JP6749574B2 - Inorganic monodisperse spherical fine particles, method for producing inorganic monodisperse spherical fine particles, battery electrode and battery - Google Patents

Description

The present invention has a spinel-type crystal structure in which the size is controlled on a nanometer to micrometer scale, and inorganic monodisperse spherical fine particles useful as electrode active material fine particles and a battery electrode using the fine particles and the same. Regarding the battery used.

A technique for efficiently producing monodisperse fine particles whose size is controlled on a nanometer to micrometer scale is an important subject in various fields such as pharmaceuticals, catalysts, and batteries. In particular, the establishment of a technique for producing monodisperse fine particles having a uniform size of 100 nm or less with a desired material is attracting attention from the viewpoint of various functional applications.
One of the fields where the monodisperse nanoparticles are expected to be applied is one of the electrode materials for various electric storage devices such as lithium-ion secondary batteries. The lithium-ion secondary battery has a higher voltage and a higher capacity than other batteries, and is therefore widely used as a power source for various mobile devices such as mobile phones and laptop computers. However, with the recent trend toward miniaturization and high performance of electronic devices and expansion of the application range such as application to power sources for electric vehicles, the demand for lighter weight and higher energy density of lithium ion batteries is increasing. The improvement of the battery performance has become an urgent issue.
Currently, as the positive electrode material of lithium-ion batteries, fine particles of 5 to 10 μm made of a lithium composite oxide typified by lithium cobalt oxide are used. In the future, it is necessary to reduce the size of these fine particles to 100 nm or less. If possible, in addition to improving the energy density by increasing the electrode surface area per unit volume, and shortening the diffusion distance of lithium ions in the electrode active material, it will be possible to realize high-speed charging and discharging, power sources for electric vehicles, etc. It is expected that it will be possible to improve various battery performances such as higher output required for applications.
Also, if nanoparticles with excellent size uniformity can be used as the positive electrode active material, it becomes possible to coat the current collector with fine particles in a dense packing structure, so that voids of uniform size are formed between the fine particles. Can be formed. Since the voids can be filled with a conductive additive and an electrolyte, it is possible to secure a lithium ion conduction path even when the size of the fine particles is reduced. Further, since the filling rate can be improved with monodisperse fine particles as compared with the case of fine particles having irregular sizes, it is possible to form a positive electrode having a high specific surface area, and further improvement in energy density can be expected. Improvements in battery performance due to such miniaturization of electrode materials are not only applicable to lithium-ion secondary batteries, but also to other secondary batteries such as sodium-ion secondary batteries and magnesium-ion secondary batteries currently under research. The same can be said.

A mechanical pulverization method using a ball mill has been known as a typical method for producing fine electrode active material fine particles. However, with the method using a ball mill, there is a limit to miniaturization, and it is difficult to control the size. In addition to this, some methods such as a spray pyrolysis method in which a raw material solution is sprayed in a gas phase for pyrolysis have been proposed. However, in these methods, in addition to the large scale of the apparatus, the size of the obtained fine particles is on the submicron scale, and the size controllability thereof is insufficient. Therefore, at present, no monodisperse electrode active material fine particles controlled to have an arbitrary size of 100 nm or less have been proposed yet, and a method for producing such fine particles with high throughput has not yet been proposed. The current situation is that it has not been established.

JP, 11-277546, A

Various methods such as the method of reducing the raw material ions in the liquid phase, the sol-gel method, the CVD method, etc. are available for producing nanometer- to micrometer-scale fine particles, which are expected to be applied in various fields including battery materials. Has been reported. However, it is usually difficult to obtain fine particles whose size and shape are controlled by existing methods for producing fine particles. Even when fine particles having a uniform size and shape are obtained, applicable materials are limited, and therefore a method applicable to a wide range of materials has not been established.
Therefore, an object of the present invention is to provide inorganic monodisperse spherical particles whose size is controlled on the nanometer to micrometer scale and which are useful as electrode active material particles.

In order to achieve the above object, the present inventors have focused on the method of forming particles by a film emulsification method, as a result of diligent examination of a material useful as a film used for film emulsification and a method of forming pores, existing The present invention has been completed by producing an optimal film for producing monodisperse particles having a size controlled of 10 nm to 5 μm, which was difficult to achieve by the method for producing fine particles.
That is, the present invention provides each of the following inventions.
1. Inorganic monodisperse spherical fine particles having a diameter of 10 nm to 5 μm and a relative standard deviation of the diameter of 30% or less.
2. 2. The inorganic monodisperse spherical fine particles according to 1, wherein the value of the relative standard deviation of the diameter is 20% or less.
3. Inorganic monodisperse dispersion according to 1 or 2, which is obtained by subjecting a fine particle precursor obtained by polymerizing and solidifying the fine droplets to a firing treatment in a state where fine droplets are generated by film emulsification. Spherical fine particles.
4. The inorganic monodisperse spherical fine particles according to any one of 1 to 3, wherein the film used for the film emulsification is a porous alumina film.
5. 5. The inorganic monodisperse spherical fine particles according to any one of 1 to 4, which contain at least one of Mg, Co and Ni.
6. A battery electrode comprising the inorganic dispersed spherical fine particles according to any one of 6.1 to 5.
A battery comprising the battery electrode according to item 7.6 as an electrode.

The inorganic monodisperse spherical particles of the present invention are controlled in size on the nanometer to micrometer scale and are useful as electrode active material particles.

FIG. 1 is a schematic diagram schematically showing the steps in the method for producing inorganic monodisperse fine particles of the present invention. FIG. 2 is an electron micrograph (drawing substitute photograph) of the MgCo ₂ O ₄ precursor fine particles obtained in Example 1. FIG. 3 is an electron micrograph (drawing substitute photograph) of MgCo ₂ O ₄ obtained in Example 1. FIG. 4 is a chart showing the results of measuring the size distribution of MgCo ₂ O ₄ produced using porous alumina having different pore sizes in Example 1.

Hereinafter, the present invention will be described in more detail.
The inorganic monodisperse spherical fine particles of the present invention are characterized by having a specific diameter and having a relative standard deviation of the specific diameter.

<Particle constituents>
The constituent component of the inorganic monodisperse spherical fine particles of the present invention is not particularly limited as long as it is an inorganic material, but Mg, Co, Ni, Mn, V, Zn, W, Ti, Fe, Al, Si and the like are used. It is preferable to contain, more preferably at least one of Mg, Co and Ni.
More specifically, it is preferable to use MgCo ₂ O ₄ , MgNiMnO ₄ , Co ₃ O ₄ , V ₂ O ₅ , ZnO, NiO, WO _3, etc. as its constituent components, and more preferably MgCo ₂ O ₄ , MgNiMnO ₄ and Co ₃ O ₄ .
In addition to the above-mentioned inorganic materials, additives such as those usually added to this type of fine particles may be added within a range that does not impair the desired effects of the invention.

<Particle shape>
The inorganic monodisperse spherical fine particles of the present invention are spherical particles each having a diameter of 10 nm to 5 μm, preferably 50 nm to 1 μm, and the relative standard deviation of the diameter is 30% or less, preferably 20% or less.
Here, the diameter of the particles can be measured by observing with an electron microscope.
The relative standard deviation of the diameter of the particles is the value of the relative standard deviation (standard deviation/average diameter) indicating the variation of the diameter, and can be calculated by measuring the size of the fine particles and creating the particle size distribution.
Further, the crystal structure in the present invention is preferably a spinel type crystal structure. In that case, MgCo ₂ O ₄ and MgNiMnO ₄ are particularly preferably used as the above-mentioned constituents. The "spinel type crystal structure" in the present invention is a concept including both a normal spinel type having a crystal structure similar to so-called spinel (MgAl ₂ O ₄ ), an inverse spinel type and a disordered spinel type.

<Method of producing particles>
The inorganic monodisperse spherical fine particles of the present invention can be prepared by preparing a hydrogel or polymer fine particles containing a desired metal salt and subjecting it to a firing treatment, and more preferably anodized porous alumina is used. Membrane emulsification processes can also be used. Specifically, it can be manufactured by performing the following steps.
That is,
A film production process for producing a metal oxide film in which a large number of pores are regularly arranged by anodizing a metal plate.
A disperse phase obtained by dissolving a monomer and a metal salt in a disperse phase solution, and a disperse phase that is a continuous phase for dispersing the disperse phase in a liquid and a surfactant dissolved in a solution for the continuous phase. A continuous phase consisting of a solution prepared, respectively, the obtained dispersed phase, a film emulsification step performed by passing through the membrane into the continuous phase,
Polymerization and solidification step of polymerizing and solidifying the droplets of the dispersed phase by heating or irradiating with ultraviolet light in the state where fine droplets of the dispersed phase are generated in the continuous phase by the film emulsification process. Can be obtained by performing a drying and firing step of drying and firing at a prescribed temperature for a prescribed time.
That is, the inorganic monodisperse spherical fine particles of the present invention are particles obtained by subjecting a fine particle precursor obtained by polymerizing and solidifying the fine droplets to a firing treatment in the state where fine droplets are generated by film emulsification. It is preferable that the film used for emulsifying the film is a porous alumina film described later.
The details will be described below.

(Film manufacturing process)
The film manufacturing process is a process performed by anodizing a metal plate, and a film obtained by this film manufacturing process, for example, when the film is anodized porous alumina, the porous alumina is used to acidify aluminum. It is a hole array structure material obtained by anodizing in an electrolytic solution, and is a porous film in which pores of uniform size are oriented perpendicular to the film surface.
Examples of the metal plate used include an aluminum plate having a purity of 99.99%. The thickness of this plate is preferably 10 to 0.05 mm.
The anodic oxidation is performed by pressing a mold having a structure in which protrusions are regularly arranged on the surface of the metal plate and performing a texturing treatment to form a fine uneven pattern on the surface of the metal plate, and then an acidic electrolytic solution, −3° C. It can be performed by energizing at 10 to 500 V for 1 minute to 100 hours under a temperature condition of 80°C.
The size of the protrusions formed on the mold is arbitrary according to the desired diameter of the pores formed on the metal plate, and the size is such that a hole of a size that is used in each example can be formed. preferable. The interval between the protrusions is preferably 300 to 1000 nm, and more preferably 400 to 700 nm.
Examples of the material for forming the mold include SiC and Ni.
As the electrolytic solution, an aqueous solution containing one or more of phosphoric acid, oxalic acid, sulfuric acid, and citric acid can be used.
Further, after the completion of the anodization, after removing the bare metal portion using a methanol solution saturated with iodine, the bottom portion of the bottomed pores formed by the anodization should be removed using an argon ion milling device or the like. Thus, a film for film emulsification, which is a through-hole membrane, can be obtained.
The obtained membrane can be further immersed in a buffer solution such as a 10 wt% phosphoric acid aqueous solution for a predetermined time so as to have a desired pore diameter, if necessary, and then subjected to pore diameter enlargement treatment. In this way, the pore size of the membrane is changed according to the desired particle size.

(Membrane emulsification process)
In the membrane emulsification step, the obtained membrane is attached to the tip of a syringe or the tip of a tube industrially, the dispersed phase is put into the inside of the syringe or the tube, and pressurized with nitrogen gas, etc. As shown in (1), the dispersed phase is passed through the membrane and added as fine droplets into the continuous phase.
As the monomer constituting the dispersed phase, water-soluble monomers such as acrylamide and N,N-methylenebisacrylamide can be used as the dispersed phase. In use, they are used alone or in combination of two or more. be able to.
As the metal salt, cobalt acetate tetrahydrate, magnesium acetate tetrahydrate, manganese acetate tetrahydrate, nickel acetate tetrahydrate, vanadium oxysulfate, zinc acetate dihydrate, tungstic acid dihydrate Etc. can be used, and when used, they can be used alone or in combination of two or more.
Further, it is preferable to add a polymerization initiator to the dispersed phase, and as the polymerization initiator to be used, both photocurable ones and thermosetting ones can be used. "IRGACURE2959" under the trade name of BASF Co., Ltd., or a commercially available product such as ammonium persulfate as a radical type polymerization initiator can be used as the agent.
Water can be used as the solvent for the dispersed phase that constitutes the solution for the dispersed phase, and when used, they can be used alone or in combination of two or more. Further, the mixing ratio of each component is preferably 50 to 150 parts by weight of the metal compound, 1 to 20 parts by weight of the polymerization initiator, and 100 to 300 parts by weight of the solvent when the total amount of the monomers is 100 parts by weight. ..
In addition, an additive such as citric acid monohydrate can be appropriately added to the dispersed phase. Furthermore, it is preferable to adjust the pH of the dispersed phase before emulsifying the film. It is preferable to adjust the pH using ammonia water or the like so that the pH becomes 3 to 5.
As the surfactant constituting the continuous phase, nonionic surfactants such as "span80" (trade name, manufactured by Sigma-Aldrich), tetraglycerin ester ("CR310" (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) Examples thereof include commercially available products such as)) and the like, and nonionic surfactants such as), and the like, and it is preferable to use a mixture of both when used.
Examples of the solvent for the continuous phase that constitutes the solution for the continuous phase include organic solvents such as kerosene. Further, the concentration of the surfactant is preferably 1 to 5% by weight of the nonionic surfactant and 0.5 to 5% by weight of the nonionic surfactant.
The amount ratio of the continuous phase and the disperse phase is not particularly limited as long as it is a dispersible amount ratio, but the disperse phase is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the continuous phase.

(Polymerization and solidification process)
Then, as shown in FIG. 1, precursor fine particles are obtained by polymerizing and solidifying the dispersed phase dropped in the continuous phase.
The conditions of polymerization and solidification are arbitrary depending on the polymerization initiator and the monomer used, but the polymerization and solidification can be carried out under the following polymerization conditions.
In case of light irradiation, irradiation light wavelength: 365 nm
Irradiation time: 30 min
For heating Heating temperature: 60 ℃
Heating time: 30min

(Dry firing process)
Then, the obtained precursor fine particles are collected by centrifugation, dried, and then heat-treated at 400 to 800° C. for 5 to 20 minutes to carry out a firing treatment to obtain the inorganic monodisperse spherical particles of the present invention. Fine particles can be obtained.

<Applications, electrodes, batteries>
The inorganic monodisperse spherical fine particles of the present invention obtained by the above production method have a spinel type structure and a uniform particle size, and are useful as fine particles of an electrode active material. That is, the battery of the present invention is characterized by having the electrode of the present invention containing the above-mentioned inorganic monodisperse spherical fine particles of the present invention. Since the particles have a monodisperse particle size as described above, the battery has high capacity and excellent high rate charge/discharge characteristics.
The electrode and the battery of the present invention can be configured in the same manner as a normal battery except that the above-mentioned inorganic monodisperse spherical fine particles of the present invention are contained as an electrode active material. The battery configurations described in Japanese Patent No. 129410 and Japanese Patent Laid-Open No. 2012-248333 can be adopted.

For example, specifically, a lithium battery or the like can be given. A lithium battery is composed of an electrode, a counter electrode, a separator and an electrolytic solution.
The electrode is formed by adding a conductive material such as carbon black and a binder such as a fluororesin to the inorganic monodisperse spherical fine particles of the present invention and appropriately molding or coating the electrode substrate.
Usually, an electrode containing the inorganic monodisperse spherical particles can be used as a positive electrode, and metallic lithium, lithium alloy, or graphite can be used as a counter electrode. Further, the electrode containing the inorganic monodisperse spherical fine particles can also be used for the negative electrode, in which case, a known material for the positive electrode, for example, lithium-manganese composite oxide, lithium-cobalt composite oxide, lithium. A lithium/transition metal composite oxide such as a nickel composite oxide or a lithium/vanazine composite oxide, or an olivine type compound such as a lithium/iron/composite phosphoric acid compound can be used.
For the separator, for example, a porous polyethylene film or the like can be used, and as an electrolyte, LiPF ₆ , LiClO ₄ , LiCF ₃ SO _{3 in} a solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate or 1,2-dimethoxyethane. , LiN(CF ₃ SO ₂ ) ₂ , LiBF ₄ and other lithium salts are dissolved in the electrolyte, solid electrolytes, molten salts, and other commonly used materials can be used.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
Example 1 Preparation of MgCo ₂ O ₄ Fine Particles by Membrane Emulsion Process Using Porous Alumina On the surface of an aluminum plate (thickness 0.5 mm) having a purity of 99.99%, protrusions were regularly arranged at a cycle of 500 nm. A SiC mold having a structure was pressed to form a fine uneven pattern on the surface of the aluminum plate.
Next, the aluminum plate subjected to the texturing treatment was anodized in a phosphoric acid aqueous solution adjusted to a concentration of 0.1 M at a bath temperature of 0° C. for 90 minutes under a direct current of 200 V. Then, the bare metal portion was dissolved and removed in a methanol solution saturated with iodine, and the bottom portion of the pores of the porous alumina was removed using an argon ion milling device to obtain a through-hole membrane. Three kinds of membranes obtained by immersing the obtained three through-hole membranes in a 10 wt% phosphoric acid aqueous solution for 0, 30, and 60 minutes, respectively, and subjecting them to pore size expansion treatment to adjust the pore size to 130 nm, 210 nm, and 250 nm. Got The obtained porous alumina through-hole membrane was attached to the tip of a syringe by using an epoxy resin to form an emulsion film for film emulsification.
As the dispersed phase, 2.92 g of acrylamide, 0.45 g of N,N-methylenebisacrylamide, 0.342 g of "IRGACURE2959", trade name, manufactured by BASF, cobalt acetate tetrahydrate 1.916 g, magnesium acetate tetrahydrate 0. An aqueous solution was prepared by dissolving 824 g and citric acid monohydrate (2.426 g) in distilled water (4.834 g). The pH of the obtained aqueous solution was adjusted to 4 with aqueous ammonia before emulsifying the membrane.
For the continuous phase, two kinds of surfactants are used, 2% by weight of "span80" (trade name, manufactured by Sigma-Aldrich) and 1% by weight of "CR310" (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.). A dissolved kerosene solution was used.
Then, the dispersed phase was dropped into the continuous phase using an emulsion film to perform film emulsification. The dropping was performed by introducing the dispersed phase into the syringe, pressurizing the inside of the syringe with nitrogen gas, and pushing out the dispersed phase from the syringe into the continuous phase. Precursor fine particles were obtained by polymerizing and solidifying the obtained droplets.
An electron micrograph of precursor fine particles obtained when the pore size is 210 nm is shown in FIG.
The precursor fine particles dispersed in kerosene were recovered by centrifugation and heat-treated at 700° C. for 10 minutes to obtain inorganic monodisperse spherical fine particles of the present invention made of MgCo ₂ O ₄ . .. When the average diameter and relative standard deviation of the obtained fine particles were measured, the average diameter was 136 nm when the pore diameter was 130 nm, the relative standard deviation was 13%, and the average diameter was 380 nm when the pore diameter was 210 nm. The relative standard deviation was 13.6%, the average diameter was 680 nm and the relative standard deviation was 17.2% when the pore size was 250 nm. An electron micrograph of the fine particles obtained when the pore size is 210 nm is shown in FIG.

In the same manner as in Production Example 1 of MgNiMnO ₄ particles by Example 2 membrane emulsification process using the porous alumina, the pore period 500 nm, to prepare a porous alumina number Lou hole membrane pore size 250 nm.
As the dispersed phase, 2.92 g of acrylamide, 0.45 g of N,N-methylenebisacrylamide, 0.342 g of "IRGACURE2959", trade name of BASF, manganese acetate tetrahydrate 0.949 g, magnesium acetate tetrahydrate 0. An aqueous solution was prepared by dissolving 829 g, nickel acetate tetrahydrate 0.964 g, and citric acid monohydrate 2.44 g in distilled water 4.818 g. The pH of the obtained aqueous solution was adjusted to 4 using aqueous ammonia before emulsifying the membrane.
For the continuous phase, two kinds of surfactants are used, 2% by weight of "span80" (trade name, manufactured by Sigma-Aldrich) and 1% by weight of "CR310" (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.). A dissolved kerosene solution was used.
Then, polymerization and solidification were performed in the same manner as in Example 1 to obtain precursor fine particles. The precursor fine particles dispersed in kerosene were recovered by centrifugation and heat-treated at 700° C. for 10 minutes to obtain inorganic monodisperse spherical fine particles of the present invention made of MgNiMnO ₄ . When the average diameter of the obtained fine particles was measured, it was 160 nm.

Example 3 Preparation of Co ₃ O ₄ Fine Particles by Membrane Emulsion Process Using Porous Alumina By the same method as in Example 1, a porous alumina multi-ruhr membrane having a pore period of 500 nm and a pore diameter of 250 nm was produced.
As a disperse phase, 2.92 g of acrylamide, 0.45 g of NN methylenebisacrylamide, 0.342 g of "IRGACURE2959", trade name of BASF, cobalt acetate tetrahydrate 2.74 g, and citric acid monohydrate 2.31 g were distilled. An aqueous solution was prepared by dissolving in 4.95 g of water. The pH of the obtained aqueous solution was adjusted to 4 using aqueous ammonia before emulsifying the membrane.
For the continuous phase, two kinds of surfactants are used, 2% by weight of "span80" (trade name, manufactured by Sigma-Aldrich) and 1% by weight of "CR310" (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.). A dissolved kerosene solution was used.
Then, polymerization and solidification were performed in the same manner as in Example 1 to obtain precursor fine particles. The precursor fine particles dispersed in kerosene were recovered by centrifugation and heat-treated at 600° C. for 10 minutes to obtain inorganic monodispersed spherical fine particles of Co ₃ O ₄ of the present invention. .. The average diameter and relative standard deviation of the obtained fine particles were measured and found to be 407 nm and 16.2%.

Example 4 Preparation of V ₂ O ₅ Fine Particles by Membrane Emulsion Process Using Porous Alumina By the same method as in Example 1, a porous alumina multi-ruhr membrane having a pore cycle of 500 nm and a pore diameter of 250 nm was prepared.
As a disperse phase, 1.46 G of acrylamide monomer, 0.225 g of N,N'-methylenebisacrylamide as a cross-linking agent, "IRGACURE 2959" as a photopolymerization initiator, trade name of BASF 0.171 g, and vanadium oxysulfate 1 g in 4 g of water. A dissolved aqueous solution was used.
For the continuous phase, two kinds of surfactants are used, 2% by weight of "span80" (trade name, manufactured by Sigma-Aldrich) and 1% by weight of "CR310" (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.). A dissolved kerosene solution was used.
Then, polymerization and solidification were performed in the same manner as in Example 1 to obtain precursor fine particles. The precursor fine particles dispersed in kerosene were collected by centrifugation and heat-treated at 500° C. for 10 minutes to obtain inorganic monodisperse spherical fine particles of V ₂ O ₅ of the present invention. When the average diameter and the relative standard deviation of the precursor fine particles formed by the film emulsification were measured, they were 270 nm and 23%, respectively. After the firing treatment, fine particles having a spherical shape were obtained.

Example 5 Preparation of ZnO Fine Particles by Membrane Emulsion Process Using Porous Alumina By the same method as in Example 1, a porous alumina multi-ruhr membrane having a pore period of 500 nm and a pore diameter of 250 nm was produced.
As the dispersed phase, 2.92 g of acrylamide, 0.45 g of N,N-methylenebisacrylamide, 0.342 g of "IRGACURE2959" trade name manufactured by BASF, zinc acetate dihydrate 2.74 g, and citric acid monohydrate 2. An aqueous solution in which 64 g was dissolved in 4.64 g of distilled water was prepared. The pH of the obtained aqueous solution was adjusted to 4 using aqueous ammonia before emulsifying the membrane.
For the continuous phase, two kinds of surfactants are used, 2% by weight of "span80" (trade name, manufactured by Sigma-Aldrich) and 1% by weight of "CR310" (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.). A dissolved kerosene solution was used.
Then, polymerization and solidification were performed in the same manner as in Example 1 to obtain precursor fine particles. The obtained precursor fine particles were recovered by centrifugation and heat-treated at 600° C. for 10 minutes to obtain inorganic monodispersed spherical fine particles of ZnO of the present invention. The average diameter and relative standard deviation of the obtained fine particles were measured and found to be 250 nm and 32%.

Example 6 Preparation of NiO Fine Particles by Membrane Emulsification Process Using Porous Alumina By the same method as in Example 1, a porous alumina multi-ruhr membrane having a pore cycle of 500 nm and a pore diameter of 250 nm was prepared.
As the disperse phase, 2.92 g of acrylamide, 0.45 g of NN methylenebisacrylamide, 0.342 g of "IRGACURE2959", trade name of BASF, nickel acetate tetrahydrate 2.74 g, and citric acid monohydrate 2.32 g were distilled. An aqueous solution dissolved in 4.94 g of water was prepared. The pH of the resulting solution was adjusted to 4 with aqueous ammonia before the film emulsification.
For the continuous phase, two kinds of surfactants are used, 2% by weight of "span80" (trade name, manufactured by Sigma-Aldrich) and 1% by weight of "CR310" (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.). A dissolved kerosene solution was used.
Then, polymerization and solidification were performed in the same manner as in Example 1 to obtain precursor fine particles. The obtained precursor fine particles were recovered by centrifugation and heat-treated at 600° C. for 10 minutes to obtain inorganic monodisperse spherical fine particles of the present invention made of NiO. The average diameter and relative standard deviation of the obtained fine particles were measured and found to be 120 nm and 23%.

Example 7 Preparation of WO ₃ Fine Particles by Membrane Emulsification Process Using Porous Alumina By the same method as in Example 1, a porous alumina multi-ruhr membrane having a pore cycle of 500 nm and a pore diameter of 250 nm was prepared.
As a dispersed phase, 2.92 g of acrylamide, 0.45 g of N,N-methylenebisacrylamide, 0.342 g of "IRGACURE2959" trade name manufactured by BASF, tungstic acid dihydrate 2.74 g, and citric acid monohydrate 1. An aqueous solution prepared by dissolving 75 g in 5.51 g of distilled water was prepared. The pH of the obtained aqueous solution was adjusted to 4 with aqueous ammonia before emulsifying the membrane.
For the continuous phase, two kinds of surfactants are used, 2% by weight of "span80" (trade name, manufactured by Sigma-Aldrich) and 1% by weight of "CR310" (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.). A dissolved kerosene solution was used.
Then, polymerization and solidification were performed in the same manner as in Example 1 to obtain precursor fine particles. The obtained precursor fine particles were recovered by centrifugation and heat-treated at 600° C. for 10 minutes to obtain inorganic monodisperse spherical fine particles of the present invention made of WO ₃ . The average diameter and relative standard deviation of the obtained fine particles were measured and found to be 430 nm and 28%.

Claims (6)

Inorganic monodisperse spherical fine particles having a diameter of 10 nm to 5 μm and a relative standard deviation value of 20% or less and being MgCo ₂ O ₄ fine particles or MgNiMnO ₄ fine particles. In a state in which fine droplets by membrane emulsification occurs, inorganic monodisperse spherical according to claim 1, characterized in that it is obtained by calcination treatment the particulate precursor obtained by the droplets is polymerized and hardened Method for producing fine particles. The method for producing inorganic monodisperse spherical fine particles according to claim 2 , wherein the film used in the film emulsification is a porous alumina film. The method for producing inorganic monodisperse spherical fine particles according to claim 2 or 3 , wherein the baking treatment is performed by heat treatment at 400 to 800°C for 5 to 20 minutes. An electrode for a battery, comprising the inorganic dispersed spherical fine particles according to claim 1 . A battery comprising the battery electrode according to claim 5 as an electrode.