accounts for 95% by mass or more in the Si particles. The SiX compound particles are mainly composed of an intermetallic compound of Si and element X. Preferably, the SiX intermetallic compound accounts for 95% by mass or more in the SiX compound particles. By including SiX compound particles in addition to Si particles in the Si-based material constituting the active material, the electrode material becomes superior in terms of cycle characteristics. This is because SiX compound particles do not easily undergo volume changes during charging and discharging.

[0053] While there are no particular limitations on the ratio of Si particles to SiX compound particles in the active material, it is preferable that the mass ratio of Si particles (the ratio of their mass to the total active material) is in the range of 10% to 90% and the mass ratio of SiX compound particles is in the range of 5% to 90%. This results in a high level of improvement in cycle characteristics. Furthermore, the electrode material exhibits high discharge characteristics. In other words, it exhibits high discharge capacity even at high-rate discharge. In particular, when the mass ratio of Si particles is in the range of 20% to 50% and the mass ratio of SiX compound particles is in the range of 30% to 85%, the effect of improving discharge characteristics is enhanced. Moreover, it is preferable that the mass ratio of Si particles is in the range of 25% to 40% and the mass ratio of SiX compound particles is in the range of 55% to 75%.

[0054] When the active material Si-based material contains Si particles and SiX compound particles, the Si-based material may further contain YCu compound particles. Here, element Y is at least one element selected from Sn, Al, In, and Bi. None of the elements Y form compounds with Si, but they can form compounds with copper (Cu). Preferably, element Y contains at least Sn. The YCu compound particles are mainly composed of an intermetallic compound of element Y and Cu. Preferably, in the YCu compound particles, the YCu intermetallic compound accounts for 95% by mass or more. Including YCu compound particles in addition to Si particles and SiX compound particles in the Si-based material constituting the active material further enhances the effect of improving cycle characteristics. This is because the YCu compound particles exhibit a buffering effect that mitigates the difference in volume expansion coefficients between Si particles and SiX compound particles. The content of YCu compound particles in the active material is not particularly limited, but it is preferable that the mass percentage in the active material is in the range of 0.1% to 1%.

[0055] When a Si-based material contains Si particles, SiX compound particles, and optionally YCu compound particles, these Si particles, SiX compound particles, and YCu compound particles each constitute independent particles. A mixture of these particles is then compounded and bound together by a phosphate-based inorganic binder to form a granulated material.

[0056] To produce an active material containing Si-based materials, for example, Si alloy powder can be prepared by atomization methods such as gas atomization. By producing powder of an alloy containing Si and, if necessary, metallic elements such as element X, element Y, and Cu, by atomization, a metal powder can be obtained in which the Si phase, and depending on the component composition, the SiX compound phase and the YCu compound phase, have crystallized. When the obtained metal powder is pulverized by methods such as bead milling, these multiple phases are separated, and Si particles, SiX compound particles, and YCu compound particles become independent particles. The resulting particle mixture can then be used as the raw material for the granulation process, which will be described later.

[0057] The shape of the active material particles is not particularly limited, and can be any shape such as spherical, elliptical, crushed, cuttlebone-shaped, belt-shaped, fibrous, flaky, donut-shaped, amorphous, etc. Also, each shape can be solid or hollow. However, from the viewpoints of easily densifying the electrode composite layer by compressing the electrode with a press and hardly causing non-uniform charge and discharge in the electrode, it is preferable that the particles are spherical and solid.

[0058] From the viewpoint of excellent cycle characteristics and output characteristics of the battery, the above-mentioned active material is preferably composed of single particles with a median diameter (D 50 ) of 10 nm or more and 1 μm or less. Note that a single particle refers to a state of a primary particle dispersed as one particle, different from an agglomerate composed of secondary particles in which a plurality of particles are aggregated or connected. In this specification, the median diameter (D 50 ) means the particle diameter based on volume in the laser diffraction / scattering particle size distribution measurement method. The laser diffraction / scattering particle size distribution measurement method is a method for measuring the particle size by utilizing the phenomenon that the light intensity distribution of the diffracted and scattered light varies depending on the particle size when laser light is applied to the particles. When the active material contains Si particles, SiX compound particles, and further, if necessary, YCu compound particles, it is preferable that each of these particles is composed of single particles having the above median diameter.

[0059] In addition to the above-mentioned active material, the suspension may further contain ceramics such as alumina, silica, and zirconia, and alkali metal-containing transition metal oxides such as lithium niobate, sodium niobate, and lithium silicate, etc. as fillers for relaxing the volume change accompanying charge and discharge, together with the active material.

[0060] The organic solvent used as the dispersion medium is not particularly limited and includes hydrocarbons such as toluene, xylene, dipentene, cyclohexane, methylcyclohexane, ethylcyclohexane, n-hexane, isohexane, n-pentane, and styrene monomer; alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol (IPA), n-butanol, isobutanol, octanol, benzyl alcohol, and diacetone alcohol; ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, methoxybutyl acetate, methyl methoxybutyl acetate, ethyl-3-ethoxypropionate, and propylene glycol Examples of organic solvents include esters such as methyl monomethyl ether propionate, dibasic acid esters, and dimethyl carbonate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl hexyl ketone, diisobutyl ketone, cyclohexanone, and isophorone; glycol ethers such as butyl glycol, methyl diglycol, ethyl diglycol, butyl diglycol, 1-methoxy-2-propanol, methyl dipropylene glycol, 3-methoxybutanol, 3-methyl-3-methoxybutanol, and tetrahydrofuran; nitrogen-based solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone (NMP); and halogen-based solvents such as alkyl halides, trichloroethylene, chloroform, hydrofluorocarbons, and hydrochlorofluorocarbons.

[0061] The above organic solvents include those soluble in water and those insoluble in water. However, for the reason that they do not separate from the aqueous solution of phosphate-based inorganic binder used in the granulation process, water-soluble organic solvents are preferred, and water-miscible organic solvents are more preferred. A water-miscible organic solvent is a water-soluble organic solvent that can be mixed with water in any ratio. From the viewpoint of having solvent volatility that is neither too high nor too low and having minimal impact on the environment and human health, alcohol-based organic solvents such as ethanol, 1-propanol, and IPA, or nitrogen-based organic solvents such as NMP are particularly preferred.

[0062] The above suspension preferably contains water to facilitate mixing with the aqueous solution of the phosphate-based inorganic binder. When the suspension contains water in this way, if the organic solvent used in the suspension is a nonpolar solvent, the suspension is prone to separation, making mixing with the phosphate-based inorganic binder difficult. Therefore, it is preferable to select a water-soluble organic solvent such as an alcohol-based or nitrogen-based solvent as the organic solvent constituting the suspension. Among these, as mentioned above, alcohol-based organic solvents such as ethanol, 1-propanol, and IPA, and nitrogen-based organic solvents such as NMP are more preferable. Furthermore, when the suspension contains water, it is preferable that the concentration of water in the suspension is 10% by mass or more relative to the organic solvent, so that the inorganic binder is less likely to aggregate or precipitate when the suspension is mixed with the aqueous solution of the phosphate-based inorganic binder. Specifically, the mass ratio of the organic solvent to water is preferably 1:9 to 9:1, and more preferably 2:8 to 7:3. In addition, the suspension preferably has a solid content concentration of 1% by mass or more and 30% by mass or less, from the viewpoint of securing a sufficient amount of active material and improving the dispersibility of the active material. The solid content concentration of the suspension refers to the proportion of the suspension that is in solid form.

[0063] [3] Inorganic binder aqueous solution In the manufacturing method according to this embodiment, as described above, an aqueous solution of an inorganic binder containing an inorganic binder with phosphate as a component (phosphate-based inorganic binder aqueous solution) is used as a raw material for manufacturing electrode materials together with the suspension described above. By using a phosphate-based inorganic binder as a granulation binder, electrode materials with high flame resistance can be manufactured, and hydrogen generation and oxidation of the active material can be suppressed during the manufacturing process of the electrode materials.

[0064] Generally, granules manufactured using active Si-based materials as the active material and resin-based binders as the granulation binder may not exhibit sufficient flame resistance. Even polyimide (PI), which is used as a resin-based binder with excellent flame resistance, possesses a certain degree of flammability.

[0065] In contrast, inorganic binders with phosphate as the main component (phosphate-based inorganic binders) are known to have superior flame resistance compared to resin-based binders such as PI. Other typical characteristics of phosphate-based inorganic binders include a high melting point, resistance to thermal decomposition, and chemical stability. For example, because inorganic binders with phosphate as the main component have a higher melting point than resin-based binders, they have long been used in applications requiring fire resistance. Furthermore, their strong cohesive force during drying makes it easy to obtain dense granules. In addition, when using Si-based materials as the active material, the specific gravity of phosphate-based inorganic binders is similar to that of Si, so if the suspension and the inorganic binder aqueous solution are thoroughly and uniformly mixed, it is expected that a homogeneous mixture will be easier to maintain. Moreover, phosphate-based inorganic binders do not easily lose their fluidity and binder function even when in contact with organic solvents contained in the suspension.

[0066] In addition to phosphate-based inorganic binders, other well-known inorganic binders include those primarily composed of silicates such as lithium silicate, sodium silicate, potassium silicate, and ammonium silicate (silicate-based inorganic binders). However, if aqueous solutions of these silicate-based inorganic binders are used, hydrogen gas is generated when they come into contact with alloy materials. Therefore, not all inorganic binders, including silicate-based inorganic binders, are suitable for this invention, which aims to suppress hydrogen generation. The inventors investigated various inorganic binders and found that aqueous solutions of phosphate-based inorganic binders effectively suppress hydrogen generation when in contact with the active material. For this reason, in the manufacturing method according to this embodiment, a phosphate-based inorganic binder is used as the inorganic binder for granulation.

[0067] The reason why using a phosphate-based inorganic binder suppresses hydrogen generation when the inorganic binder aqueous solution comes into contact with the active material is that, for example, phosphates such as aluminum phosphate are acidic solutes, and therefore have the function of making the water near the electrode material acidic when the electrode material comes into contact with water. Since hydrogen generation is suppressed in acidic water, it is thought that the oxidation of the active material such as Si alloy by water is also suppressed.

[0068] However, phosphates, which are components of inorganic binders, are practically insoluble in organic solvents. For example, even if aluminum phosphate (Al2O3·3P2O5·5H2O) is added in powder form to a suspension (40% solid content) consisting of ethanol and Si-based material, a homogeneous fine particle mixture cannot be obtained. If a homogeneous fine particle mixture cannot be obtained, the granulated material will be heterogeneous, and the cycle characteristics and stability in high-temperature environments of electrodes made from the granulated material will deteriorate, and the electrode impedance will tend to increase. It can also cause large variations in the characteristics of each electrode.

[0069] Therefore, in the manufacturing method according to this embodiment, the phosphate-based inorganic binder is mixed with the suspension as an aqueous solution with a solid content concentration of 30% by mass or less. This allows for the acquisition of a homogeneous fine particle mixture after mixing with the suspension. The reason the solid content concentration is set to 30% by mass or less is that if the solid content concentration exceeds 30% by mass, the water that was hydrating the phosphate ions hydrates with the organic solvent constituting the suspension, such as alcohol, due to phenomena known as salting out or alcohol precipitation, causing the phosphate ions to be released as phosphates. Depending on various conditions such as the solid content concentration and solvent type of the mixture, the liquid temperature, and the dropping rate, this released substance can take on the form of heterogeneous bulk aggregates, powdery precipitates, or homogeneous gel-like substances. For example, even when attempting to produce granules by adding an aqueous solution of aluminum phosphate (Al2O3·3P2O5) with a solid content concentration of 35% by mass to a suspension (solid content concentration of 40% by mass) consisting of ethanol and a Si-based material, large bulk aggregates are formed immediately after adding the aqueous solution of aluminum phosphate to the suspension containing ethanol. Therefore, controlling the particle size of the granulated material is extremely difficult, and obtaining a homogeneous granulated material also becomes challenging.

[0070] However, by keeping the solid content concentration of the aluminum phosphate aqueous solution below 30% by mass, even if the liberation of phosphates by salting out cannot be completely suppressed when mixed with the suspension, aggregation and precipitation of phosphates are significantly reduced, resulting in a homogeneous fine-grained mixture or gel-like mixture. This enables the production of homogeneous granules and increases the production efficiency of electrode materials. The same applies to other phosphates. However, if the solid content concentration of the phosphate-based inorganic binder aqueous solution is less than 1% by mass, the effects of the phosphate-based inorganic binder, such as suppression of hydrogen generation and the production of granules with high mechanical strength, cannot be fully realized. For this reason, in the production method according to this embodiment, the solid content concentration of the phosphate-based inorganic binder aqueous solution is set to 1% by mass or more and 30% by mass or less. More preferably, the solid content concentration is 3% by mass or more and 20% by mass or less. Note that the solid content concentration of the phosphate-based inorganic binder aqueous solution refers to the proportion of the solid content of the phosphate-based inorganic binder in the entire aqueous solution.

[0071] The solid content concentration of the phosphate-based inorganic binder aqueous solution can be appropriately determined within the range of 1% to 30% by mass, as described above. However, in the manufactured granules, as the proportion of granulation binder decreases and the proportion of active material increases, the electrode material tends to provide electrodes with superior output characteristics and high energy density. On the other hand, the mechanical strength and flame resistance of the granules tend to decrease. If the granules are brittle, they may collapse during the slurry mixing process when forming electrodes from the granules, or during the charging and discharging process of the manufactured electrodes, potentially increasing electrode impedance. Furthermore, if the proportion of non-flammable phosphate-based inorganic binder is low, the granules are more prone to overheating and ignition. Therefore, considering the viewpoints of ensuring sufficient strength to maintain the shape of the granules and sufficient flame resistance, as well as ensuring the required output characteristics of the electrodes, the solid content concentration of the phosphate-based inorganic binder aqueous solution and the mixing ratio of the phosphate-based inorganic binder aqueous solution to the suspension containing the active material should be set accordingly. Specifically, although it depends on the type and particle size of the active material, if the active material has a median diameter (D 50 When the particles are Si-based single particles between 10 nm and 1 μm in size, the ratio of the granulation binder to the entire granule is preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less.

[0072] Furthermore, the phosphate constituting the phosphate-based inorganic binder is not particularly limited, but aluminum phosphate is preferred. In particular, it is preferable that it contains aluminum phosphate represented by the structural formula Al2O3·nP2O5·mH2O (0.5≦n≦4, 0≦m≦10). When the condition that n is a real number between 0.5 and 4 is met, a granule with high mechanical strength and high flame resistance can be obtained even with a small amount of granulation binder used. Also, within the above range, the smaller n is, the better the water resistance of the granule after heat treatment. High water resistance of the granule makes it easier to use an aqueous binder as an electrode binder (a binder used when forming the granule into an electrode). Also, when heat treatment is performed on the phosphate, if the value of n is small, aluminum tetrametaphosphate (Al4(P4O 12 )3) is easily produced, and when the value of n is large, aluminum orthophosphate (AlPO4) tends to be produced more easily.

[0073] The phosphates constituting the above-mentioned phosphate-based inorganic binder may include, in place of Al2O3, or in addition to Al2O3, B2O3, SiO2, GeO2, Fe2O3, TiO2, MnO, CaO, MgO, V2O5, As2O3, TeO2, ZnO, PbO, etc. However, if these metal oxides are present in large quantities, it may cause a decrease in strength or an irreversible increase in the battery's capacity. For this reason, even if these metal oxides are included in the phosphate, it is preferable that the amount is less than that of Al2O3. More preferably, the entire amount of phosphate constituting the phosphate-based inorganic binder is the above-mentioned aluminum phosphate.

[0074] The phosphate constituting the phosphate-based inorganic binder may be anhydrous (m=0) or hydrated (m>0). However, in the case of a hydrate, as described above, the hydration number m of aluminum phosphate is a real number of 10 or less. Furthermore, if the hydration number m is a real number greater than 8, the mechanical strength of the granules may decrease, which may cause the granule structure to easily collapse during the slurry manufacturing process, or the flame resistance may not be sufficiently improved, or the irreversible capacity may increase. For this reason, the hydration number m of aluminum phosphate is preferably 8 or less, and more preferably 6 or less.

[0075] The phosphates such as aluminum phosphate mentioned above harden upon drying and, upon further heat treatment at high temperatures, undergo dehydration to form metallophosphate bonds such as aluminophosphate bonds, transforming into strong substances. Specifically, at heat treatment temperatures of 100-150°C, the hydration number m is between 6 and 8; at 150-200°C, it is between 5 and 6; at 200-300°C, it is between 2 and 5; and at 450-500°C, it is almost 0. Thus, after heating and drying at temperatures above 450°C, the hydration water contained in the phosphate is completely removed, but at temperatures above 1000°C, a dephosphorization reaction occurs, and the value of n decreases. From this viewpoint, in heat treatment performed after mixing an aqueous solution of phosphate-based inorganic binder with a suspension containing an active material, it is preferable to set the heating temperature to between 100°C and 500°C.

[0076] When preparing an aqueous solution of phosphate-based inorganic binder, the phosphate can be a pre-prepared phosphate dissolved in water, or it can be produced by reacting orthophosphoric acid (H3PO4) with a metal source such as an aluminum source. For example, aluminum phosphate can be produced by reacting 1 mole of orthophosphoric acid with 3 moles of aluminum hydroxide. If the reactivity is poor, heating tends to improve it. Since orthophosphoric acid is soluble in water, alcohol, and ether, it may also be added to a suspension consisting of an organic solvent and an active material.

[0077] In addition to the phosphate mentioned above, the inorganic binder aqueous solution may also contain alkali metal oxides (A2O; A is an alkali metal element) or alkali metal salts. The inclusion of alkali metal oxides or alkali metal salts in the inorganic binder aqueous solution is expected to reduce the resistance of batteries manufactured using the electrode material. However, if alkali metal oxides or alkali metal salts are present in excess, the strength of the granules will decrease; therefore, it is preferable that they be included at a concentration of 20% by mass or less relative to the phosphate mentioned above. A sum of approximately 0.1% by mass or more is generally sufficient to obtain the desired effect.

[0078] In addition to the phosphate salts mentioned above, the inorganic binder aqueous solution may also contain boron compounds such as boric acid (B(OH)3), metaboric acid (HBO2), and boron oxide (B2O3). The inclusion of boron compounds has the effect of making the electrode material less susceptible to moisture absorption, and is therefore expected to suppress moisture degradation of the electrolyte and electrolyte in batteries. In this case, it is preferable that the boron compound is included in an amount of 20% by mass or less relative to the phosphate salts. The effect of the addition can be sufficiently obtained if the amount added is approximately 0.1% by mass or more.

[0079] In addition to the phosphates mentioned above, the inorganic binder aqueous solution may also contain organic nitrogen compounds such as ammonium salts, urea, and urea phosphate. The inclusion of organic nitrogen compounds has the effect of making the electrode material less susceptible to moisture absorption, and is therefore expected to suppress moisture degradation of the electrolyte and electrolyte in the battery. In this case, it is preferable that the organic nitrogen compound is included in an amount of 20% by mass or less relative to the phosphates mentioned above. A sufficient amount of addition, approximately 0.1% by mass or more, is sufficient to obtain the effect of the addition.

[0080] The aqueous solution of the inorganic binder may also contain a resin-based binder in addition to the phosphate-based inorganic binder mentioned above, as a binder for granulation. Known resin-based binders can be used. For example, resin-based binders commonly used for positive and negative electrodes can be used. From the viewpoint of chemical stability, heat resistance, and reduction resistance of the granulated material, polybenzimidazole, styrene-butadiene rubber, polyvinylidene fluoride, carboxymethylcellulose salt, polyvinyl alcohol, polyacrylic acid, polyacrylate, cellulose nanofiber, polyimide, polyamic acid, polyamide, and polyamideimide are preferred. However, from the viewpoint of maintaining high flame resistance of the granulated material, the content of the resin-based binder should be kept below 100% of the phosphate-based inorganic binder. If particularly high heat resistance of the granulated material is required, it is better not to add a resin-based binder.

[0081] Furthermore, the aqueous inorganic binder solution may also contain ceramic particles in addition to the phosphate-based inorganic binder described above, as a granulation binder. Known ceramic particles can be used. Examples include silica, alumina, zirconia, titania, and yttria. When ceramic particles are added, the amount added should be between 0.1% and 20% relative to the phosphate. Note that if the aqueous inorganic binder solution contains solid components other than the phosphate-based inorganic binder, such as alkali metal compounds, boron compounds, organic nitrogen compounds, resin-based binders, and ceramic particles listed here, the solid content concentration of the phosphate-based inorganic binder described above as 1% to 30% by mass shall be defined as the solid content concentration of the phosphate-based inorganic binder only, excluding those other solid components.

[0082] [4] Granulation process As described above, in the manufacturing method according to this embodiment, as a granulation step, an aqueous solution of an inorganic binder containing phosphate is mixed with a suspension containing an active material dispersed in an organic solvent, and the mixture is heated to vaporize the water to obtain granules. The method of mixing the aqueous solution of the inorganic binder and the suspension is not particularly limited as long as a homogeneous mixture of each material can be obtained, but known stirring or mixing methods such as multi-axis planetary mixers, rolling mills, vibrating mills, planetary mills, oscillating mills, horizontal mills, attritor mills, jet mills, grinders, ultrasonic homogenizers, agitated homogenizers, fludizers, paint shakers, mixers, and magnetic stirrers can be used.

[0083] Furthermore, the above mixture may consist only of an aqueous solution of an inorganic binder containing phosphate and a suspension in which the active material is dispersed in an organic solvent, but it is preferable to add carbon as a conductive additive. By adding carbon, the cycle characteristics and input / output characteristics of the manufactured electrode can be improved. The carbon may be added in any of the following forms: dispersed in the aqueous solution of the inorganic binder containing phosphate, dispersed together with the suspension in which the active material is dispersed in an organic solvent, or dispersed in a mixture consisting of the aqueous solution of the inorganic binder and the suspension.

[0084] As for the carbon, there are no particular restrictions as long as it improves the conductivity of the granules, and known carbons can be used as conductive additives for electrodes. Examples include graphite, furnace black, channel black, acetylene black, thermal black, lamp black, disk black, roller black, carbon black, soft carbon, hard carbon, glassy carbon, carbon nanotubes, carbon nanofibers (e.g., vapor-grown carbon fibers such as the registered trademark "VGCF"), graphene, and carbon nanohorns, and one or more of these may be used.

[0085] When the total amount of active material, inorganic binder, and carbon contained in the granules is taken as 100% by mass, it is preferable that the carbon content is 1 to 40% by mass. There are carbon materials that combine the functions of both a conductive additive and an active material (such as graphite, soft carbon, and hard carbon), but when using materials other than these carbon materials as the active material, such as materials that can form an alloy phase with alkali metals, if the carbon content exceeds 40% by mass, the proportion of active material in the battery decreases accordingly, which tends to result in a lower electrode capacity density.

[0086] There are no particular restrictions on the method of heat treatment to obtain granules containing the inorganic binder and active material after mixing an aqueous solution of the inorganic binder with a suspension containing the active material to prepare a mixture. For example, known heat treatments such as heating and drying, hot air drying, vacuum heating and drying, far-infrared drying, spray drying, and fluidized bed drying can be used. Among these, it is preferable to include the spray drying method in the heat treatment, as this makes it easier to form spherical granules and control the particle size. As explained above in the section on aqueous solution of inorganic binder, it is preferable that the heating temperature during the heat treatment be between 100°C and 500°C.

[0087] In the spray-drying method, the mixed solution is formed into fine droplets and instantly dried to remove the liquid components, thereby forming a granule in which the active material is bound together by an inorganic binder. For example, a mixed solution in which the active material is dispersed in an aqueous solution of an inorganic binder is sprayed from above into a heated room at 50-300°C at a rate of 1-30 mL / min and an air pressure of 0.01-5 MPa to create aggregated granules, which are then dried to obtain a granule. The granule obtained by the spray-drying method may be further subjected to vacuum drying.

[0088] The median diameter (D) of the granules produced by the manufacturing method according to this embodiment 50The median diameter of the granules is preferably 0.5 μm or more and 50 μm or less. Setting the median diameter of the granules to 0.5 μm or more suppresses deterioration of the powder's handling properties due to scattering or aggregation of the granule powder. On the other hand, setting the median diameter of the granules to 50 μm or less suppresses surface irregularities on the electrode during electrode fabrication, making it easier to produce a uniform electrode. To adjust the particle size of the granules, it is preferable to perform sieving classification, cyclone classification, gravimetric classification, inertial classification, centrifugal classification, or precipitation classification.

[0089] The resulting granules may be further coated with carbon, metal oxides, solid electrolytes, etc. In this case, the amount of coating material is preferably 0.1% to 20% by mass relative to the granules. For example, if a carbon film is formed on the surface of the granules by CVD, the decomposition of the electrolyte is suppressed in batteries manufactured using electrode materials, and very good cycle characteristics can be obtained.

[0090] A granulated body for use as an electrode material according to this embodiment is obtained through a granulation process. The granulated body contains an inorganic binder with phosphate as a component and an active material. Furthermore, the granulated body may contain additives such as carbon as a conductive aid, if necessary. In the electrode material, it is preferable that the content of the phosphate-based inorganic binder is 1% by mass or more and 30% by mass or less. Having the content of the phosphate-based inorganic binder within this range allows for a high level of effect from using the phosphate-based inorganic binder, such as improved mechanical strength and flame resistance of the granulated body, and also makes it easier to obtain a homogeneous granulated body by avoiding precipitation and aggregation of the phosphate-based inorganic binder during the manufacturing process. More preferably, the content of the phosphate-based inorganic binder is 3% by mass or more, and more preferably 10% by mass or more. It is also preferable that it be 20% by mass or less, and more preferably 15% by mass or less. Note that the content of the phosphate-based inorganic binder in the electrode material refers to the ratio of the phosphate-based inorganic binder to the total solid content of the electrode material.

[0091] In the manufacturing method according to this embodiment, granules containing an active material and a binder can be manufactured efficiently while suppressing hydrogen generation and surface oxidation of the active material. The electrode material obtained in this manner according to this embodiment has high flame resistance and thermal stability, as well as high cycle characteristics. Furthermore, when made into a slurry, the slurry has high coating properties. Generally, in granules of electrode materials, as the particle size increases, granules with excellent flame resistance are obtained, and the scattering of the electrode material decreases, resulting in excellent handling, but the input / output characteristics tend to decrease. Also, if the active material contains a material that undergoes a large volume change with charging and discharging (for example, an alloy material that can form an alloy phase with alkali metals), the cycle characteristics of the energy storage device deteriorate. However, as shown in later examples, the granules manufactured by the manufacturing method of this embodiment provide electrodes with high flame resistance and high thermal stability, as well as high input / output characteristics and high cycle characteristics.

[0092] [5] Use of electrode materials The electrode material obtained according to this embodiment as described above can be used as a material for the positive or negative electrode (electrode) of a non-aqueous electrolyte secondary battery. Specifically, the electrode can be manufactured by molding the electrode material together with an electrode binder onto a current collector.

[0093] Any electrode binder can be used that can be dispersed or dissolved in water or an organic solvent and has the function of adhering the current collector and the granular active material. The electrode material in this embodiment has the characteristic of not generating hydrogen even when in contact with water. For this reason, the electrode binder may be a water-based binder. Examples of electrode binders include polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyimide (PI), polyamide, polyamide-imide, polyacrylic, styrene-butadiene rubber (SBR), ethylene-vinyl acetate copolymer (EVA), styrene-ethylene-butylene-styrene copolymer (SEBS), carboxymethylcellulose (CMC), xanthan gum, polyvinyl alcohol (PVA), polyvinyl butyral (PVB), ethylene vinyl alcohol, polyethylene (PE), polypropylene (PP), polyacrylic acid, lithium polyacrylate, sodium polyacrylate, potassium polyacrylate, ammonium polyacrylate, methyl polyacrylate, ethyl polyacrylate, polyacrylate amine, polyacrylic acid ester, epoxy resin, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), nylon, vinyl chloride, silicone rubber, nitrile rubber, shear Noacrylate, urea resin, melamine resin, phenol resin, latex, polyurethane, silylated urethane, nitrocellulose, dextrin, polyvinylpyrrolidone, vinyl acetate, polystyrene, chloropropylene, resorcinol resin, polyaromatic, modified silicone, methacrylic resin, polybutene, butyl rubber, 2-propenoic acid, cyanoacrylic acid, methyl methacrylate, glycidyl methacrylate, acrylic oligomer, 2-hydroxyethyl acrylate Resin-based binders such as phosphate, polyacetal, alginic acid, starch, sucrose, lacquer, animal glue, casein, and cellulose nanofiber can be used, as well as inorganic binders such as lithium silicate (Li2O·nSiO2; n=0.5~6), sodium silicate (Na2O·nSiO2; n=0.5~6), potassium silicate (K2O·nSiO2; n=0.5~6), colloidal silica, cement, and aluminum phosphate (Al2O3·nP2O5; n=0.5~6).These electrode binders may be used individually or in combination of two or more types.

[0094] When forming electrodes, electrode material is mixed with an electrode binder to prepare an electrode slurry. Preferably, the electrode slurry contains 0.1 to 30% by mass of electrode binder, where the total solid content of the electrode slurry is 100% by mass. Including 0.1% by mass or more of electrode binder increases the flexibility of the electrode, making it less likely for peeling or detachment to occur during the electrode pressing and winding processes. On the other hand, keeping the binder content below 30% by mass results in high ionic conductivity and low electrical resistance in the electrode, as well as ensuring a sufficient proportion of active material for the battery, thereby increasing the electrode capacity density.

[0095] Preferably, the electrode slurry further contains a conductive additive. When the total amount of solids in the electrode slurry is taken as 100%, it is preferable that the conductive additive is contained in an amount of 0.5% by mass or more and 20% by mass or less. The conductive additive for the electrode is not particularly limited as long as it has electronic conductivity; for example, the same carbon used as the granulation conductive additive described above can be used.

[0096] The current collector used in the electrode can be any material that has electronic conductivity and can conduct electricity to the active material it holds. For example, it is desirable to use a current collector made of Cu, Ni, Ti, Al, stainless steel (SUS), carbon, or alloys or coatings containing these elements. The shape of the current collector can be linear, rod-shaped, plate-shaped, foil-shaped, or porous, and any of these can be used. The electrode can be manufactured by molding the electrode slurry into the desired shape on the surface of the current collector by coating or other means, and then drying it as appropriate.

[0097] The electrodes obtained in this way can be used as the positive or negative electrode of a non-aqueous electrolyte secondary battery. A non-aqueous electrolyte secondary battery is a battery that comprises a positive electrode, a negative electrode, and a non-aqueous electrolyte interposed between the positive and negative electrodes, and examples include lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, lithium-ion capacitors, sodium-ion capacitors, and potassium-ion capacitors.

[0098] When the fabricated electrode is used as the positive electrode of a secondary battery, the secondary battery can be manufactured by combining it with an electrode whose charge / discharge potential is less noble than that electrode. On the other hand, when the fabricated electrode is used as the negative electrode of a secondary battery, the secondary battery can be manufactured by combining it with an electrode whose charge / discharge potential is more noble than that electrode. For example, when the fabricated electrode is used as the positive electrode, the counter electrode (negative electrode) is not particularly limited as long as it is an electrode used as the negative electrode of a secondary battery.

[0099] The electrolyte used in a secondary battery can be any liquid or solid capable of moving alkali metal ions or fluorine compound anions from the positive electrode to the negative electrode, or from the negative electrode to the positive electrode (e.g., lithium-supported salts). In other words, the same electrolytes used in secondary batteries using known non-aqueous electrolytes can be used. Examples include electrolyte solutions, gel electrolytes, solid electrolytes, ionic liquids, and molten salts. Here, an electrolyte solution refers to a state in which the electrolyte is dissolved in a solvent.

[0100] The structure of a secondary battery is not particularly limited, but existing forms and structures such as stacked and wound types can be adopted. In these forms, an electrode group in which the positive and negative electrodes are stacked or wound with a separator between them is sealed while immersed in an electrolyte to form a secondary battery. Alternatively, an electrode group in which the positive and negative electrodes are stacked or wound with a solid electrolyte between them is sealed to form a secondary battery.

[0101] Lithium-ion capacitors can be manufactured in the same manner as lithium-ion batteries, except that the operation of the counter electrode is the main difference. Specifically, for example, they can be manufactured in the same manner as batteries, except that the electrode of this embodiment is used as the positive electrode and a conventional negative electrode for lithium-ion capacitors is used as the negative electrode. Alkali metal ion batteries other than lithium-ion batteries can be manufactured in the same manner as lithium-ion batteries, except that lithium, which is the charge carrier of lithium-ion batteries, is replaced with sodium or potassium. Specifically, sodium-ion batteries can be manufactured in the same manner as the above-mentioned batteries, except that the electrode manufactured above is used as the positive electrode, a conventional negative electrode for sodium-ion batteries is used as the negative electrode, and a sodium-supporting salt is used as the electrolyte. Potassium-ion batteries can be manufactured in the same manner as lithium-ion batteries, except that the electrode manufactured above is used as the positive electrode, a conventional negative electrode for potassium-ion batteries is used as the negative electrode, and a potassium-supporting salt is used as the electrolyte.

[0102] As described above, the electrode material according to this embodiment has high flame resistance and high thermal stability, and electrodes made using this electrode material have high input / output characteristics and high cycle characteristics. As shown in the examples described later, the flame resistance and thermal stability of the electrode material can be evaluated by determining whether it is a Class 2 hazardous material and by performing differential scanning calorimetry (DSC), respectively. Furthermore, the input / output characteristics and cycle characteristics of the electrodes can be evaluated by making a lithium-ion battery using the electrode material and performing charge / discharge tests. [Examples]

[0103] Examples of the present invention are shown below. However, the present invention is not limited to these examples.

[0104] [1] Sample preparation - 1 [Fabrication of Si alloys] A molten alloy consisting of Si (70% by mass) and Fe (30% by mass) was powdered by gas atomization, then pulverized using a bead mill, and further classified to 150 μm or less using a sieve to produce a fine Si alloy powder. The atmosphere during alloy preparation and gas atomization was an argon atmosphere. During gas atomization, high-pressure (4 MPa) argon gas was sprayed onto the molten alloy falling in a rod shape within the spray chamber.

[0105] [Preparation of Si alloy suspension] Using a wet bead mill, the finely powdered Si alloy obtained above and ethanol are mixed together with zirconia beads (φ0.3 mm) to obtain the median diameter (D) of the Si alloy. 50 The mixture was stirred until the temperature reached 700 nm (at a peripheral speed of 10 m / sec) to prepare a Si alloy suspension with a solid content of 40% by mass. Here, the median diameter (D) of the Si alloy was determined. 50 The particle size was measured using a laser diffraction / scattering particle size distribution analyzer (Partica LA-960V2, manufactured by Horiba, Ltd.) to determine the particle size based on volume.

[0106] [Fabrication of electrode materials] (Example 1) As the electrode material for Example 1, a granule containing an inorganic binder with phosphate as a component and an active material was prepared by the following method. Water was added to the Si alloy suspension prepared above to a solid content concentration of 10% by mass, and the mixture was mixed to prepare suspension A. Meanwhile, an aqueous solution of aluminum phosphate (Al2O3·3P2O5) and carbon black (CB, average primary particle size 35 nm, specific surface area 70 m²) were mixed. 2Suspension B was prepared by adding ( / g) of aluminum phosphate to water and mixing so that the solid content concentration of aluminum phosphate was 10% by mass. Furthermore, suspension A and suspension B were mixed so that the solid content composition was Si alloy:Al2O3·3P2O5:CB=93:5:2% by mass to prepare a mixture for use in spray drying. At this time, the presence or absence of hydrogen generation was checked by visual inspection for the formation of bubbles, and no bubbles were observed, confirming that no hydrogen was generated from the mixture. The mixing of suspension A, suspension B, and the spray drying mixture was all performed using a rotation-and-revolution type mixer (Sinky, Awatori Rentaro ARE-310) in air under conditions of 2000 rpm and 10 min.

[0107] Furthermore, the spray-drying mixture obtained above was spray-dried using a spray dryer (Yamato Scientific, ADL311S-A), and then vacuum-dried (300°C, 12 hours) to obtain granules for use as electrode material. The spray-drying conditions were: inlet drying temperature 170°C, outlet drying temperature 70-90°C, pressure 0.04-0.05 MPa, and average drying airflow rate 0.1-0.2 m³. 3 I set it to / min.

[0108] (Examples 2-6) The electrode materials for Examples 2 to 6 were prepared in the same manner as in Example 1, except that the solid content composition of the spray-drying mixture obtained by mixing suspension A and suspension B was as follows. In all of Examples 2 to 6, as in Example 1, no hydrogen generation from the mixture was observed. Example 2 - Si alloy: Al2O3·3P2O5:CB=88:10:2 mass% • Example 3 - Si alloy: Al2O3·3P2O5:CB=91:7:2 mass% • Example 4 - Si alloy: Al2O3·3P2O5:CB=88:7:5 mass% • Example 5 - Si alloy: Al2O3·3P2O5:CB=85:5:10 mass% Example 6 - Si alloy: Al2O3·3P2O5:CB=90:5:5 mass%

[0109] (Comparative Example 1) For Comparative Example 1, an electrode material was prepared using a resin-based binder instead of a phosphate-based inorganic binder. Specifically, water was added to a Si alloy suspension to a solid content concentration of 5% by mass and mixed to prepare suspension A. On the other hand, a polyimide aqueous solution (Yupia-LB2001, manufactured by Ube Industries) and CB were mixed with water to a polyimide solid content concentration of 5% by mass to prepare suspension B. Furthermore, suspension A and suspension B were mixed to prepare a spray-drying mixture so that the solid content composition was Si alloy:polyimide:CB = 93:5:2% by mass. The electrode material for Comparative Example 1 was prepared under the same conditions as in Example 1.

[0110] (Comparative Example 2) As the electrode material for Comparative Example 2, a Si alloy suspension was simply dried under reduced pressure to obtain fine Si alloy powder.

[0111] (Comparative Example 3) Suspension A was prepared by adding water to a Si alloy suspension to achieve a solid content concentration of 35% by mass and mixing. Meanwhile, suspension B was prepared by adding an aqueous solution of aluminum phosphate (Al2O3·3P2O5) and CB along with water to achieve a solid content concentration of 35% by mass for the aluminum phosphate, and mixing. Furthermore, when suspensions A and B were mixed so that the solid content composition was Si alloy:Al2O3·3P2O5:CB = 93:5:2% by mass, aggregates of several millimeters in size formed as a precipitate. These aggregates did not disappear or decrease even when the mixture was later diluted with water and mixed again. The presence of millimeter-sized aggregates in the spray-drying mixture clogs the spray nozzle. Therefore, the manufacturing method of Comparative Example 3 could not produce a mixture suitable for spray drying. Conditions not specified were the same as in Example 1.

[0112] [2] Evaluation Method and Evaluation Results - 1 [Evaluation of the manufacturing process for electrode materials] As described above, in all of Examples 1 to 6, a spray-drying mixture was prepared by mixing suspension A, in which the active material of a Si alloy was suspended in an organic solvent, with suspension B, which contained an aqueous solution of an inorganic binder with phosphate as a component. In Examples 1 to 6, no hydrogen generation from the mixture was observed, and the production of electrode materials could be carried out safely. Furthermore, in Comparative Example 3, where the solid content concentration of phosphate in suspension B exceeded 30% by mass, aggregates formed due to precipitation, and spray drying could not be performed. In contrast, in Examples 1 to 6, where the solid content concentration of phosphate in suspension B was kept below 30% by mass, no precipitation occurred, and spray drying could be carried out normally. From this, it is confirmed that by keeping the solid content concentration of the aqueous solution of the inorganic binder below 30% by mass, phosphate precipitation can be suppressed, and the production of electrode materials as granules can be carried out efficiently. Note that the electrode material from Comparative Example 3, from which a mixture suitable for spray drying could not be obtained, was not used in the subsequent evaluations.

[0113] [Observation of electrode materials] To confirm the particle structure of the electrode materials, samples from Examples 1-6 and Comparative Examples 1 and 2 were observed using a scanning electron microscope (SEM). The electrode composite layers for SEM observation were prepared by embedding the granules obtained as electrode materials for each example and comparative example in resin and mechanically polishing them. Figures 2-7 show surface SEM images of the electrode composite layers for Examples 1-6, and Figures 8 and 9 show surface SEM images of the electrode composite layers for Comparative Examples 1 and 2.

[0114] As is clear from Figures 2-9, spherical granules are observed in Examples 1-6 and Comparative Example 1, but no spherical granules are observed in Comparative Example 2, which does not use a binder; only fine particles are observed. From this, it is confirmed that granules are formed when the active material is bound together by the binder.

[0115] [Evaluation of flame resistance] To evaluate the flame resistance of each electrode material, small gas flame ignition tests were performed on each electrode material of Examples 1-6 and Comparative Examples 1 and 2 in accordance with the Hazardous Materials Class 2 testing standards. The small gas flame ignition tests were conducted under ambient temperature of 20°C, ambient humidity of 50%, atmospheric pressure, no wind, and a flame contact area of ​​2 cm². 2 Under conditions of a flame contact angle of 30°, the ease with which the electrode material could be ignited was confirmed by exposing a 3 mL hemispherical electrode material on an insulating plate to the flame for 10 seconds.

[0116] Table 1 shows the results of the flame resistance assessment. A "×" indicates ignition within 3 seconds of flame contact, a "○" indicates ignition between 3 and 10 seconds after flame contact, and a "◎" indicates no ignition even after more than 10 seconds of flame contact. Even if ignition occurs, if the time to ignition is 3 seconds or more, the electrode material can be considered sufficiently flame-resistant.

[0117] [Table 1]

[0118] As is clear from Table 1, Examples 1 to 6 are powder materials that are less ignitable than Comparative Examples 1 and 2. In particular, Example 2, which contains 10% by mass of aluminum phosphate, did not ignite even after more than 10 seconds, suggesting that the ignition resistance increases as the aluminum phosphate content increases.

[0119] [Evaluation of thermal stability] To confirm the thermal stability of the electrode materials, differential scanning calorimetry (DSC) measurements were performed on each electrode material of Examples 1-6 and Comparative Examples 1 and 2. DSC measurements were performed by sealing each electrode material (6.3-8.5 mg) in an open aluminum pan. During the DSC measurements, air was flowed at 5 mL / min, the heating rate was 10°C / min, and the measurement range was 50-450°C.

[0120] Figures 10-15 show the DSC measurement results for Examples 1-6, and Figures 16 and 17 show the DSC measurement results for Comparative Examples 1 and 2. In each figure, the solid line represents the DSC curve, and an upward shift in the curve indicates that the electrode material is self-heating. The dotted line in the figure is a reference line showing the DSC value at 50°C. As is clear from Figures 10-17, Examples 1-6 are powder electrode materials that generate less heat compared to Comparative Examples 1 and 2. In detail, in Examples 1-6, where aluminum phosphate is used to construct the granules, the total heat generated by the electrode material is low and the heat generation onset temperature is high, suggesting that aluminum phosphate has the effect of improving the thermal stability of the electrode material.

[0121] In Comparative Example 2, the exothermic onset temperature is higher than that of Comparative Example 1, but a significant exothermic reaction is observed from 270°C onwards. On the other hand, none of Examples 1 to 6 exhibit the large exothermic reaction seen in Comparative Example 2.

[0122] [3] Sample preparation - 2 [Electrode fabrication] Electrodes were prepared using the electrode materials of Examples 1-6 and Comparative Examples 1 and 2. The electrodes were prepared by coating a slurry consisting of 90% by mass of electrode material, 3% by mass of acetylene black (Denka Black, manufactured by Denka), 1% by mass of vapor-grown carbon fiber (VGCF-H, manufactured by Showa Denko), and 6% by mass of polyimide (Yupia-LB1001, manufactured by Ube Industries) onto nickel-plated steel foil (Super Nickel, manufactured by Nippon Steel, 10 μm thick) as a current collector, and then vacuum-drying (300°C, 12 hours). The reversible capacity per unit area was 3 mAh / cm². 2 The slurry was prepared by mixing in air at 2000 rpm for 6 minutes using a rotation-and-revolution type mixer (Sinky, Awatori Rentaro ARE-310).

[0123] [Battery making] Using the electrode materials from Examples 1-6 and Comparative Examples 1 and 2, the electrodes obtained above were used as test electrodes. A coin-type battery (R2032) was then fabricated using a metallic lithium counter electrode (made of this metal, lithium foil with a thickness of 500 μm), a PP / PE / PP three-layer microporous membrane (Cellguard, 2325), a glass filter (Advantec, GA100), and a non-aqueous electrolyte. As the non-aqueous electrolyte, LiPF6 at a concentration of 1 mol / L was dissolved in a solvent consisting of a mixture of ethylene carbonate (EC):diethyl carbonate (DEC) = 1:1 (volume ratio) to which 1% by mass of fluoroethylene carbonate (FEC) was added. The batteries were fabricated in a drying booth (Nippon Spindle Manufacturing Co., Ltd., NS Drying Booth, dew point -80°C).

[0124] [4] Evaluation Method and Evaluation Results - 2 [Charge-discharge cycle characteristics] Charge-discharge tests were performed on batteries equipped with test electrodes using the electrode materials of Examples 1-6 and Comparative Examples 1 and 2. The charge-discharge cycle tests were conducted under conditions of repeated charge-discharge at a cutoff voltage of 0.001-1.5V and a rate of 0.1C in a 30°C environment.

[0125] Table 2 shows the measured discharge capacity and capacity retention rate for each test electrode at cycle 1 and cycle 60, representing the cycle characteristics. The discharge capacity was calculated by dividing the electrode's capacitance obtained during discharge by the electrode material mass. The capacity retention rate represents the relative discharge capacity, with the discharge capacity at cycle 1 as the baseline (100%).

[0126] [Table 2]

[0127] In Comparative Example 2, the electrode material did not contain a granulation binder or a granulation conductive additive. As a result, the initial discharge capacity was high at 1664.6 mAh / g, but the discharge capacity at 60 cycles was lower than the initial discharge capacity, and the capacity retention rate was low at 76.6%. On the other hand, in Examples 1-6 and Comparative Example 1, where a granulation binder and a granulation conductive additive were used to form spherical granules, the initial discharge capacity was lower than that of Comparative Example 2, but the capacity retention rate was higher than that of Comparative Example 2.

[0128] [High-rate discharge characteristics] High-rate discharge tests were performed on batteries equipped with test electrodes using the electrode materials of Examples 1-6 and Comparative Examples 1 and 2. The high-rate discharge tests were conducted in a 30°C environment under the following conditions: a cutoff voltage of 0.001-1.5V, 5 cycles of 0.1C rate charge / discharge, followed by discharge at rates of 0.2C, 0.5C, 1C, and 3C.

[0129] Table 3 shows the electrode capacities obtained for each discharge rate for each test electrode, with the discharge capacity at a 0.1C rate as the reference.

[0130] [Table 3]

[0131] According to Table 3, at low rates of 0.5C or less, all samples showed almost equivalent discharge capacity. However, at 3C rate discharge, it was confirmed that Examples 1-6, which used aluminum phosphate as the granulation binder, had a larger discharge capacity compared to Comparative Examples 1 and 2.

[0132] [5] Examination of the composition of the active material Furthermore, electrode materials were fabricated by changing the composition of the active material Si alloy, and their properties were evaluated.

[0133] [Sample preparation] Electrode materials for Examples 7 to 14 were prepared using the same method as described in item [1] above. However, in the preparation of the Si alloy, the alloy composition of the molten alloy used as the raw material for the gas atomization method was as shown in the left column of Table 4 below. By grinding the powder obtained by the gas atomization method with a bead mill, Si alloy powder containing Si particles, Si2Fe compound particles, and SnCu compound particles was obtained. The compound ratios in the obtained alloy powder, i.e., the ratios of Si phase, Si2Fe phase, and SnCu compound phase, were as shown in the right column of Table 4 below.

[0134] The above compound proportions were calculated by referring to the results of X-ray diffraction (XRD) measurements. The method for calculating the compound proportions will be explained using Example 7 as an example. (1) First, the constituent phases of the alloy powder are confirmed by XRD analysis. In Example 7, the Si phase, the Si2Fe phase as a SiX compound phase, and the SnCu phase (Sn5Cu6) as a SnY compound phase were confirmed. (2) Next, assuming that all of element X in the alloy composition constitutes the SiX phase confirmed in (1), the mass percentage of the SiX phase in the alloy powder is determined from the mass ratio of Si to element X in the SiX phase. The mass ratio of Si to Fe in the Si2Fe phase is Si:Fe = 50.1:49.9. The Fe content in the alloy composition of Example 7 is 44.6 mass%, and the amount of Si that constitutes the Si2Fe phase is 44.6 × 50.1 / 49.9 = 44.8 mass%. The compound percentage of the SiX phase consisting of Si2Fe is the sum of the masses of Si and Fe that constitute Si2Fe, and in the case of Example 7, it is 44.6 + 44.8 = 89.4 mass%. (3) Furthermore, the compound percentage of the Si phase is determined by subtracting the Si that constitutes the SiX phase, as determined in (2), from the Si content in the alloy composition. In the case of Example 7, the compound percentage of the Si phase is 54.9-44.8, which is 10.1 mass%. Finally, the compound percentage of the YCu phase is determined as the sum of the content of elements Y and Cu in the alloy composition. In the case of Example 7, the compound percentage of the SnCu phase is 0.3+0.2, which is 0.5 mass%.

[0135] [Table 4]

[0136] In preparing the sample, the steps after the preparation of the Si alloy were carried out in the same manner as in Example 1. The composition of the spray-drying mixture was also the same as in Example 1, except for the composition of the Si alloy powder, and a granule having the composition shown in Table 5 below was obtained as the electrode material. Furthermore, a carbon film was formed on the surface of the obtained granule by thermal CVD. In the thermal CVD method, acetylene gas was supplied to the furnace as an organic gas while the granule was held at 700°C for 1 hour.

[0137] [Evaluation of flame resistance] For each electrode material obtained, the flame resistance was evaluated using the same method as the evaluation in item [2] above. Table 5 below shows the flame resistance evaluation results along with the composition of the granules.

[0138] [Table 5]

[0139] According to Table 5, in all of Examples 7 to 14, high flame resistance, rated as "○", was obtained, similar to Example 1. This confirms that by including a predetermined amount of an inorganic binder containing phosphate in the granules, high flame resistance can be obtained even if the composition of the Si-based material constituting the active material changes.

[0140] [Evaluation of charge / discharge characteristics and high-rate discharge characteristics] Using the electrode materials from Examples 7 to 14, electrodes and batteries were fabricated using the same method as in item [3] above. Then, the charge-discharge cycle characteristics and high-rate discharge characteristics were evaluated using the same method as in item [4] above. The evaluation results for the charge-discharge cycle characteristics are shown in Table 6 below, and the evaluation results for the high-rate discharge characteristics are shown in Table 7 below.

[0141] [Table 6]

[0142] [Table 7]

[0143] According to Table 6, all samples achieved a high capacity retention rate exceeding 80% at 60 cycles, demonstrating excellent cycle characteristics. In particular, Examples 7-13, where the Si phase content ranged from 10-90% and the Si2Fe phase content from 5-90%, achieved a capacity retention rate of 83% or higher. The discharge characteristics results in Table 7 also show that Examples 7-13 exhibit high discharge characteristics, with a discharge capacity of 80% or higher at the 3C rate. Furthermore, Examples 8 and 9, where the Si phase content ranged from 20-50% and the Si2Fe phase content from 30-85%, showed well-balanced and high values ​​for both the capacity retention rate at 60 cycles in Table 6 and the discharge capacity at the 3C rate in Table 7, indicating excellent cycle and discharge characteristics. In particular, Example 8 achieved the second-highest capacity retention rate at 60 cycles among samples 7-14, while also achieving the highest discharge capacity at the 3C rate, demonstrating a high degree of balance between cycle and discharge characteristics.

[0144] As described above, preferred embodiments and examples of the present invention have been explained, but various additions, modifications, or deletions are possible without departing from the spirit of the invention. Therefore, such additions and deletions are also included within the scope of the present invention. Furthermore, in this specification, the numbers listed in the general formulas of compounds may be represented as integers for mere expression, but if they satisfy electrical neutrality and are substantially the same, they are included within the scope of the present invention. [Explanation of Symbols]

[0145] 1 Inorganic Binder 2 Active material 3. Granulated material 4. Inorganic binder aqueous solution 5. Organic solvents 6. Suspension 7 Mixed liquid

Claims

1. A method for manufacturing electrode materials for non-aqueous electrolyte secondary batteries, An aqueous solution of an inorganic binder containing an inorganic binder with phosphate as a component, A mixture is obtained by mixing a suspension in which an active substance is dispersed in an organic solvent with another substance. By heating, the water in the mixture is vaporized. The process includes obtaining a granule containing the inorganic binder and the active material, A method for producing an electrode material, wherein the solid content concentration of the aqueous solution of the inorganic binder is 1% by mass or more and 30% by mass or less.

2. The aforementioned phosphate has the structural formula Al ２ O ３ nP ２ O ５ mH ２ A method for producing an electrode material according to claim 1, comprising aluminum phosphate represented by O (0.5 ≤ n ≤ 4, 0 ≤ m ≤ 8).

3. The solid content concentration of the suspension is 1% by mass or more and 30% by mass or less. The suspension further contains water, The method for producing an electrode material according to claim 1 or claim 2, wherein the concentration of water relative to the organic solvent in the suspension is 10% by mass or more.

4. The method for producing an electrode material according to claim 1 or claim 2, wherein the organic solvent is a water-soluble organic solvent.

5. The method for producing an electrode material according to claim 4, wherein the water-soluble organic solvent is alcohol-based.

6. The method for manufacturing an electrode material according to claim 1 or claim 2, wherein the heat treatment is a step of heating at a temperature of 100°C or more and 500°C or less.

7. The active material has a median diameter (D ５０ A method for producing an electrode material according to claim 1 or claim 2, comprising single particles of 10 nm or more and 1 μm or less.

8. A method for producing an electrode material according to claim 1 or claim 2, wherein the active material includes a material capable of forming an alloy phase with an alkali metal.

9. The method for manufacturing an electrode material according to claim 8, wherein the material capable of forming an alloy phase with the alkali metal is a Si-based material.

10. The method for producing an electrode material according to claim 1 or claim 2, wherein the mixed liquid further contains carbon.

11. Median diameter (D) ５０ A method for producing an electrode material according to claim 1 or claim 2, wherein a spherical granule with a diameter of 0.5 μm or more and 50 μm or less is obtained.

12. A method for producing an electrode material according to claim 1 or claim 2, wherein the heat treatment includes a step by spray drying.

13. Electrode material for non-aqueous electrolyte secondary batteries, The electrode material is a granular material containing an inorganic binder with phosphate as a component and an active material. An electrode material containing the inorganic binder in an amount of 1% by mass or more and 30% by mass or less.

14. where the phosphate is of the empirical formula Al ２ O ３ ·nP ２ O ５ ·mH ２ O (0.5 ≤ n ≤ 4, 0 ≤ m ≤ 8), the electrode material according to claim 13.

15. The electrode material according to claim 13 or claim 14, wherein the active material includes a Si-based material.

16. The electrode material according to claim 15, wherein the Si-based material comprises Si particles and SiX compound particles, wherein X is at least one element selected from Fe, Co, Ni, Zr, Ti, Cr, V, and Nb.

17. In the aforementioned active material, The mass ratio of the Si particles is 10% or more and 90% or less. The electrode material according to claim 16, wherein the mass ratio of the SiX compound particles is 5% or more and 90% or less.

18. In the aforementioned active material, The mass ratio of the Si particles is 20% or more and 50% or less. The electrode material according to claim 17, wherein the mass ratio of the SiX compound particles is 30% or more and 85% or less.

19. The electrode material according to claim 16, wherein the Si-based material further comprises YCu compound particles, wherein Y is at least one element selected from Sn, Al, In, and Bi.

Images