Inorganic binder emulsion, electrode, nonaqueous electrolyte battery, and nonaqueous electrolyte capacitor including the same, and method for producing inorganic binder emulsion

Abstract

To provide an inorganic binder emulsion; an electrode, a nonaqueous electrolyte battery, and a nonaqueous electrolyte capacitor including the inorganic binder emulsion; and a method for producing the inorganic binder emulsion, wherein the inorganic binder emulsion has high heat resistance, superior bonding strength, and a higher drying speed compared to aqueous binders.SOLUTION: An inorganic binder emulsion of the present invention is an emulsion including an aqueous phase, an oil phase, and a surfactant. The aqueous phase is an inorganic binder aqueous solution having a solid concentration of 20 mass% or more and 70 mass% or less. The oil phase is an organic solvent or halogen-based solvent having a boiling point lower than that of water and a specific gravity higher than that of water. The inorganic binder aqueous solution comprises a silicate or phosphate dissolved in water.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an inorganic binder emulsion, an electrode including the same, a non-aqueous electrolyte battery, a non-aqueous electrolyte capacitor, and a method for producing an inorganic binder emulsion.

Background Art

[0002] Emulsions are used in a wide variety of fields such as cosmetics, food and beverages, pharmaceuticals, paints, dyes, and the chemical industry. For example, milk and mayonnaise are oil-in-water (O / W) type emulsions, in which the fat that forms the oil phase is dispersed in the water phase.

[0003] An emulsifier (surfactant) such as casein covers the droplets of the oil phase, thereby stabilizing the oil droplets so that the oil phase and the water phase do not phase-separate even over time and the emulsified state is maintained. That is, an emulsion is a state in which one of two liquids that do not normally mix is finely dispersed in the other.

[0004] On the other hand, butter and margarine are water-in-oil (W / O) type emulsions, in which water is dispersed in the oil phase. Surfactants (emulsifiers) such as monoglycerides and soy lecithin are included, which allows the water droplets to continue to be dispersed in the oil.

[0005] As described above, an emulsion contains at least three components: a water phase, an oil phase, and an emulsifier, and is roughly classified into two types: oil-in-water type and water-in-oil type. The distinction between the oil-in-water type and the water-in-oil type can be confirmed by what can dilute the emulsion. Generally, if it can be diluted with water, it is determined to be of the oil-in-water type, and if it can be diluted with oil, it is determined to be of the water-in-oil type.

[0006] Here, the water phase refers to the water or aqueous solution component in the emulsion, and the oil phase refers to the organic solvent component in the emulsion.

[0007] By the way, in recent years, from the viewpoints of reducing environmental impact, improving safety during work, and reducing manufacturing costs, etc., reduction or elimination (VOC removal) of volatile organic compounds (VOCs) has been strongly demanded in various industrial fields.

[0008] As an example, taking the manufacturing process of lithium-ion batteries, in the process of manufacturing electrodes, the aqueous dispersion of slurry is progressing. Electrodes are roughly composed of a current collector and a composite material layer (active material layer). In lithium-ion batteries, aluminum foil, copper foil, etc. are used as the current collector. On the other hand, the composite material layer contains active materials such as lithium transition metal oxides and graphite, and a binder for binding them.

[0009] Such a binder is used for the purpose of binding powder to powder or powder to metal foil. As a medium for dissolving or emulsifying (dispersing) the solid component, an organic solvent or water is used for the binder. Generally, the former is called an organic solvent-based binder, and the latter is called an aqueous (water-based) binder.

[0010] In the case of an aqueous binder, although there is no VOC emission, it has the drawback that it takes time to remove moisture compared to an organic solvent-based binder. On the other hand, in the case of an organic solvent-based binder, although the time required for moisture removal is short, it has the drawback that the risk of ignition during manufacturing becomes high.

[0011] As the negative electrode binder of lithium-ion batteries, from the viewpoints of VOC removal and cost, etc., an O / W type styrene-butadiene rubber (SBR) emulsion is widely adopted. Since the main component of the dispersion medium of this SBR emulsion is water, it has the advantage of significantly reducing the emission of VOCs harmful to the environment and the human body.

[0012] On the other hand, the present inventors have previously proposed a skeleton-forming agent containing a silicate or a phosphate in the components, an electrode using the same, and a method for manufacturing the electrode (for example, Patent Document 1, Patent Document 2, etc.).

[0013] The invention of Patent Document 1 has the effect of improving characteristics such as the heat resistance, cycle characteristics, and electrode strength of a battery by using water in which inorganic components such as silicate and phosphate are dissolved as a binder or a skeleton-forming agent (coating material for an active material or a composite layer).

[0014] Further, in the invention of Patent Document 2, by further including a surfactant in water in which inorganic substances such as silicate and phosphate are dissolved, the liquid affinity for the electrode composite layer is improved, and effects such as the silicate and phosphate being likely to uniformly penetrate into the active material layer are obtained.

Prior Art Documents

Patent Documents

[0015]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0016] However, when using a conventional O / W type aqueous binder for battery applications, several technical problems exist. For example, in the SBR binder widely used as a binder for the negative electrode of a lithium-ion battery, the following problems exist.

[0017] Insufficient adhesion: The adhesion of SBR emulsion is suitable for active materials with small volume changes during charge and discharge, such as graphite. However, for active materials with large volume changes, such as Si and SiO (specifically, active materials with a volume change of 120% or more during charge and discharge), the adhesion is insufficient, and capacity degradation is likely to occur early. To improve adhesion, emulsions replacing SBR with acrylic resin have been proposed, but further improvement in adhesion is desired for Si, SiO, etc.

[0018] Water removal time: Using a large amount of water as the dispersion medium can reduce VOC emissions, but it may increase the time required for water removal in the manufacturing process and cause compatibility problems with certain materials. For example, in a slurry composed of a high-Ni cathode active material such as Li(Ni-Co-Al)O2 (NCA) or Li(Ni 0.8 Co 0.1 Mn 0.1 )O2 (NCM811) and an aqueous binder, the alkaline components contained in the active material elute into the water, increasing the pH of the slurry, making it difficult to coat on aluminum foil.

[0019] Oxidation degradation: In the positive electrode, the butadiene component is prone to oxidation degradation, so it is not suitable for use in the positive electrode and is mainly limited to use as a negative electrode application. Polyvinylidene fluoride (PVdF) binder is mainly used as a binder for the positive electrode in practical batteries. The PVdF binder is a dissolution-type binder and uses N-methyl-2-pyrrolidone (NMP), which causes VOC emissions, as a solvent. In addition, the PVdF binder has the drawback of being inferior in binding properties to the SBR binder.

[0020] Low heat resistance: Since SBR is a hydrocarbon-based resin, it undergoes thermal decomposition at temperatures exceeding 200°C and loses its function as a binder. Even polyimide (PI) and aramid with excellent heat resistance have a heat resistance limit of about 400°C.

[0021] In addition, in the inventions of Patent Documents 1 and 2, although silicates and phosphates are easily soluble in water, they are insoluble in organic solvents such as alcohols, ketones, and NMP. Therefore, it was difficult to replace the solvent with an organic solvent or add an organic solvent to shorten the drying time. For example, when ethanol or NMP is added to an aqueous sodium silicate solution, silanol groups undergo a dehydration reaction to form siloxane bonds. As this reaction progresses, polymerization occurs and a solid precipitates in the liquid phase.

[0022] As described above, the conventional binders had several problems. As a result of intensive research to solve these problems, the inventors found a configuration that enables the combination of an inorganic binder aqueous solution and an organic solvent. Thus, they invented an inorganic binder emulsion that has high heat resistance, excellent adhesive strength, and a faster drying rate than aqueous binders.

[0023] By the way, halogen-based solvents (solvents) are utilized in a wide range of applications due to their multifunctionality, including roles as aerosol propellants, refrigerants, solvents, cleaning agents, as well as thermoplastic materials, blowing agents, heat transfer media, fire extinguishing agents, power operating fluids, replacement desiccants, and so on.

[0024] In recent years, halogen-based solvents that are less burdensome on the environment, have low toxicity, and are non-flammable and stable have been discovered (for example, Patent Documents 3, Patent Document 4, etc.). These solvents can be easily recovered in a state free of impurities by methods such as distillation and can also be reused (for example, Patent Documents 5, Patent Document 6, etc.). In particular, if it becomes possible to recycle halogen-based solvents, it is expected that an increase in manufacturing costs can be suppressed.

[0025] However, although such halogen-based solvents have advantages such as a small environmental load, they have the problem of being non-polar with respect to water and hardly mixing with water.

[0026] The inventors considered that if an inorganic binder aqueous solution and a halogen-based solvent could be combined to form a new fluid having these characteristics, it would be an inorganic binder with high heat resistance, excellent adhesive strength, and a faster drying rate than an aqueous binder, similar to the combination of an inorganic binder aqueous solution and an organic solvent. As a result of intensive research, they found that by using a configuration similar to the one that combines the above-mentioned inorganic binder aqueous solution and an organic solvent, it is possible to combine the inorganic binder aqueous solution and the halogen-based solvent, thus completing the present invention.

[0027] As described above, the object of the present invention is to provide an inorganic binder emulsion with high heat resistance, excellent adhesive strength, and a fast drying rate.

Means for Solving the Problems

[0028] An inorganic binder emulsion according to one aspect of the present invention is an emulsion containing an aqueous phase, an oil phase, and a surfactant, wherein the aqueous phase is an inorganic binder aqueous solution with a solid content concentration of 20% by mass or more and 70% by mass or less, the oil phase is an organic solvent or a halogen-based solvent having a boiling point lower than that of water and a specific gravity higher than that of water, and the inorganic binder aqueous solution is characterized in that a silicate or a phosphate is dissolved in water.

[0029] According to this configuration, by combining an inorganic binder aqueous solution containing a silicate or a phosphate with an organic solvent or a halogen-based solvent, an inorganic binder emulsion with high heat resistance, excellent adhesive strength, and a faster drying rate than an aqueous binder can be obtained. Also, if a halogen-based solvent is used, the environmental load can be reduced.

[0030] In this inorganic binder emulsion, it is characterized by being a water-in-oil type with oil as the continuous phase. Here, the water-in-oil type includes the W / O type (water-in-oil type) and the O / W / O type (oil-in-water-in-oil type). That is, any configuration with oil as the continuous phase is acceptable. According to this configuration, by setting the inorganic binder aqueous solution to be confined within the continuous oil phase, it becomes possible to combine the inorganic binder aqueous solution with an organic solvent or a halogen-based solvent.

[0031] In this inorganic binder emulsion, it is characterized in that the aqueous phase is 20% by mass or more and 97% by mass or less, and the oil phase is 3% by mass or more and 80% by mass or less. According to this configuration, by mixing the aqueous phase and the oil phase within this range, the stability of the emulsion can be ensured, and the above-mentioned effects can be achieved.

[0032] In this inorganic binder emulsion, it is characterized in that the mass percentage (X) of the aqueous phase and the mass percentage (Y) of the oil phase satisfy the following formula. (Formula) 1 / 4 < X / Y < 23 / 2 By mixing the aqueous phase and the oil phase within this range, the stability of the emulsion can be ensured, and the above-mentioned effects can be achieved.

[0033] In this inorganic binder emulsion, it is characterized in that the surfactant is 0.01% by mass or more and 20% by mass or less. In the invention of Patent Document 2 described above, when the composite layer is thick, dense, or contains a water-repellent material, a large amount of surfactant is required. Also, in the process of drying the water in which inorganic substances such as silicates and phosphates are dissolved, sometimes water vapor is trapped within the dry film, and a phenomenon where it expands under pressure has been observed. However, in the present invention that combines the aqueous phase and the oil phase, it becomes possible to suppress the amount of surfactant to be less than that of the prior art.

[0034] This inorganic binder emulsion is such that the halogen-based solvent is at least any one fluorine-based solvent selected from chlorofluorocarbons, hydrofluoroethers, hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroolefins, and hydrochlorofluoroolefins.

[0035] In this inorganic binder emulsion, it is desirable that the surfactant includes an acrylic surfactant or a silicone surfactant that can dissolve in the oil phase.

[0036] In this inorganic binder emulsion, the surfactant may include a nonionic surfactant that can dissolve in the aqueous phase. In this inorganic binder emulsion, it is desirable that the pH value of the aqueous phase is 1 or more and 5 or less.

[0037] In this inorganic binder emulsion, it is desirable that the phosphate includes aluminum phosphate represented by the empirical formula Al2O3·nP2O5·mH2O (0.5 ≤ n ≤ 4, 0 ≤ m ≤ 10).

[0038] In this inorganic binder emulsion, it is desirable that the average particle diameter of the micelles in the aqueous phase contained in the emulsion is 10 nm or more and 10 μm or less.

[0039] This inorganic binder emulsion is desirably applied to a binder used for binding powders to each other or a surface coating material used for coating the powder surface.

[0040] This inorganic binder emulsion is desirably applied to a battery material having a median diameter (D 50 ) of 10 nm or more and 50 μm or less.

[0041] Using this inorganic binder emulsion, an electrode for a nonaqueous electrolyte battery or a nonaqueous electrolyte capacitor can be formed.

[0042] Using this electrode, a non-aqueous electrolyte battery or a non-aqueous electrolyte capacitor can be formed.

[0043] A method for producing an inorganic binder emulsion according to one aspect of the present invention is a method for producing a water-in-oil type emulsion having an oil as a continuous phase, including an aqueous phase, an oil phase, and a surfactant. The aqueous phase is an aqueous solution of an inorganic binder having a solid content concentration of 20% by mass or more and 70% by mass or less, and the oil phase is an organic solvent or a halogen-based solvent having a boiling point lower than that of water and a specific gravity higher than that of water. The method includes a step of dissolving a silicate or a phosphate in water to form the aqueous solution of the inorganic binder, and a step of stirring the oil phase and adding and mixing the aqueous phase to the stirred oil phase.

[0044] Further, in the method for producing an inorganic binder emulsion, the mixing method of the oil phase and the aqueous phase is characterized in that the temperatures of the oil phase and the aqueous phase are mixed at -30°C or higher and 30°C or lower.

[0045] In this method for producing an inorganic binder emulsion, the step of mixing the oil phase and the aqueous phase is characterized in that a pressure type that stirs under pressure or an ultrasonic type homogenizer that stirs using ultrasonic waves is used for mixing.

Advantages of the Invention

[0046] According to the present invention described above, an inorganic binder emulsion having high heat resistance, excellent adhesive strength, and a high drying speed can be provided.

Brief Description of the Drawings

[0047]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0048] Hereinafter, an inorganic binder emulsion according to an embodiment of the present invention will be described. The present invention is not limited to this embodiment.

[0049] [Inorganic Binder Emulsion] The inorganic binder emulsion of this embodiment is, as an example, an emulsion composed of an aqueous phase, an oil phase, and a surfactant, wherein the aqueous phase is an aqueous solution of an inorganic binder having a solid content concentration of 15% by mass or more and 65% by mass or less, the oil phase is an organic solvent or a halogen-based solvent having a boiling point lower than that of water and a specific gravity higher than that of water, and the aqueous solution of the inorganic binder is formed by dissolving a silicate or a phosphate in water.

[0050] That is, by including at least three components of an aqueous phase, an oil phase, and a surfactant, the inorganic binder emulsion of this embodiment can be obtained.

[0051] For example, if only the aqueous phase and the oil phase are mixed, they will immediately phase-separate into the aqueous phase and the oil phase. If only the aqueous phase and the surfactant are mixed, the time required for water removal cannot be shortened. Also, if only the oil phase and the surfactant are mixed, it does not have the function as an inorganic binder.

[0052] When the oil phase is not water-soluble, an oil-in-water (W / O) type inorganic binder emulsion has better stability against moisture and carbon dioxide in the atmosphere than an oil-in-water (O / W) type inorganic binder emulsion or an inorganic binder aqueous solution consisting only of an aqueous phase. A W / O type inorganic binder emulsion is preferred because it can extend the pot life of the product.

[0053] Aqueous silicate solutions are hygroscopic and have the property of absorbing carbon dioxide. Therefore, when an O / W type inorganic binder emulsion or an aqueous silicate solution is left in the atmosphere, it reacts with moisture and carbon dioxide to form solids such as sodium carbonate, silica, and modified silicate, so the binding property, viscosity, concentration, pH, etc. are likely to change. On the other hand, in a W / O type inorganic binder emulsion, since the aqueous phase (aqueous silicate solution) is covered with the oil phase, the reaction with moisture and carbon dioxide can be suppressed.

[0054] Also, when the oil phase has a lower boiling point than water, the W / O type inorganic binder emulsion can dry faster than the O / W type inorganic binder emulsion or the inorganic binder aqueous solution consisting only of the aqueous phase.

[0055] In addition, when the oil phase exhibits lipophilicity, the W / O type inorganic binder emulsion is more likely to achieve uniform coating and penetration due to the presence of the oil phase component even on a coating target with low wettability to water. For example, it can be uniformly coated or penetrated into a composite layer containing a hydrophobic sulfur-based material.

[0056] Moreover, the inorganic binder emulsion of this embodiment can remove the oil component and form an inorganic binder even when a hydrocarbon-based oil component adheres to the coating target. For example, it can be uniformly coated or penetrated into a composite layer containing an oil component.

[0057] In addition, the inorganic binder emulsion of the present embodiment has a corrosion inhibition effect on aluminum and aluminum alloys regardless of pH. That is, the inorganic binder emulsion has the property of not corroding aluminum or aluminum alloys whether it is acidic or alkaline.

[0058] Note that the emulsion of the present embodiment may be an O / W / O type multiple emulsion composed of an aqueous phase, an oil phase, and a surfactant.

[0059] By being a water-in-oil type such as W / O or O / W / O, the oil phase becomes the continuous phase of the outer phase. When the emulsion is dried, the oil phase is preferentially vaporized and removed, increasing the density of the aqueous phase micelles and enabling aggregation. It is difficult to form a continuous film composed of a solid inorganic binder with an O / W type emulsion or only an aqueous phase.

[0060] [Aqueous phase] In the inorganic binder emulsion of the present embodiment, the aqueous phase corresponds to the dispersed phase of the inner phase, and its components are composed of an inorganic component of silicate or phosphate and water. That is, it is an aqueous solution in which either silicate or phosphate is dissolved in water, and it is an inorganic binder aqueous solution.

[0061] Since the oil phase and the aqueous phase are less likely to undergo phase separation such as creaming or Ostwald ripening even over time and the emulsified state is easily maintained, the solid content concentration of the aqueous phase is preferably 30% by mass or more and 70% by mass or less, and more preferably 40% by mass or more and 70% by mass or less.

[0062] When the solid content concentration of the inorganic binder in the aqueous phase is less than 20% by mass or exceeds 70% by mass, the emulsion becomes unstable and is likely to undergo phase separation over time. In particular, when it is less than 20% by mass, the content of silicate or phosphate as the binder component is too small, making it difficult to exhibit the function as a binder. When it exceeds 70% by mass, the viscosity of the aqueous phase becomes too high, making it difficult to disperse even when mixed, and it is difficult to obtain a stable emulsion.

[0063] Phosphates include aluminum primary phosphate (Al(H2PO4)3), aluminum hydrogen phosphate (Al2(H2PO4)3), aluminum metaphosphate (Al(PO3)3), aluminum phosphates such as Al(H2P3O 10 )3, magnesium primary phosphate (Mg(H2PO4)3), magnesium hydrogen phosphate (MgHPO4), magnesium metaphosphate (Mg(PO3)2) and other magnesium phosphate salts, calcium primary phosphate (Ca(H2PO4)3), calcium hydrogen phosphate (CaHPO4), tricalcium phosphate (Ca3(H2PO4)2), calcium metaphosphate (Ca(PO3)2) and other calcium phosphate salts, etc. These are also known to exist as hydrates.

[0064] Among these, it is preferable to contain aluminum phosphate represented by the empirical formula Al2O3·nP2O5·mH2O (0.5 ≦ n ≦ 4, 0 ≦ m ≦ 10). When the condition that n is a real number of 0.5 or more and 4 or less is satisfied, even if the amount of the aqueous phase in the emulsion is small, an emulsion having sufficient mechanical strength can be obtained, and the dried product of the emulsion exhibits excellent flame resistance. Also, the smaller n is, the less likely the dried product of the emulsion is to absorb moisture. By making the dried product less likely to absorb moisture, gas generation can be less likely to occur in a battery system using a non-aqueous electrolyte such as a fluorine compound. Further, when the above phosphate is heat-treated, when n has a small value, aluminum tetrametaphosphate (Al4(P4O 12 )3) is likely to be generated, and when n has a large value, aluminum orthophosphate (AlPO4) is likely to be generated.

[0065] The above phosphate may further contain B2O3, SiO2, GeO2, Fe2O3, TiO2, MnO, CaO, MgO, V2O5, As2O3, TeO2, ZnO, PbO, etc. However, when contained in a large amount, it may cause a decrease in the strength of the dried product of the emulsion and an irreversible capacity of the battery. Therefore, it is preferably in an amount less than that of Al2O3 contained in the phosphate. The above phosphate aqueous solution has a corrosion inhibitory effect on aluminum and aluminum alloys.

[0066] The above-mentioned phosphate is dissolved in water in the emulsion, but in its dried product, it becomes a substance from which water has been removed. As drying methods, there are heat drying, vacuum drying, freeze drying, natural drying, etc. However, in order to completely remove water from the phosphate, heat treatment at a high temperature is required. When m is a real number greater than 8, the dried phosphate has low mechanical strength of the granulated body, the structure of the granulated body is likely to collapse in the slurry manufacturing process, the flame resistance is not sufficient, and the irreversible capacity becomes large. Therefore, it is preferably 8 or less, and more preferably 6 or less.

[0067] The above-mentioned aluminum phosphate aqueous solution has the property of hardening by drying and further dehydrating by heat treatment at a high temperature to form an aluminophosphate bond and changing into a strong substance. Specifically, the temperature of the heat treatment is approximately 0 at 450 - 500 °C, 2 or more and 5 or less at 200 - 300 °C, 5 or more and 6 or less at 150 - 200 °C, and 6 or more and 8 or less at 100 - 150 °C. Thus, in order to completely remove the hydrate contained in the phosphate, heat drying at 450 °C or higher is required, but at 1000 °C or higher, a dephosphorization reaction occurs and the value of n becomes small.

[0068] The above-mentioned phosphate may further contain an alkali metal oxide (A2O; A is an alkali metal element such as Li, Na, K, Rb) or an alkali metal salt (AX; A is an alkali metal element such as Li, Na, K, Rb, and X is a halogen element such as F, Cl, Br, I or a compound containing a halogen element). By containing an alkali metal oxide or an alkali metal salt, an effect of reducing the resistance of the battery can be expected. However, if an excessive amount of an alkali metal oxide or an alkali metal salt is contained, the strength of the dried product decreases. Therefore, it is preferably contained in an amount of 20% by mass or less with respect to the above-mentioned phosphate.

[0069] The above-mentioned phosphate may further contain boron compounds such as boric acid (B(OH)3), metaboric acid (HBO2), and boron oxide (B2O3). Since the inclusion of boron compounds has the effect of making the electrode material less likely to absorb moisture, it is expected that the moisture deterioration of the electrolyte and the electrolyte can be suppressed. In this case, it is preferably contained in an amount of 20% by mass or less based on the above-mentioned phosphate.

[0070] The above-mentioned phosphate may further contain organic nitrogen compounds such as ammonium, urea, and urea phosphate. Since the inclusion of organic nitrogen compounds has the effect of making the electrode material less likely to absorb moisture, it is expected that the moisture deterioration of the electrolyte and the electrolyte can be suppressed. In this case, it is preferably contained in an amount of 20% by mass or less based on the above-mentioned phosphate.

[0071] Silicates include orthosilicates (A4SiO4), metasilicates (A2SiO3), pyrosilicates (A6Si2O7), disilicates (A2Si2O5), tetrasilicates (A2Si4O9), etc., and there are various types such as A2Si2O5, A2Si3O7, A2Si4O9, etc., and these are also known to exist as hydrates.

[0072] Among these, in the silicate represented by the empirical formula A2O·nSiO2, when A is at least one of Li, Na, K, or Rb and n satisfies the condition of being 1.7 or more and 5 or less, a function of binding aluminum or an aluminum alloy can be imparted.

[0073] When n is less than 1.7, the corrosion inhibition effect on aluminum or an aluminum alloy is not exhibited, but rather corrosion is promoted. When n exceeds 5, a gel-like film is likely to be formed in the drying process after emulsion coating, which becomes a factor increasing the resistance when used in a chemical battery.

[0074] Also, when n exceeds 5, the emulsion has a short pot life, and precipitation occurs when the emulsion is left in the air, making it prone to deterioration. For these reasons, n is preferably 1.7 or more and 5 or less, more preferably 1.9 or more and 4.8 or less.

[0075] In this embodiment, the aqueous silicate solution or aqueous phosphate solution means water in which the above silicate or phosphate is dissolved, and it may be in a state of complete dissolution or partial dissolution in water. However, in an emulsion containing solid-state silicate or phosphate such as powder or granules, aggregation adhesion between the salts occurs, and when the emulsion is dried, it becomes non-uniform, which is likely to cause problems in quality control. Therefore, it is preferable that the above silicate or the above phosphate is in a liquid state having fluidity as an aqueous solution.

[0076] As a battery material, when the material does not react with the phosphoric acid aqueous solution or does not significantly reduce the battery function even if it reacts, phosphate is preferable as the aqueous phase.

[0077] As a battery material, when the material does not react with the silicic acid aqueous solution or does not significantly reduce the battery function even if it reacts, silicate is preferable as the aqueous phase.

[0078] The reason is not clear, but when comparing the phosphoric acid aqueous solution and the silicic acid aqueous solution as the aqueous phase, the phosphoric acid aqueous solution is less likely to cause phase separation such as creaming, Ostwald ripening, and aggregation, and can be easily emulsified.

[0079] Also, the above aqueous phase may contain ceramic powder. By containing the ceramic powder, the mechanical strength of the inorganic binder is improved. However, as the content of the ceramic powder increases, the binding property decreases. Therefore, it is preferable that the ceramic powder is contained at 50% or less based on the solid content of the aqueous phase.

[0080] [Oil phase] The above oil phase is a continuous phase and is a halogen-based solvent that has a boiling point lower than water and a specific gravity higher than water. By using a liquid with a boiling point lower than water in the oil phase, when the emulsion is dried, the oil phase is preferentially vaporized and removed. After the density of the aqueous phase increases, the micelles of the aqueous phase aggregate and fuse to form a continuous film composed of a solid inorganic binder (Figure 1).

[0081] When the boiling point of the oil phase is higher than that of water, when the emulsion is dried, the water in the aqueous phase will be preferentially volatilized, so a continuous film composed of a solid inorganic binder cannot be formed.

[0082] Also, since the boiling point is lower than that of water, the drying rate of the inorganic binder emulsion can be increased. The lower the boiling point of the oil phase, the faster the drying rate can be increased.

[0083] Also, the above oil phase is preferably a fluid that is insoluble in water (including poorly soluble). When the oil phase is soluble in water, the aqueous solution of the inorganic binder may be deteriorated. For example, when the material of the oil phase is soluble in water, the phosphate or silicate contained in the aqueous phase will precipitate, and an emulsion having the binder function of the present invention cannot be obtained.

[0084] Also, when the oil phase is a hydrocarbon-based organic solvent such as benzene or toluene, flammable organic gas will be generated during drying, so the fire risk will increase.

[0085] For these reasons, in the present invention, it is preferred to use a halogen-based solvent with a boiling point lower than that of water as the oil phase.

[0086] The above halogen-based solvent is preferably any fluorine-based solvent selected from chlorofluorocarbons, hydrofluoroethers, hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroolefins, and hydrochlorofluoroolefins because of its low impact on the human body and the environment and non-flammability.

[0087] In addition, it is preferable to add a thickener because the inorganic binder emulsion is less likely to phase-separate. Examples of the thickener include halogen-based resins, ceramic fine particles, and organic solvents. Note that these are preferably non-polar substances.

[0088] [Surfactant] As the surfactant used in the inorganic binder emulsion of the present embodiment, any appropriate surfactant can be used as long as the effects of the present embodiment can be obtained.

[0089] A surfactant is a general term for substances that act on an interface and change its properties. It has a structure with both a hydrophilic group and a lipophilic group (hydrophobic group) in one molecule, and is also called an emulsifier or an amphiphilic substance.

[0090] Since surfactants have functions such as lowering surface tension, forming micelles, penetration, and dispersion, they are used in a wide variety of applications such as lubricants, detergents, soaps, pharmaceuticals, cosmetics, and foods.

[0091] Surfactants are roughly classified into acrylic, vinyl, silicone, and fluorine types, and further, these can be classified into ionic surfactants and non-ionic surfactants according to the structure of the hydrophilic group.

[0092] An ionic surfactant is a material that ionizes into anionic, cationic, or amphoteric ions when the surfactant dissolves in water or an organic solvent. Examples include anionic surfactants such as carboxylates, sulfonates, sulfate esters, polyoxyethylene alkyl ether sulfate esters, and naphthalene sulfonic acid formalin condensates, cationic surfactants such as amine salts and quaternary ammonium salts, and amphoteric surfactants such as amino acid salts and betaine hydrochloride salts.

[0093] A nonionic surfactant is a material that has a hydrophilic group that does not ionize when the surfactant dissolves in water or an organic solvent. Examples include polyoxyethylene alkyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene alkyl phenyl ether (e.g., trade name: Triton X-100, Union Carbide, average HLB = 13.5), fatty acid alkanolamide, and the like.

[0094] An acrylic surfactant is a surfactant that contains a polymer obtained from an acrylic monomer. For example, those used as high molecular weight wetting and dispersing agents can be used. Examples include polyacrylic acid, styrene-acrylic acid copolymer, styrene-maleic acid-acrylic acid ester copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, styrene-maleic acid copolymer, styrene-maleic acid-acrylic acid alkyl copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, and their salts.

[0095] A vinyl surfactant is a surfactant that contains a polymer obtained from a vinyl monomer. Also, as a vinyl surfactant, a surfactant containing a polymer obtained from a vinyl monomer and silicone can be used.

[0096] A silicone surfactant is a surfactant having an organosiloxane structure in its molecular structure. Specifically, derivatives having a polydimethylsiloxane as a basic structure, such as polyether-modified siloxane, polyether-modified polymethylalkylsiloxane, polyether-modified polydimethylsiloxane, araalkyl-modified polymethylalkylsiloxane, and polyether-modified hydroxyl group-containing polydimethylsiloxane, can be mentioned.

[0097] A fluorosurfactant is a surfactant containing fluorine. Generally, it is a substance in which all or part of the hydrogen atoms of the hydrophobic group of a hydrocarbon surfactant are substituted with fluorine atoms.

[0098] For each of the above surfactants, those synthesized as appropriate may be used, or commercially available products may be used. Commercially available products can be obtained, for example, from BYK Chemie, Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Kao Corporation, Nippon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd., Takemoto Yushi Co., Ltd., Neos Co., Ltd., AGC Inc., Sumitomo 3M Limited, Dainippon Ink and Chemicals, Inc., Daikin Industries, Ltd., etc.

[0099] The above surfactant is preferably dissolved in the oil phase, but it may also be dissolved in the water phase or both.

[0100] The content ratio of the above surfactant is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.02% by mass or more and 15% by mass or less, and even more preferably 0.5% by mass or more and 10% by mass or less, based on the emulsion.

[0101] When the surfactant contained in the emulsion is less than 0.01% by mass, the water phase and the oil phase are likely to phase-separate, the emulsion becomes unstable, and phase separation such as creaming and Ostwald ripening is likely to occur over time. As the content ratio of the surfactant increases, the emulsion tends to be more stable, but when it exceeds 20% by mass, the function as a binder significantly decreases. That is, when emphasizing the function as a binder, it should be as little as possible while being 0.01% by mass or more, and when emphasizing stability, it should be as much as possible while being 20% by mass or less.

[0102] In order to obtain a long-term stable emulsion, it is preferable to contain an acrylic surfactant or a silicone surfactant in the oil phase. By using a surfactant that is easily soluble in the oil phase, the interfacial tension of the oil phase becomes low, and it is likely to become the continuous phase.

[0103] Note that surfactants include those having only an amine value, those having only an acid value, those having both an amine value and an acid value, and those having neither an amine value nor an acid value. In the present embodiment, it is preferable to have an acid value. When the acid value is low, it tends to be difficult to obtain a dispersion stabilization effect. Therefore, the acid value is preferably 1 mgKOH / g or more and 90 mgKOH / g or less. Also, it may have an amine value, but if it does, it is preferably 100 mgKOH / g or less.

[0104] In addition, the HLB (Hydrophile-Lipophile-Balance) of the surfactant is preferably 0.1 or more and 10 or less. HLB is a numerical representation of the balance between the hydrophilicity and lipophilicity of a surfactant. Generally, when the HLB value is low, the lipophilicity is high, and when it is high, the hydrophilicity is high.

[0105] As the surfactant to be included in the oil phase, an anionic or nonionic surfactant is preferable.

[0106] When used for binding battery materials with poor hydrophilicity (for example, carbon or powders supported with oil, etc.), it is preferably further included in the aqueous phase. From the perspective that when used as an electrode binder, it is difficult to form nodules in the slurry and a homogeneous electrode can be manufactured, as the surfactant to be included in the aqueous phase, a nonionic surfactant is preferable.

[0107] The above surfactant adsorbs at the interface between the oil phase and the aqueous phase, and emulsifies by reducing the interfacial energy to form an emulsion. Instead of the surfactant, hydrophobic solid fine particles (median diameter D 50 is 5 nm or more and 1 μm or less) or hydrophilic soft nanoparticles (median diameter D 50 is 5 nm or more and 1 μm or less) may be added. Thereby, the solid fine particles and soft nanoparticles can be attached to the oil phase interface by physical acting forces (van der Waals forces) and emulsified (so-called Pickering emulsification method or three-phase emulsification method).

[0108] Therefore, in the present embodiment, the above-mentioned solid fine particles and soft nanoparticles are also included in the surfactant.

[0109] Examples of the above-mentioned solid fine particles include materials obtained by hydrophobizing the surfaces of silica, alumina, zirconia, boehmite, titania, barium titanate, titanium carbide, silicon nitride, silicon carbide, boron nitride, magnesia, bismuth oxide, aluminum nitride, ferrite, and the like.

[0110] Soft nanoparticles are hydrophilic materials that do not dissolve in either the aqueous phase or the oil phase. They are stably dispersed in the aqueous phase and can convert the hydrophobicity of the oil-phase surface to hydrophilicity by adhering to the oil-phase surface through physical forces.

[0111] Examples of the above-mentioned hydrophilic soft nanoparticles include polysaccharides such as ribose, xylose, rhamnose, fucose, glucose, mannose, glucuronic acid, gluconic acid, phospholipids, polyesters, potato, glutinous rice flour, tapioca flour, kelp powder, chitosan, agar, starch, carboxymethyl cellulose salt, hydroxyethyl cellulose, methyl cellulose, hydroxypropyl methyl cellulose, sanjeroose, cellulose nanofibers, etc., derivatives of polyoxyethylene hydrogenated castor oil, dialkylammonium derivatives, trialkylammonium derivatives, tetraalkylammonium derivatives, dialkenylammonium derivatives, trialkenylammonium derivatives, or tetraalkenylammonium derivative halogen salts, phospholipids, and particles made from phospholipid derivatives.

[0112] The content ratio of the above-mentioned hydrophobic solid fine particles or hydrophilic soft nanoparticles is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.02% by mass or more and 5% by mass or less, and even more preferably 0.03% by mass or more and 3% by mass or less with respect to the emulsion.

[0113] An inorganic binder emulsion can be generated by mixing hydrophobic solid fine particles or hydrophilic soft nanoparticles together with the aqueous phase and the oil phase.

[0114] However, when manufacturing an inorganic binder emulsion by the Pickering emulsification method or the three-phase emulsification method and using this as a battery material, it is necessary to select materials in which hydrophobic solid fine particles and hydrophilic soft nanoparticles do not have an adverse effect on the charge-discharge characteristics. Further, since the aqueous phase of the present embodiment is acidic with a pH of 4 or less or alkaline with a pH of 9 or more, hydrophobic solid fine particles and hydrophilic soft nanoparticles also require resistance to acidity or alkalinity.

[0115] [Other Additives] The above aqueous phase, oil phase, or both may further contain a resin-based binder. As the resin-based binder, known resins can be used. For example, it may be a resin-based binder used for a positive electrode or a negative electrode. However, from the viewpoints of chemical stability, heat resistance, and reduction resistance of the granulated body, polybenzimidazole, styrene-butadiene rubber, polyvinylidene fluoride, carboxymethyl cellulose salt, polyvinyl alcohol, polyacrylic acid, polyacrylate, cellulose nanofiber, polyimide, polyamic acid, polyamide, and polyamideimide are preferable.

[0116] Further, the above aqueous phase, oil phase, or both may further contain ceramic particles. As the ceramic particles, known ceramics can be used. For example, silica, alumina, zirconia, titania, yttria, kaolin, metakaolin, etc. can be mentioned. Moreover, it may contain a salt showing ionic conductivity. For example, ionic liquids, alkali metal salts, solid electrolytes, electrolytic solutions, etc. can be mentioned.

[0117] Further, it is preferable that the above emulsion further contains carbon because the cycle characteristics, input characteristics, and output characteristics of the battery are improved. In this case, an emulsion may be prepared using a dispersion of carbon in the aqueous phase or the oil phase in advance, or carbon may be added to the emulsion composed of both.

[0118] As the carbon, any carbon that can improve the conductivity of the dried product of the emulsion can be used without particular limitation, and the same carbon as that known as a conductive aid for electrodes used in chemical batteries can be used. For example, 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 (for example, vapor-grown carbon fibers named VGCF as a registered trademark), graphene, carbon nanohorns, etc. can be mentioned, and one or more of these may be used.

[0119] The carbon contained in the emulsion is preferably contained in an amount of 0.1% by mass or more and 20% by mass or less with respect to the phosphate contained in the liquid phase. If it exceeds 20% by mass, the fluidity of the emulsion will decrease, and when used as a binder for a battery, the electrode capacity density tends to be low.

[0120] [Manufacturing method] The emulsion of the present embodiment can be produced by mixing the aqueous phase and the oil phase after dissolving the above surfactant in either the aqueous phase or the oil phase, or after dissolving the above surfactant in both.

[0121] The mixing method is not particularly limited as long as the aqueous phase and the oil phase can be mixed homogeneously. For example, known stirring methods or mixing methods such as a multi-axis planetary mixer, a rotating and revolving mixer, a rolling mill, a vibration mill, a planetary mill, a rocking mill, a horizontal mill, an attritor mill, a jet mill, a crusher, an ultrasonic homogenizer, a homogenizer, a fluidizer, a paint shaker, a magnetic stirrer, and hand stirring can be used. Among these, a homogenizer is preferable because of its high production speed, less contamination of the product, and tendency to become a stable emulsion over a long period of time.

[0122] Homogenizers include pressure type, ultrasonic type, rotor / stator type, bead type, etc., and any of them can be preferably used. Among them, the pressure type and the ultrasonic type are preferable, and in particular, the pressure type can stably maintain the emulsion for a long period of time.

[0123] Here, the pressure type homogenizer is a device that manufactures an emulsion by mixing an oil phase and an aqueous phase by extruding them through a thin nozzle under high pressure. As a result, the liquid particles become smaller and have a uniform size. The ultrasonic type homogenizer is a device that manufactures an emulsion by using high-frequency sound waves to make the particles in the liquid finer. The rotor / stator type homogenizer is a device that obtains an emulsion by adding an oil phase and an aqueous phase to a rotating rotor and a fixed stator and applying the shearing force between the rotor and the stator. The bead type homogenizer is a device that produces an emulsion by vibrating an oil phase and an aqueous phase in a container containing small beads or spheres.

[0124] In addition, since the added aqueous phase is likely to be always surrounded by a relatively large amount of oil, it is preferable to manufacture the above mixing method by adding the aqueous phase to the agitated oil phase.

[0125] Also, during mixing, it is preferable to adjust the temperature of the liquid (oil phase, aqueous phase, emulsion) to -30°C or higher and 30°C or lower. When it exceeds 30°C, the oil phase is likely to vaporize, and not only can it not be effectively mixed, but also the ratio deviation between the oil phase and the aqueous phase is likely to occur. When it is less than -30°C, the aqueous phase solidifies, making it difficult to produce a uniform emulsion.

[0126] The temperature can be controlled by circulating a chiller through the mixing device.

[0127] By the above-described production method, an inorganic binder emulsion in which the average particle diameter of the micelles in the aqueous phase contained in the emulsion is 10 nm or more and 10 μm or less can be obtained. The micelle diameter can be determined by observation with a microscope or particle size distribution measurement, but it is easier to understand when a coloring agent is dissolved in either the aqueous phase or the oil phase. Note that the average particle diameter of the micelles forming the emulsion according to the present embodiment is different from the median diameter (D 50 ). The average particle diameter of the micelles is measured, for example, by the dynamic light scattering method using a high-concentration particle size analyzer FPAR-1000AS (manufactured by Otsuka Electronics Co., Ltd.) equipped with an autosampler.

[0128] [Binder or coating agent for granulation of active material for battery or capacitor] As described above, the produced inorganic binder emulsion can be used as a binder or coating agent for granulation of an active material used in a battery or a capacitor. In that case, the primary particles of the active material are preferably in the range of 0.01 μm to 10 μm in median diameter (D 50 ), and the active material particles (secondary particles) after granulation are preferably in the range of 1 μm to 100 μm in median diameter (D 50 ).

[0129] As the granulation method of the active material, known granulation methods can be applied, and examples thereof include a fluidized bed granulation method, a stirring granulation method, a rolling granulation method, a spray drying method, an extrusion granulation method, a rolling granulation method, and a coating granulation method. Among these, the spray drying method and the fluidized bed granulation method are particularly preferable.

[0130] In the spray drying method, for example, a suspension in which an active material is dispersed in an inorganic binder emulsion is prepared, and this suspension is sprayed from above into a greenhouse heated to 50 to 300 °C at 1 to 30 mL / min and an air pressure of 0.01 to 5 MPa to form agglomerated particles, which are then dried to obtain a granulated product.

[0131] In the fluidized bed granulation method, for example, a powder raw material is put into a fluidized bed granulation apparatus, and hot air heated to 50 to 300 °C is sent in from below to fluidize and mix the powder raw material (granule precursor). An inorganic binder emulsion is spray - atomized from above onto this mixed powder raw material nozzle. By spraying the inorganic binder emulsion uniformly on the powder surface at 1 to 30 mL / min and an air pressure of 0.01 to 5 MPa, agglomerated particles are formed, and these are dried to obtain granules.

[0132] The amount of the binder for granulation is not particularly limited as long as it can bind the active material particles, but it is preferably in the range of 0.1 to 30% by mass with respect to the granulated body. The inorganic binder emulsion is preferably contained in the range of 0.2 to 30% by mass with respect to the granulated body. The granulated body obtained in this way not only improves the cycle life characteristics but also improves the coating property of the slurry.

[0133] Also, the above - mentioned granulated product may contain a solid electrolyte or may be coated with a solid electrolyte.

[0134] Active materials are generally synthesized by a firing method or a hydrothermal method. After synthesis, using techniques such as spray - drying, the particle size is granulated to about 5 to 30 μm, and further production is carried out through a sieving process.

[0135] In order to enhance the performance of such active materials, it is known that by coating the particle surface of the active material with carbon, the conductivity is improved and the resistance of the battery is reduced. Also, when carbon is replaced with ceramics, solid electrolytes, resins, etc., it is known that the decomposition of the electrolyte solution and electrolyte is suppressed, and the life and safety of the battery are improved.

[0136] For example, since LiFePO4 has a drawback of poor conductivity, organic substances and hydrocarbon gases are heated and carbonized at 700 °C or higher using a rotary kiln or the like to coat the particle surface of LiFePO4 with carbon. However, this method is not suitable for materials that are prone to thermal decomposition and carbon reduction, and also has a small heat transfer coefficient and a large waste heat loss during processing, so a large amount of energy is discarded.

[0137] In a battery using a solid electrolyte, it is known as an issue that the solid electrolyte in contact with the positive electrode active material reacts and the properties such as ionic conductivity deteriorate. Therefore, a method of coating active material particles with ceramics such as Li4Ti5O 12 , LiNbO3, and LiTaO3 as a buffer layer has been developed, but these ceramics have a weak adhesive force and are easily peeled off in the kneading process of the slurry, and there is an issue that it is difficult to exhibit sufficient performance.

[0138] Also, this material is produced by spraying a dispersion liquid containing ceramics or a liquid in which a ceramic precursor is dissolved on the surface of active material particles using a fluidized bed coating device and then performing heat treatment in a high-temperature oxygen atmosphere.

[0139] Generally, the dispersion medium or solvent used in these liquids is water or an organic solvent. In the case of water, it takes more time to dry compared to an organic solvent, resulting in a lack of productivity. On the other hand, an organic solvent with high volatility has the drawback that although drying is fast, the risk of ignition during manufacturing is high.

[0140] When using the inorganic binder emulsion of this embodiment, the above-mentioned issues can be solved. That is, the drying time can be shortened and granulated products with uniform particle size can be safely produced.

[0141] Also, when using aluminum or an aluminum alloy for the current collector, if the pH of the slurry is too low or too high, the current collector may corrode and hydrogen gas may be generated. However, in the case of the granulated body containing the inorganic binder emulsion of the present invention, it does not corrode aluminum or an aluminum alloy, so it can be used regardless of the pH of the slurry.

[0142] Also, in the process of drying the slurry, the phenomenon that water vapor is trapped in the dry film and expands due to the pressure is less likely to occur.

[0143] [Binder for battery or capacitor electrodes] A battery or capacitor is composed of a positive electrode, a negative electrode, an electrolyte, and an outer casing (housing case). When the electrolyte has fluidity, a separator is interposed between the positive electrode and the negative electrode.

[0144] Note that both the positive electrode and the negative electrode are electrodes. However, in a battery or capacitor, the electrode that releases electrons during discharge is the positive electrode, and the electrode that releases ions (carriers) during discharge is the negative electrode.

[0145] As components of the electrode, there are a current collector and a composite material layer (active material layer). For example, in a lithium-ion battery, an aluminum foil or a copper foil is used as the current collector, and a composite material layer containing an active material such as a lithium transition metal oxide or graphite and a binder is provided.

[0146] As described above, the manufactured inorganic binder emulsion can be used as a binder for the electrodes of non-aqueous electrolyte batteries and non-aqueous electrolyte capacitors. In that case, the median diameter (D 50 ) of the secondary particles of the active material is preferably in the range of 1 μm to 100 μm.

[0147] When the total of the active material, binder, and conductive assistant contained in the electrode is 100% by mass, it is preferable that the binder is contained in an amount of 0.1 to 60% by mass, and more preferably 0.2 to 30% by mass.

[0148] If the binder is less than 0.1% by mass, the mechanical strength of the electrode is low. Therefore, when the inorganic binder emulsion dries, the active material is likely to fall off, and the cycle characteristics of the battery may deteriorate. On the other hand, if it exceeds 60% by mass, the ionic conductivity is low, the electrical resistance is high, and the proportion of the active material as a battery is small, so the electrode capacity density is likely to be low.

[0149] The current collector used for the electrode is not particularly limited as long as it has electronic conductivity and can conduct electricity to the held active material. For example, conductive substances such as C, Ti, Cr, Ni, Cu, Mo, Ru, Rh, Ta, W, Os, Ir, Pt, Al, Au, etc., and alloys containing two or more of these conductive substances (for example, stainless steel) can be used. When using something other than the above-mentioned conductive substances, for example, a multi-layer structure of different metals such as iron coated with Cu or Ni may be used.

[0150] When Al or an Al alloy is used for the current collector, if the pH of the slurry is too low or too high, the current collector may corrode and generate hydrogen gas. However, when the inorganic binder emulsion of the present invention is included as a binder for the electrode, it does not corrode aluminum or an aluminum alloy, so it can be used regardless of the pH.

[0151] The shapes of the current collector include linear, rod-shaped, plate-shaped, foil-shaped, and porous. Among these, the porous shape is preferable because the packing density can be increased and the inorganic binder emulsion easily penetrates into the composite layer. Examples of the porous shape include mesh, woven fabric, non-woven fabric, embossed body, punched body, perforated foil, expanded body, or foam. The active material used for the electrode (positive electrode or negative electrode) is not particularly limited as long as it is an active material used in a non-aqueous electrolyte secondary battery or a capacitor.

[0152] In the case of the negative electrode, at least one or more elements selected from the group consisting of Li, Na, K, C, Mg, Al, Si, P, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Sb, W, Pb, and Bi, alloys, compounds, oxides, chalcogenides, or halides using these elements may be used.

[0153] In the case of the positive electrode, known active materials including alkali metal transition metal oxide systems, vanadium systems, sulfur systems, solid solution systems (lithium excess systems, sodium excess systems, potassium excess systems), carbon systems, organic matter systems, etc. are used.

[0154] The shape of the active material particles is not particularly limited, and may be spherical, elliptical, rhombic, strip-shaped, fibrous, flaky, donut-shaped, or hollow.

[0155] In addition to the above-mentioned active material, binder, and conductive aid, a solid electrolyte may also be contained.

[0156] [Coating agent or skeleton former for electrodes of batteries or capacitors] As described above, the manufactured inorganic binder emulsion can be used as a coating agent or skeleton former for electrodes of non-aqueous electrolyte batteries and non-aqueous electrolyte capacitors.

[0157] By applying the inorganic binder emulsion to the composite material layer of the electrode, the inorganic binder emulsion penetrates into the active material layer. By drying this, an aqueous phase component (phosphate or silicate) remains in the composite material layer, which functions as a strong skeleton. This skeleton relaxes the volume change of the electrode and improves the insulation of the electrode surface.

[0158] For example, a mixture of an active material, a binder, and a conductive aid added as necessary is slurried and applied to a current collector and pre-dried. Then, the inorganic binder emulsion is coated or filled on the composite material layer, and heat treatment is performed at 60 °C or higher to obtain an electrode. That is, an electrode is obtained by applying or filling the inorganic binder emulsion to the composite material layer obtained by the slurry coating method and then performing heat treatment.

[0159] The pre-drying is not particularly limited as long as it can volatilize and remove the solvent in the slurry. For example, a method of performing heat treatment in an atmosphere at a temperature of 45 to 200 °C in the air can be mentioned. By coating or filling the inorganic binder on the composite material layer, an electrode with excellent heat resistance, high strength, and improved cycle characteristics can be obtained.

[0160] Inorganic binder emulsions are more likely to penetrate into porous bodies such as the composite material layer compared to only O / W type emulsions or the aqueous phase (water in which the inorganic binder is dissolved), and can be dried at low temperatures. Therefore, even when the composite material layer of the electrode is thick, dense, or contains a water-repellent material, it penetrates uniformly and requires less energy for drying.

[0161] [Coating agent for metal surface] As described above, the produced inorganic binder emulsion can be used as a coating agent for aluminum or an aluminum alloy.

[0162] For example, by applying an inorganic binder emulsion to an aluminum foil used as a current collector and drying it, the surface of the aluminum can be coated with a solid substance (silicate or phosphate) in the aqueous phase.

[0163] The aluminum foil coated with the solid substance in the aqueous phase has significantly improved alkali resistance compared to the uncoated aluminum foil. Also, the solid substance in the aqueous phase also functions as a primer layer when applying the electrode slurry.

[0164] Depending on the thickness of the film composed of the solid substance in the aqueous phase, if it is 500 nm or less in thickness, other metals can be joined by methods such as spot welding, ultrasonic welding, and laser welding. For example, five sheets of aluminum foil with a 100 nm thick film formed can be spot welded to be joined in a state where each conduction is obtained.

[0165] [Battery or capacitor] Batteries are broadly classified into primary batteries and secondary batteries. A primary battery is a disposable type of battery that cannot be restored once the chemical reaction is completed. In contrast, a secondary battery is a type of battery that can be charged and discharged.

[0166] Commonly circulated general primary batteries include alkaline primary batteries, zinc-carbon primary batteries, mercury primary batteries, silver oxide primary batteries, air primary batteries, lithium primary batteries, etc.

[0167] Common secondary batteries include lead-acid batteries, nickel-metal hydride (Ni-MH) secondary batteries, nickel-cadmium (Ni-Cd) secondary batteries, lithium-ion secondary batteries, etc., which are generally in circulation. In particular, lithium-ion batteries, due to their characteristics of being small, lightweight, high-voltage, and having no memory effect, are experiencing a rapid increase in demand as a representative example of non-aqueous electrolyte secondary batteries.

[0168] The inorganic binder emulsion of this embodiment is preferably applied to non-aqueous electrolyte batteries or non-aqueous electrolyte capacitors. Although it can also be used in battery systems mainly composed of water, compared with those applied to non-aqueous electrolyte batteries, a significant improvement in battery performance is not confirmed.

[0169] Here, a non-aqueous electrolyte battery is a battery system using an electrolyte that does not mainly contain water. Examples of non-aqueous electrolyte secondary batteries include lithium-ion batteries, lithium polymer batteries, lithium semi-solid batteries, lithium all-solid-state batteries, lithium-air batteries, lithium-sulfur batteries, sodium-ion batteries, sodium-sulfur batteries, sodium semi-solid batteries, sodium all-solid-state batteries, potassium-ion batteries, polyvalent ion batteries, fluoride ion batteries, etc. Note that a semi-solid battery refers to a battery that combines a solid electrolyte and a liquid electrolyte.

[0170] For a battery or capacitor using the above electrode (positive electrode or negative electrode), a battery structure can be considered in which the positive electrode and the negative electrode are joined via a separator and sealed in a state of being immersed in an electrolyte solution. Note that the structure of the battery is not limited to this, and it can be applied to existing battery forms and structures such as laminated batteries and wound batteries.

[0171] In addition, the electrolyte used in this battery or capacitor may be a liquid or a solid capable of moving ions from the positive electrode to the negative electrode or from the negative electrode to the positive electrode, and the same electrolyte as that used in known non-aqueous electrolyte secondary batteries can be used. For example, there are electrolytic solutions, gel electrolytes, solid electrolytes, ionic liquids, and molten salts, and two or more of them may be used in combination. Here, the electrolytic solution refers to a state in which an electrolyte is dissolved in a solvent.

[0172] Since the electrolyte needs to contain ions serving as carriers, the electrolyte salt is not particularly limited as long as it is used in non-aqueous electrolyte secondary batteries. For example, metal salts such as lithium salts, sodium salts, potassium salts, magnesium salts, and calcium salts are suitable.

[0173] The battery or capacitor according to this embodiment can be used as a power source for electrical equipment.

Examples

[0174] Hereinafter, the examples according to the present invention will be described more specifically, but the present invention is not limited to these examples at all. In particular, in the examples, an aqueous solution of aluminum dihydrogen trisphosphate is described as an example of the aqueous phase, but the present invention is not limited thereto.

[0175] [Examination of the ratio of the aqueous phase to the oil phase (1)] In order to examine the influence of the ratio of the aqueous phase to the oil phase on emulsion formation, an inorganic binder emulsion was prepared by attempting to mix an aqueous solution of aluminum dihydrogen trisphosphate (CAS 13530-50-2) (concentration: 39% by mass) as the aqueous phase, a fluorine-based solvent (manufactured by AGC, Amolea, AS-300) as the oil phase, and an acrylic high-molecular-weight wetting dispersant (solution of a modified styrene maleic acid copolymer) as the surfactant at a predetermined ratio by manual stirring (shaking) at 20°C.

[0176] In Examples 1 to 5 and Comparative Example 1, an inorganic binder emulsion was prepared by mixing an aqueous solution of aluminum dihydrogen trisphosphate (CAS 13530-50-2) (concentration: 39% by mass) as the aqueous phase, a fluorine-based solvent (manufactured by AGC, Amolea, AS-300) as the oil phase, and an acrylic high-molecular-weight wetting dispersant (solution of a modified styrene maleic acid copolymer) as the surfactant by manual stirring (shaking) so as to have the compositions shown in the table of FIG. 3 at 20°C.

[0177] Figure 3 shows the stability of the emulsions in each example. After mixing, the inorganic binder emulsion was allowed to stand in an environment of 20°C. When the state of the emulsion was maintained for 30 minutes or more, it was marked as "〇"; when the state of the emulsion was maintained for more than 10 minutes and less than 30 minutes, it was marked as "△"; when the state of the emulsion was less than 10 minutes or phase separation occurred immediately, it was marked as "×".

[0178] As is clear from Figure 3, it was found that the ratio of the aqueous phase to the oil phase has a great influence on the stability of the emulsion. Also, when the aqueous phase is rich, there is a tendency that phase separation is difficult to occur. However, when the aqueous phase exceeds 92%, the stability of the emulsion decreases.

[0179] [Study on the ratio of the aqueous phase to the oil phase (2)] In Examples 6 to 9 and Comparative Example 2, an inorganic binder emulsion was prepared by mixing an aqueous solution of aluminum dihydrogen trisphosphate (concentration: 39% by mass) as the aqueous phase, a fluorine-based solvent (Amolea, AS-300, manufactured by AGC) as the oil phase, and an acrylic high-molecular-weight wetting dispersant (solution of a modified styrene maleic acid copolymer) and a silicone-based dispersant (polyether-modified product) as surfactants in an environment of 20°C and mixing them by manual stirring (shaking) so as to have the compositions shown in the table of Figure 4.

[0180] That is, Example 6 is the same as Example 1 except that an acrylic high-molecular-weight wetting dispersant and a silicone-based dispersant mixed at a weight ratio of 8:2 are used as the surfactant.

[0181] That is, Example 7 is the same as Example 2 except that an acrylic high-molecular-weight wetting dispersant and a silicone-based dispersant mixed at a weight ratio of 8:2 are used as the surfactant.

[0182] Example 8 is the same as Example 3 except that an acrylic high-molecular-weight wetting dispersant and a silicone-based dispersant mixed at a weight ratio of 8:2 are used as the surfactant.

[0183] Example 9 is the same as Example 4, except that an acrylic high molecular weight wetting dispersant and a silicone-based dispersant are mixed at a weight ratio of 8:2 as the surfactant.

[0184] Comparative Example 2 is the same as Comparative Example 1, except that an acrylic high molecular weight wetting dispersant and a silicone-based dispersant are mixed at a weight ratio of 8:2 as the surfactant.

[0185] Figure 4 shows the stability of the emulsions in each example. After mixing, the inorganic binder emulsion was allowed to stand in a 20°C environment. When the state of the emulsion was maintained for 30 minutes or more, it was marked as "〇"; when the state of the emulsion was maintained for more than 10 minutes and less than 30 minutes, it was marked as "△"; when the state of the emulsion was less than 10 minutes or phase separation occurred immediately, it was marked as "×".

[0186] As is clear from Figure 4, it was found that the ratio of the aqueous phase to the oil phase has a great influence on the stability of the emulsion. Also, it was found that when the aqueous phase is rich, there is a tendency for less phase separation.

[0187] [Investigation of the amount of surfactant] To investigate the influence of the amount of surfactant on emulsion formation, an inorganic binder emulsion was prepared by attempting to mix an aluminum dihydrogen trisphosphate aqueous solution (concentration 39% by mass) as the aqueous phase, a fluorine-based solvent (manufactured by AGC, Amolea, AS-300) as the oil phase, and an acrylic high molecular weight wetting dispersant (solution of modified styrene maleic acid copolymer) as the surfactant by hand stirring (shaking) at a predetermined composition.

[0188] In Examples 10 - 11 and Comparative Examples 3 - 6, an inorganic binder emulsion was prepared by mixing an aluminum dihydrogen trisphosphate aqueous solution (concentration 39% by mass) as the aqueous phase, a fluorine-based solvent (manufactured by AGC, Amolea, AS-300) as the oil phase, and an acrylic high molecular weight wetting dispersant (solution of modified styrene maleic acid copolymer) as the surfactant by hand stirring (shaking) at the compositions described in the table of Figure 5 under a 20°C environment.

[0189] Figure 5 shows the stability of the emulsions of Examples 10 to 11 and Comparative Examples 3 to 6. After mixing, the inorganic binder emulsion was allowed to stand in an environment of 20°C. When the state of the emulsion was maintained for 30 minutes or more, it was marked as "〇"; when the state of the emulsion was maintained for more than 10 minutes and less than 30 minutes, it was marked as "△"; when the state of the emulsion was less than 10 minutes, it was marked as "×"; when phase separation occurred immediately after mixing and it did not even form an emulsion state, it was marked as "××".

[0190] As is clear from Figure 5, when 80% by mass of the oil phase was present, even when the amount of surfactant added was increased and mixed, the emulsion was not stable and phase separation occurred over time.

[0191] The tendency was that the larger the amount of surfactant added, the easier it was to stably form an emulsion. However, even when added excessively, no significant change was observed in the stability of the emulsion. It was found that the ratio of the aqueous phase to the oil phase had a greater influence than the amount of surfactant added.

[0192] Figure 2 compares and shows the appearance photos of the inorganic binder emulsions of Example 1 and Comparative Example 6. In addition, in order to make it easier to distinguish the aqueous phase and the oil phase, the oil phase was used after being immersed in and colored with blue ink (manufactured by Zebra Co., Ltd., oil-based marker Mackie Pen Blue) in advance.

[0193] As is clear from Figure 2, it can be seen that when no surfactant is contained at all, it separates into two phases immediately after mixing.

[0194] [Investigation of the type of surfactant] In order to investigate the influence of the type of surfactant on emulsion formation, various surfactants were investigated.

[0195] That is, Comparative Example 7 is the same as Example 3 except that a cationic polyethyleneimine (molecular weight 10,000) is used as the surfactant. Comparative Example 8 is the same as Example 3 except that a nonionic polyoxyethylene (3) lauryl ether is used as the surfactant. Comparative Example 9 is the same as Example 3 except that a nonionic polyoxyethylene (47) lauryl ether is used as the surfactant.

[0196] Comparative Example 10 is the same as Example 3 except that a nonionic polyoxyethylene (9) lauryl ether is used as the surfactant. Comparative Example 11 is the same as Example 3 except that a sodium salt of an anionic β-naphthalenesulfonic acid formalin condensate is used as the surfactant. Comparative Example 12 is the same as Example 3 except that a nonionic polyoxyethylene (5) lauryl ether is used as the surfactant. Comparative Example 13 is the same as Example 3 except that a nonionic polyoxyethylene (10) octylphenyl ether is used as the surfactant. Comparative Example 14 is the same as Example 3 except that an anionic synthetic hectorite is used as the surfactant.

[0197] The table in Fig. 6 shows the stability of the emulsions of Comparative Examples 7 to 14. In all cases, since the emulsion phase separated in less than 10 minutes, it was found that the choice of surfactant is a very important factor.

[0198] [Examination of the solid content concentration of the aqueous phase] To examine the influence of the solid content concentration of the aqueous phase on emulsion formation, attempts were made to prepare inorganic binder emulsions by changing the solid content concentration.

[0199] As shown in the table of Fig. 7, Examples 12 to 15 and Comparative Examples 15 to 17 were prepared using an aqueous solution of aluminum dihydrogen trisphosphate adjusted to a predetermined concentration.

[0200] That is, Example 12 is the same as Example 1 except that an aqueous solution of aluminum dihydrogen trisphosphate (solid content concentration: 60% by mass) is used. Example 13 is the same as Example 1 except that an aqueous solution of aluminum dihydrogen trisphosphate (solid content concentration: 50% by mass) is used. Example 14 is the same as Example 1 except that an aqueous solution of aluminum dihydrogen trisphosphate (solid content concentration: 30% by mass) is used.

[0201] Example 15 is the same as Example 1 except that an aqueous solution of aluminum dihydrogen trisphosphate (solid content concentration: 25% by mass) is used. Comparative Example 15 is the same as Example 1 except that an aqueous solution of aluminum dihydrogen trisphosphate (solid content concentration: 19% by mass) is used. Comparative Example 16 is the same as Example 1 except that an aqueous solution of aluminum dihydrogen trisphosphate (solid content concentration: 10% by mass) is used. Comparative Example 17 is the same as Example 1 except that an aqueous solution of aluminum dihydrogen trisphosphate (solid content concentration: 5% by mass) is used.

[0202] Fig. 7 shows the stability of the emulsions of Examples 12 to 15 and Comparative Examples 15 to 17. After mixing, the inorganic binder emulsion was allowed to stand in an environment at 20°C. When the state of the emulsion was maintained for 30 minutes or more, it was marked as "〇"; when the state of the emulsion was maintained for more than 10 minutes and less than 30 minutes, it was marked as "△"; when the state of the emulsion was less than 10 minutes, it was marked as "×".

[0203] The emulsion showed a tendency to be more stable as the solid content concentration of the aqueous phase increased. Phase separation occurred in a short time at 19% by mass or less.

[0204] [Investigation of dispersion conditions] To investigate the influence of the mixing method on emulsion formation, attempts were made to prepare an inorganic binder emulsion using various mixing devices.

[0205] Examples 16 to 18 were prepared by mixing an aluminum dihydrogen trisphosphate aqueous solution (concentration: 40% by mass) as the aqueous phase, a fluorine-based solvent (Amolea, AS-300, manufactured by AGC) as the oil phase, and an acrylic high-molecular-weight wetting and dispersing agent (solution of a modified styrene maleic acid copolymer) as the surfactant under the conditions described in the table of FIG. 8 at 20°C to obtain an inorganic binder emulsion.

[0206] Also, the case without using a surfactant was similarly examined. That is, Comparative Example 17 is the same as Example 16 except that no surfactant was used. Comparative Example 19 is the same as Example 17 except that no surfactant was used. Comparative Example 20 is the same as Example 18 except that no surfactant was used.

[0207] FIG. 8 shows the stability of the emulsions of Examples 16 to 18 and Comparative Examples 18 to 20. After mixing, the inorganic binder emulsion was allowed to stand at 20°C. When the state of the emulsion was maintained for 30 minutes or more, it was marked as "〇"; when the state of the emulsion was maintained for 10 minutes or more but less than 30 minutes, it was marked as "△"; when the state of the emulsion was less than 10 minutes, it was marked as "×"; and when phase separation occurred immediately after mixing and the emulsion state was not even achieved, it was marked as "××".

[0208] It was found that using an ultrasonic or high-pressure homogenizer rather than manual stirring (shaking) could maintain the emulsion for a longer time. Comparing the ultrasonic and high-pressure methods, the high-pressure method could maintain the emulsion for an even longer time.

[0209] Also, when no surfactant was used, phase separation occurred immediately regardless of the mixing method, and the emulsion state was not even achieved.

[0210] [Evaluation of Ceramic Adhesive] The inorganic binder emulsion of Example 1 and alumina (median diameter D 50=50 μm) were mixed at a solid content ratio of 20:80 mass %, and the resulting slurry was applied to an aluminum plate (thickness 20 μm) using a doctor blade (slit 300 μm), dried at 80 °C for 10 hours, and then heat-treated at 100 °C, 200 °C, and 300 °C for 1 hour each to obtain an aluminum foil provided with an alumina composite layer.

[0211] As a result of bending the aluminum foil provided with the alumina composite layer, it was found that as the heat treatment temperature increased, the composite layer became harder and was firmly bonded to the aluminum foil.

[0212] [Antioxidant] The aqueous solution of aluminum dihydrogen trisphosphate exhibits acidity with a pH value of 2 - 3. Therefore, except for Al and Al alloys, it has the property of corroding iron as it is. Thus, the inorganic binder emulsion of Example 1 was mixed with an aqueous solution of zinc chloride (concentration 20 mass %), and the resulting precipitate was filtered and dried, and then pulverized with a ball mill (made of zirconia, rotation speed 200 rpm, 1 hour) to produce antioxidant powder.

[0213] Antioxidant powder (80 mass %) and an acrylic resin (20 mass %) were mixed with water and applied to the surface of degreased iron in a slurry state. Then, after hot air drying at 80 °C, a salt spray test (ambient temperature 35 °C, salt concentration 5 mass %) was conducted to confirm the presence or absence of its antioxidant property. In the above salt spray test, the conditions not specifically described conform to ASTM D610 - 68.

[0214] As a result of the salt spray test, it was confirmed that oxidation progressed less easily compared to iron without the antioxidant applied. It can protect against rust and corrosion.

[0215] In addition, in order to obtain the antioxidant powder, in addition to zinc chloride, zinc compounds, magnesium compounds, and calcium compounds also exhibit an antioxidant effect. Also, the resin does not have to be an acrylic resin, and an existing binder may be used. For example, a binder used for electrodes of a battery may be used.

[0216] [Fiber Reinforcement Material and Flyaway Inhibitor] Glass nonwoven fabric (manufactured by Advantech Co., Ltd., GA100) was filled with the inorganic binder emulsion of Example 1 and the inorganic binder phase-separated body of Comparative Example 6, respectively, dried (100 °C, 3 h, in air), and after drying, each nonwoven fabric was compared with the state before filling.

[0217] In the glass nonwoven fabric using Example 1, the inorganic binder was dried uniformly, and compared with that before drying, the strength was improved and the flyaway on the surface of the nonwoven fabric was also suppressed. This is presumably due to the uniform fixation of the intersections of the fibers with the inorganic binder.

[0218] On the other hand, in the case of using Comparative Example 6, in the glass nonwoven fabric, the inorganic binder was dried non-uniformly and existed. Compared with that before drying, although the strength was improved, the suppression of the flyaway on the surface of the nonwoven fabric was partial. This is presumably due to the non-uniform fixation of the intersections of the fibers with the inorganic binder.

[0219] [Other Embodiments] As described above, the preferred embodiments of the present invention have been described, but it is needless to say that the present invention is not limited to the above-described embodiments. Various modification examples or correction examples within the scope described in the claims also belong to the technical scope of the present invention. [Industrial Applicability]

[0220] The above embodiments have been described by taking the use for the electrode of a battery as an example, but the present invention can be applied not only to batteries but also to other applications such as the automotive industry, electrical equipment, concrete, civil engineering, ground improvement, building materials, paints, and the aerospace industry.

[0221] For example, in the automotive industry, it can be used to reduce weight and increase strength. In the field of electrical equipment, it functions as a coating material for enhancing heat resistance, durability, and electrical insulation. By adding it to cement, mortar, concrete, and ground improvement materials, the strength and durability of these materials can be enhanced.

[0222] Moreover, when applied to wood and building materials, it improves heat resistance, fire resistance, and chemical resistance, playing an important role in buildings where safety against earthquakes and fires is required. It can also be used as a ground improvement material for solidifying soil, improving water retention capacity, and adjusting pH. When added to paints, it enhances adhesiveness.

[0223] Furthermore, it can be used as a binder and molding aid for ceramics and glass, thereby improving the strength and heat resistance of the products. In the aerospace industry, it can serve as an adhesive and coating material that can withstand high-temperature environments and pressure fluctuations, contributing to the improvement of safety for spaceships, artificial satellites, airplanes, etc. As can be seen from these application examples, the inorganic binder emulsion of the present invention can provide new solutions in various fields due to its excellent properties.

Claims

1. An emulsion comprising an aqueous phase, an oil phase, and a surfactant, wherein the aqueous phase is an aqueous solution of an inorganic binder having a solid content concentration of 20% by mass or more and 70% by mass or less, the oil phase is an organic solvent or a halogen-based solvent having a boiling point lower than that of water and a specific gravity higher than that of water, the aqueous solution of the inorganic binder has a silicate or a phosphate dissolved in water, an inorganic binder emulsion.

2. An oil-in-water type having oil as a continuous phase, the inorganic binder emulsion according to Claim 1.

3. wherein the aqueous phase is 20% by mass or more and less than 97% by mass, the oil phase is 3% by mass or more and less than 80% by mass, the inorganic binder emulsion according to Claim 1.

4. wherein the mass % (X) of the aqueous phase and the mass % (Y) of the oil phase satisfy the following formula, the inorganic binder emulsion according to Claim 3. (Formula) 1 / 4 < X / Y < 23 / 2

5. wherein the surfactant is 0.01% by mass or more and 20% by mass or less, the inorganic binder emulsion according to Claim 4.

6. wherein the halogen-based solvent is at least one fluorine-based solvent selected from chlorofluorocarbons, hydrofluoroethers, hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroolefins, and hydrochlorofluoroolefins, the inorganic binder emulsion according to Claim 1.

7. wherein the surfactant contains an acrylic surfactant or a silicone surfactant that can be dissolved in the oil phase, the inorganic binder emulsion according to Claim 1.

8. wherein the surfactant contains a nonionic surfactant that can be dissolved in the aqueous phase, the inorganic binder emulsion according to Claim 1.

9. wherein the pH value of the aqueous phase is 1 or more and 5 or less, the inorganic binder emulsion according to Claim 1.

10. wherein the phosphate is, Empirical formula Al 2 O 3 ·nP 2 O 5 ·mH 2 containing aluminum phosphate represented by O (0.5 ≤ n ≤ 4, 0 ≤ m ≤ 10) the inorganic binder emulsion according to Claim 1.

11. wherein the average particle diameter of the micelles in the aqueous phase is 10 nm or more and 10 µm or less, the inorganic binder emulsion according to Claim 1.

12. a binder used for binding powders to each other, or a surface coating material used for coating the surface of powders, the inorganic binder emulsion according to Claim 1.

13. The median diameter (D 50 ) of the powder is a material for a battery that is 10 nm or more and 50 μm or less, the inorganic binder emulsion according to Claim 12.

14. An electrode for a non-aqueous electrolyte battery or a non-aqueous electrolyte capacitor using the inorganic binder emulsion according to Claim 1, ​

15. A non-aqueous electrolyte battery or a non-aqueous electrolyte capacitor using the electrode according to claim 14.

16. A method for producing a water-in-oil type emulsion having an oil continuous phase, comprising an aqueous phase, an oil phase and a surfactant, wherein the aqueous phase is an aqueous solution of an inorganic binder having a solid content concentration of 20% by mass or more and 70% by mass or less, the oil phase is an organic solvent or a halogen-based solvent having a boiling point lower than that of water and a specific gravity higher than that of water, a step of dissolving a silicate or a phosphate in water to obtain the aqueous solution of the inorganic binder, and a step of stirring the oil phase and adding and mixing the aqueous phase to the stirred oil phase, characterized by comprising: A method for producing an inorganic binder emulsion.

17. The method for mixing the oil phase and the aqueous phase is mixing the oil phase and the aqueous phase at a temperature of -30°C or higher and 30°C or lower. The method for producing an inorganic binder emulsion according to claim 16.

18. The step of mixing the oil phase and the aqueous phase is mixing using a pressure type homogenizer that stirs under pressure or an ultrasonic type homogenizer that stirs using ultrasonic waves. The method for producing an inorganic binder emulsion according to claim 16.

Images