WO2012057340A1 - Composé de silicate-phosphate, électrode positive de batterie secondaire, batterie secondaire et leurs procédés de fabrication - Google Patents

Composé de silicate-phosphate, électrode positive de batterie secondaire, batterie secondaire et leurs procédés de fabrication Download PDF

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WO2012057340A1
WO2012057340A1 PCT/JP2011/074999 JP2011074999W WO2012057340A1 WO 2012057340 A1 WO2012057340 A1 WO 2012057340A1 JP 2011074999 W JP2011074999 W JP 2011074999W WO 2012057340 A1 WO2012057340 A1 WO 2012057340A1
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silicic acid
phosphoric acid
compound
formula
group
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PCT/JP2011/074999
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English (en)
Japanese (ja)
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義久 別府
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旭硝子株式会社
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/20—Silicates
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/37—Phosphates of heavy metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a silicic acid-phosphoric acid compound, a positive electrode for a secondary battery, a secondary battery, and a production method thereof.
  • Patent Document 1 describes a positive electrode using an active material containing a silicon phosphate salt.
  • the active material includes the formula Li 3 M ′ (2-b) M ′′ b SiP 2 O 12 (M ′ is +3 valent).
  • M ′ is +3 valent
  • an active material represented by a metal or metalloid element, M ′′ is a +4 valent metal or metalloid element, and b is 0 to 2 is proposed.
  • Patent Document 2 describes a solid solution represented by the formula Li 1.7 Mn 0.7 Fe 0.3 Si 0.7 P 0.3 O 4 as a positive electrode material for a secondary battery containing P and Si. Has been. In addition, it is described that the solid solution was obtained by a method in which Li 2 MnSiO 4 and LiFePO 4 were pulverized, heated and then allowed to cool.
  • Li 2 FeSiO 4 described in Non-Patent Document 1 is manufactured by a solid-phase reaction, the manufacturing process is complicated and the manufacturing cost increases.
  • Patent Document 1 does not describe the compound of the present invention in which the composition ratio of Li, M ′ and M ′′, Si, and P is a specific ratio. Further, only the NASICON structure is disclosed as the crystal structure of the obtained active material.
  • the NASICON active material is a material that does not provide a sufficient capacity per unit mass.
  • the manufacturing method described in Patent Document 1 is a method in which a raw material is heated at 170 ° C. for 4 hours, then held at about 900 ° C. for about 16 hours, and is allowed to react by repeating cooling, polishing and reheating as necessary. . In this method, the manufacturing process is complicated, takes time, and increases the manufacturing cost.
  • Patent Document 2 The production method described in Patent Document 2 is a method for producing Li 2 MnSiO 4 and LiFePO 4 by solid-phase reaction.
  • the solid-phase reaction has a complicated manufacturing process, is expensive to manufacture, is difficult to mass-produce, and composition control is not easy.
  • Patent Document 3 Since the manufacturing method of Patent Document 3 is manufactured by a solid-phase reaction, the manufacturing process is complicated and the manufacturing cost increases.
  • An object of the present invention is to provide a production method in which the composition and particle size of a silicic acid-phosphoric acid compound capable of increasing the capacity per unit mass can be easily controlled.
  • the compound is useful as an active material used for a positive electrode for a secondary battery and a positive electrode for a secondary battery.
  • the present invention also provides a positive electrode for a secondary battery having excellent characteristics and reliability and a method for producing the secondary battery.
  • a method for producing a silicic acid-phosphoric acid compound In this order.
  • element A is at least one element selected from the group consisting of Li, Na and K
  • element M is at least one element selected from the group consisting of Fe, Mn, Co and Ni.
  • the melting step includes Compound containing element A is A carbonate, A bicarbonate, A hydroxide, A silicate, A phosphate, A hydrogen phosphate, A nitrate, A chloride Or at least one selected from the group consisting of A sulfate, A acetate, and A oxalate (however, some
  • the compound comprising element M is M oxide, M oxyhydroxide, M silicate, M metal, M phosphate, M chloride, M nitrate, M sulfate, and Included as at least one selected from the group consisting of organic salts of M;
  • a compound containing Si is included as at least one selected from the group consisting of silicon oxide, A silicate, M silicate, and silicon alkoxide,
  • the compound containing P is selected from the group consisting of phosphorus oxide, ammonium phosphate, ammonium hydrogen phosphate, phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphorous acid, A phosphate, and M phosphate Included as at least one The method for producing a silicic acid-phosphoric acid compound according to [1], wherein the raw material preparation is heated to obtain a melt having a composition represented by the formula (1).
  • the melt having the composition represented by the formula (1) is a melt having the composition represented by the following formula (3A), and the silicic acid having the composition represented by the formula (2)
  • the solidified product includes at least one carbon source selected from the group consisting of an organic compound and carbon powder, and a ratio of a carbon conversion amount (mass) in the carbon source is
  • the silicic acid-phosphoric acid compound of [1] to [6] is 0.1 to 20% by mass relative to the total mass of the mass of the solidified product and the carbon equivalent amount (mass) in the carbon source. Production method.
  • a silicic acid-phosphoric acid compound is obtained by the production method of [1] to [8], and then a positive electrode for a secondary battery is produced using the silicic acid-phosphoric acid compound as a positive electrode material for a secondary battery.
  • a method for producing a positive electrode for a secondary battery comprising obtaining a positive electrode for a secondary battery by the production method of [9], and then producing a secondary battery using the positive electrode for a secondary battery.
  • element A is at least one element selected from the group consisting of Li, Na and K
  • element M is at least one element selected from the group consisting of Fe, Mn, Co and Ni.
  • a is ⁇ 0.1 ⁇ a ⁇ 0.4
  • b is 0.7 ⁇ b ⁇ 1.3
  • x is 0.3 ⁇ x ⁇ 0.7
  • c2 is a, b, and M
  • the number depends on the valence N of [12]
  • the production method of the present invention is useful as an electrode material because the composition, particle size and uniformity of the silicic acid-phosphoric acid compound can be easily controlled, and the silicic acid-phosphoric acid compound having various compositions is efficiently used. Can be manufactured.
  • the silicic acid-phosphoric acid compound of the present invention is a compound that exhibits a multi-electron type reaction. Therefore, by using the silicic acid-phosphoric acid compound of the present invention, a positive electrode material for a secondary battery and a secondary battery having excellent characteristics and reliability can be manufactured. Furthermore, the present invention provides a silicic acid-phosphoric acid compound.
  • FIG. 4 is a view showing an X-ray diffraction pattern of silicic acid-phosphoric acid compounds produced in Examples 1, 2, 3 and 4.
  • FIG. 6 is a view showing an X-ray diffraction pattern of silicic acid-phosphoric acid compounds produced in Examples 5, 6 and 7.
  • FIG. 4 is a diagram showing an X-ray diffraction pattern of silicic acid-phosphoric acid compounds produced in Examples 19, 20, 21 and 22.
  • FIG. 4 is a view showing an X-ray diffraction pattern of silicic acid-phosphoric acid compounds produced in Examples 32, 33, 34 and 35.
  • ⁇ Method for producing silicic acid-phosphoric acid compound> In the method for producing a silicic acid-phosphoric acid compound of the present invention, the following melting step (I), cooling step (II), pulverization step (III), and heating step (IV) are performed in this order. Other steps may be performed before, between, and after the steps (I) to (IV) as long as each step is not affected.
  • Melting step (I) a step of obtaining a melt having a composition represented by the formula A 1 + x + a M b Si x P 1-x O 4 + c1 (wherein the symbols have the same meaning as described above), Cooling step (II): a step of cooling the melt to obtain a solidified product, Grinding step (III): step of obtaining the pulverized product by pulverizing the solidified product, and heating step (IV): heating the pulverized product to obtain a formula A 1 + x + a M b Si x P 1-x O 4 + c2 (wherein The symbols have the same meaning as above.)
  • the melting step (I) in the production method of the present invention is a step for obtaining a melt represented by the following formula (1).
  • a raw material formulation prepared by adjusting a raw material containing an element source (element A, element M, Si, and P) to have a composition represented by the formula (1) is prepared. It is preferable to do this.
  • a is in the range of ⁇ 0.1 ⁇ a ⁇ 0.4
  • b is in the range of 0.7 ⁇ b ⁇ 1.3.
  • a silicic acid-phosphoric acid compound having a target composition can be produced by setting a and b in the raw material formulation within the above ranges.
  • the raw material formulation can be melted well, and a uniform melt can be obtained.
  • a and b can cause a multi-electron type reaction more easily, so that ⁇ 0.1 ⁇ a ⁇ 0.3 and 0.8 ⁇ b ⁇ 1.3 are more preferable. preferable. Moreover, 0.3 ⁇ x ⁇ 1.0 may be sufficient.
  • the element A in the formula (1) is at least one element selected from the group consisting of Li, Na, and K. Since the element A is suitable as a positive electrode material for a secondary battery, it is preferable to make Li essential, and it is particularly preferable to use only Li.
  • the silicic acid-phosphoric acid compound containing Li increases the capacity per unit volume (mass) of the secondary battery.
  • the element M in the formula (1) is at least one element selected from the group consisting of Fe, Mn, Co, and Ni.
  • the element M is preferably composed of only one kind or two kinds.
  • the element M consists of only Fe, Mn alone, or Fe and Mn. This is preferable in terms of cost.
  • the valence N of the element M is a numerical value that can be changed in each step of the production method of the present invention, and is in the range of +2 to +4.
  • the valence N is +2, +8/3 or +3 when the element M is Fe, +2, +3 or +4 when Mn, +2, +8/3 or +3 when Co, and +2 or when Ni +4 is preferred.
  • the valence N is more preferably +2 in order to simplify the melting step (I). In the present invention, melting in the melting step (I) can be facilitated by setting the composition of the raw material formulation to a specific range.
  • the compound containing element A in the raw material formulation includes A carbonate (A 2 CO 3 ), A hydrogen carbonate (AHCO 3 ), A hydroxide (AOH), and A silicate (A 2 O ⁇ 2SiO 2 , A 2 O ⁇ SiO 2 , 2A 2 O ⁇ SiO 2, etc.), A phosphate, A hydrogen phosphate, A nitrate (ANO 3 ), A chloride (ACl), A sulfate (A 2 SO 4 ) of A and at least one selected from the group consisting of organic acid salts such as acetate (CH 3 COOA) and oxalate ((COOA) 2 ) of A are preferred.
  • the element A is preferably Li. Furthermore, these compounds may be hydrates. Of these, carbonates and bicarbonates of A are more preferred because they are inexpensive and easy to handle.
  • the compound containing the element M is at least selected from the group consisting of Fe 3 O 4 , Fe 2 O 3 , MnO, Mn 2 O 3 , MnO 2 , Co 3 O 4 , and NiO because of availability and cost.
  • One type is more preferable, and at least one selected from the group consisting of Fe 3 O 4 , Fe 2 O 3 , and MnO 2 is particularly preferable.
  • These Fe 3 O 4 , Fe 2 O 3 , and MnO 2 may be used alone or in combination of two or more.
  • the compound containing Si in the raw material preparation includes silicon oxide (SiO 2 ), A silicate, M silicate, and silicon alkoxide (Si (OCH 3 ) 4 , Si (OC 2 H 5 ) 4. Etc.) is preferred, and silicon oxide is particularly preferred because it is inexpensive.
  • the compound containing Si may be crystalline or amorphous.
  • the phosphate of A is preferably Li 3 PO 4
  • the phosphate of M is at least 1 selected from the group consisting of Fe 3 (PO 4 ) 2 , FePO 4 , and Mn 3 (PO 4 ) 2. Species are preferred.
  • a combination of A carbonate or hydrogen carbonate, M oxide or M oxyhydroxide, silicon oxide, and ammonium hydrogen phosphate is preferable.
  • Li 2 CO 3 or LiHCO 3 one or more compounds selected from the group consisting of Fe 3 O 4 , Fe 2 O 3 , and MnO 2 ; silicon oxide; and a combination of ammonium hydrogen phosphate Is particularly preferred.
  • the composition of the raw material preparation is made to correspond to the composition of the melt in the method for producing a silicate-phosphate compound.
  • the composition of the obtained melt is the composition of the raw material formulation And may be slightly different. In such a case, it is preferable to appropriately change the composition of the raw material formulation in consideration of the amount lost due to volatilization or the like.
  • the purity of each raw material included in the raw material preparation is not particularly limited. Considering reactivity, characteristics of the positive electrode material for secondary batteries, and the like, the purity excluding hydrated water is preferably 99% by mass or more.
  • the melting step (I) in the present invention is a step of obtaining a melt having a composition represented by the formula (1). This step is preferably carried out by heating and melting the raw material formulation. Prior to melting, each raw material or raw material preparation is preferably pulverized and / or mixed dry or wet using a mixer, ball mill, jet mill, planetary mill or the like. The particle size of the raw material in each raw material preparation is not limited as long as it does not adversely affect the mixing operation, the filling operation of the raw material preparation into the melting container, the meltability of the raw material preparation, and the like.
  • the container is preferably made of alumina, carbon, silicon carbide, zirconium boride, titanium boride, boron nitride, carbon, platinum, or a platinum alloy containing rhodium.
  • a container made of a refractory-based brick and a reducing material (eg, graphite) can also be employed.
  • a lid to the container and melt it.
  • the heating furnace is preferably a resistance heating furnace, a high frequency induction furnace, or a plasma arc furnace.
  • the resistance heating furnace is preferably an electric furnace provided with a heating element made of an alloy such as a nichrome alloy, silicon carbide, or molybdenum silicide.
  • the melting step (I) is preferably carried out in air, in an inert gas or in a reducing gas. Melting conditions can be changed as appropriate depending on conditions such as the type of container or heating furnace and the heating method such as a heat source.
  • the pressure may be any of normal pressure, pressurization, and reduced pressure (0.9 ⁇ 10 5 Pa or less). Although it is preferably in reducing gas, it may be in oxidizing gas. In the case of the oxidation conditions, reduction (for example, change from M 3+ to M 2+ ) can be performed in the next heating step (IV).
  • the inert gas is a gas containing 99% by volume or more of at least one inert gas selected from the group consisting of nitrogen gas (N 2 ) and rare gases such as helium gas (He) and argon gas (Ar). It is a condition.
  • the term “in the reducing gas” refers to a gas condition in which a reducing gas is added to the inert gas and substantially does not contain oxygen. Examples of the reducing gas include hydrogen gas (H 2 ), carbon monoxide gas (CO), and ammonia gas (NH 3 ).
  • the amount of the reducing gas in the inert gas is preferably 0.1% by volume or more, and particularly preferably 1 to 10% by volume of the reducing gas in the total gas.
  • the oxygen content in the gas is preferably 1% by volume or less, particularly preferably 0.1% by volume or less.
  • the heating temperature in the melting step (I) is preferably 1,300 to 1,600 ° C., particularly preferably 1,400 to 1,550 ° C.
  • melting means that each raw material is melted and is in a transparent state visually.
  • the heating time is preferably 0.2 to 2 hours, particularly preferably 0.5 to 2 hours. By setting the time, the homogeneity of the melt is sufficient, and the raw material is difficult to volatilize.
  • stirring may be performed to increase the uniformity of the melt.
  • the melt may be clarified at a temperature lower than the heating temperature until the next cooling step (II) is performed. Furthermore, the melt obtained in the melting step (I) may be subjected to another step before the cooling step (II) as long as it does not adversely affect the next cooling step (II).
  • the cooling step (II) is a step of cooling the melt obtained in the melting step (I) to near room temperature to obtain a solidified product.
  • the solidified product is preferably an amorphous material, but a part of the solidified product may be a crystallized product.
  • the next pulverization step (III) can be easily performed, and the composition and particle size of the silicic acid-phosphoric acid compound can be easily controlled. Further, in the subsequent heating step (IV), there is an advantage that the product can be prevented from being agglomerated and the particle size of the product can be easily controlled.
  • the crystallized product becomes a crystal nucleus in the heating step (IV), which is a subsequent step, and it is easy to crystallize.
  • the amount of crystallized product in the solidified product is preferably 0 to 30% by mass with respect to the total mass of the solidified product.
  • the cooling step (II) is preferably performed in air from the viewpoint of equipment and the like.
  • the cooling step (II) may be performed in an inert gas or a reducing gas.
  • the cooling rate of the melt is preferably not less than -1 ⁇ 10 3 °C / sec, -1 ⁇ 10 4 °C / sec or more is particularly preferable.
  • a temperature change per unit time (ie, cooling rate) in the case of cooling is indicated by a negative value
  • a temperature change per unit time in case of heating ie, the heating rate
  • the cooling rate is higher than this value, an amorphous material is easily obtained.
  • the upper limit of the cooling rate is preferably about ⁇ 1 ⁇ 10 10 ° C./second from the viewpoint of manufacturing equipment and mass productivity, and is particularly preferably ⁇ 1 ⁇ 10 8 ° C./second from the viewpoint of practicality.
  • the cooling rate of the melt is particularly preferably from -10 3 ° C / second to -10 10 ° C / second from 1000 ° C to 50 ° C.
  • the method of cooling the melt is, for example, a method in which a melt is dropped between twin rollers rotating at high speed to obtain a flake-like solidified product, or a melt is dropped on a rotating single roller to form a flake-like or plate-like solidified product. It is preferable that the method is obtained by sweeping an object, or a method in which a melt is pressed on a cooled carbon plate or metal plate to obtain a lump solidified product. Among these, a cooling method using twin rollers is more preferable because the cooling rate is high and a large amount of processing can be performed. As the double roller, it is preferable to use one made of metal, carbon, or ceramic.
  • a cooling method there is a method in which the melt is directly poured into water, but this method is difficult to control, and the cooling rate is about ⁇ 1 ⁇ 10 ° C./second to ⁇ 1 ⁇ 10 2 ° C./second. It is difficult to obtain a crystalline material. Further, the solidified product becomes a lump and requires a lot of labor for pulverization.
  • a cooling method there is also a method in which a melt is directly charged into liquid nitrogen, and the cooling rate can be made faster than in the case of water, but there are problems similar to the method using water and the cost is high.
  • the solidified product obtained in the cooling step (II) is preferably flaky or fibrous.
  • the flaky solidified product preferably has an average thickness of 200 ⁇ m or less, particularly preferably 100 ⁇ m or less.
  • the average diameter of the plane perpendicular to the average thickness as the flaky solidified product is not particularly limited.
  • the fibrous solidified product preferably has an average diameter of 50 ⁇ m or less, particularly preferably 30 ⁇ m or less.
  • the average thickness and average diameter can be measured with a caliper or a micrometer. The average diameter can also be measured by microscopic observation.
  • the solidified product obtained in the cooling step (II) may be subjected to other steps before the pulverization step (III) as long as the pulverization step (III) is not adversely affected.
  • the pulverization step (III) is a step in which the solidified product obtained in the cooling step (II) is pulverized to obtain a pulverized product. Since the solidified product usually contains a large amount of amorphous material or consists of an amorphous material, there is an advantage that it is easy to grind. Further, there is an advantage that grinding can be performed without imposing a burden on the apparatus used for grinding and the particle size can be easily controlled. On the other hand, in the conventional solid phase reaction, pulverization is performed after the heating step (IV), but the present inventor has noticed that there is a problem that residual stress is generated by pulverization and battery characteristics are deteriorated. Therefore, the manufacturing method of the present invention employs a method of pulverizing before the heating step (IV) and reducing or removing the generated residual stress in the subsequent heating step (IV).
  • the pulverization is preferably performed using a jaw crusher, a hammer mill, a ball mill, a jet mill, a planetary mill or the like.
  • the method of pulverization may be either dry or wet.
  • the solidified product be struck by hand or a hammer to make it finer, because the burden of the pulverization step (III) is reduced.
  • the heating step (IV) after removing the dispersion medium by sedimentation, filtration, drying under reduced pressure, heat drying and the like.
  • the heating step (IV) may be performed with the pulverized product containing the dispersion medium as it is.
  • the silicic acid-phosphoric acid compound in the present invention is an insulating substance, when used as a positive electrode material for a secondary battery, it is preferable to include a conductive material in the solidified product. Moreover, when using as a positive electrode material for secondary batteries, it is preferable that it is a fine particle form.
  • the average particle diameter of the pulverized product is preferably 10 nm to 10 ⁇ m, and particularly preferably 10 nm to 5 ⁇ m, in terms of volume-based median diameter.
  • the particle size can be measured by a sedimentation method or a laser diffraction / scattering particle size measuring device.
  • the particle size of the pulverized product When the particle size of the pulverized product is small, the reduction reaction is promoted, and the heating temperature and time in the heating step (IV) can be reduced, which is preferable.
  • the average particle size of the pulverized product By making the average particle size of the pulverized product within the above range, the workability of the pulverization step (III) and the heating step (IV) is improved, and the average particle size of the product of the heating step (IV) can be easily controlled. There is.
  • the conductive material is preferably at least one carbon source selected from the group consisting of organic compounds and carbon powder.
  • the amount of at least one carbon source selected from the group consisting of an organic compound and carbon powder is such that the carbon equivalent amount (mass) in the carbon source is the mass of the solidified product and the carbon equivalent amount (mass in the carbon source). ) In an amount of 0.1 to 20% by mass, particularly preferably 2 to 10% by mass.
  • the organic compound and carbon powder contained in the solidified product prevent oxidation in the pulverization step (III) and the heating step (IV), and further promote reduction. Further, the organic compound and the carbon powder remain after the heating step (IV) and function as a conductive material. Therefore, the conductivity of the positive electrode material for secondary batteries can be increased.
  • the organic compound at least one selected from the group consisting of saccharides, amino acids, peptides, aldehydes, ketones, glycols, polyvinyl alcohol, and fatty acids is preferable, and saccharides, glycols, or polyvinyl alcohol is particularly preferable.
  • the saccharide include monosaccharides such as glucose, fructose, and galactose, oligosaccharides such as sucrose, maltose, cellobiose, and trehalose, invert sugar, polysaccharides such as dextrin, amylose, amylopectin, and cellulose, and ascorbic acid. It is done.
  • amino acids examples include amino acids such as alanine and glycine.
  • Peptides include low molecular weight peptides having a molecular weight of 1,000 or less.
  • carbon powder carbon black, graphite, acetylene black and the like are preferable.
  • the carbon powder may be fibrous carbon or plate-like carbon.
  • the pulverization step (III) when the solidified product is pulverized with an organic compound or carbon powder, there is an advantage that the step of mixing the conductive material can be omitted after the heating step (IV). Moreover, the organic compound and carbon powder can suppress the grain growth of the solidified product.
  • wet pulverization is preferably employed in order to uniformly disperse the pulverized product on the surface.
  • a dispersion medium for pulverization water or an organic solvent such as ethanol, isopropyl alcohol, acetone, hexane, or toluene can be used. Of these, water is preferable because it is inexpensive.
  • a dry method is preferable for the pulverization step (III) when the solidified product contains carbon powder.
  • the pulverized product obtained in the pulverization step (III) may be subjected to another step before the heating step (IV) as long as it does not adversely affect the next heating step (IV).
  • the heating step (IV) is a step of heating the pulverized product obtained in the pulverizing step (III).
  • a silicic acid-phosphoric acid compound having a composition represented by the following formula (2) is obtained.
  • a 1 + x + a M b Si x P 1-x O 4 + c2 (2) (In the formula, A, M, a, b and x have the same meaning as described above, but take an independent value from the value in formula (1), and c2 depends on the valence N of a, b and M. Number to do.)
  • the valence of N is preferably +2.
  • the product of the heating step (IV) is preferably crystal particles, and more preferably olivine type crystal particles.
  • the pulverized material is heated, so that the relaxation of the residual stress is promoted.
  • the composition, grain size, and distribution thereof are easier to control than those in the temperature lowering process.
  • the heating step (IV) in the case where the organic compound and / or carbon powder is included in the solidified product in the pulverizing step (III) causes the conductive material to be bonded to the surface of the product, preferably the crystal grains of the product. It can be a process.
  • the organic compound is thermally decomposed in the heating step (IV) and becomes a carbide to function as a conductive material.
  • the heating temperature in the heating step (IV) is preferably 500 to 1,000 ° C. When the heating temperature is 500 ° C. or higher, crystals are easily generated. When the heating temperature is 1,000 ° C. or less, melting of the pulverized product can be prevented.
  • the heating temperature is more preferably 600 to 900 ° C. When the heating temperature is used, crystal particles having appropriate crystallinity, particle diameter, particle size distribution, and the like are easily obtained, and olivine-type crystal particles are preferably obtained.
  • the heating step (IV) can be a step of removing the dispersion medium when the heating step (IV) is performed while the dispersion medium is included.
  • the heating in the heating step (IV) may be performed at a constant temperature after raising the temperature at once, or may be performed by changing the temperature in multiple stages. Since the particle diameter to be generated tends to increase as the heating temperature increases, the heating temperature is preferably set according to the desired particle diameter.
  • the heating time (holding time depending on the heating temperature) is preferably 1 to 72 hours in consideration of a desired particle size. Heating is preferably performed in a box furnace, tunnel kiln furnace, roller hearth furnace, rotary kiln furnace, microwave heating furnace, or the like that uses electricity, oil, gas, or the like as a heat source.
  • the heating step (IV) can be carried out in air, in an inert gas or in a reducing gas, and is preferably carried out in an inert gas or in a reducing gas.
  • the conditions in the inert gas and the reducing gas are the same as those in the melting step (I).
  • the heating step (IV) may be performed under reduced pressure (0.9 ⁇ 10 5 Pa or less) in an inert gas or a reducing gas.
  • a reducing agent eg, graphite
  • pulverized material eg, change from M 3+ to M 2+
  • the heating step (IV) after the heating step (IV), it is usually cooled to room temperature.
  • the cooling rate in the cooling is preferably ⁇ 30 ° C./hour to ⁇ 300 ° C./hour. By setting the cooling rate within this range, distortion due to heating can be removed, and when the product is a crystal, the target product can be obtained while maintaining the crystal structure. Moreover, it can cool without using a cooling means.
  • the cooling is preferably allowed to cool to room temperature. Cooling is preferably performed in an inert gas or a reducing gas.
  • the silicic acid-phosphoric acid compound obtained by the production method of the present invention is a novel compound useful as a positive electrode material for secondary batteries.
  • the silicic acid-phosphoric acid compound in the present invention has a multi-electron type as compared with the case where the number of atoms of the element A is 1.2 or more and is less than 1.2. Sometimes the capacity per unit mass increases. That is, when the element A is Li, the silicic acid-phosphoric acid compound in the present invention has a structure containing more than one and not more than two Li per unit ([SiO 4 ] + [PO 4 ]) tetrahedron.
  • the number of Li atoms can be 1.2 or more.
  • a silicic acid-phosphate compound in which [SiO 4 ] tetrahedron, [PO 4 ] tetrahedron, [LiO 4 ] tetrahedron and [MO 4 ] tetrahedron are uniformly distributed can be obtained.
  • the silicic acid-phosphoric acid compound preferably contains olivine type crystal particles.
  • the crystal particles include both primary particles and secondary particles. When secondary particles are present in the product, they may be crushed and pulverized as long as the primary particles are not destroyed.
  • a conductive material made of carbon derived from the organic compound or carbon powder on the surface of the silicic acid-phosphoric acid compound can be bonded uniformly and firmly.
  • the silicic acid-phosphoric acid compound to which the conductive material is bonded can be used as a positive electrode material for a secondary battery as it is.
  • the silicic acid-phosphate compound produced by the production method of the present invention preferably contains olivine type crystal particles, and is preferably olivine type crystal particles.
  • the olivine type crystal particle is a material that exhibits a multi-electron type theoretical electric capacity.
  • the composition of the silicic acid-phosphoric acid compound is preferably a compound represented by the following formula (3), wherein A is Li and M is at least one selected from the group consisting of Fe and Mn. y is particularly preferably 0 ⁇ y ⁇ 1.
  • the silicic acid-phosphoric acid compound having the composition represented by the formula (2) is a crystal, it is preferably a solid solution crystal or a eutectic crystal.
  • a solid solution crystal is likely to be formed. The reason is considered that a part of Si is substituted with P by the formula represented by formula (4).
  • AMPO 4 A 1 + x M [Si x P 1-x ] O 4 (4) (In the formula, x is 0.7 ⁇ x ⁇ 1.0, and [] represents a solid solution.)
  • the solid solution crystal has a sparse crystal structure and a Li ion easily moves in the crystal as compared with a crystal made of only Si. Therefore, a high capacity can be obtained and the electrical conductivity can be increased. Therefore, when used as a positive electrode material for a secondary battery, charge / discharge cycleability can be improved.
  • the silicic acid-phosphoric acid compound in the present invention contains a solid solution crystalline silicic acid-phosphoric acid compound
  • the silicic acid-phosphoric acid compound includes olivine type crystal particles which are solid solution crystals in which a part of Si is substituted with P. Is preferred.
  • the silicic acid-phosphoric acid compound is a solid solution crystal
  • Li ions easily move in the crystal, resulting in high capacity and increased electrical conductivity. To do. Therefore, when used as a positive electrode material for a secondary battery, a theoretical capacity is easily obtained, and it is considered that the charge / discharge cycleability is improved.
  • silicic acid-phosphoric acid compound eutectic when x is 0.3 ⁇ x ⁇ 0.7, eutectic is likely to occur. 0.3 ⁇ x ⁇ 0.7 is preferable, and 0.35 ⁇ x ⁇ 0.65 is more preferable.
  • the eutectic silicic acid-phosphoric acid compound (hereinafter referred to as “silicic acid-phosphoric acid compound eutectic” or simply “eutectic”) includes a crystal containing a silicon atom, a crystal containing a phosphorus atom, And a crystal containing a phosphorus atom and a silicon atom-containing crystal.
  • a eutectic containing at least one selected from the group consisting of type crystals is preferred.
  • the silicic acid-phosphoric acid compound eutectic is considered to be produced by the reaction mechanism represented by the following formula (5).
  • xA 2 MSiO 4 + (1-x) AMPO 4 (x ⁇ w 1 ) A 2 MSiO 4 + (1-x ⁇ w 2 ) AMPO 4 + wA 1 + z MSi z P 1 ⁇ z O 4 (5)
  • the silicic acid-phosphoric acid compound of the present invention is preferably a eutectic because it tends to increase electrical conductivity.
  • the reason is that, due to the generation of crystallites having a plurality of crystal structures and different electrical conductivities, a potential difference is generated between the crystallites when a potential is applied. This is thought to be due to the rise.
  • a structure having a grain boundary is formed between the crystallites in the primary particle, and this grain boundary is extremely thin as compared with the inside of the primary particle, which is considered to be because the electrical conductivity of the primary particle itself is increased.
  • the silicic acid-phosphoric acid compound of the present invention is particularly preferably an eutectic because it is easy to obtain high electric conductivity and charge / discharge cycleability is improved.
  • the silicic acid-phosphoric acid compound of the present invention has a high capacity when the silicic acid-phosphoric acid compound is applied to a positive electrode for a secondary battery, and solid solution crystals are particularly preferable in that good cycle characteristics can be easily obtained.
  • eutectic is particularly preferable from the viewpoint that high electrical conductivity is easily obtained when applied to a positive electrode for a secondary battery.
  • the average particle diameter of the silicic acid-phosphoric acid compound of the present invention is preferably 10 nm to 10 ⁇ m, more preferably 10 nm to 6 ⁇ m, and particularly preferably 10 nm to 2 ⁇ m in terms of volume-based median diameter.
  • the lower limit value may be 100 nm. By making the average particle diameter within this range, the conductivity becomes higher.
  • the average particle size can be determined by, for example, observation with an electron microscope or measurement with a laser diffraction particle size distribution meter.
  • Silicate - specific surface area of the phosphoric acid compound is preferably 0.2 ⁇ 200m 2 / g, preferably 0.5 ⁇ 200m 2 / g, 1 ⁇ 200m 2 / g is particularly preferred.
  • the upper limit value may be 100 m 2 / g or 10 m 2 / g.
  • the specific surface area can be measured by, for example, a specific surface area measuring apparatus using a nitrogen adsorption method.
  • the silicic acid-phosphoric acid compound obtained by the method for producing a silicic acid-phosphoric acid compound of the present invention is useful as a positive electrode material for a secondary battery. Therefore, a positive electrode for a secondary battery and a secondary battery can be produced using the silicic acid-phosphoric acid compound.
  • the secondary battery include a metal lithium secondary battery, a lithium ion secondary battery, and a lithium polymer secondary battery, and a lithium ion secondary battery is preferable.
  • the battery shape is not limited, and various shapes and sizes such as a cylindrical shape, a square shape, and a coin shape can be appropriately employed.
  • the production of the positive electrode for the secondary battery may be carried out in accordance with a known electrode production method except that the silicic acid-phosphate compound obtained by the production method of the present invention is used.
  • a known binder polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, ethylene propylene diene polymer, styrene-butadiene rubber, acrylonitrile-butadiene rubber, Fluorine rubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose, etc.
  • known conductive materials acetylene black, carbon, graphite, natural graphite, artificial graphite, needle coke, etc.
  • the obtained mixed powder may be pressure-bonded on a support made of stainless steel or filled in a metal container.
  • the mixed powder is mixed with an organic solvent (N-methylpyrrolidone, toluene, cyclohexane, dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran.
  • organic solvent N-methylpyrrolidone, toluene, cyclohexane, dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran.
  • the electrode can also be produced by a method such as applying a slurry obtained by mixing with a metal substrate such as aluminum, nickel, stainless steel or copper.
  • the positive electrode for a secondary battery obtained by the production method of the present invention is used as an electrode.
  • the negative electrode a known negative electrode active material can be used as the active material, but it is preferable to use at least one selected from the group consisting of a carbon material, an alkali metal material, and an alkaline earth metal material.
  • the electrolyte solution is preferably non-aqueous. That is, as the secondary battery obtained by the production method of the present invention, a nonaqueous electrolyte lithium ion secondary battery is preferable.
  • Lithium (Li 2 CO 3 ), sodium carbonate (Na 2 CO 3 ), triiron tetroxide (Fe 3 O 4 ), manganese dioxide (MnO 2 ), tricobalt tetroxide (Co 3 O 4 ), nickel oxide (NiO ), Silicon dioxide (SiO 2 ), and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) were weighed, mixed and pulverized in a dry process to obtain a raw material formulation.
  • Each raw material formulation was filled in a platinum alloy crucible containing 20% by mass of rhodium.
  • the crucible was placed in an electric furnace (manufactured by Motoyama, apparatus name: NH-3035) equipped with a heating element made of molybdenum silicide.
  • the temperature was raised at a rate of + 300 ° C./hour and heated at 1,450 to 1,500 ° C. for 0.5 hour.
  • Each melt was obtained after confirming that it became transparent visually.
  • the composition formula of the obtained melt is shown in the right column of Table 1.
  • the flake solidified product obtained in the cooling step was lightly kneaded and finely ground, and then coarsely pulverized using a pestle and mortar. Further, the coarsely pulverized solidified product was pulverized in a dry manner using a planetary mill using zirconia balls as a pulverizing medium to obtain a pulverized product.
  • the particle diameter of the pulverized product of Example 1 was measured using a laser diffraction / scattering particle size analyzer (manufactured by Horiba, Ltd., apparatus name: LA-950), the median diameter in terms of volume was 2.8 ⁇ m.
  • the pulverized product obtained in the pulverization step was placed in a 3% by volume H 2 —Ar atmosphere, and each example was heated for 8 hours at four temperature conditions of 600 ° C., 700 ° C., 800 ° C., and 900 ° C. Then, the mixture was cooled (air-cooled) at a rate of ⁇ 200 ° C./hour to precipitate silicic acid-phosphoric acid compound particles.
  • X-ray diffraction, particle size distribution, and composition analysis were performed on the particles subjected to the heating step at 700 ° C.
  • the mineral phase of the obtained silicic acid-phosphate compound particles was measured using an X-ray diffraction apparatus (manufactured by Rigaku Corporation, apparatus name: RINT TTRIII).
  • the particles obtained in Examples 1 to 4 and Examples 8 to 24 are all orthorhombic olivine type Li 2 MSiO 4 (K. Zaghib et al., Journal of Power Sources, 160, 1381-1386, 2006 and R. Dominko et al., Electrochemistry Communications, 8, 217-222 (2006)). From the results, it was confirmed that the silicic acid-phosphoric acid compound particles were crystals and consisted of solid solution crystals in which part of Si in the A 2 MSiO 4 crystals was substituted with P.
  • FIGS. 2 (a), 2 (b), and 2 (c), respectively, in Examples 19, 20, 21, and 22. are shown in (a), (b), (c), and (d) of FIG. 3, respectively.
  • composition analysis The chemical composition of the resulting silicic acid-phosphoric acid compound particles was measured. First, the particles were heated and decomposed at 120 ° C. with a 2.5 mol / L KOH solution, and the decomposition solution was dried under hydrochloric acid acidity. Next, after filtration as a hydrochloric acid acidic solution, a filtrate and a residue were obtained. The amounts of Si, Fe, Mn, Co, and Ni in the filtrate were quantified using an inductively coupled emission spectroscopic analyzer (manufactured by Seiko Instruments Inc., apparatus name: SPS3100).
  • the amounts of Li and Na in the filtrate were quantified using an atomic absorption photometer (manufactured by Hitachi High-Technologies Corporation, apparatus name: Z-2310). Calculate the amounts of SiO 2 , P 2 O 5 , FeO, MnO, CoO, NiO, Li 2 O, and Na 2 O from the quantitative values of Si, P, Fe, Mn, Co, Ni, Li, and Na, respectively. did. Further, the residue was ashed and then decomposed with hydrofluoric acid-sulfuric acid, and the weight loss due to this treatment was defined as the amount of SiO 2 . The total amount of SiO 2 was the sum of the amount calculated from the weight loss and the amount of SiO 2 in the filtrate. Table 2 shows the quantitative values of the chemical composition of the silicic acid-phosphate compound particles obtained in Examples 1 to 7 and Examples 15 to 18.
  • Examples 25 to 35 The coarsely pulverized product obtained by melting, cooling, and coarsely pulverizing in Examples 1 to 7 and Examples 19 to 22 and carbon black were mixed at a mass ratio of 9: 1 between the pulverized product and the amount of carbon in the carbon black. Each was mixed and ground using a planetary mill in the same manner as in Example 1.
  • the carbon-containing pulverized product in each example was heated in Ar gas at two temperatures of 700 ° C. and 800 ° C. for 8 hours, cooled (air-cooled) at a rate of ⁇ 200 ° C./hour, and then silicic acid-phosphoric acid. Compound particles were obtained.
  • the X-ray diffraction pattern of the resulting silicate-phosphate compound was consistent with that of olivine type lithium iron silicate.
  • Examples 32, 33, 34, and 35 the X-ray diffraction patterns of silicic acid-phosphoric acid compounds obtained by heating at 700 ° C. are shown in FIGS. 4 (a), (b), (c), ( d).
  • Example 27 the carbon content of silicic acid-phosphate compound particles obtained by heating at 700 ° C. for 8 hours and cooling (air cooling) at a rate of ⁇ 200 ° C./hour was measured using a carbon analyzer (Horiba). They were 9.5% by mass and 9.1% by mass, respectively, as measured by Seisakusho, apparatus name: EMIA-920V. Moreover, when the specific surface area of this particle
  • Example 36 The composition of the melt is 32.8%, 34.5%, 31.0%, 1.7% in terms of Li 2 O, FeO, SiO 2 and P 2 O 5 (unit: mol%).
  • Lithium carbonate (Li 2 CO 3 ), ferric trioxide (Fe 2 O 3 ), silicon dioxide (SiO 2 ), and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) were weighed and dried
  • a raw material formulation was prepared by mixing and grinding. Except that this raw material formulation was melted in air without controlling the atmosphere, it was melted, cooled, and coarsely pulverized in the same manner as in Example 3 to obtain a coarsely pulverized product.
  • the obtained coarsely pulverized product and carbon black were mixed and pulverized in the same manner as in Example 27, and the carbon-containing pulverized product was heated in Ar gas at 700 ° C. for 8 hours, at a rate of ⁇ 200 ° C./hour.
  • silica-phosphate compound particles were obtained.
  • the X-ray diffraction pattern of the resulting silicate-phosphate compound was consistent with that of olivine type lithium iron silicate.
  • the carbon content of the obtained silicic acid-phosphoric acid compound particles was measured and found to be 7.2% by mass.
  • the specific surface area was measured and found to be 24 m 2 / g.
  • the composition of the melt is 27.1%, 50.3%, 20.1%, and 2.5% in terms of Li 2 O, FeO, SiO 2 , and P 2 O 5 (unit: mol%).
  • Lithium carbonate (Li 2 CO 3 ), triiron tetroxide (Fe 3 O 4 ), silicon dioxide (SiO 2 ), and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) were weighed and dried Were mixed and pulverized to obtain a raw material formulation.
  • the raw material formulation was melted in the same manner as in Example 1, but could not be melted.
  • the composition of the melt is Li 2 O, FeO, SiO 2 , P 2 O 5 equivalent (unit: mol%), 50.6. %, 25.3%, 22.8%, and 1.3% to be lithium carbonate (Li 2 CO 3 ), triiron tetroxide (Fe 3 O 4 ), silicon dioxide (SiO 2 ), phosphorus Ammonium dihydrogenammonium (NH 4 H 2 PO 4 ) was weighed, mixed and pulverized in a dry process to obtain a raw material formulation. Although this raw material formulation was melted in the same manner as in Example 1, the melt was crystallized by the cooling step, and the cooling step could not be performed.
  • the composition of the melt is 31.6%, 35.0%, 31.6%, and 1.8% in terms of Li 2 O, FeO, SiO 2 , and P 2 O 5 (unit: mol%).
  • Lithium carbonate (Li 2 CO 3 ), triiron tetroxide (Fe 3 O 4 ), silicon dioxide (SiO 2 ), and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) were weighed and dried And mixed and pulverized to obtain a raw material formulation.
  • the raw material formulation was melted at 1,450 ° C. and then cooled at ⁇ 300 ° C./hour to obtain a crystallized product.
  • the mineral phase of the obtained crystallized product was identified using XRD, it was mainly composed of Li 2 SiO 3 and Fe 3 O 4 . That is, the target compound cannot be obtained unless the cooling step, the pulverizing step and the heating step are performed.
  • Examples 37 to 40 Production examples of positive electrode for Li-ion secondary battery and battery for evaluation
  • a pulverized product of silicic acid-phosphate compound particles obtained by heating at 700 ° C. for 8 hours and cooling (air cooling) at a rate of ⁇ 200 ° C./hour
  • the mass% sucrose solution was mixed and pulverized so that the mass ratio of the pulverized product and the amount of carbon in the sucrose was 95: 5, heated in N 2 gas at 600 ° C. for 2 hours, and cooled. After pulverization, an active material was obtained.
  • the active material, polyvinylidene fluoride resin (binder) and acetylene black (conductive material) are weighed so that the mass ratio is 85: 5: 10, and uniform in N-methylpyrrolidone (solvent)
  • a slurry was prepared by mixing until Next, the slurry was applied to an aluminum foil having a thickness of 30 ⁇ m with a bar coater. After drying this at 120 degreeC in the air and removing a solvent, after consolidating the coating layer with the roll press, it cut out to the strip shape of width 10mm * length 40mm.
  • the coating layer was peeled off leaving a 10 ⁇ 10 mm tip of strip-shaped aluminum foil, which was used as an electrode.
  • the coating thickness of the obtained electrode after roll pressing was 20 ⁇ m.
  • the obtained electrode was vacuum-dried at 150 ° C., then carried into a glove box filled with purified Ar gas, and opposed to a counter electrode in which a lithium foil was pressure-bonded to a nickel mesh with a porous polyethylene film separator. Both sides were fixed with a polyethylene plate.
  • the discharge capacities at the third cycle were 161 mAh / g (Example 37), 145 mAh / g (Example 38), 203 mAh / g (Example 39), and 241 mAh / g (Example 40), respectively.
  • Example 41 to 42 Using the silicic acid-phosphoric acid compound particles obtained in Examples 26 and 33 as an active material, the mass ratio of this to polyvinylidene fluoride resin (binder) and acetylene black (conductive material) is 90: 5.
  • the electrode was produced in the same manner as in Example 37 except that the weight was adjusted so that the ratio was 5 and the charge / discharge characteristics were evaluated in the same manner as in Example 37.
  • the discharge capacity at the third cycle was 153 mAh / g (Example 41) and 191 mAh / g (Example 42).
  • Examples 1 to 36 a silicic acid-phosphoric acid compound having a desired composition could be easily produced. Further, it was confirmed that the produced silicic acid-phosphoric acid compound had excellent characteristics as a positive electrode material for a secondary battery and further as a secondary battery (Examples 37 to 42).
  • the method for producing a silicic acid-phosphoric acid compound of the present invention is useful because the composition of the silicic acid-phosphoric acid compound can be easily controlled and produced.
  • the obtained silicic acid-phosphoric acid compound is useful for a positive electrode material for a secondary battery and further for a secondary battery.
  • a secondary battery using the silicate-phosphate compound of the present invention as a positive electrode material is useful as a secondary battery mounted in a plug-in hybrid vehicle or an electric vehicle, and as a storage battery for storing power.

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Abstract

L'invention concerne un procédé de fabrication d'un composé de silicate-phosphate, ledit procédé fournissant un contrôle accru sur la composition et la dimension de particule. Après qu'une matière solidifiée est obtenue par refroidissement d'une matière fondue représentée par A1+ x + a M b Si x P1− x O4+ c1 (dans laquelle A représente au moins un élément choisi dans le groupe comprenant le lithium, le sodium et le potassium; M représente au moins un élément choisi dans le groupe comprenant le fer, le manganèse, le cobalt et le nickel; a satisfait −0,1 ≤ a ≤ 0,4; b satisfait 0,7 ≤ b ≤ 1,3; x satisfait 0,3 ≤ x < 1,0; et c1 est un nombre qui dépend de a, de b et de la valence (N) de M et devient c2 après une étape de chauffage), une matière pulvérisée est obtenue par pulvérisation de ladite matière solidifiée. Un composé de silicate-phosphate ayant une composition représentée par A1+ x + a M b Si x P1− x O4+ c2 (dans laquelle A, M, a, b et x ont les mêmes significations que ci-dessus, et c2 est un nombre qui dépend de a, de b et de la valence (N) de M) est fabriqué par chauffage de la matière pulvérisée.
PCT/JP2011/074999 2010-10-29 2011-10-28 Composé de silicate-phosphate, électrode positive de batterie secondaire, batterie secondaire et leurs procédés de fabrication WO2012057340A1 (fr)

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WO2015177567A1 (fr) * 2014-05-22 2015-11-26 Faradion Limited Silicates de métal de transition contenant du sodium
US10205168B2 (en) 2014-05-22 2019-02-12 Faradion Limited Sodium transition metal silicates
WO2022176627A1 (fr) * 2021-02-16 2022-08-25 国立大学法人長岡技術科学大学 Procédé de fabrication de matière active d'électrode positive pour batterie secondaire à ions alcalins
WO2023162040A1 (fr) * 2022-02-22 2023-08-31 株式会社オキサイド Méthode de préparation de phosphate de lithium métallique, phosphate de lithium métallique, matériau d'électrode positive pour batterie secondaire au lithium-ion, électrode positive pour batterie secondaire au lithium-ion, et batterie secondaire au lithium-ion

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