WO2012086722A1 - Silicic acid-vanadic acid compound, positive electrode for secondary battery, and manufacturing method for secondary battery - Google Patents

Silicic acid-vanadic acid compound, positive electrode for secondary battery, and manufacturing method for secondary battery Download PDF

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Publication number
WO2012086722A1
WO2012086722A1 PCT/JP2011/079716 JP2011079716W WO2012086722A1 WO 2012086722 A1 WO2012086722 A1 WO 2012086722A1 JP 2011079716 W JP2011079716 W JP 2011079716W WO 2012086722 A1 WO2012086722 A1 WO 2012086722A1
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silicic acid
formula
acid compound
group
vanadic acid
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PCT/JP2011/079716
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French (fr)
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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    • 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
    • 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
    • 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
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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-vanadic acid compound, a positive electrode for a secondary battery, and a method for producing the secondary battery.
  • Patent Document 1 includes k Li in the unit formula, and [SiO 4 ], [SO 4 ], [PO 4 ], [GeO 4 ], [VO 4 ], [AlO 4 ], A compound having an orthosilicate structure having a composition of a wide general formula including [BO 4 ] and the like has been proposed as an electrode material.
  • Non-Patent Document 1 Li 2 FeSiO 4 is produced by solid phase reaction as an olivine-type silicate compound. The reaction involves complicated manufacturing processes, high manufacturing costs, difficulty in mass production, and control of composition and particle size is not easy.
  • the electrode materials disclosed in Patent Literature 1 it is Li 1.7 Mn 0.7 Fe 0.3 Si 0.7 P 0.3 O 4 that can be confirmed as a compound containing Si. Since the compound is produced by a solid-phase reaction in which Li 2 MnSiO 4 and LiFePO 4 are mixed and pulverized, sealed in a tube, and heated, there are similar problems.
  • An object of the present invention is to provide a production method in which the composition and particle size of a silicic acid-vanadic 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.
  • This invention also provides the manufacturing method of the positive electrode for secondary batteries which is excellent in a characteristic and reliability, and a secondary battery.
  • the present invention is the following [1] to [15].
  • a method for producing a silicic acid-vanadic acid compound having a composition represented by the formula (B), A f M b Si x (V c X 1-c ) 1-x O 4 + d2 (B) (In the formula, A is at least one element selected from the group consisting of Li, Na, and K.
  • M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn.
  • X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 ⁇ f ⁇ 2.4, b is 0.7 ⁇ b ⁇ 1.3, c is 0 ⁇ c ⁇ 1, x is 0.6 ⁇ x ⁇ 1, and d2 is a number depending on the valence N of X, f, b, c, x, and M.)
  • the raw material containing element A, element M, Si, V, and element X is adjusted so that the molar ratio of element A, element M, Si, V, and element X is the molar ratio represented by formula (B) Heating the raw material formulation to obtain a melt, A cooling step of cooling the melt to obtain a solidified product, A pulverization step of pulverizing the solidified product to obtain a pulverized product, and a heating step of heating the pulverized product to obtain a silicate compound.
  • a method for producing a silicic acid compound [2] A melting step for obtaining a melt having a composition represented by the following formula (A): A cooling step of cooling the melt to obtain a solidified product, A pulverization step of pulverizing the solidified product to obtain a pulverized product, and a heating step of heating the pulverized product to obtain a silicic acid-vanadic acid compound having a composition represented by the following formula (B) are performed in this order: [1] A process for producing a silicic acid-vanadic acid compound.
  • A is at least one element selected from the group consisting of Li, Na, and K.
  • M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn.
  • X is at least one element selected from the group consisting of P, B, and Al
  • f is 0.8 ⁇ f ⁇ 2.4
  • b is 0.7 ⁇ b ⁇ 1.3
  • c is 0 ⁇ c ⁇ 1
  • x is 0.6 ⁇ x ⁇ 1
  • d1 is a number depending on the valence N ′ of X, f, b, c, x, and M, and d2 after the heating step Is a number.
  • A, M, X, f, b, c, and x have the same meanings as described above, but are independent values
  • d2 is X, f, b, c, x, and M.
  • the number depends on the valence N of [3]
  • the melt having the composition represented by the formula (A) is a melt having the composition represented by the following formula (1)
  • the silicic acid having the composition represented by the formula (B) The method for producing a silicic acid-vanadic acid compound according to [2], wherein the vanadic acid compound is a silicic acid-vanadic acid compound having a composition represented by the following formula (2):
  • a is ⁇ 1.0 ⁇ a ⁇ 0.6
  • d11 is X, a, b, c, x
  • the melting step includes Element A is A carbonate, A bicarbonate, A hydroxide, A silicate, A vanadate, A chloride, A nitrate, A sulfate, and A And at least one selected from the group consisting of organic acid salts (however, at least one of the at least one kind may each form a hydrated salt), Element M is M oxide, M oxyhydroxide, M hydroxide, M silicate, M vanadate, metal M, M chloride, M nitrate, M sulfate And at least one selected from the group consisting of organic acid salts of M, Si is included as at least one selected from the group consisting of silicon oxide, A silicate, M silicate, vanadium silicate, and silicon alkoxide, V is included as at least one selected from the group consisting of vanadium oxide, A vanadate, M vanadate, ammonium vanadate, vanadium silicate, vanadium chloride, and vanadium oxysulfate.
  • A is A
  • the raw material preparation further contains element X as phosphorus oxide, phosphoric acid, ammonium phosphate, ammonium hydrogen phosphate, A phosphate, A hydrogen phosphate, M phosphate, boron oxide.
  • the solidified product contains at least one carbon source selected from the group consisting of an organic compound and carbon powder, and a carbon equivalent amount (mass) in the carbon source is a solidified product.
  • the silicic acid-vanadic acid compound production method of [1] to [8], which is 0.1 to 20% by mass relative to the total mass of the mass and the carbon equivalent amount (mass) in the carbon source is 0.1 to 20% by mass relative to the total mass of the mass and the carbon equivalent amount (mass) in the carbon source.
  • the melt having the composition represented by the formula (1) is a melt having the composition represented by the following formula (1A), and the silicic acid having the composition represented by the formula (2)
  • a silicic acid-vanadic acid compound is obtained by the production method of [1] to [11], and then a positive electrode for a secondary battery is produced using the silicic acid-vanadic acid compound as a positive electrode material for a secondary battery.
  • a method for producing a positive electrode for a secondary battery characterized by comprising: [13] A method for producing a secondary battery, comprising obtaining a positive electrode for a secondary battery by the production method of [12], and then producing a secondary battery using the positive electrode for a secondary battery.
  • X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 ⁇ f ⁇ 2.4, b is 0.7 ⁇ b ⁇ 1.3, c is 0 ⁇ c ⁇ 1, x is 0.6 ⁇ x ⁇ 1, and d2 is a number depending on the valence N of X, f, b, c, x, and M.)
  • the production method of the present invention is a method in which the composition and particle size of the silicic acid-vanadic acid compound can be easily controlled. Therefore, silicic acid-vanadic acid compounds having various compositions useful as electrode materials can be efficiently produced. Further, by using the silicic acid-vanadic acid compound of the present invention, a positive electrode for a secondary battery and a secondary battery having excellent battery characteristics and reliability can be produced. Furthermore, according to the present invention, a novel silicic acid-vanadic acid compound is provided.
  • FIG. 3 is an X-ray diffraction pattern of silicic acid-vanadic acid compounds produced in Examples 1, 2, 3, and 4.
  • FIG. 6 is a diagram showing an X-ray diffraction pattern of silicic acid-vanadic acid compounds produced in Examples 5, 6, 7, and 8.
  • FIG. 4 is a diagram showing an X-ray diffraction pattern of silicic acid-vanadic acid compounds produced in Examples 16, 17, 18, and 19.
  • Method for producing silicic acid-vanadic acid compound In the method for producing a silicic acid-vanadic 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 method for producing a silicic acid-vanadic acid compound having a composition represented by formula (B), A f M b Si x (V c X 1-c ) 1-x O 4 + d2 (B) (In the formula, A is at least one element selected from the group consisting of Li, Na, and K. M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn.
  • X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 ⁇ f ⁇ 2.4, b is 0.7 ⁇ b ⁇ 1.3, c is 0 ⁇ c ⁇ 1, x is 0.6 ⁇ x ⁇ 1, and d2 is a number depending on the valence N of X, f, b, c, x, and M.)
  • the raw material containing element A, element M, Si, V, and element X is adjusted so that the molar ratio of element A, element M, Si, V, and element X is the molar ratio represented by formula (B) Heating the raw material formulation to obtain a melt, Cooling step (II): a step of cooling the melt to obtain a solidified product, Pulverization step (III): a step of pulverizing the solidified product to obtain a pulverized product; Heating step (IV): A heating step of heating the pulverized product to obtain a silicate compound having a composition represented
  • a raw material containing element A, element M, Si, V, and element X is converted into a molar ratio in which the molar ratio of element A, element M, Si, V, and element X is represented by formula (B) It is also the process of heating the raw material formulation prepared so that it may become, and obtaining a melt.
  • the melting step is preferably a step of obtaining a melt having a composition represented by the formula (A).
  • a f M b Si x (V c X 1-c ) 1-x O 4 + d1 (A) (In the formula, A is at least one element selected from the group consisting of Li, Na, and K.
  • M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn.
  • X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 ⁇ f ⁇ 2.4, b is 0.7 ⁇ b ⁇ 1.3, c is 0 ⁇ c ⁇ 1, x is 0.6 ⁇ x ⁇ 1, d1 is a number depending on the valence N ′ of X, f, b, c, x, and M, and d2 after the heating step Is a number.)
  • the element A is at least one 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-vanadic acid compound containing Li can have a high capacity per unit volume (mass) of the secondary battery.
  • the element M in the formula (A) is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn.
  • the element M is preferably composed of only one kind or two kinds.
  • the silicic acid-vanadic acid compound produced by the production method of the present invention is used for a positive electrode material for a secondary battery, the element M is composed of only Fe, Mn, or Fe and Mn. Is preferable.
  • the valence N ′ of the element M is a numerical value that can change in each step of the production method of the present invention, and is preferably 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 M is M, +2, +8/3, or +3 when Co is Ni, Is preferably +2 or +4. It is particularly preferred that the valence N ′ is +2, since the melting step (I) is simplified.
  • the element X in the formula (A) is at least one element selected from the group consisting of P, B, and Al.
  • the melt contains the element X
  • the structure of the silicic acid-vanadic acid compound having the composition represented by the formula (B) obtained is stabilized, and when used as a positive electrode material for a secondary battery, It is thought that cycle characteristics can be improved.
  • the melt may contain an element other than element A, element M, silicon (Si), vanadium (V), element X, and oxygen (O).
  • the element is preferably at least one element selected from the group consisting of La, Ca, Mg, and Zn (hereinafter referred to as element Z).
  • element Z the melt can be easily melted.
  • the content of element Z (the total amount in the case of a plurality of elements) is preferably 0.1 to 3% in terms of oxide equivalent (unit: mol%) of each element when it becomes a melt.
  • the melt may contain at least one element selected from the group consisting of S, Ge, W, Mo, As, and Sb.
  • f is in the range of 0.8 ⁇ f ⁇ 2.4, and b is in the range of 0.7 ⁇ b ⁇ 1.3.
  • a silicic acid-vanadic acid compound having the desired composition can be produced.
  • a raw material formulation can be melt
  • f is preferably 1.7 ⁇ f ⁇ 2.2.
  • a melt having a composition represented by the following formula (1) is preferable, and a melt having a composition represented by the following formula (1A) is particularly preferable.
  • formula (1), and formula (1A) b and c have the same meaning as described above.
  • a satisfies ⁇ 1.0 ⁇ a ⁇ 0.6.
  • X in Formula (A), Formula (1), and Formula (1A) is 0.6 ⁇ x ⁇ 1.
  • the theoretical capacity of the secondary battery can be increased.
  • 0.7 ⁇ x ⁇ 1 is preferable, and 0.8 ⁇ x ⁇ 1 is preferable.
  • a and b are more preferably ⁇ 0.1 ⁇ a ⁇ 0.4 and 0.8 ⁇ b ⁇ 1.3, more preferably ⁇ 0.1 ⁇ a ⁇ 0.3 and 0.9 ⁇ b ⁇ 1.3. preferable. In such a case, it is easy to obtain a silicic acid-vanadic acid compound exhibiting a multi-electron type reaction.
  • x is particularly preferably 0.8 ⁇ x ⁇ 1, and in such a case, V atoms tend to be a solid solution in which Si atoms are substituted, and the theoretical capacity can be further increased.
  • the value of d1 in the formula (A) is a number that depends on the valence N ′ of X, f, b, c, x, and M.
  • the value of d11 in the formulas (1) and (1A) is a number that depends on the valence N ′ of X, a, b, c, x, and M. Since the valence of the element in the formula can change in the subsequent heating step (IV), d1 is adjusted to a value that becomes d2 after the heating step (IV), or a value that becomes d12 in the heating step (IV). To adjust d11.
  • d1 is preferably ⁇ 0.25 ⁇ d1 ⁇ 0.25, and particularly preferably ⁇ 0.12 ⁇ d1 ⁇ 0.12.
  • d11 is preferably ⁇ 0.25 ⁇ d11 ⁇ 0.25, and particularly preferably ⁇ 0.12 ⁇ d11 ⁇ 0.12.
  • d1 is preferably 0.9 to 1.2 times as large as d2.
  • the value of y in the formula (1A) is preferably 0 ⁇ y ⁇ 1, and particularly preferably 0 ⁇ y ⁇ 1.
  • the molar ratio of Fe to Mn is preferably 20 to 80:80 to 20, and particularly preferably 25 to 75:75 to 25.
  • raw materials containing each element are prepared so as to be a melt having a composition represented by formula (1). It is preferable to obtain a raw material formulation and then heat the raw material formulation to obtain a melt.
  • the raw material preparation is preferably mixed and pulverized.
  • the pulverization is preferably performed by a dry method or a wet method using a mixer, a ball mill, a jet mill, a planetary mill or the like, and a dry method is preferable because a solvent removal step is unnecessary.
  • the particle size of each raw material in the mixture is not limited as long as it does not adversely affect the mixing operation, the filling operation of the mixture into the melting container, the meltability of the mixture, and the like.
  • the compound containing element A in the raw material formulation includes A carbonate (A 2 CO 3 etc.), A bicarbonate (AHCO 3 etc.), A hydroxide (AOH etc.), A silicate (a 2 O ⁇ 2SiO 2, a 2 O ⁇ SiO 2, 2A 2 O ⁇ SiO 2 , etc.), vanadate a (AVO 3, a 3 VO 4, a 4 VO 7 , etc.), chlorides of a ( ACl), A nitrates (ANO 3 ), A sulfates (A 2 SO 4 ), and organic acid salts such as A acetates (CH 3 COOA, etc.) and oxalates ((COOA) 2, etc.)
  • at least one selected from the group consisting of (provided that a part or all of the one or more may each form a hydrated salt).
  • carbonates or bicarbonates of A are particularly preferred because they are inexpensive and easy to handle.
  • Examples of the compound containing element M in the raw material preparation include oxides of M (FeO, Fe 3 O 4 , Fe 2 O 3 , MnO, Mn 2 O 3 , MnO 2 , CoO, Co 3 O 4 , Co 2 O 3 NiO, CuO, Cu 2 O, ZnO, etc.), M oxyhydroxide (MO (OH) etc.), M hydroxide (M (OH) 2 , M (OH) 3 etc.), M Acid salt (MO ⁇ SiO 2 , 2MO ⁇ SiO 2 etc.), M vanadate (M 2 V 2 O 7 etc.), metal M, M chloride (MCl 2 , MCl 3 etc.), M nitrate ( M (NO 3 ) 2 , M (NO 3 ) 3 etc.), M sulfate (MSO 4 , M 2 (SO 4 ) 3 etc.), and M acetate (M (CH 3 COO) 2 etc.) At least one selected from the group consisting of organic acid salts such as o
  • the compound containing the element M Fe 3 O 4 , Fe 2 O 3 , MnO, Mn 2 O 3 , MnO 2 , Co 3 O 4 , NiO, CuO, and ZnO are available from the viewpoint of availability and cost. More preferred is at least one selected from the group consisting of In particular, the compound when the element M is Fe is preferably Fe 3 O 4 and / or Fe 2 O 3 , and the compound when the element M is Mn is preferably MnO 2 and / or MnO. . Only 1 type may be used for the compound containing the element M, or 2 or more types may be used for it.
  • the compound containing Si in the raw material formulation includes silicon oxide (SiO 2 etc.), A silicate, M silicate, vanadium silicate ((0.1 ⁇ n ⁇ 10) etc.), and silicon At least one selected from the group consisting of alkoxides (Si (OCH 3 ) 4 , Si (OC 2 H 5 ) 4, etc.) is preferred.
  • silicon oxide is particularly preferable from the viewpoint of inexpensiveness.
  • the compound containing Si may be crystalline or amorphous.
  • Examples of the compound containing V in the raw material preparation include vanadium oxide (VO, V 2 O 3 , VO 2 , V 2 O 5, etc.), A vanadate, M vanadate, ammonium vanadate (NH 4 VO). 3 ) At least one selected from the group consisting of vanadium silicate, vanadium chloride (such as VCl 3 ), and vanadium oxysulfate (such as VOSO 4 ) is preferable. As the compound containing V, vanadium oxide is particularly preferable because it is inexpensive and easy to handle.
  • Element X in the raw material formulation is an optional component and is contained as necessary.
  • the compound includes phosphorus oxide (P 2 O 5 etc.), phosphoric acid (H 3 PO 4 etc.) ), Ammonium phosphate (such as (NH 4 ) 3 PO 4 ), ammonium hydrogen phosphate (such as (NH 4 ) 2 HPO 4 , NH 4 H 2 PO 4 ), A phosphate (such as A 3 PO 4 ) At least one selected from the group consisting of hydrogen phosphate of A (A 2 HPO 4 etc.) and M phosphate (M 3 (PO 4 ) 2 etc.) is preferable.
  • the compounds include boron oxide (B 2 O 3 etc.), boric acid (H 3 BO 3 etc.), A borate (A 2 B 4 O 7 etc.), and M Of these, at least one selected from the group consisting of borate salts (such as MB 4 O 7 ) is preferred.
  • the compound is preferably at least one selected from the group consisting of aluminum oxide (such as Al 2 O 3 ) and aluminum oxyhydroxide (such as AlOOH).
  • the raw material preparation a combination of A carbonate or hydrogen carbonate; M oxide or M oxyhydroxide; silicon oxide; vanadium oxide is preferable.
  • the compound containing the element X is preferably at least one selected from the group consisting of ammonium phosphate, boric acid, aluminum oxide, and aluminum oxyhydroxide.
  • the raw material formulation at least one selected from the group consisting of Li 2 CO 3 or LiHCO 3 ; Fe 3 O 4 , Fe 2 O 3 , MnO 2 , and MnO; SiO 2 ; V 2 O 5 or V
  • the combination of 2 O 3 is particularly preferred.
  • the element X is included, a combination in which at least one selected from the group consisting of NH 4 H 2 PO 4 , B 2 O 3 , H 3 BO 3 , Al 2 O 3 , and AlOOH is further added is preferable.
  • the composition of the raw material formulation should in principle correspond to the composition of the melt.
  • the raw material formulation contains a component that is easily lost due to volatilization or the like during the melting step (I), such as Li or V
  • the composition of the obtained melt is slightly different from the composition of the raw material formulation. There is. In such a case, it is preferable to set the amount of each compound charged in consideration of the amount lost due to volatilization or the like.
  • the purity of each raw material in the raw material preparation is not particularly limited, but a range that does not deteriorate the desired characteristics is preferable. Considering reactivity and characteristics of silicic acid-vanadic acid compound (for example, characteristics of positive electrode material for secondary battery), the purity excluding hydrated water is preferably 99% by mass or more.
  • each raw material in the raw material preparation it is preferable to use a pulverized raw material.
  • the pulverization may be performed after the raw materials are pulverized or mixed, or may be pulverized after mixing.
  • the pulverization is preferably performed by a dry method or a wet method using a mixer, a ball mill, a jet mill, a planetary mill or the like, and a dry method is preferable because a solvent removal step is unnecessary.
  • the particle size of each raw material in the raw material preparation is not limited as long as it does not adversely affect the mixing operation, the filling operation of the mixture into the melting container, the meltability of the mixture, and the like.
  • the raw material formulation obtained by the above method is then heated and melted.
  • Melting is preferably performed by placing the raw material preparation in a container or the like, and placing the container in a heating furnace and heating.
  • the container is preferably made of alumina, carbon, silicon carbide, zirconium boride, titanium boride, boron nitride, carbon, platinum, or a platinum alloy containing rhodium.
  • Containers made of refractory bricks and reducing materials for example, graphite
  • 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.
  • Heating is preferably performed in air, inert gas, or 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 normal pressure, increased pressure (1.1 ⁇ 10 5 Pa or more), and reduced pressure (0.9 ⁇ 10 5 Pa or less).
  • the melting condition is preferably in a reducing gas, but may be in an oxidizing gas. When melted in oxidizing gas, it is preferable to perform reduction (for example, change from M 3+ to M 2+ ) in the 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).
  • the reducing gas refers to a gas that is substantially free of oxygen by adding a reducing gas to the above-described inert gas.
  • 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 contained in the total gas volume.
  • the oxygen content is preferably 1% by volume or less, and particularly preferably 0.1% by volume or less in the gas volume.
  • the heating temperature is preferably 1,300 to 1,600 ° C, particularly preferably 1,300 to 1,450 ° 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. Further, the melt may be clarified at a temperature lower than the melting temperature until the next cooling step (II) is performed.
  • 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. However, 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-vanadic acid compound can be easily controlled. Furthermore, there is an advantage that the product can be prevented from becoming agglomerated in the subsequent heating step (IV) and the particle size of the product can be easily controlled.
  • the crystallized product becomes a crystal nucleus in the heating step (IV), and it is easy to crystallize.
  • the amount of the crystallized product in the solidified product is preferably 0 to 30% by mass with respect to the total mass of the solidified product.
  • a method for cooling the melt a method in which the melt is dropped between twin rollers rotating at high speed, a method in which the melt is dropped on a single rotating roller, and cooling is performed, or a carbon plate on which the melt is cooled.
  • a method of cooling by pressing on a metal plate is preferable.
  • a cooling method using twin rollers is particularly preferable because the cooling rate is high and a large amount of processing can be performed.
  • the double roller it is preferable to use one made of metal, carbon, or ceramic.
  • cooling method there is also a method in which the molten material is directly poured into water, but this method is difficult to control, it is difficult to obtain an amorphous material, the solidified material becomes a lump, and a disadvantage that requires much labor for pulverization There is.
  • a cooling method there is also a method in which a melt is directly added to 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 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 is indicated by a positive value.
  • 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 1 ⁇ 10 8 ° C./second is particularly preferable 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 solidified product obtained in the cooling step (II) is preferably flaky or fibrous.
  • the average thickness is preferably 200 ⁇ m or less, particularly preferably 100 ⁇ m or less.
  • the average diameter of the surface perpendicular to the average thickness in the case of flakes is not particularly limited.
  • the average diameter is preferably 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 pulverization step (III) is a step of pulverizing the solidified product obtained in the cooling step (II) 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 pulverization can be performed without imposing a burden on an apparatus used for pulverization 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, but the present inventor has noticed that there is a problem that residual stress is generated by the pulverization and battery characteristics are deteriorated. Therefore, in the production method of the present invention, since the pulverization step (III) is performed before the heating step (IV), the residual stress generated in the pulverization step (III) can be reduced or removed in the 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. It is preferable to preliminarily make the solidified product fine by hitting it with a hammer or a hammer before pulverization because the burden of the pulverization step (III) is reduced.
  • the heating step (IV) is preferably performed after the dispersion medium is removed by sedimentation, filtration, drying under reduced pressure, drying by heating, and the like.
  • the silicic acid-vanadic 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.
  • the silicic acid-vanadic acid compound is preferably in the form of fine particles.
  • 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 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 particle size can be measured by a sedimentation method or a laser diffraction / scattering particle size measuring device.
  • the conductive material is preferably at least one carbon source selected from the group consisting of organic compounds and carbon powder.
  • the amount of the carbon source is preferably such that the ratio of the carbon equivalent (mass) to the total mass of the solidified product and the carbon equivalent (mass) in the carbon source is 0.1 to 20% by mass. An amount of 10% by mass is particularly preferred.
  • 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.
  • 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.
  • the organic compound specifically, glucose, sucrose, glucose-fructose invert sugar, caramel, starch, pregelatinized starch, carboxymethylcellulose and the like are preferable.
  • Carbon powder As the carbon powder, carbon black, graphite, acetylene black and the like are preferable.
  • the carbon powder may be fibrous carbon or plate-like carbon.
  • 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.
  • the pulverization step (III) when the solidified product contains only carbon powder is preferably dry.
  • the heating step (IV) is a step of heating the pulverized product obtained in the pulverizing step (III) to obtain a silicic acid-vanadic acid compound having a composition represented by the formula (B).
  • the melt is represented by the formula (B).
  • a silicic acid-vanadic acid compound having the composition represented by the following formula (2) is obtained.
  • Preferred embodiments of element A, element M, and element X in formula (B), formula (2), and formula (2A) are the same as in formula (A), formula (1), and formula (1A). .
  • F, a, b, c, x, and y in formula (B), formula (2), and formula (2A) have the same meaning as described above, but formula (A), formula (1), and formula ( A value independent of the value in 1A) is shown.
  • the preferred ranges of f, a, b, c, and x in formula (B), formula (2), and formula (2A) are the same as in formula (A), formula (1), and formula (1A). is there.
  • the value of d2 in the formula (B) is a number that depends on the type of element X, f, b, c, x, and the valence N of M.
  • the value of d12 in Formula (2) and Formula (2A) is a number that depends on the type of element X, a, b, c, x, and the average valence N of M or Fe y Mn 1-y .
  • d2 is preferably ⁇ 0.2 ⁇ d2 ⁇ 0.2, particularly preferably ⁇ 0.1 ⁇ d2 ⁇ 0.1.
  • d12 is preferably ⁇ 0.2 ⁇ d12 ⁇ 0.2, particularly preferably ⁇ 0.1 ⁇ d12 ⁇ 0.1.
  • the value of y in the formula (2A) is preferably 0 ⁇ y ⁇ 1, and particularly preferably 0 ⁇ y ⁇ 1.
  • the molar ratio of Fe to Mn is preferably 20 to 80:80 to 20, more preferably 25 to 75:75 to 25, and particularly preferably 40 to 60:60 to 40.
  • the product of the heating step (IV) is preferably a silicic acid-vanadic acid compound crystal particle, more preferably an olivine type crystal particle.
  • the pulverized material is heated, so that the relaxation of residual stress is promoted.
  • the composition, particle diameter, and distribution of the silicic acid-vanadic acid compound can be easily controlled.
  • the heating step (IV) when the carbon source is included in the pulverization step (III) can be a step of bonding a conductive material to the surface of the product, preferably the crystal grains of the product.
  • the organic compound in the carbon source is thermally decomposed in the heating step (IV), becomes a carbide, and functions as a conductive material.
  • the heating temperature in the heating step (IV) is preferably 500 to 1,000 ° C.
  • the heating temperature is particularly preferably 600 to 900 ° C.
  • crystal particles having appropriate crystallinity, particle diameter, particle size distribution, and the like are easily obtained, and olivine-type crystal particles are easily obtained.
  • the heating is not limited to holding at a constant temperature, and may be performed by setting the holding temperature in multiple stages.
  • the heating temperature is increased, the particle diameter of the generated particles tends to increase. Therefore, it is preferable to set the heating temperature 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 the 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.
  • Heating is preferably performed in air, an inert gas, or a reducing gas, and particularly preferably performed in an inert gas or a reducing gas.
  • the conditions of the inert gas and the reducing gas are the same as those in the melting step (I).
  • the pressure may be normal pressure, increased pressure (1.1 ⁇ 10 5 Pa or more), and reduced pressure (0.9 ⁇ 10 5 Pa or less).
  • a container containing a reducing agent for example, graphite
  • pulverized material is loaded in a heating furnace, reduction of M in the pulverized material (for example, change from M 3+ to M 2+ ) is performed. Can be promoted.
  • 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.
  • the cooling can be performed without using a cooling means.
  • the cooling may be left to cool to room temperature. Cooling is preferably performed in an inert gas or a reducing gas.
  • the silicic acid-vanadic acid compound obtained by the production method of the present invention is a useful compound as a positive electrode material for a secondary battery.
  • the silicic acid-vanadic acid compound having the composition represented by the formula (2) has a multi-electron type because the number of atoms of the element A exceeds 1.0, and was used as a positive electrode material for a secondary battery. Sometimes the capacity per unit mass increases.
  • the silicic acid-vanadic acid compound having the composition represented by the formula (2) exceeds one unit tetrahedron ([SiO 4 ] + [VO 4 ]). Since it has a structure containing two or less Li, the number of Li atoms can be more than 1.0. Furthermore, according to the production method of the present invention, the [SiO 4 ] tetrahedron, [VO 4 ] tetrahedron, [LiO 4 ] tetrahedron, [X tetrahedron], and [MO 4 ] tetrahedron or octahedron are uniform.
  • a silicic acid-vanadic acid compound distributed in the above can be obtained.
  • the silicic acid-vanadic 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-vanadic acid compound can be bonded uniformly and firmly.
  • the silicic acid-vanadic acid compound to which the conductive material is bonded can be used as it is as a positive electrode material for a secondary battery.
  • the silicic acid-vanadic acid compound having the composition represented by the formula (2) is a crystal, it is preferably a solid solution crystal.
  • x in the formula (2) is 0.8 ⁇ x ⁇ 1, it tends to be a solid solution crystal. The reason is considered that a part of Si is substituted with V or V and X by the reaction represented by the formula (3), for example, and a solid solution crystal is generated.
  • the solid solution crystal has a stable crystal structure as compared with a crystal made of only Si, and Li ions easily move in the crystal. Therefore, since a high capacity is obtained and the electrical conductivity is increased, when used as a positive electrode material for a secondary battery, a theoretical capacity can be easily obtained and the charge / discharge cycleability can be improved.
  • the silicic acid-vanadic acid compound in the present invention preferably contains olivine type crystal particles which are solid solution crystals in which a part of Si is substituted with V or V and X.
  • the average particle diameter of the silicic acid-vanadic acid compound of the present invention is preferably 10 nm to 10 ⁇ m, particularly preferably 10 nm to 2 ⁇ m, in terms of volume median diameter. By making the average particle diameter within this range, the conductivity of the silicic acid-vanadic acid compound becomes higher.
  • the average particle diameter 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 vanadate compound is preferably 0.2 ⁇ 200m 2 / g, 1 ⁇ 200m 2 / g is particularly preferred. By setting the specific surface area within this range, the conductivity of the silicic acid-vanadic acid compound is increased.
  • the specific surface area can be measured by, for example, a specific surface area measuring apparatus using a nitrogen adsorption method.
  • Examples of the silicic acid-vanadic acid compound in the present invention include the compounds described in Examples.
  • a positive electrode for a secondary battery and a secondary battery can be produced.
  • 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 positive electrode for a secondary battery of the present invention can be manufactured according to a known electrode manufacturing method except that the silicic acid-vanadic acid compound obtained by the manufacturing 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.
  • known organic solvents N-methylpyrrolidone, toluene, cyclohexane, dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, methyl acrylate
  • the structure of the secondary battery a structure in a known secondary battery can be adopted except that 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, and at least one selected from the group consisting of carbon materials, alkali metal materials, and alkaline earth metal materials is preferably used.
  • the electrolytic solution a non-aqueous electrolytic solution is preferable. That is, as the secondary battery obtained by the production method of the present invention, a nonaqueous electrolyte lithium ion secondary battery is preferable.
  • the composition of the melt is Li 2 O, Na 2 O, FeO, MnO, CoO, NiO, SiO 2 , V 2 O 5 , P 2 O 5 , B 2 O 3 , and Al 2 O 3 equivalent (unit: mole) %), So that the proportions shown in Table 1 are obtained, respectively, lithium carbonate (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 ), vanadium oxide (V 2 O 5 ), ammonium hydrogen phosphate (NH 4 H 2 PO 4 ), boron oxide ( B 2 O 3), and were weighed aluminum oxide (Al 2 O 3), were mixed and pulverized in a dry, to obtain a raw material formulation.
  • composition formula of the obtained melt is shown in the right column of Table 1.
  • 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) having a heating element made of molybdenum silicide.
  • the electric furnace was heated at a rate of + 300 ° C./hour and heated at 1,400 to 1,500 ° C. for 0.5 hours while flowing N 2 gas at a flow rate of 2 L / min.
  • Each melt was obtained after confirming that it became transparent visually.
  • Heating step (IV) The pulverized product obtained in the pulverization step (III) was placed in 3% by volume H 2 —Ar gas, and each example was heated for 8 hours under three temperature conditions of 600 ° C., 700 ° C., and 800 ° C. Then, cooling (air cooling) was performed at a rate of ⁇ 200 ° C./hour to precipitate silicic acid-vanadic acid compound particles. Among each Example, X-ray diffraction, particle size distribution measurement, and composition analysis were performed about the particle
  • the mineral phase of the obtained silicic acid-vanadic acid compound particles was examined using an X-ray diffraction apparatus (manufactured by Rigaku Corporation, apparatus name: RINT TTR III).
  • the particles obtained in Examples 1 to 29 are all orthorhombic olivine-type Li 2 SiO 4 (K. Zaghib et al., Journal of Power Sources, 160, 1361-1386, 2006 and R. Dominko et al. , Electrochemistry Communications, 8, 217-222 (2006)). From this result, it was confirmed that the silicic acid-vanadic acid compound particles were crystals and consisted of solid solution crystals in which a part of Si in the A 2 MSiO 4 crystals was substituted with V.
  • composition analysis The chemical composition of the resulting silicic acid-vanadic 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. Si, V, P, B, Al, Fe, Mn, Co, and Ni in the filtrate were quantified using an inductively coupled emission spectroscopic analyzer (manufactured by Seiko Instruments Inc., apparatus name: SVS3100).
  • Li and Na in the filtrate were quantified using an atomic absorption photometer (manufactured by Hitachi High-Technologies Corporation, apparatus name: Z-2310). From the quantitative values of Si, V, P, B, Al, Fe, Mn, Co, Ni, Li, and Na, SiO 2 , V 2 O 5 , P 2 O 5 , B 2 O 3 , Al 2 O 3 , The amounts of FeO, MnO, CoO, NiO, Li 2 O, and Na 2 O were calculated. 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 value and the amount of SiO 2 in the filtrate.
  • Table 2 shows the quantitative values of the chemical compositions of the silicic acid-vanadic acid compound particles obtained in Examples 1 to 4, Examples 16 to 19, Examples 22 to 24, and Examples 27 to 30.
  • Example 41 to 44 The coarsely pulverized product obtained by melting, cooling, and coarsely pulverizing in Examples 1, 2, 3, and 4 and carbon black were 9: 1 in mass ratio of the coarsely pulverized product and the amount of carbon in the carbon black.
  • the mixture was mixed and ground in the same manner as in Example 1 using a planetary mill.
  • 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-vanadic acid. Compound particles were obtained.
  • the X-ray diffraction patterns of the resulting silicic acid-vanadic acid compound particles almost coincided with those of Examples 1, 2, 3, and 4, respectively.
  • Example 41 and 44 the carbon content of the silicic acid-vanadic acid compound 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, Ltd.).
  • Product, device name: EMIA-920V which were 9.8 mass% (Example 41) and 9.6 mass% (Example 44), respectively.
  • the specific surface areas of the silicic acid-vanadic acid compound particles obtained by heating at 700 ° C. for 8 hours and cooling (air cooling) at a rate of ⁇ 200 ° C./hour were measured. 2 / g (Example 41) and 28 m 2 / g (Example 44).
  • Example 45 to 46 The coarsely pulverized product obtained by melting, cooling, and coarsely pulverizing in Examples 2 and 6, carbon black, and the sucrose aqueous solution, the mass of the coarsely pulverized product, the carbon amount in carbon black, and the carbon amount in sucrose. The mixture was mixed so that the ratio was 0.90: 0.05: 0.05, and pulverized, heated and air-cooled in the same manner as in Example 41 to obtain silicic acid-vanadic acid compound particles. The X-ray diffraction patterns of the obtained silicic acid-vanadic acid compounds almost coincided with those of Examples 2 and 6, respectively.
  • Example 45 the carbon content of the silicic acid-vanadic acid compound 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, Ltd.).
  • Product, device name: EMIA-920V which were 7.1% by mass (Example 45) and 7.0% by mass (Example 46), respectively.
  • composition of the melt is 32.6%, 46.5%, 18.6%, and 2.3% in terms of Li 2 O, FeO, SiO 2 , and V 2 O 5 (unit: mol%).
  • Lithium carbonate (Li 2 CO 3 ), triiron tetroxide (Fe 3 O 4 ), silicon dioxide (SiO 2 ), and vanadium oxide (V 2 O 5 ) were weighed, mixed and pulverized in a dry manner.
  • the raw material formulation was obtained.
  • the raw material formulation was heated as in Example 1, but could not be melted.
  • Examples 47 to 52 Production Examples of Positive Electrode for Li-ion Secondary Battery and Evaluation Battery
  • silicic acid-vanadic acid compound particles obtained by heating at 700 ° C. for 8 hours and cooling (air cooling) at a rate of ⁇ 200 ° C./hour, and 20 mass % Sucrose solution was mixed and pulverized so that the mass ratio of the pulverized product to the amount of carbon in the sucrose was 95: 5, heated in N 2 gas at 600 ° C. for 2 hours, and after cooling
  • the active material was obtained by grinding.
  • 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 argon gas, and opposed to a counter electrode made by pressure bonding a lithium foil to a nickel mesh with a porous polyethylene film separator, Both sides were fixed with a polyethylene plate.
  • the counter electrode was put in a polyethylene beaker, and a nonaqueous electrolyte solution in which lithium hexafluorophosphate was dissolved in a mixed solvent of ethylene carbonate and ethyl methyl carbonate (1: 1 volume ratio) at a concentration of 1 mol / L was injected. Fully impregnated. The electrode after impregnation with the electrolytic solution was taken out from the beaker, put in an aluminum laminate film bag, the lead wire part was taken out and sealed to form a half battery. The characteristics of this half-cell were measured as follows.
  • the discharge capacities at the third cycle were 150 mAh / g (Example 47), 152 mAh / g (Example 48), 148 mAh / g (Example 49), 145 mAh / g (Example 50), and 155 mAh / g (implemented), respectively.
  • the method for producing a silicic acid-vanadic acid compound of the present invention is useful because the composition and particle size of the silicic acid-vanadic acid compound can be easily controlled and produced.
  • the obtained silicic acid-vanadic acid compound is useful when applied to a positive electrode material for a secondary battery and further to 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.

Abstract

Provided is a silicic acid-vanadic acid compound manufacturing method which simplifies the control of composition and grain size. The manufacturing method is for a silicic acid-vanadic acid compound having a composition represented by formula (B). A silicic acid compound is manufactured by implementing the following steps in order: a step in which a melt is obtained by heating a starting material preparation formed by preparing a starting material comprising element A, element M, Si, V, and element X so that the molar ratio of element A, element M, Si, V, and element X satisfy the molar ratio represented in formula (B); a cooling step in which the melt is cooled and a solid is obtained; a pulverizing step in which a powder is obtained by pulverizing the solid; and a heating step in which the silicic acid compound is obtained by heating the powder. (B) AfMbSix(VcX1-c)1-xO4+d2 (In the formula, A represents at least one element selected from the group consisting of Li, Na, and K. M represents at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. X represents at least one element selected from the group consisting of P, B, and Al. f satisfies 0.8<f<2.4, b satisfies 0.7≤b≤1.3, c satisfies 0<c≤1, x satisfies 0.6<x<1, and d2 is a number dependent on X, f, b, c, x, and the valency (N) of M.)　

Description

ケイ酸－バナジン酸化合物、二次電池用正極、および二次電池の製造方法Silicic acid-vanadic acid compound, positive electrode for secondary battery, and method for producing secondary battery
　本発明は、ケイ酸－バナジン酸化合物、二次電池用正極、および二次電池の製造方法に関する。 The present invention relates to a silicic acid-vanadic acid compound, a positive electrode for a secondary battery, and a method for producing the secondary battery.
　近年、世界的な二酸化炭素排出規制や省エネルギーの観点から、プラグインハイブリッド自動車や電気自動車の開発ならびに普及が進められている。また、スマートシティやスマートコミュニティの構想の実現ために、電力貯蔵用の蓄電池の開発が望まれている。これらの実現には、使用される二次電池の安全性を維持しつつ、高容量化、高エネルギー化、大型化することが課題とされている。次世代のリチウムイオン二次電池の正極材料等として、資源面、安全面、コスト面、安定性等の点での優位性から、オルトケイ酸構造の化合物が注目されている。 In recent years, development and popularization of plug-in hybrid vehicles and electric vehicles have been promoted from the viewpoint of global carbon dioxide emission regulations and energy saving. In addition, in order to realize the concept of a smart city and a smart community, development of a storage battery for power storage is desired. In order to realize these, it is an issue to increase the capacity, increase the energy, and increase the size while maintaining the safety of the secondary battery used. As a positive electrode material for the next-generation lithium ion secondary battery, an orthosilicate compound has attracted attention because of its advantages in terms of resources, safety, cost, and stability.
　上記した二次電池用正極の候補材料として、単位格子中に２個のＬｉを含み、多電子反応による高容量化が可能なオリビン型ケイ酸化合物（Ｌｉ2ＦｅＳｉＯ4等）が提案されている（非特許文献１参照）。また、特許文献１には、単位式中にｋ個のＬｉを含み、かつ［ＳｉＯ4］、［ＳＯ4］、［ＰＯ4］、［ＧｅＯ4］、［ＶＯ4］、［ＡｌＯ4］、［ＢＯ4］等を含む広い一般式の組成を有するオルトケイ酸構造の化合物が電極材料として提案されている。 As a candidate material for the positive electrode for the secondary battery described above, an olivine-type silicic acid compound (Li 2 FeSiO 4 or the like) that includes two Li in the unit cell and can increase the capacity by a multi-electron reaction has been proposed. (Refer nonpatent literature 1). Patent Document 1 includes k Li in the unit formula, and [SiO 4 ], [SO 4 ], [PO 4 ], [GeO 4 ], [VO 4 ], [AlO 4 ], A compound having an orthosilicate structure having a composition of a wide general formula including [BO 4 ] and the like has been proposed as an electrode material.
日本特開２００１－２６６８８２号公報Japanese Unexamined Patent Publication No. 2001-266882
　非特許文献１では、オリビン型ケイ酸化合物としてＬｉ2ＦｅＳｉＯ4を固相反応により製造している。該反応は、製造工程が複雑で製造コストがかさみ、大量生産することが困難であり、組成や粒径の制御も容易でない。
　特許文献１には開示される電極材料のうち、Ｓｉを含む化合物として確認できるのは、Ｌｉ1.7Ｍｎ0.7Ｆｅ0.3Ｓｉ0.7Ｐ0.3Ｏ4である。該化合物は、Ｌｉ2ＭｎＳｉＯ4およびＬｉＦｅＰＯ4を混合・粉砕し、管に封入し、加熱して製造する固相反応で製造しているため、同様な難点がある。 In Non-Patent Document 1, Li 2 FeSiO 4 is produced by solid phase reaction as an olivine-type silicate compound. The reaction involves complicated manufacturing processes, high manufacturing costs, difficulty in mass production, and control of composition and particle size is not easy.
Among the electrode materials disclosed in Patent Literature 1, it is Li 1.7 Mn 0.7 Fe 0.3 Si 0.7 P 0.3 O 4 that can be confirmed as a compound containing Si. Since the compound is produced by a solid-phase reaction in which Li 2 MnSiO 4 and LiFePO 4 are mixed and pulverized, sealed in a tube, and heated, there are similar problems.
　本発明の目的は、単位質量当たりの高容量化が可能なケイ酸－バナジン酸化合物の組成や粒径の制御がしやすい製造方法の提供にある。該化合物は、二次電池用正極および二次電池の正極に用いる活物質として有用である。本発明は、特性や信頼性に優れる二次電池用正極および二次電池の製造方法をも提供する。 An object of the present invention is to provide a production method in which the composition and particle size of a silicic acid-vanadic 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. This invention also provides the manufacturing method of the positive electrode for secondary batteries which is excellent in a characteristic and reliability, and a secondary battery.
　本発明は、下記［１］～［１５］の発明である。
［１］式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物の製造方法であって、
　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d2　　　（Ｂ）
（式中、ＡはＬｉ、Ｎａ、およびＫからなる群より選ばれる少なくとも１種の元素である。ＭはＦｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、およびＺｎからなる群より選ばれる少なくとも１種の元素である。ＸはＰ、Ｂ、およびＡｌからなる群より選ばれる少なくとも１種の元素である。ｆは０．８＜ｆ＜２．４、ｂは０．７≦ｂ≦１．３、ｃは０＜ｃ≦１、ｘは０．６＜ｘ＜１であり、ｄ２はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。）
　元素Ａ、元素Ｍ、Ｓｉ、Ｖ、および元素Ｘを含む原料を、元素Ａ、元素Ｍ、Ｓｉ、Ｖ、および元素Ｘのモル比が式（Ｂ）で表されるモル比となるように調整してなる原料調合物を加熱して溶融物を得る工程、
　前記溶融物を冷却し固化物を得る冷却工程、
　前記固化物を粉砕し粉砕物を得る粉砕工程、および
　前記粉砕物を加熱してケイ酸化合物を得る加熱工程、
　をこの順に実施することを特徴とするケイ酸化合物の製造方法。
［２］下式（Ａ）で表される組成を有する溶融物を得る溶融工程、
　前記溶融物を冷却して固化物を得る冷却工程、
　前記固化物を粉砕して粉砕物を得る粉砕工程、および
　前記粉砕物を加熱して、下式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物を得る加熱工程、をこの順に実施する［１］のケイ酸－バナジン酸化合物の製造方法。
　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d1　　　（Ａ）
（式中、ＡはＬｉ、Ｎａ、およびＫからなる群より選ばれる少なくとも１種の元素である。ＭはＦｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、およびＺｎからなる群より選ばれる少なくとも１種の元素である。ＸはＰ、Ｂ、およびＡｌからなる群より選ばれる少なくとも１種の元素である。ｆは０．８＜ｆ＜２．４、ｂは０．７≦ｂ≦１．３、ｃは０＜ｃ≦１、ｘは０．６＜ｘ＜１であり、ｄ１はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎ’に依存する数であり、加熱工程後にｄ２となる数である。）
　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d2　　　（Ｂ）
（式中、Ａ、Ｍ、Ｘ、ｆ、ｂ、ｃ、およびｘは前記と同じ意味を示すが、前記とは独立した値であり、ｄ２はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。）
［３］前記式（Ａ）で表される組成を有する溶融物が、下式（１）で表される組成を有する溶融物であり、前記式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物が、下式（２）で表される組成を有するケイ酸－バナジン酸化合物である、［２］のケイ酸－バナジン酸化合物の製造方法。
　Ａ1+x+aＭbＳｉx（ＶcＸ1-c）1-xＯ4+d11　　　（１）
　Ａ1+x+aＭbＳｉx（ＶcＸ1-c）1-xＯ4+d12　　　（２）
（式中、Ａ、Ｍ、Ｘ、ｂ、ｃ、およびｘは前記と同じ意味を示し、ａは－１．０≦ａ≦０．６であり、ｄ１１はＸ、ａ、ｂ、ｃ、ｘ、およびＭの価数Ｎ’に依存する数であり、加熱工程後にｄ１２となる数であり、ｄ１２はＸ、ａ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。）
［４］前記溶融工程が、
　元素Ａが、Ａの炭酸塩、Ａの炭酸水素塩、Ａの水酸化物、Ａのケイ酸塩、Ａのバナジン酸塩、Ａの塩化物、Ａの硝酸塩、Ａの硫酸塩、およびＡの有機酸塩からなる群より選ばれる少なくとも１種（ただし、該少なくとも１種の一部または全部は、それぞれ水和塩を形成していてもよい。）として含まれ、
　元素Ｍが、Ｍの酸化物、Ｍのオキシ水酸化物、Ｍの水酸化物、Ｍのケイ酸塩、Ｍのバナジン酸塩、金属Ｍ、Ｍの塩化物、Ｍの硝酸塩、Ｍの硫酸塩、およびＭの有機酸塩からなる群より選ばれる少なくとも１種として含まれ、
　Ｓｉが、酸化ケイ素、Ａのケイ酸塩、Ｍのケイ酸塩、ケイ酸バナジウム、およびケイ素のアルコキシドからなる群より選ばれる少なくとも１種として含まれ、
　Ｖが、酸化バナジウム、Ａのバナジン酸塩、Ｍのバナジン酸塩、バナジン酸アンモニウム、ケイ酸バナジウム、塩化バナジウム、およびオキシ硫酸バナジウムからなる群より選ばれる少なくとも１種として含まれる、
　原料調合物を加熱して、前記溶融物を得る工程である、［１］～［３］のケイ酸－バナジン酸化合物の製造方法。
［５］前記原料調合物が、さらに元素Ｘを、酸化リン、リン酸、リン酸アンモニウム、リン酸水素アンモニウム、Ａのリン酸塩、Ａのリン酸水素塩、Ｍのリン酸塩、酸化ホウ素、ホウ酸、Ａのホウ酸塩、Ｍのホウ酸塩、酸化アルミニウム、およびオキシ水酸化アルミニウムからなる群より選ばれる少なくとも１種として含む、［４］のケイ酸－バナジン酸化合物の製造方法。
［６］元素ＡがＬｉである、［１］～［５］のケイ酸－バナジン酸化合物の製造方法。
［７］元素ＭがＦｅおよびＭｎからなる群より選ばれる少なくとも１種である、［１］～［６］のケイ酸－バナジン酸化合物の製造方法。
［８］前記冷却工程において、冷却速度を－１×１０3 ℃／秒～－１×１０10 ℃／秒とする、［１］～［７］のケイ酸－バナジン酸化合物の製造方法。
［９］前記粉砕工程において、前記固化物に、有機化合物および炭素粉末からなる群より選ばれる少なくとも１種の炭素源を含ませ、かつ該炭素源中の炭素換算量（質量）が、固化物の質量と、該炭素源中の炭素換算量（質量）との合計質量に対して０．１～２０質量％である、［１］～［８］のケイ酸－バナジン酸化合物の製造方法。
［１０］前記加熱工程を５００～１，０００℃に加熱することにより行う、［１］～［９］のケイ酸－バナジン酸化合物の製造方法。
［１１］前記式（１）で表される組成を有する溶融物が、下式（１Ａ）で表される組成を有する溶融物であり、前記式（２）で表される組成を有するケイ酸－バナジン酸化合物が、下式（２Ａ）で表される組成を有するオリビン型結晶粒子を含むケイ酸－バナジン酸化合物である、［２］～［１０］のケイ酸－バナジン酸化合物の製造方法。
　Ｌｉ1+x+a（ＦｅyＭｎ1-y）bＳｉxＶ1-xＯ4+d11　　　（１Ａ）
　Ｌｉ1+x+a（ＦｅyＭｎ1-y）bＳｉxＶ1-xＯ4+d12　　　（２Ａ）
（式中、ａ、ｂ、ｄ１１、ｄ１２、およびｘは前記と同じ意味を示し、ｙは０≦ｙ≦１である。ただし、式（１Ａ）と式（２Ａ）において、ａ、ｂ、ｘ、およびｙは独立した値を示す。） The present invention is the following [1] to [15].
[1] A method for producing a silicic acid-vanadic acid compound having a composition represented by the formula (B),
A f M b Si x (V c X 1-c ) 1-x O 4 + d2 (B)
(In the formula, A is at least one element selected from the group consisting of Li, Na, and K. M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 <f <2.4, b is 0.7 ≦ b ≦ 1.3, c is 0 <c ≦ 1, x is 0.6 <x <1, and d2 is a number depending on the valence N of X, f, b, c, x, and M.)
The raw material containing element A, element M, Si, V, and element X is adjusted so that the molar ratio of element A, element M, Si, V, and element X is the molar ratio represented by formula (B) Heating the raw material formulation to obtain a melt,
A cooling step of cooling the melt to obtain a solidified product,
A pulverization step of pulverizing the solidified product to obtain a pulverized product, and a heating step of heating the pulverized product to obtain a silicate compound.
Are carried out in this order. A method for producing a silicic acid compound.
[2] A melting step for obtaining a melt having a composition represented by the following formula (A):
A cooling step of cooling the melt to obtain a solidified product,
A pulverization step of pulverizing the solidified product to obtain a pulverized product, and a heating step of heating the pulverized product to obtain a silicic acid-vanadic acid compound having a composition represented by the following formula (B) are performed in this order: [1] A process for producing a silicic acid-vanadic acid compound.
A f M b Si x (V c X 1-c ) 1-x O 4 + d1 (A)
(In the formula, A is at least one element selected from the group consisting of Li, Na, and K. M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 <f <2.4, b is 0.7 ≦ b ≦ 1.3, c is 0 <c ≦ 1, x is 0.6 <x <1, d1 is a number depending on the valence N ′ of X, f, b, c, x, and M, and d2 after the heating step Is a number.)
A f M b Si x (V c X 1-c ) 1-x O 4 + d2 (B)
(In the formula, A, M, X, f, b, c, and x have the same meanings as described above, but are independent values, and d2 is X, f, b, c, x, and M. The number depends on the valence N of
[3] The melt having the composition represented by the formula (A) is a melt having the composition represented by the following formula (1), and the silicic acid having the composition represented by the formula (B) The method for producing a silicic acid-vanadic acid compound according to [2], wherein the vanadic acid compound is a silicic acid-vanadic acid compound having a composition represented by the following formula (2):
A 1 + x + a M b Si x (V c X 1-c ) 1-x O 4 + d11 (1)
A 1 + x + a M b Si x (V c X 1-c ) 1-x O 4 + d12 (2)
(Wherein A, M, X, b, c, and x have the same meaning as described above, a is −1.0 ≦ a ≦ 0.6, and d11 is X, a, b, c, x , And a number that depends on the valence N ′ of M, and is a number that becomes d12 after the heating step, and d12 is a number that depends on the valence N of X, a, b, c, x, and M. )
[4] The melting step includes
Element A is A carbonate, A bicarbonate, A hydroxide, A silicate, A vanadate, A chloride, A nitrate, A sulfate, and A And at least one selected from the group consisting of organic acid salts (however, at least one of the at least one kind may each form a hydrated salt),
Element M is M oxide, M oxyhydroxide, M hydroxide, M silicate, M vanadate, metal M, M chloride, M nitrate, M sulfate And at least one selected from the group consisting of organic acid salts of M,
Si is included as at least one selected from the group consisting of silicon oxide, A silicate, M silicate, vanadium silicate, and silicon alkoxide,
V is included as at least one selected from the group consisting of vanadium oxide, A vanadate, M vanadate, ammonium vanadate, vanadium silicate, vanadium chloride, and vanadium oxysulfate.
The method for producing a silicic acid-vanadic acid compound of [1] to [3], which is a step of heating the raw material preparation to obtain the melt.
[5] The raw material preparation further contains element X as phosphorus oxide, phosphoric acid, ammonium phosphate, ammonium hydrogen phosphate, A phosphate, A hydrogen phosphate, M phosphate, boron oxide. [4] The process for producing a silicic acid-vanadic acid compound according to [4], comprising at least one selected from the group consisting of boric acid, borate A, borate M, aluminum oxide, and aluminum oxyhydroxide.
[6] The method for producing a silicic acid-vanadic acid compound of [1] to [5], wherein the element A is Li.
[7] The method for producing a silicic acid-vanadic acid compound of [1] to [6], wherein the element M is at least one selected from the group consisting of Fe and Mn.
[8] The method for producing a silicic acid-vanadate compound according to [1] to [7], wherein, in the cooling step, a cooling rate is set to -1 × 10 3 ° C / second to -1 × 10 10 ° C / second.
[9] In the pulverization step, the solidified product contains at least one carbon source selected from the group consisting of an organic compound and carbon powder, and a carbon equivalent amount (mass) in the carbon source is a solidified product. And the silicic acid-vanadic acid compound production method of [1] to [8], which is 0.1 to 20% by mass relative to the total mass of the mass and the carbon equivalent amount (mass) in the carbon source.
[10] The method for producing a silicic acid-vanadic acid compound according to [1] to [9], wherein the heating step is performed by heating to 500 to 1,000 ° C.
[11] The melt having the composition represented by the formula (1) is a melt having the composition represented by the following formula (1A), and the silicic acid having the composition represented by the formula (2) The method for producing a silicic acid-vanadic acid compound according to [2] to [10], wherein the vanadic acid compound is a silicic acid-vanadic acid compound containing olivine type crystal particles having a composition represented by the following formula (2A): .
Li 1 + x + a (Fe y Mn 1-y ) b Si x V 1-x O 4 + d11 (1A)
Li 1 + x + a (Fe y Mn 1-y ) b Si x V 1-x O 4 + d12 (2A)
(Wherein, a, b, d11, d12, and x have the same meaning as described above, and y is 0 ≦ y ≦ 1, where a, b, x in Formula (1A) and Formula (2A)). , And y are independent values.)
［１２］［１］～［１１］の製造方法によってケイ酸－バナジン酸化合物を得て、次に、該ケイ酸－バナジン酸化合物を二次電池用正極材料として用いて二次電池用正極を製造することを特徴とする二次電池用正極の製造方法。
［１３］［１２］の製造方法で二次電池用正極を得て、次に、該二次電池用正極を用いて二次電池を製造することを特徴とする二次電池の製造方法。
［１４］下式（Ｂ）で表される組成を有することを特徴とするケイ酸－バナジン酸化合物。
　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d2　　　（Ｂ）
（式中、ＡはＬｉ、Ｎａ、およびＫからなる群より選ばれる少なくとも１種の元素である。ＭはＦｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、およびＺｎからなる群より選ばれる少なくとも１種の元素である。ＸはＰ、Ｂ、およびＡｌからなる群より選ばれる少なくとも１種の元素である。ｆは０．８＜ｆ＜２．４、ｂは０．７≦ｂ≦１．３、ｃは０＜ｃ≦１、ｘは０．６＜ｘ＜１であり、ｄ２はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。）
［１５］下式（２Ａ）で表される組成を有することを特徴とするケイ酸－バナジン酸化合物。
　Ｌｉ1+x+a（ＦｅyＭｎ1-y）bＳｉxＶ1-xＯ4+d12　　　（２Ａ）
（式中、ａは－１．０≦ａ≦０．４、ｂは０．７≦ｂ≦１．３、ｘは０．６＜ｘ＜１、ｙは０≦ｙ≦１であり、ｄ１２はａ、ｂ、ｘ、およびＦｅyＭｎ1-yの平均価数Ｎに依存する数である。） [12] A silicic acid-vanadic acid compound is obtained by the production method of [1] to [11], and then a positive electrode for a secondary battery is produced using the silicic acid-vanadic acid compound as a positive electrode material for a secondary battery. A method for producing a positive electrode for a secondary battery, characterized by comprising:
[13] A method for producing a secondary battery, comprising obtaining a positive electrode for a secondary battery by the production method of [12], and then producing a secondary battery using the positive electrode for a secondary battery.
[14] A silicic acid-vanadic acid compound having a composition represented by the following formula (B):
A f M b Si x (V c X 1-c ) 1-x O 4 + d2 (B)
(In the formula, A is at least one element selected from the group consisting of Li, Na, and K. M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 <f <2.4, b is 0.7 ≦ b ≦ 1.3, c is 0 <c ≦ 1, x is 0.6 <x <1, and d2 is a number depending on the valence N of X, f, b, c, x, and M.)
[15] A silicic acid-vanadic acid compound having a composition represented by the following formula (2A):
Li 1 + x + a (Fe y Mn 1-y ) b Si x V 1-x O 4 + d12 (2A)
(Where a is −1.0 ≦ a ≦ 0.4, b is 0.7 ≦ b ≦ 1.3, x is 0.6 <x <1, y is 0 ≦ y ≦ 1, d12 Is a number that depends on the average valence N of a, b, x, and Fe y Mn 1-y .)
　本発明の製造方法は、ケイ酸－バナジン酸化合物の組成や粒径の制御がしやすい方法である。よって、電極材料として有用な種々の組成を有するケイ酸－バナジン酸化合物を効率的に製造できる。また、本発明のケイ酸－バナジン酸化合物を用いることにより、電池特性や信頼性に優れる二次電池用正極および二次電池が製造できる。さらに、本発明によれば、新規なケイ酸－バナジン酸化合物が提供される。 The production method of the present invention is a method in which the composition and particle size of the silicic acid-vanadic acid compound can be easily controlled. Therefore, silicic acid-vanadic acid compounds having various compositions useful as electrode materials can be efficiently produced. Further, by using the silicic acid-vanadic acid compound of the present invention, a positive electrode for a secondary battery and a secondary battery having excellent battery characteristics and reliability can be produced. Furthermore, according to the present invention, a novel silicic acid-vanadic acid compound is provided.
実施例１、２、３、および４で製造したケイ酸－バナジン酸化合物のＸ線回折パターンを示す図である。FIG. 3 is an X-ray diffraction pattern of silicic acid-vanadic acid compounds produced in Examples 1, 2, 3, and 4. 実施例５、６、７、および８で製造したケイ酸－バナジン酸化合物のＸ線回折パターンを示す図である。FIG. 6 is a diagram showing an X-ray diffraction pattern of silicic acid-vanadic acid compounds produced in Examples 5, 6, 7, and 8. 実施例１６、１７、１８、および１９で製造したケイ酸－バナジン酸化合物のＸ線回折パターンを示す図である。FIG. 4 is a diagram showing an X-ray diffraction pattern of silicic acid-vanadic acid compounds produced in Examples 16, 17, 18, and 19.
＜ケイ酸－バナジン酸化合物の製造方法＞
　本発明のケイ酸－バナジン酸化合物の製造方法は、以下の溶融工程（Ｉ）、冷却工程（ＩＩ）、粉砕工程（ＩＩＩ）、および加熱工程（ＩＶ）の各工程を、この順に行う。（Ｉ）～（ＩＶ）の工程前、工程間、および工程後には、各工程に影響を及ぼさない限り、他の工程を行ってもよい。 <Method for producing silicic acid-vanadic acid compound>
In the method for producing a silicic acid-vanadic 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.
　溶融工程（Ｉ）：式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物の製造方法であって、
　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d2　　　（Ｂ）
（式中、ＡはＬｉ、Ｎａ、およびＫからなる群より選ばれる少なくとも１種の元素である。ＭはＦｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、およびＺｎからなる群より選ばれる少なくとも１種の元素である。ＸはＰ、Ｂ、およびＡｌからなる群より選ばれる少なくとも１種の元素である。ｆは０．８＜ｆ＜２．４、ｂは０．７≦ｂ≦１．３、ｃは０＜ｃ≦１、ｘは０．６＜ｘ＜１であり、ｄ２はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。）
　元素Ａ、元素Ｍ、Ｓｉ、Ｖ、および元素Ｘを含む原料を、元素Ａ、元素Ｍ、Ｓｉ、Ｖ、および元素Ｘのモル比が式（Ｂ）で表されるモル比となるように調整してなる原料調合物を加熱して溶融物を得る工程、
　冷却工程（ＩＩ）：前記溶融物を冷却して固化物を得る工程、
　粉砕工程（ＩＩＩ）：前記固化物を粉砕して粉砕物を得る工程、
　加熱工程（ＩＶ）：前記粉砕物を加熱して、前記式（Ｂ）で表わされる組成を有するケイ酸化合物を得る加熱工程。
　以下、各工程について具体的に説明する。 Melting step (I): a method for producing a silicic acid-vanadic acid compound having a composition represented by formula (B),
A f M b Si x (V c X 1-c ) 1-x O 4 + d2 (B)
(In the formula, A is at least one element selected from the group consisting of Li, Na, and K. M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 <f <2.4, b is 0.7 ≦ b ≦ 1.3, c is 0 <c ≦ 1, x is 0.6 <x <1, and d2 is a number depending on the valence N of X, f, b, c, x, and M.)
The raw material containing element A, element M, Si, V, and element X is adjusted so that the molar ratio of element A, element M, Si, V, and element X is the molar ratio represented by formula (B) Heating the raw material formulation to obtain a melt,
Cooling step (II): a step of cooling the melt to obtain a solidified product,
Pulverization step (III): a step of pulverizing the solidified product to obtain a pulverized product;
Heating step (IV): A heating step of heating the pulverized product to obtain a silicate compound having a composition represented by the formula (B).
Hereinafter, each step will be specifically described.
［溶融工程（Ｉ）］
　溶融工程は、元素Ａ、元素Ｍ、Ｓｉ、Ｖ、および元素Ｘを含む原料を、元素Ａ、元素Ｍ、Ｓｉ、Ｖ、および元素Ｘのモル比が式（Ｂ）で表されるモル比となるように調整してなる原料調合物を加熱して溶融物を得る工程でもある。溶融工程は、式（Ａ）で表される組成を有する溶融物を得る工程であることが好ましい。
　　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d1　　　（Ａ）
（式中、ＡはＬｉ、Ｎａ、およびＫからなる群より選ばれる少なくとも１種の元素である。ＭはＦｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、およびＺｎからなる群より選ばれる少なくとも１種の元素である。ＸはＰ、Ｂ、およびＡｌからなる群より選ばれる少なくとも１種の元素である。ｆは０．８＜ｆ＜２．４、ｂは０．７≦ｂ≦１．３、ｃは０＜ｃ≦１、ｘは０．６＜ｘ＜１であり、ｄ１はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎ’に依存する数であり、加熱工程後にｄ２となる数である。） [Melting step (I)]
In the melting step, a raw material containing element A, element M, Si, V, and element X is converted into a molar ratio in which the molar ratio of element A, element M, Si, V, and element X is represented by formula (B) It is also the process of heating the raw material formulation prepared so that it may become, and obtaining a melt. The melting step is preferably a step of obtaining a melt having a composition represented by the formula (A).
A f M b Si x (V c X 1-c ) 1-x O 4 + d1 (A)
(In the formula, A is at least one element selected from the group consisting of Li, Na, and K. M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 <f <2.4, b is 0.7 ≦ b ≦ 1.3, c is 0 <c ≦ 1, x is 0.6 <x <1, d1 is a number depending on the valence N ′ of X, f, b, c, x, and M, and d2 after the heating step Is a number.)
　式（Ａ）において、元素ＡはＬｉ、Ｎａ、およびＫからなる群より選ばれる少なくとも１種ある。元素Ａは二次電池用正極材料として適しているため、Ｌｉを必須とするのが好ましく、Ｌｉのみであることが特に好ましい。Ｌｉを含むケイ酸－バナジン酸化合物は、二次電池の単位体積（質量）当たりの容量が高くできる。 In the formula (A), the element A is at least one 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-vanadic acid compound containing Li can have a high capacity per unit volume (mass) of the secondary battery.
　式（Ａ）の元素Ｍは、Ｆｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、およびＺｎからなる群より選ばれる少なくとも１種の元素である。元素Ｍは１種のみ、または、２種からなるのが好ましい。特に本発明の製造方法で製造するケイ酸－バナジン酸化合物を二次電池用正極材料に使用する場合には、元素ＭはＦｅのみ、Ｍｎのみ、またはＦｅおよびＭｎからなるのが、コストの点で好ましい。元素Ｍの価数Ｎ’は、本発明の製造方法の各工程で変化しうる数値であり、＋２～＋４の範囲が好ましい。該価数Ｎ’は、元素ＭがＦｅの場合は＋２、＋８／３、または＋３、Ｍｎの場合は＋２、＋３、または＋４、Ｃｏの場合は＋２、＋８／３、または＋３、Ｎｉの場合は＋２または＋４が好ましい。該価数Ｎ’が＋２であると、溶融工程（Ｉ）が単純化するので特に好ましい。 The element M in the formula (A) is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. The element M is preferably composed of only one kind or two kinds. In particular, when the silicic acid-vanadic acid compound produced by the production method of the present invention is used for a positive electrode material for a secondary battery, the element M is composed of only Fe, Mn, or Fe and Mn. Is preferable. The valence N ′ of the element M is a numerical value that can change in each step of the production method of the present invention, and is preferably 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 M is M, +2, +8/3, or +3 when Co is Ni, Is preferably +2 or +4. It is particularly preferred that the valence N ′ is +2, since the melting step (I) is simplified.
　式（Ａ）の元素Ｘは、Ｐ、Ｂ、およびＡｌからなる群より選ばれる少なくとも１種の元素である。溶融物が元素Ｘを含むと、得られる式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物の構造が安定化し、二次電池用正極材料に使用する場合には、充放電におけるサイクル特性を高めることができると考えられる。
　式（Ａ）中のｃは０＜ｃ≦１であり、０．５≦ｃ≦１が特に好ましい。理論容量を高める点からは、ｃ＝１すなわち溶融物が元素Ｘを含まないことが好ましい。 The element X in the formula (A) is at least one element selected from the group consisting of P, B, and Al. When the melt contains the element X, the structure of the silicic acid-vanadic acid compound having the composition represented by the formula (B) obtained is stabilized, and when used as a positive electrode material for a secondary battery, It is thought that cycle characteristics can be improved.
C in the formula (A) is 0 <c ≦ 1, and 0.5 ≦ c ≦ 1 is particularly preferable. From the viewpoint of increasing the theoretical capacity, it is preferable that c = 1, that is, the melt does not contain the element X.
　なお、溶融物は、元素Ａ、元素Ｍ、ケイ素（Ｓｉ）、バナジウム（Ｖ）、元素Ｘ、および酸素（Ｏ）以外の元素を含んでいてもよい。該元素としては、Ｌａ、Ｃａ、Ｍｇ、およびＺｎからなる群より選ばれる少なくとも１種の元素（以下、元素Ｚという）が好ましい。元素Ｚを含有させることで、溶融物を溶融しやすくすることができる。元素Ｚの含有量（複数の元素の場合には合計量）は、溶融物になったときの各元素の酸化物換算量（単位：モル％）が０．１～３％が好ましい。また、溶融物は、Ｓ、Ｇｅ、Ｗ、Ｍｏ、Ａｓ、およびＳｂからなる群より選ばれる少なくとも１種の元素を含んでいてもよい。 The melt may contain an element other than element A, element M, silicon (Si), vanadium (V), element X, and oxygen (O). The element is preferably at least one element selected from the group consisting of La, Ca, Mg, and Zn (hereinafter referred to as element Z). By containing the element Z, the melt can be easily melted. The content of element Z (the total amount in the case of a plurality of elements) is preferably 0.1 to 3% in terms of oxide equivalent (unit: mol%) of each element when it becomes a melt. The melt may contain at least one element selected from the group consisting of S, Ge, W, Mo, As, and Sb.
　式（Ａ）において、ｆは０．８＜ｆ＜２．４、ｂは０．７≦ｂ≦１．３の範囲である。原料調合物におけるｆおよびｂを該範囲にすることによって、目的とする組成を有するケイ酸－バナジン酸化合物を製造できる。また、原料調合物を良好に溶融でき、均一な溶融物が得られる。ｆは１．７≦ｆ≦２．２であるのが好ましい。 In the formula (A), f is in the range of 0.8 <f <2.4, and b is in the range of 0.7 ≦ b ≦ 1.3. By setting f and b in the raw material formulation within this range, a silicic acid-vanadic acid compound having the desired composition can be produced. Moreover, a raw material formulation can be melt | dissolved favorably and a uniform melt is obtained. f is preferably 1.7 ≦ f ≦ 2.2.
　式（Ａ）において、下式（１）で表される組成を有する溶融物が好ましく、特に下式（１Ａ）で表される組成を有する溶融物が好ましい。
　Ａ1+x+aＭbＳｉx（ＶcＸ1-c）1-xＯ4+d11　　　（１）
　Ｌｉ1+x+a（ＦｅyＭｎ1-y）bＳｉxＶ1-xＯ4+d11　　　（１Ａ） In the formula (A), a melt having a composition represented by the following formula (1) is preferable, and a melt having a composition represented by the following formula (1A) is particularly preferable.
A 1 + x + a M b Si x (V c X 1-c ) 1-x O 4 + d11 (1)
Li 1 + x + a (Fe y Mn 1-y ) b Si x V 1-x O 4 + d11 (1A)
　式（Ａ）、式（１）、および式（１Ａ）中のｂ、およびｃは前記と同じ意味を示す。式（１）および式（１Ａ）中のａは－１．０≦ａ≦０．６である。式（１）および式（１Ａ）で表される組成を有する溶融物におけるａおよびｂを該範囲にすることによって、目的のケイ酸－バナジン酸化合物を製造できる。
　式（Ａ）、式（１）、および式（１Ａ）中のｘは０．６＜ｘ＜１である。該範囲であると、二次電池用正極材料として用いた場合に多電子型の反応（単位モル数当たり１モルを超えるＡを引き抜く反応）を起こすケイ酸－バナジン酸化合物を製造することができ、二次電池の理論容量を高めることができる。０．７＜ｘ＜１であることが好ましく、０．８＜ｘ＜１であることが好ましい。 In formula (A), formula (1), and formula (1A), b and c have the same meaning as described above. In the formula (1) and the formula (1A), a satisfies −1.0 ≦ a ≦ 0.6. By setting a and b in the melt having the compositions represented by the formulas (1) and (1A) within this range, the target silicic acid-vanadic acid compound can be produced.
X in Formula (A), Formula (1), and Formula (1A) is 0.6 <x <1. Within this range, it is possible to produce a silicic acid-vanadic acid compound that causes a multi-electron type reaction (a reaction that pulls out more than 1 mol per unit mole) when used as a positive electrode material for a secondary battery. The theoretical capacity of the secondary battery can be increased. 0.7 <x <1 is preferable, and 0.8 <x <1 is preferable.
　ａおよびｂは－０．１≦ａ≦０．４、０．８≦ｂ≦１．３がより好ましく、－０．１≦ａ≦０．３、０．９≦ｂ≦１．３がさらに好ましい。このような場合に多電子型の反応を示すケイ酸－バナジン酸化合物が得られやすい。また、ｘは０．８＜ｘ＜１が特に好ましく、このような場合には、Ｖ原子がＳｉ原子を置換した固溶体となりやすく、より理論容量を高めることができる。 a and b are more preferably −0.1 ≦ a ≦ 0.4 and 0.8 ≦ b ≦ 1.3, more preferably −0.1 ≦ a ≦ 0.3 and 0.9 ≦ b ≦ 1.3. preferable. In such a case, it is easy to obtain a silicic acid-vanadic acid compound exhibiting a multi-electron type reaction. In addition, x is particularly preferably 0.8 <x <1, and in such a case, V atoms tend to be a solid solution in which Si atoms are substituted, and the theoretical capacity can be further increased.
　式（Ａ）中のｄ１の値は、Ｘ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎ’に依存する数である。式（１）および式（１Ａ）中のｄ１１の値は、Ｘ、ａ、ｂ、ｃ、ｘ、およびＭの価数Ｎ’に依存する数である。式中の元素の価数は、後工程の加熱工程（ＩＶ）で変化しうるため、加熱工程（ＩＶ）後にｄ２となる値にｄ１を調節し、または加熱工程（ＩＶ）でｄ１２となる値にｄ１１を調節する。例えば、加熱工程（ＩＶ）で成分の酸化還元、揮発等によりｄ１の値が増減する場合には、該増減を考慮に入れた値とするのが好ましい。ｄ１は、－０．２５≦ｄ１≦０．２５が好ましく、－０．１２≦ｄ１≦０．１２が特に好ましい。ｄ１１は、－０．２５≦ｄ１１≦０．２５が好ましく、－０．１２≦ｄ１１≦０．１２が特に好ましい。本発明の製造方法において、ｄ１はｄ２に対して０．９～１．２倍の値にしておくのが好ましい。 The value of d1 in the formula (A) is a number that depends on the valence N ′ of X, f, b, c, x, and M. The value of d11 in the formulas (1) and (1A) is a number that depends on the valence N ′ of X, a, b, c, x, and M. Since the valence of the element in the formula can change in the subsequent heating step (IV), d1 is adjusted to a value that becomes d2 after the heating step (IV), or a value that becomes d12 in the heating step (IV). To adjust d11. For example, when the value of d1 increases or decreases due to oxidation / reduction or volatilization of the component in the heating step (IV), it is preferable to set the value taking into account the increase / decrease. d1 is preferably −0.25 ≦ d1 ≦ 0.25, and particularly preferably −0.12 ≦ d1 ≦ 0.12. d11 is preferably −0.25 ≦ d11 ≦ 0.25, and particularly preferably −0.12 ≦ d11 ≦ 0.12. In the production method of the present invention, d1 is preferably 0.9 to 1.2 times as large as d2.
　式（１Ａ）中のｙの値は、０≦ｙ≦１が好ましく、０＜ｙ＜１が特に好ましい。ＦｅとＭｎのモル比は２０～８０：８０～２０が好ましく、２５～７５：７５～２５が特に好ましい。 The value of y in the formula (1A) is preferably 0 ≦ y ≦ 1, and particularly preferably 0 <y <1. The molar ratio of Fe to Mn is preferably 20 to 80:80 to 20, and particularly preferably 25 to 75:75 to 25.
　溶融工程（Ｉ）においては、まず各元素（元素Ａ、元素Ｍ、Ｓｉ、Ｖ、および元素Ｘ）を含む原料を、式（１）で表される組成を有する溶融物となるように調合して原料調合物を得て、次に、該原料調合物を加熱して溶融物を得ることが好ましい。該原料調合物は混合・粉砕することが好ましい。粉砕は、ミキサー、ボールミル、ジェットミル、または遊星ミル等を用いて、乾式または湿式で行うことが好ましく、溶媒の除去工程が不要なことから、乾式が好ましい。混合物中の各原料の粒度は、混合操作、混合物の溶融容器への充填操作、混合物の溶融性等に悪影響を及ぼさない範囲であれば、限定されない。 In the melting step (I), first, raw materials containing each element (element A, element M, Si, V, and element X) are prepared so as to be a melt having a composition represented by formula (1). It is preferable to obtain a raw material formulation and then heat the raw material formulation to obtain a melt. The raw material preparation is preferably mixed and pulverized. The pulverization is preferably performed by a dry method or a wet method using a mixer, a ball mill, a jet mill, a planetary mill or the like, and a dry method is preferable because a solvent removal step is unnecessary. The particle size of each raw material in the mixture is not limited as long as it does not adversely affect the mixing operation, the filling operation of the mixture into the melting container, the meltability of the mixture, and the like.
（原料調合物）
　原料調合物における元素Ａを含む化合物としては、Ａの炭酸塩（Ａ2ＣＯ3等）、Ａの炭酸水素塩（ＡＨＣＯ3等）、Ａの水酸化物（ＡＯＨ等）、Ａのケイ酸塩（Ａ2Ｏ・２ＳｉＯ2、Ａ2Ｏ・ＳｉＯ2、２Ａ2Ｏ・ＳｉＯ2等）、Ａのバナジン酸塩（ＡＶＯ3、Ａ3ＶＯ4、Ａ4ＶＯ7等）、Ａの塩化物（ＡＣｌ）、Ａの硝酸塩（ＡＮＯ3）、Ａの硫酸塩（Ａ2ＳＯ4）、およびＡの酢酸塩（ＣＨ3ＣＯＯＡ等）やシュウ酸塩（（ＣＯＯＡ）2等）のような有機酸塩からなる群より選ばれる少なくとも１種（ただし、該１種以上の一部または全部は、それぞれ水和塩を形成していてもよい。）が好ましい。なかでも、安価でかつ取扱いが容易な点で、Ａの炭酸塩または炭酸水素塩が特に好ましい。 (Raw material formulation)
The compound containing element A in the raw material formulation includes A carbonate (A 2 CO 3 etc.), A bicarbonate (AHCO 3 etc.), A hydroxide (AOH etc.), A silicate (a 2 O · 2SiO 2, a 2 O · SiO 2, 2A 2 O · SiO 2 , etc.), vanadate a (AVO 3, a 3 VO 4, a 4 VO 7 , etc.), chlorides of a ( ACl), A nitrates (ANO 3 ), A sulfates (A 2 SO 4 ), and organic acid salts such as A acetates (CH 3 COOA, etc.) and oxalates ((COOA) 2, etc.) Preferably, at least one selected from the group consisting of (provided that a part or all of the one or more may each form a hydrated salt). Of these, carbonates or bicarbonates of A are particularly preferred because they are inexpensive and easy to handle.
　原料調合物における元素Ｍを含む化合物としては、Ｍの酸化物（ＦｅＯ、Ｆｅ3Ｏ4、Ｆｅ2Ｏ3、ＭｎＯ、Ｍｎ2Ｏ3、ＭｎＯ2、ＣｏＯ、Ｃｏ3Ｏ4、Ｃｏ2Ｏ3、ＮｉＯ、ＣｕＯ、Ｃｕ2Ｏ、ＺｎＯ等）、Ｍのオキシ水酸化物（ＭＯ（ＯＨ）等）、Ｍの水酸化物（Ｍ（ＯＨ）２、Ｍ（ＯＨ）３等）、Ｍのケイ酸塩（ＭＯ・ＳｉＯ2、２ＭＯ・ＳｉＯ2等）、Ｍのバナジン酸塩（Ｍ2Ｖ2Ｏ7等）、金属Ｍ、Ｍの塩化物（ＭＣｌ2、ＭＣｌ3等）、Ｍの硝酸塩（Ｍ（ＮＯ3）2、Ｍ（ＮＯ3）3等）、Ｍの硫酸塩（ＭＳＯ4、Ｍ2（ＳＯ4）3等）、およびＭの酢酸塩（Ｍ（ＣＨ3ＣＯＯ）2等）やシュウ酸塩（Ｍ（ＣＯＯ）2等）のような有機酸塩からなる群より選ばれる少なくとも１種が好ましい。元素Ｍを含む化合物としては、入手のしやすさやコストの面から、Ｆｅ3Ｏ4、Ｆｅ2Ｏ3、ＭｎＯ、Ｍｎ2Ｏ3、ＭｎＯ2、Ｃｏ3Ｏ4、ＮｉＯ、ＣｕＯ、およびＺｎＯからなる群より選ばれる少なくとも１種がより好ましい。特に元素Ｍが、Ｆｅである場合の該化合物としては、Ｆｅ3Ｏ4および／またはＦｅ2Ｏ3が好ましく、元素ＭがＭｎである場合の該化合物としては、ＭｎＯ2および／またはＭｎＯが好ましい。元素Ｍを含む化合物は、１種のみを用いても、２種以上を用いてもよい。 Examples of the compound containing element M in the raw material preparation include oxides of M (FeO, Fe 3 O 4 , Fe 2 O 3 , MnO, Mn 2 O 3 , MnO 2 , CoO, Co 3 O 4 , Co 2 O 3 NiO, CuO, Cu 2 O, ZnO, etc.), M oxyhydroxide (MO (OH) etc.), M hydroxide (M (OH) 2 , M (OH) 3 etc.), M Acid salt (MO · SiO 2 , 2MO · SiO 2 etc.), M vanadate (M 2 V 2 O 7 etc.), metal M, M chloride (MCl 2 , MCl 3 etc.), M nitrate ( M (NO 3 ) 2 , M (NO 3 ) 3 etc.), M sulfate (MSO 4 , M 2 (SO 4 ) 3 etc.), and M acetate (M (CH 3 COO) 2 etc.) At least one selected from the group consisting of organic acid salts such as oxalate (M (COO) 2 etc.) is preferred. As the compound containing the element M, Fe 3 O 4 , Fe 2 O 3 , MnO, Mn 2 O 3 , MnO 2 , Co 3 O 4 , NiO, CuO, and ZnO are available from the viewpoint of availability and cost. More preferred is at least one selected from the group consisting of In particular, the compound when the element M is Fe is preferably Fe 3 O 4 and / or Fe 2 O 3 , and the compound when the element M is Mn is preferably MnO 2 and / or MnO. . Only 1 type may be used for the compound containing the element M, or 2 or more types may be used for it.
　原料調合物におけるＳｉを含む化合物としては、酸化ケイ素（ＳｉＯ2等）、Ａのケイ酸塩、Ｍのケイ酸塩、ケイ酸バナジウム（（０．１≦ｎ≦１０）等）、およびケイ素のアルコキシド（Ｓｉ（ＯＣＨ3）4、Ｓｉ（ＯＣ2Ｈ5）4等）からなる群より選ばれる少なくとも１種が好ましい。Ｓｉを含む化合物としては、安価な点で、酸化ケイ素が特に好ましい。Ｓｉを含む化合物は結晶質であっても、非晶質であってもよい。 The compound containing Si in the raw material formulation includes silicon oxide (SiO 2 etc.), A silicate, M silicate, vanadium silicate ((0.1 ≦ n ≦ 10) etc.), and silicon At least one selected from the group consisting of alkoxides (Si (OCH 3 ) 4 , Si (OC 2 H 5 ) 4, etc.) is preferred. As the compound containing Si, silicon oxide is particularly preferable from the viewpoint of inexpensiveness. The compound containing Si may be crystalline or amorphous.
　原料調合物におけるＶを含む化合物としては、酸化バナジウム（ＶＯ、Ｖ2Ｏ3、ＶＯ2、Ｖ2Ｏ5等）、Ａのバナジン酸塩、Ｍのバナジン酸塩、バナジン酸アンモニウム（ＮＨ4ＶＯ3）、ケイ酸バナジウム、塩化バナジウム（ＶＣｌ3等）、およびオキシ硫酸バナジウム（ＶＯＳＯ4等）からなる群より選ばれる少なくとも１種が好ましい。Ｖを含む化合物としては、安価でかつ取扱いが容易な点で、酸化バナジウムが特に好ましい。 Examples of the compound containing V in the raw material preparation include vanadium oxide (VO, V 2 O 3 , VO 2 , V 2 O 5, etc.), A vanadate, M vanadate, ammonium vanadate (NH 4 VO). 3 ) At least one selected from the group consisting of vanadium silicate, vanadium chloride (such as VCl 3 ), and vanadium oxysulfate (such as VOSO 4 ) is preferable. As the compound containing V, vanadium oxide is particularly preferable because it is inexpensive and easy to handle.
　原料調合物における元素Ｘは任意の成分であり、必要に応じて含有させるものである。原料調合物が元素Ｘを含有する場合、元素Ｘを含む化合物のうち、元素ＸがＰを含む場合に該化合物としては、酸化リン（Ｐ2Ｏ5等）、リン酸（Ｈ3ＰＯ4等）、リン酸アンモニウム（（ＮＨ4）3ＰＯ4等）、リン酸水素アンモニウム（（ＮＨ4）2ＨＰＯ4、ＮＨ4Ｈ2ＰＯ4等）、Ａのリン酸塩（Ａ3ＰＯ4等）、Ａのリン酸水素塩（Ａ2ＨＰＯ4等）、およびＭのリン酸塩（Ｍ3（ＰＯ4）2等）からなる群より選ばれる少なくとも１種が好ましい。元素ＸがＢを含む場合に該化合物としては、酸化ホウ素（Ｂ2Ｏ3等）、ホウ酸（Ｈ3ＢＯ3等）、Ａのホウ酸塩（Ａ2Ｂ4Ｏ7等）、およびＭのホウ酸塩（ＭＢ4Ｏ7等）からなる群より選ばれる少なくとも１種が好ましい。元素ＸがＡｌを含む場合に該化合物としては、酸化アルミニウム（Ａｌ2Ｏ3等）、およびオキシ水酸化アルミニウム（ＡｌＯＯＨ等）からなる群より選ばれる少なくとも１種が好ましい。 Element X in the raw material formulation is an optional component and is contained as necessary. When the raw material preparation contains the element X, among the compounds containing the element X, when the element X contains P, the compound includes phosphorus oxide (P 2 O 5 etc.), phosphoric acid (H 3 PO 4 etc.) ), Ammonium phosphate (such as (NH 4 ) 3 PO 4 ), ammonium hydrogen phosphate (such as (NH 4 ) 2 HPO 4 , NH 4 H 2 PO 4 ), A phosphate (such as A 3 PO 4 ) At least one selected from the group consisting of hydrogen phosphate of A (A 2 HPO 4 etc.) and M phosphate (M 3 (PO 4 ) 2 etc.) is preferable. When the element X contains B, the compounds include boron oxide (B 2 O 3 etc.), boric acid (H 3 BO 3 etc.), A borate (A 2 B 4 O 7 etc.), and M Of these, at least one selected from the group consisting of borate salts (such as MB 4 O 7 ) is preferred. When the element X contains Al, the compound is preferably at least one selected from the group consisting of aluminum oxide (such as Al 2 O 3 ) and aluminum oxyhydroxide (such as AlOOH).
　原料調合物としては、Ａの炭酸塩または炭酸水素塩；Ｍの酸化物またはＭのオキシ水酸化物；酸化ケイ素；酸化バナジウムの組み合わせが好ましい。原料調合物に元素Ｘを含有させる場合、元素Ｘを含む化合物は、リン酸アンモニウム、ホウ酸、酸化アルミニウム、およびオキシ水酸化アルミニウムからなる群より選ばれる少なくとも１種が好ましい。
　さらに、原料調合物としては、Ｌｉ2ＣＯ3またはＬｉＨＣＯ3；Ｆｅ3Ｏ4、Ｆｅ2Ｏ3、ＭｎＯ2、およびＭｎＯからなる群より選ばれる少なくとも１種；ＳｉＯ2；Ｖ2Ｏ5またはＶ2Ｏ3の組み合わせが特に好ましい。元素Ｘを含む場合には、さらにＮＨ4Ｈ2ＰＯ4、Ｂ2Ｏ3、Ｈ3ＢＯ3、Ａｌ2Ｏ3、およびＡｌＯＯＨからなる群より選ばれる少なくとも１種を加える組み合わせが好ましい。 As the raw material preparation, a combination of A carbonate or hydrogen carbonate; M oxide or M oxyhydroxide; silicon oxide; vanadium oxide is preferable. When the element X is contained in the raw material preparation, the compound containing the element X is preferably at least one selected from the group consisting of ammonium phosphate, boric acid, aluminum oxide, and aluminum oxyhydroxide.
Furthermore, as the raw material formulation, at least one selected from the group consisting of Li 2 CO 3 or LiHCO 3 ; Fe 3 O 4 , Fe 2 O 3 , MnO 2 , and MnO; SiO 2 ; V 2 O 5 or V The combination of 2 O 3 is particularly preferred. When the element X is included, a combination in which at least one selected from the group consisting of NH 4 H 2 PO 4 , B 2 O 3 , H 3 BO 3 , Al 2 O 3 , and AlOOH is further added is preferable.
　原料調合物の組成は、原則として、溶融物の組成と対応させる。ただし、該原料調合物が溶融工程（Ｉ）中に揮発等により失われやすい成分、例えばＬｉやＶ等を含む場合には、得られる溶融物の組成は原料調合物の組成と若干相違することがある。そのような場合には、揮発等により失われる量を考慮して、各化合物の仕込み量を設定することが好ましい。 The composition of the raw material formulation should in principle correspond to the composition of the melt. However, when the raw material formulation contains a component that is easily lost due to volatilization or the like during the melting step (I), such as Li or V, the composition of the obtained melt is slightly different from the composition of the raw material formulation. There is. In such a case, it is preferable to set the amount of each compound charged in consideration of the amount lost due to volatilization or the like.
　原料調合物中の各原料の純度は特に限定されないが、所望特性を低下させない範囲が好ましい。反応性やケイ酸－バナジン酸化合物の特性（例えば二次電池用正極材料の特性）等を考慮すると、水和水を除いた純度が９９質量％以上であることが好ましい。 The purity of each raw material in the raw material preparation is not particularly limited, but a range that does not deteriorate the desired characteristics is preferable. Considering reactivity and characteristics of silicic acid-vanadic acid compound (for example, characteristics of positive electrode material for secondary battery), the purity excluding hydrated water is preferably 99% by mass or more.
　原料調合物中の各原料としては、粉砕した原料を用いるのが好ましい。粉砕は、原料を粉砕してから混合しても、混合した後に粉砕してもよい。粉砕は、ミキサー、ボールミル、ジェットミル、または遊星ミル等を用いて、乾式または湿式で行うことが好ましく、溶媒の除去工程が不要なことから、乾式が好ましい。原料調合物中の各原料の粒度は、混合操作、混合物の溶融容器への充填操作、混合物の溶融性等に悪影響を及ぼさない範囲であれば、限定されない。 As each raw material in the raw material preparation, it is preferable to use a pulverized raw material. The pulverization may be performed after the raw materials are pulverized or mixed, or may be pulverized after mixing. The pulverization is preferably performed by a dry method or a wet method using a mixer, a ball mill, a jet mill, a planetary mill or the like, and a dry method is preferable because a solvent removal step is unnecessary. The particle size of each raw material in the raw material preparation is not limited as long as it does not adversely affect the mixing operation, the filling operation of the mixture into the melting container, the meltability of the mixture, and the like.
　溶融工程（Ｉ）においては、前記の方法で得た原料調合物を、次に加熱して溶融する。溶融は、該原料調合物を容器等に入れ、該容器を加熱炉に入れて加熱して行うことが好ましい。該容器は、アルミナ製、カーボン製、炭化ケイ素製、ホウ化ジルコニウム製、ホウ化チタン製、窒化ホウ素製、炭素製、白金製、またはロジウムを含む白金合金製等が好ましい。耐火物系煉瓦、還元材料（例えばグラファイト）からなる容器も採用できる。加熱炉中での揮発および蒸発防止のためには、容器に蓋を装着して溶融することが好ましい。加熱炉は、抵抗加熱炉、高周波誘導炉、またはプラズマアーク炉が好ましい。抵抗加熱炉はニクロム合金等の合金製、炭化ケイ素製、またはケイ化モリブデン製の発熱体を備えた電気炉であることが好ましい。 In the melting step (I), the raw material formulation obtained by the above method is then heated and melted. Melting is preferably performed by placing the raw material preparation in a container or the like, and placing the container in a heating furnace and heating. The container is preferably made of alumina, carbon, silicon carbide, zirconium boride, titanium boride, boron nitride, carbon, platinum, or a platinum alloy containing rhodium. Containers made of refractory bricks and reducing materials (for example, graphite) can also be employed. In order to prevent volatilization and evaporation in the heating furnace, it is preferable to attach 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.
　加熱は、空気中、不活性ガス中、または還元ガス中で実施することが好ましい。溶融の条件は、容器または加熱炉の種類や熱源等の加熱方法等の条件により、適宜変更できる。圧力は、常圧、加圧（１．１×１０5Ｐａ以上）、減圧（０．９×１０5Ｐａ以下）のいずれでもよい。溶融の条件は還元ガス中が好ましいが、酸化ガス中であってもよい。酸化ガス中で溶融した場合には、加熱工程（ＩＶ）で還元（例えばＭ3+からＭ2＋への変化）を行うのが好ましい。 Heating is preferably performed in air, inert gas, or 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 normal pressure, increased pressure (1.1 × 10 5 Pa or more), and reduced pressure (0.9 × 10 5 Pa or less). The melting condition is preferably in a reducing gas, but may be in an oxidizing gas. When melted in oxidizing gas, it is preferable to perform reduction (for example, change from M 3+ to M 2+ ) in the heating step (IV).
　不活性ガスとは、窒素ガス（Ｎ2）、およびヘリウムガス（Ｈｅ）およびアルゴンガス（Ａｒ）等の希ガスからなる群より選ばれる少なくとも１種の不活性ガスを９９体積％以上含む気体をいう。還元ガスとは、上記した不活性ガスに、還元性を有するガスを添加し、実質的に酸素を含まない気体をいう。還元性を有するガスとしては、水素ガス（Ｈ2）、一酸化炭素ガス（ＣＯ）、およびアンモニアガス（ＮＨ3）等が挙げられる。不活性ガス中の還元性を有するガスの量は、全気体体積中に含まれる還元性を有するガスの量が０．１体積％以上であるのが好ましく、１～１０体積％が特に好ましい。酸素の含有量は、該気体体積中に１体積％以下が好ましく、０．１体積％以下が特に好ましい。 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). Say. The reducing gas refers to a gas that is substantially free of oxygen by adding a reducing gas to the above-described inert gas. 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 contained in the total gas volume. The oxygen content is preferably 1% by volume or less, and particularly preferably 0.1% by volume or less in the gas volume.
　加熱の温度は、１，３００～１，６００℃が好ましく、１，３００～１，４５０℃が特に好ましい。ここで、溶融とは各原料が融解し、目視で透明な状態となることをいう。加熱温度が上記範囲の下限値以上であると溶融が容易になり、上記範囲の上限値以下であると原料の揮発が起こりにくくなる。加熱時間は０．２～２時間が好ましく、０．５～２時間が特に好ましい。該時間とすることにより溶融物の均一性が充分になり、また原料が揮発しにくい。溶融工程（Ｉ）においては、溶融物の均一性を上げるために撹拌してもよい。また、次の冷却工程（ＩＩ）を行うまで、溶融温度より低い温度で溶融物を清澄させてもよい。 The heating temperature is preferably 1,300 to 1,600 ° C, particularly preferably 1,300 to 1,450 ° C. Here, melting means that each raw material is melted and is in a transparent state visually. When the heating temperature is equal to or higher than the lower limit value of the above range, melting becomes easy, and when the heating temperature is equal to or lower than the upper limit value of the above range, the raw material is less likely to volatilize. 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. In the melting step (I), stirring may be performed to increase the uniformity of the melt. Further, the melt may be clarified at a temperature lower than the melting temperature until the next cooling step (II) is performed.
［冷却工程（ＩＩ）］
　冷却工程（ＩＩ）は、溶融工程（Ｉ）で得た溶融物を室温付近まで冷却して固化物を得る工程である。固化物は非晶質物であることが好ましい。ただし、固化物の一部は結晶化物であってもよい。固化物が非晶質物を含むことにより、次工程の粉砕工程（ＩＩＩ）が実施しやすくなり、ケイ酸－バナジン酸化合物の組成や粒度が制御しやすくなる。さらに、後工程の加熱工程（ＩＶ）において、生成物が塊状になるのを防ぐことができ、かつ生成物の粒度が制御しやすくなる利点がある。 [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. However, a part of the solidified product may be a crystallized product. When the solidified product contains an amorphous material, the next pulverization step (III) can be easily performed, and the composition and particle size of the silicic acid-vanadic acid compound can be easily controlled. Furthermore, there is an advantage that the product can be prevented from becoming agglomerated in the subsequent heating step (IV) and the particle size of the product can be easily controlled.
　固化物が結晶化物を含む場合、加熱工程（ＩＶ）で結晶化物が結晶核となり、結晶化しやすくなる。固化物中の結晶化物の量は、固化物の全質量に対して０～３０質量％であることが好ましい。結晶化物を多く含むと粒状やフレーク状の固化物を得ることが困難となる。また、冷却機器の損耗を早め、その後の粉砕工程（ＩＩＩ）の負担が大きくなる。 When the solidified product contains a crystallized product, the crystallized product becomes a crystal nucleus in the heating step (IV), and it is easy to crystallize. The amount of the crystallized product in the solidified product is preferably 0 to 30% by mass with respect to the total mass of the solidified product. When a large amount of crystallized material is contained, it becomes difficult to obtain a granular or flaky solidified material. Moreover, the wear of the cooling device is accelerated, and the burden of the subsequent pulverization step (III) is increased.
　溶融物の冷却方法としては、高速で回転する双ローラの間に溶融物を滴下して冷却する方法、回転する単ローラに溶融物を滴下して冷却する方法、または溶融物を冷却したカーボン板や金属板にプレスして冷却する方法が好ましい。なかでも、双ローラを用いた冷却方法が、冷却速度が速く、大量に処理できるので特に好ましい。双ローラとしては、金属製、カーボン製、またはセラミックス製のものを用いることが好ましい。 As a method for cooling the melt, a method in which the melt is dropped between twin rollers rotating at high speed, a method in which the melt is dropped on a single rotating roller, and cooling is performed, or a carbon plate on which the melt is cooled. Alternatively, a method of cooling by pressing on a metal plate is preferable. Among these, a cooling method using twin rollers is particularly 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.
　なお、冷却方法としては、溶融物を水に直接投入する方法もあるが、該方法は制御が難しく、非晶質物を得るのが難しく、固化物が塊状となり、粉砕に多くの労力を要する欠点がある。冷却方法としては、液体窒素に溶融物を直接投入する方法もあり、水の場合よりも冷却速度を速くできるが、水を使用する方法と同様な問題があり、高コストである。 In addition, as a cooling method, there is also a method in which the molten material is directly poured into water, but this method is difficult to control, it is difficult to obtain an amorphous material, the solidified material becomes a lump, and a disadvantage that requires much labor for pulverization There is. As a cooling method, there is also a method in which a melt is directly added to 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.
　溶融物の冷却は、空気中、不活性ガス中、または還元ガス中で行うのが、設備が簡便であることから好ましい。このような冷却方法によれば、非晶質物をより簡便に得ることができる。
　溶融物の冷却速度は－１×１０3℃／秒以上が好ましく、－１×１０4℃／秒以上が特に好ましい。本明細書では、冷却する場合の単位時間当たりの温度変化（すなわち冷却速度）を負の値で示し、加熱する場合の単位時間当たりの温度変化（すなわち加熱速度）を正の値で示す。冷却速度を該値以上にすると非晶質物が得られやすい。冷却速度の上限値は製造設備や大量生産性の点から－１×１０10℃／秒程度が好ましく、実用性の点からは１×１０8℃／秒が特に好ましい。溶融物の冷却速度は１０００℃から５０℃までの冷却速度を－１０３℃／秒～－１０１０℃／秒とすることが特に好ましい。 It is preferable to cool the melt in the air, in an inert gas, or in a reducing gas because the equipment is simple. According to such a cooling method, an amorphous material can be obtained more easily.
The cooling rate of the melt is preferably not less than -1 × 10 3 ℃ / sec, -1 × 10 4 ℃ / sec or more is particularly preferable. In the present specification, a temperature change per unit time (ie, cooling rate) in the case of cooling is indicated by a negative value, and a temperature change per unit time in case of heating (ie, the heating rate) is indicated by a positive value. When 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 1 × 10 8 ° C./second is particularly preferable 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.
　冷却工程（ＩＩ）で得る固化物は、フレーク状または繊維状が好ましい。フレーク状の場合には、平均厚さが２００μｍ以下が好ましく、１００μｍ以下が特に好ましい。フレーク状の場合の平均厚さに垂直な面の平均直径は、特に限定されない。繊維状の場合には、平均直径が５０μｍ以下が好ましく、３０μｍ以下が特に好ましい。平均厚さや平均直径の上限値以下であると、粉砕工程（ＩＩＩ）の手間を低減することができ、結晶化効率を高くすることができる。平均厚さおよび平均直径は、ノギスやマイクロメータにより測定することができる。平均直径は、顕微鏡観察により測定することもできる。 The solidified product obtained in the cooling step (II) is preferably flaky or fibrous. In the case of flakes, the average thickness is preferably 200 μm or less, particularly preferably 100 μm or less. The average diameter of the surface perpendicular to the average thickness in the case of flakes is not particularly limited. In the case of a fibrous form, the average diameter is preferably 50 μm or less, particularly preferably 30 μm or less. When the average thickness or the average diameter is not more than the upper limit value, the labor of the pulverization step (III) can be reduced, and the crystallization efficiency can be increased. 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.
［粉砕工程（ＩＩＩ）］
　粉砕工程（ＩＩＩ）は、冷却工程（ＩＩ）で得た固化物を粉砕して粉砕物を得る工程である。固化物は通常の場合、非晶質物を多く含む、または、非晶質物からなるため、粉砕がしやすい利点がある。また、粉砕に使用する装置に負担をかけずに粉砕ができ、かつ粒径が制御しやすい利点がある。一方、従来の固相反応は加熱工程後に粉砕を行うが、粉砕によって残留応力が生じ、電池特性を悪化させる問題があることに本発明者は気づいた。よって、本発明の製造方法では、加熱工程（ＩＶ）の前に粉砕工程（ＩＩＩ）を行うため、粉砕工程（ＩＩＩ）で生じた残留応力を加熱工程（ＩＶ）で低減または除去することができる。 [Crushing step (III)]
The pulverization step (III) is a step of pulverizing the solidified product obtained in the cooling step (II) 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 pulverization can be performed without imposing a burden on an apparatus used for pulverization 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, but the present inventor has noticed that there is a problem that residual stress is generated by the pulverization and battery characteristics are deteriorated. Therefore, in the production method of the present invention, since the pulverization step (III) is performed before the heating step (IV), the residual stress generated in the pulverization step (III) can be reduced or removed in the heating step (IV). .
　粉砕は、ジョークラッシャー、ハンマーミル、ボールミル、ジェットミル、遊星ミル等を用いて行うことが好ましい。粉砕の方式は、乾式または湿式のいずれであってもよい。粉砕前に固化物を手揉みやハンマー等で叩いて予備的に細かくすると、粉砕工程（ＩＩＩ）の負担が軽減するので好ましい。粉砕工程（ＩＩＩ）を湿式で行った場合、分散媒を沈降、濾過、減圧乾燥、加熱乾燥等で除去した後に、加熱工程（ＩＶ）を実施するのが好ましい。ただし、分散媒が少ない場合、特に粉砕物に占める固形分の割合が３０％以上の場合、泥状の粉砕混合物のままで加熱工程（ＩＶ）に供してもよい。 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. It is preferable to preliminarily make the solidified product fine by hitting it with a hammer or a hammer before pulverization because the burden of the pulverization step (III) is reduced. When the pulverization step (III) is performed by a wet method, the heating step (IV) is preferably performed after the dispersion medium is removed by sedimentation, filtration, drying under reduced pressure, drying by heating, and the like. However, when there are few dispersion media, especially when the ratio of the solid content to a ground material is 30% or more, you may use for a heating process (IV) with a mud-like ground mixture.
　本発明におけるケイ酸－バナジン酸化合物は絶縁物質であるため、二次電池用正極材料として用いる場合には、固化物に導電材を含ませるのが好ましい。また、二次電池用正極材料として用いる場合、ケイ酸－バナジン酸化合物は微粒子状であるのが好ましい。粉砕物の平均粒径は、体積換算のメディアン径で１０ｎｍ～１０μｍが好ましく、１０ｎｍ～５μｍが特に好ましい。粉砕物の粒径が小さい場合には、還元反応が促進され、加熱工程（ＩＶ）の加熱温度や時間を低減できるために好ましい。粉砕物の平均粒径を上記範囲とすることにより、粉砕工程（ＩＩＩ）および加熱工程（ＩＶ）の作業性を向上させ、加熱工程（ＩＶ）の生成物の平均粒径を制御しやすくなる利点がある。粒径の測定は、沈降法やレーザ回折／散乱式粒子径測定装置で測定できる。 Since the silicic acid-vanadic 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. When used as a positive electrode material for a secondary battery, the silicic acid-vanadic acid compound is preferably in the form of fine particles. The average particle diameter of the pulverized product is preferably 10 nm to 10 μm, and particularly preferably 10 nm to 5 μm, in terms of volume-based median diameter. When the particle size of the pulverized product is small, the reduction reaction is promoted, which is preferable because the heating temperature and time in the heating step (IV) can be reduced. 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 particle size can be measured by a sedimentation method or a laser diffraction / scattering particle size measuring device.
　導電材としては、有機化合物および炭素粉末からなる群より選ばれる少なくとも１種の炭素源が好ましい。該炭素源の量は、固化物と炭素源中の炭素換算量（質量）との合計質量に対する該炭素換算量（質量）の割合が０．１～２０質量％となる量が好ましく、２～１０質量％となる量が特に好ましい。炭素源の量を上記範囲とすることにより、ケイ酸－バナジン酸化合物を二次電池用正極材料として用いる場合の導電性を充分に高めることができる。また、固化物に含ませた有機化合物および炭素粉末は、粉砕工程（ＩＩＩ）や加熱工程（ＩＶ）における酸化を防止し、さらに還元を促進する。さらに、有機化合物および炭素粉末は、加熱工程後に炭素や炭化物等として残り、導電材として機能する。よって、二次電池用正極材料の導電性を高めることができる。 The conductive material is preferably at least one carbon source selected from the group consisting of organic compounds and carbon powder. The amount of the carbon source is preferably such that the ratio of the carbon equivalent (mass) to the total mass of the solidified product and the carbon equivalent (mass) in the carbon source is 0.1 to 20% by mass. An amount of 10% by mass is particularly preferred. By setting the amount of the carbon source in the above range, the conductivity when the silicic acid-vanadic acid compound is used as a positive electrode material for a secondary battery can be sufficiently increased. Moreover, 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. Furthermore, the organic compound and the carbon powder remain as carbon, carbide, etc. after the heating step, and function as a conductive material. Therefore, the conductivity of the positive electrode material for secondary batteries can be increased.
（有機化合物）
　有機化合物としては、糖類、アミノ酸類、ペプチド類、アルデヒド類、ケトン類、グリコール類、ポリビニルアルコール、および脂肪酸からなる群より選ばれる少なくとも１種が好ましく、糖類、グリコール類、またはポリビニルアルコールが特に好ましい。
　糖類としては、グルコース、フラクトース、およびガラクトース等の単糖類、スクロース、マルトース、セロビオース、およびトレハロース等のオリゴ糖、転化糖、デキストリン、アミロース、アミロペクチン、およびセルロース等の多糖類、ならびにアスコルビン酸等が挙げられる。
　アミノ酸類としては、アラニン、グリシン等のアミノ酸が挙げられる。
　ペプチド類としては、分子量が１，０００以下の低分子ペプチドが挙げられる。
　有機化合物としては、具体的にはグルコース、スクロース、グルコース－フラクトース転化糖、カラメル、澱粉、α化した澱粉、カルボキシメチルセルロース等が好適である。 (Organic compounds)
As 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. .
Examples of 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.
Examples of amino acids include amino acids such as alanine and glycine.
Peptides include low molecular weight peptides having a molecular weight of 1,000 or less.
As the organic compound, specifically, glucose, sucrose, glucose-fructose invert sugar, caramel, starch, pregelatinized starch, carboxymethylcellulose and the like are preferable.
（炭素粉末）
　炭素粉末としては、カーボンブラック、グラファイト、アセチレンブラック等が好ましい。また、炭素粉末は繊維状炭素または板状炭素であってもよい。炭素粉末を固化物に含ませることによって、加熱工程（ＩＶ）後に炭素粉末を混合する工程を別途設ける必要がなくなる。さらに、炭素粉末を有機化合物と共に固化物に含ませることによって、ケイ酸－バナジン酸化合物内での炭素粉末の分布が均一となり、また有機化合物やその熱分解物（炭化物）との接触面積が大きくなる。これらによって、ケイ酸－バナジン酸化合物を用いた二次電池用正極材料の導電性を高めることができる。 (Carbon powder)
As the carbon powder, carbon black, graphite, acetylene black and the like are preferable. The carbon powder may be fibrous carbon or plate-like carbon. By including the carbon powder in the solidified product, it is not necessary to separately provide a step of mixing the carbon powder after the heating step (IV). Furthermore, by including the carbon powder in the solidified product together with the organic compound, the distribution of the carbon powder in the silicic acid-vanadic acid compound becomes uniform, and the contact area with the organic compound and its thermal decomposition product (carbide) is large. Become. Accordingly, the conductivity of the positive electrode material for a secondary battery using the silicic acid-vanadic acid compound can be increased.
　固化物に有機化合物を含ませる場合の粉砕工程（ＩＩＩ）は、粉砕物の表面に均一に分散させるために、湿式粉砕を採用するのが好ましい。粉砕する際の分散媒としては、水、またはエタノール、イソプロピルアルコール、アセトン、ヘキサン、トルエン等の有機溶媒を用いることができる。なかでも、水は安価であるために好ましい。固化物に炭素粉末のみを含ませる場合の粉砕工程（ＩＩＩ）は、乾式が好ましい。 In the pulverization step (III) when the organic compound is included in the solidified product, wet pulverization is preferably employed in order to uniformly disperse the pulverized product on the surface. As 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. The pulverization step (III) when the solidified product contains only carbon powder is preferably dry.
［加熱工程（ＩＶ）］
　加熱工程（ＩＶ）は、粉砕工程（ＩＩＩ）で得た粉砕物を加熱し、式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物を得る工程である。
　式（Ａ）で表される組成を有する溶融物として、式（１）で表される組成を有する溶融物を使用して本発明の製造方法を実施した場合には、式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物として、下式（２）で表される組成を有するケイ酸－バナジン酸化合物が得られる。また、式（１）で表される組成を有する溶融物の好ましい態様である、式（１Ａ）で表される組成を有する溶融物を使用して本発明の製造方法を実施した場合には、式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物として、下式（２Ａ）で表される組成を有するケイ酸－バナジン酸化合物が得られる。
　Ａ1+x+aＭbＳｉx（ＶcＸ1-c）1-xＯ4+d12　　　（２）
　Ｌｉ1+x+a（ＦｅyＭｎ1-y）bＳｉxＶ1-xＯ4+d12　　　（２Ａ） [Heating step (IV)]
The heating step (IV) is a step of heating the pulverized product obtained in the pulverizing step (III) to obtain a silicic acid-vanadic acid compound having a composition represented by the formula (B).
When the manufacturing method of the present invention is carried out using the melt having the composition represented by the formula (1) as the melt having the composition represented by the formula (A), the melt is represented by the formula (B). As the silicic acid-vanadic acid compound having the composition, a silicic acid-vanadic acid compound having the composition represented by the following formula (2) is obtained. Moreover, when the manufacturing method of this invention is implemented using the melt which has a composition represented by Formula (1A) which is a preferable aspect of the melt which has a composition represented by Formula (1), As the silicic acid-vanadic acid compound having the composition represented by the formula (B), a silicic acid-vanadic acid compound having the composition represented by the following formula (2A) is obtained.
A 1 + x + a M b Si x (V c X 1-c ) 1-x O 4 + d12 (2)
Li 1 + x + a (Fe y Mn 1-y ) b Si x V 1-x O 4 + d12 (2A)
　式（Ｂ）、式（２）、および式（２Ａ）における元素Ａ、元素Ｍ、元素Ｘの好ましい態様は、式（Ａ）、式（１）、および式（１Ａ）におけるのと同じである。
　式（Ｂ）、式（２）、および式（２Ａ）中のｆ、ａ、ｂ、ｃ、ｘおよびｙは前記と同じ意味を示すが、式（Ａ）、式（１）、および式（１Ａ）における値とは独立した値を示す。
　式（Ｂ）、式（２）、および式（２Ａ）におけるｆ、ａ、ｂ、ｃ、ｘの好ましい範囲は、式（Ａ）、式（１）、および式（１Ａ）におけるのと同じである。
　式（Ｂ）におけるｄ２の値は、元素Ｘの種類、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。
　式（２）および式（２Ａ）におけるｄ１２の値は、元素Ｘの種類、ａ、ｂ、ｃ、ｘ、およびＭまたはＦｅyＭｎ1-yの平均価数Ｎに依存する数である。例えば、ａ＝０、ｂ＝１、ｃ＝１、ｘ＝０．９、Ｖが＋５、およびＮ＝＋２であれば、ｄ１２は０である。ｄ２は－０．２≦ｄ２≦０．２が好ましく、－０．１≦ｄ２≦０．１が特に好ましい。ｄ１２は－０．２≦ｄ１２≦０．２が好ましく、－０．１≦ｄ１２≦０．１が特に好ましい。 Preferred embodiments of element A, element M, and element X in formula (B), formula (2), and formula (2A) are the same as in formula (A), formula (1), and formula (1A). .
F, a, b, c, x, and y in formula (B), formula (2), and formula (2A) have the same meaning as described above, but formula (A), formula (1), and formula ( A value independent of the value in 1A) is shown.
The preferred ranges of f, a, b, c, and x in formula (B), formula (2), and formula (2A) are the same as in formula (A), formula (1), and formula (1A). is there.
The value of d2 in the formula (B) is a number that depends on the type of element X, f, b, c, x, and the valence N of M.
The value of d12 in Formula (2) and Formula (2A) is a number that depends on the type of element X, a, b, c, x, and the average valence N of M or Fe y Mn 1-y . For example, if a = 0, b = 1, c = 1, x = 0.9, V is +5, and N = + 2, d12 is 0. d2 is preferably −0.2 ≦ d2 ≦ 0.2, particularly preferably −0.1 ≦ d2 ≦ 0.1. d12 is preferably −0.2 ≦ d12 ≦ 0.2, particularly preferably −0.1 ≦ d12 ≦ 0.1.
　式（２Ａ）中のｙの値は、０≦ｙ≦１が好ましく、０＜ｙ＜１が特に好ましい。ＦｅとＭｎのモル比は２０～８０：８０～２０が好ましく、２５～７５：７５～２５がさらに好ましく、４０～６０：６０～４０が特に好ましい。 The value of y in the formula (2A) is preferably 0 ≦ y ≦ 1, and particularly preferably 0 <y <1. The molar ratio of Fe to Mn is preferably 20 to 80:80 to 20, more preferably 25 to 75:75 to 25, and particularly preferably 40 to 60:60 to 40.
　加熱工程（ＩＶ）の生成物は、ケイ酸－バナジン酸化合物の結晶粒子が好ましく、さらにオリビン型の結晶粒子が特に好ましい。 The product of the heating step (IV) is preferably a silicic acid-vanadic acid compound crystal particle, more preferably an olivine type crystal particle.
　本発明における加熱工程（ＩＶ）は、粉砕物を加熱することから、残留応力の緩和が促進される。また、加熱により結晶核の生成および粒成長を行うため、ケイ酸－バナジン酸化合物の組成、粒径およびその分布の制御が容易である。さらに、粉砕工程（ＩＩＩ）で炭素源を含ませた場合の加熱工程（ＩＶ）は、生成物、好ましくは生成物の結晶粒子の表面に、導電材を結合させる工程となりうる。炭素源のうちの有機化合物は、加熱工程（ＩＶ）で熱分解され、炭化物となって導電材として機能する。 In the heating step (IV) in the present invention, the pulverized material is heated, so that the relaxation of residual stress is promoted. In addition, since the formation of crystal nuclei and grain growth are performed by heating, the composition, particle diameter, and distribution of the silicic acid-vanadic acid compound can be easily controlled. Further, the heating step (IV) when the carbon source is included in the pulverization step (III) can be a step of bonding a conductive material to the surface of the product, preferably the crystal grains of the product. The organic compound in the carbon source is thermally decomposed in the heating step (IV), becomes a carbide, and functions as a conductive material.
　加熱工程（ＩＶ）における加熱温度は、５００～１，０００℃が好ましい。加熱温度が５００℃以上であると、反応が生じやすくなり、ケイ酸－バナジン酸化合物の結晶が生成しやすくなる。加熱温度が１，０００℃以下であると、粉砕物が融解しにくく、結晶系や粒子径を制御しやすい。加熱温度は６００～９００℃が特に好ましい。該加熱温度である場合には、適度な結晶性、粒子径、粒度分布等を有する結晶粒子が得られやすく、さらにオリビン型の結晶粒子が得られやすい。 The heating temperature in the heating step (IV) is preferably 500 to 1,000 ° C. When the heating temperature is 500 ° C. or higher, a reaction is likely to occur, and crystals of a silicic acid-vanadic acid compound are likely to be generated. When the heating temperature is 1,000 ° C. or less, the pulverized product is difficult to melt, and the crystal system and particle diameter can be easily controlled. The heating temperature is particularly 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 easily obtained.
　加熱は一定温度で保持することに限らず、多段階に保持温度を設定して行ってもよい。加熱温度が高くなると、生成する粒子の粒子径が大きくなる傾向があるため、所望の粒子径に応じて加熱温度を設定するのが好ましい。また、加熱時間（加熱温度による保持時間）は、所望の粒子径を考慮して１～７２時間が好ましい。加熱は、ボックス炉、トンネルキルン炉、ローラーハース炉、ロータリーキルン炉、マイクロウェーブ加熱炉等で行うのが好ましい。 The heating is not limited to holding at a constant temperature, and may be performed by setting the holding temperature in multiple stages. When the heating temperature is increased, the particle diameter of the generated particles tends to increase. Therefore, it is preferable to set the heating temperature 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 the 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.
　加熱は、空気中、不活性ガス中、または還元ガス中で実施することが好ましく、不活性ガス中または還元ガス中で実施することが特に好ましい。不活性ガスおよび還元ガスの条件は、溶融工程（Ｉ）における条件と同じである。圧力は、常圧、加圧（１．１×１０5Ｐａ以上）、減圧（０．９×１０5Ｐａ以下）のいずれでもよい。また、還元剤（例えばグラファイト）と粉砕物とを入れた容器を加熱炉内に装填して実施した場合には、粉砕物中のＭの還元（例えばＭ3+からＭ2＋への変化）を促進することができる。 Heating is preferably performed in air, an inert gas, or a reducing gas, and particularly preferably performed in an inert gas or a reducing gas. The conditions of the inert gas and the reducing gas are the same as those in the melting step (I). The pressure may be normal pressure, increased pressure (1.1 × 10 5 Pa or more), and reduced pressure (0.9 × 10 5 Pa or less). Further, when a container containing a reducing agent (for example, graphite) and pulverized material is loaded in a heating furnace, reduction of M in the pulverized material (for example, change from M 3+ to M 2+ ) is performed. Can be promoted.
　加熱工程（ＩＶ）後において、通常は常温まで冷却する。該冷却における冷却速度は、－３０℃／時間～－３００℃／時間が好ましい。冷却速度を該範囲にすることにより、加熱による歪みを除去でき、生成物が結晶体である場合は、結晶構造を保ったまま目的物を得ることができる。また、冷却手段を用いずに冷却できる利点もある。冷却は放置して常温まで冷却させてもよい。冷却は、不活性ガス中または還元ガス中で行うのが好ましい。 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. There is also an advantage that cooling can be performed without using a cooling means. The cooling may be left to cool to room temperature. Cooling is preferably performed in an inert gas or a reducing gas.
＜ケイ酸－バナジン酸化合物＞
　本発明の製造方法により得られるケイ酸－バナジン酸化合物は、二次電池用正極材料として有用な化合物である。特に、式（２）で表される組成を有するケイ酸－バナジン酸化合物は、元素Ａの原子数が１．０超であるため、多電子型になり、二次電池用正極材料として用いたときに単位質量当たりの容量が大きくなる。 <Silic acid-vanadic acid compound>
The silicic acid-vanadic acid compound obtained by the production method of the present invention is a useful compound as a positive electrode material for a secondary battery. In particular, the silicic acid-vanadic acid compound having the composition represented by the formula (2) has a multi-electron type because the number of atoms of the element A exceeds 1.0, and was used as a positive electrode material for a secondary battery. Sometimes the capacity per unit mass increases.
　すなわち、式（２）で表される組成を有するケイ酸－バナジン酸化合物は、元素ＡがＬｉである場合、単位四面体（［ＳｉＯ4］＋［ＶＯ4］）に対して、１個超２個以下のＬｉを含む構造を有するため、Ｌｉの原子数を１．０超にすることができる。さらに、本発明の製造方法によれば、［ＳｉＯ4］四面体、［ＶＯ4］四面体、［ＬｉＯ4］四面体、［Ｘ四面体］、および［ＭＯ4］四面体または八面体が均一に分布するケイ酸－バナジン酸化合物を得ることができる。
　該ケイ酸－バナジン酸化合物は、オリビン型結晶粒子を含むことが好ましい。該結晶粒子としては、一次粒子および二次粒子の双方を含む。生成物中に二次粒子が存在する場合、一次粒子が破壊されない程度の範囲で解砕および粉砕してもよい。 That is, when the element A is Li, the silicic acid-vanadic acid compound having the composition represented by the formula (2) exceeds one unit tetrahedron ([SiO 4 ] + [VO 4 ]). Since it has a structure containing two or less Li, the number of Li atoms can be more than 1.0. Furthermore, according to the production method of the present invention, the [SiO 4 ] tetrahedron, [VO 4 ] tetrahedron, [LiO 4 ] tetrahedron, [X tetrahedron], and [MO 4 ] tetrahedron or octahedron are uniform. A silicic acid-vanadic acid compound distributed in the above can be obtained.
The silicic acid-vanadic 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.
　本発明の製造方法において、有機化合物および炭素粉末からなる群より選ばれる少なくとも１種を添加した場合には、ケイ酸－バナジン酸化合物の表面に有機化合物や炭素粉末に由来する炭素からなる導電材を均一にかつ強固に結合させうる。導電材が結合したケイ酸－バナジン酸化合物は、そのまま二次電池用正極材料として用いることができる。 In the production method of the present invention, when at least one selected from the group consisting of an organic compound and carbon powder is added, a conductive material made of carbon derived from the organic compound or carbon powder on the surface of the silicic acid-vanadic acid compound Can be bonded uniformly and firmly. The silicic acid-vanadic acid compound to which the conductive material is bonded can be used as it is as a positive electrode material for a secondary battery.
　式（２）で表される組成を有するケイ酸－バナジン酸化合物が結晶である場合、固溶体結晶であるのが好ましい。特に、式（２）中のｘが０．８≦ｘ＜１である場合に、固溶体結晶になりやすい。その理由は、例えば式（３）で表される反応により、Ｓｉの一部がＶ、または、ＶおよびＸで置換されて、固溶体結晶が生成するためと考えられる。
　ｘＡ2ＭＳｉＯ4＋（１－ｘ）ＡＭ（Ｖ，Ｘ）Ｏ4-e
　→　Ａ1+xＭ［Ｓｉx（Ｖ，Ｘ）1-x］Ｏ4-e（ｘ－１）　　　（３）
（式中、Ａ、Ｍは前記と同じ意味を示し、ｘは０．８≦ｘ＜１、ｅは０≦ｅ＜０．１であり、［　］は固溶体であることを表す。） When the silicic acid-vanadic acid compound having the composition represented by the formula (2) is a crystal, it is preferably a solid solution crystal. In particular, when x in the formula (2) is 0.8 ≦ x <1, it tends to be a solid solution crystal. The reason is considered that a part of Si is substituted with V or V and X by the reaction represented by the formula (3), for example, and a solid solution crystal is generated.
xA 2 MSiO 4 + (1-x) AM (V, X) O 4-e
→ A 1 + x M [Si x (V, X) 1-x ] O 4-e (x-1) (3)
(In the formula, A and M have the same meaning as above, x is 0.8 ≦ x <1, e is 0 ≦ e <0.1, and [] represents a solid solution.)
　該固溶体結晶は、Ｓｉのみからなる結晶に比べて安定な結晶構造となり、Ｌｉイオンが結晶内で移動しやすくなる。よって、高い容量が得られ、かつ電気伝導度が上昇するため、二次電池用正極材料に用いた場合に、理論容量が得られやすく、充放電のサイクル性が向上しうる。本発明におけるケイ酸－バナジン酸化合物は、Ｓｉの一部をＶ、または、ＶおよびＸで置換した固溶体結晶であるオリビン型結晶粒子を含むのが好ましい。 The solid solution crystal has a stable crystal structure as compared with a crystal made of only Si, and Li ions easily move in the crystal. Therefore, since a high capacity is obtained and the electrical conductivity is increased, when used as a positive electrode material for a secondary battery, a theoretical capacity can be easily obtained and the charge / discharge cycleability can be improved. The silicic acid-vanadic acid compound in the present invention preferably contains olivine type crystal particles which are solid solution crystals in which a part of Si is substituted with V or V and X.
　本発明のケイ酸－バナジン酸化合物の平均粒径は、体積換算のメディアン径で１０ｎｍ～１０μｍが好ましく、１０ｎｍ～２μｍが特に好ましい。平均粒径を該範囲とすることにより、ケイ酸－バナジン酸化合物の導電性がより高くなる。平均粒径は、例えば電子顕微鏡による観察やレーザ回折式粒度分布計による測定等によって求められる。ケイ酸－バナジン酸化合物の比表面積は、０．２～２００ｍ2／ｇが好ましく、１～２００ｍ2／ｇが特に好ましい。比表面積を該範囲とすることにより、ケイ酸－バナジン酸化合物の導電性が高くなる。比表面積は、例えば窒素吸着法による比表面積測定装置で測定できる。 The average particle diameter of the silicic acid-vanadic acid compound of the present invention is preferably 10 nm to 10 μm, particularly preferably 10 nm to 2 μm, in terms of volume median diameter. By making the average particle diameter within this range, the conductivity of the silicic acid-vanadic acid compound becomes higher. The average particle diameter 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 vanadate compound is preferably 0.2 ~ 200m 2 / g, 1 ~ 200m 2 / g is particularly preferred. By setting the specific surface area within this range, the conductivity of the silicic acid-vanadic acid compound is increased. The specific surface area can be measured by, for example, a specific surface area measuring apparatus using a nitrogen adsorption method.
　本発明におけるケイ酸－バナジン酸化合物としては、実施例に記載の化合物が例示される。 Examples of the silicic acid-vanadic acid compound in the present invention include the compounds described in Examples.
＜二次電池用正極および二次電池の製造方法＞
　本発明の製造方法によって得られたケイ酸－バナジン酸化合物を、二次電池用正極材料として用いて、二次電池用正極および二次電池を製造できる。二次電池としては、金属リチウム二次電池、リチウムイオン二次電池、リチウムポリマー二次電池等が挙げられるが、リチウムイオン二次電池が好ましい。電池形状は制限されることはなく、例えば円筒状、角型、コイン型等の種々の形状およびサイズを適宜採用できる。 <Positive electrode for secondary battery and method for producing secondary battery>
Using the silicic acid-vanadic acid compound obtained by the production method of the present invention as a positive electrode material for a secondary battery, a positive electrode for a secondary battery and a secondary battery can be produced. Examples of 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.
　本発明の二次電池用正極は、本発明の製造方法で得られるケイ酸－バナジン酸化合物を用いる以外は、公知の電極の製造方法に従って製造できる。例えば、本発明のケイ酸－バナジン酸化合物を必要に応じて公知の結着材（ポリテトラフルオロエチレン、ポリビニリデンフルオライド、ポリビニルクロライド、エチレンプロピレンジエンポリマー、スチレン－ブタジエンゴム、アクリロニトリル－ブタジエンゴム、フッ素ゴム、ポリ酢酸ビニル、ポリメチルメタクリレート、ポリエチレン、ニトロセルロース等）、さらに必要に応じて公知の導電材（アセチレンブラック、カーボン、グラファイト、天然黒鉛、人造黒鉛、ニードルコークス等）と混合した後、さらに、公知の有機溶媒（Ｎ－メチルピロリドン、トルエン、シクロヘキサン、ジメチルホルムアミド、ジメチルアセトアミド、メチルエチルケトン、酢酸メチル、アクリル酸メチル、ジエチルトリアミン、Ｎ－Ｎ－ジメチルアミノプロピルアミン、エチレンオキシド、テトラヒドロフラン等）を用いてスラリーとし、公知の集電体（アルミニウム、またはステンレスの金属箔等）に塗布する等の方法によって、製造できる。 The positive electrode for a secondary battery of the present invention can be manufactured according to a known electrode manufacturing method except that the silicic acid-vanadic acid compound obtained by the manufacturing method of the present invention is used. For example, 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.), and further mixed with known conductive materials (acetylene black, carbon, graphite, natural graphite, artificial graphite, needle coke, etc.) if necessary, Further, known organic solvents (N-methylpyrrolidone, toluene, cyclohexane, dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylamino Propylamine, ethylene oxide, was slurried with tetrahydrofuran), by a method such as coating the known current collector (aluminum or stainless steel metal foil and the like), can be produced.
　二次電池の構造は、本発明の製造方法で得られる二次電池用正極を電極として用いる以外は、公知の二次電池における構造を採用することができる。セパレータ、電池ケース等についても同様である。負極としては、活物質として公知の負極用活物質を使用でき、炭素材料、アルカリ金属材料およびアルカリ土類金属材料からなる群から選ばれる少なくとも１種を用いることが好ましい。電解液としては、非水系の電解液が好ましい。すなわち、本発明の製造方法で得られる二次電池としては、非水電解質リチウムイオン二次電池が好ましい。 As the structure of the secondary battery, a structure in a known secondary battery can be adopted except that the positive electrode for a secondary battery obtained by the production method of the present invention is used as an electrode. The same applies to separators, battery cases, and the like. As the negative electrode, a known negative electrode active material can be used as the active material, and at least one selected from the group consisting of carbon materials, alkali metal materials, and alkaline earth metal materials is preferably used. As the electrolytic solution, a non-aqueous electrolytic solution is preferable. That is, as the secondary battery obtained by the production method of the present invention, a nonaqueous electrolyte lithium ion secondary battery is preferable.
　本発明を実施例を挙げて具体的に説明するが、本発明は以下の説明に限定されない。 The present invention will be specifically described with reference to examples, but the present invention is not limited to the following description.
［実施例１～３０］
（溶融工程（Ｉ））
　溶融物の組成がＬｉ2Ｏ、Ｎａ2Ｏ、ＦｅＯ、ＭｎＯ、ＣｏＯ、ＮｉＯ、ＳｉＯ2、Ｖ2Ｏ5、Ｐ2Ｏ5、Ｂ2Ｏ3、およびＡｌ2Ｏ3換算量（単位：モル％）で、それぞれ表１に示す割合となるように、炭酸リチウム（Ｌｉ2ＣＯ3）、炭酸ナトリウム（Ｎａ2ＣＯ3）、四酸化三鉄（Ｆｅ3Ｏ4）、二酸化マンガン（ＭｎＯ2）、四酸化三コバルト（Ｃｏ3Ｏ4）、酸化ニッケル（ＮｉＯ）、二酸化ケイ素（ＳｉＯ2）、酸化バナジウム（Ｖ2Ｏ5）、リン酸水素アンモニウム（ＮＨ4Ｈ2ＰＯ4）、酸化ホウ素（Ｂ2Ｏ3）、および酸化アルミニウム（Ａｌ2Ｏ3）を秤量し、乾式で混合・粉砕して、原料調合物を得た。得られた溶融物の組成式を表１の右欄に示す。なお、表１において、Ｑは、Ｑ ＝ ＳｉＯ２ ＋２（ Ｖ２Ｏ５ ＋ Ｐ２Ｏ５ ＋ Ｂ２Ｏ３ ＋ Ａｌ２Ｏ３ ） を意味し、Ｒ ＝Ｖ２Ｏ５ ＋ Ｐ２Ｏ５ ＋ Ｂ２Ｏ３ ＋ Ａｌ２Ｏ３ を意味する。 [Examples 1 to 30]
(Melting step (I))
The composition of the melt is Li 2 O, Na 2 O, FeO, MnO, CoO, NiO, SiO 2 , V 2 O 5 , P 2 O 5 , B 2 O 3 , and Al 2 O 3 equivalent (unit: mole) %), So that the proportions shown in Table 1 are obtained, respectively, lithium carbonate (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 ), vanadium oxide (V 2 O 5 ), ammonium hydrogen phosphate (NH 4 H 2 PO 4 ), boron oxide ( B 2 O 3), and were weighed aluminum oxide (Al 2 O 3), were mixed and pulverized in a dry, to obtain a raw material formulation. The composition formula of the obtained melt is shown in the right column of Table 1. In Table 1, Q means Q = SiO 2 +2 (V 2 O 5 + P 2 O 5 + B 2 O 3 + Al 2 O 3 ), and R = V 2 O 5 + P 2 O 5 means + B 2 O 3 + Al 2 O 3.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　各原料調合物を、ロジウムを２０質量％含む白金合金製のるつぼにそれぞれ充填した。次に、該るつぼをケイ化モリブデン製の発熱体を備える電気炉（モトヤマ社製、装置名：ＮＨ－３０３５）の中に入れた。該電気炉を、流量２Ｌ／分でＮ2ガスを流通しつつ、＋３００℃／時間の速度で昇温し、１，４００～１，５００℃で０．５時間加熱した。目視で透明になったことを確認して、それぞれの溶融物を得た。 Each raw material formulation was filled in a platinum alloy crucible containing 20% by mass of rhodium. Next, the crucible was placed in an electric furnace (manufactured by Motoyama, apparatus name: NH-3035) having a heating element made of molybdenum silicide. The electric furnace was heated at a rate of + 300 ° C./hour and heated at 1,400 to 1,500 ° C. for 0.5 hours while flowing N 2 gas at a flow rate of 2 L / min. Each melt was obtained after confirming that it became transparent visually.
（冷却工程（ＩＩ））
　溶融工程（Ｉ）で得たるつぼ中の溶融物を、毎分４００回転する直径約１５ｃｍのステンレス製双ローラを通すことにより、－１×１０5℃／秒で冷却し、フレーク状の固化物を得た。 (Cooling step (II))
The molten material in the crucible obtained in the melting step (I) is cooled at -1 × 10 5 ° C / second by passing through a stainless steel double roller having a diameter of about 15 cm and rotating at 400 revolutions per minute. Got.
（粉砕工程（ＩＩＩ））
　冷却工程（ＩＩ）で得たフレーク状固化物を、軽く手で揉んで細かくした後、乳棒と乳鉢を用いて粗粉砕した。さらに、粉砕媒体としてジルコニア製ボールを用いた遊星ミルで、粗粉砕後の固化物を乾式で粉砕して粉砕物を得た。実施例１の粉砕物をレーザ回折／散乱式粒度分析計（堀場製作所社製、装置名：ＬＡ－９５０）を用いて粒子径を測定したところ、体積換算のメディアン径は２．０μｍであった。 (Crushing step (III))
The flaky solidified product obtained in the cooling step (II) 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. When the particle size 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 2.0 μm. .
（加熱工程（ＩＶ））
　粉砕工程（ＩＩＩ）で得た粉砕物を３体積％Ｈ2－Ａｒガス中に配置し、それぞれの実施例について、６００℃、７００℃、および８００℃の３種類の温度条件で８時間加熱し、次に－２００℃／時間の速度で冷却（空冷）し、ケイ酸－バナジン酸化合物粒子を析出させた。各実施例のうち、加熱工程（ＩＶ）を７００℃で実施した粒子について、Ｘ線回折、粒度分布測定、および組成分析を行った。 (Heating step (IV))
The pulverized product obtained in the pulverization step (III) was placed in 3% by volume H 2 —Ar gas, and each example was heated for 8 hours under three temperature conditions of 600 ° C., 700 ° C., and 800 ° C. Then, cooling (air cooling) was performed at a rate of −200 ° C./hour to precipitate silicic acid-vanadic acid compound particles. Among each Example, X-ray diffraction, particle size distribution measurement, and composition analysis were performed about the particle | grains which performed heating process (IV) at 700 degreeC.
（Ｘ線回折）
　得られたケイ酸－バナジン酸化合物粒子の鉱物相を、Ｘ線回折装置（リガク社製、装置名：ＲＩＮＴ　ＴＴＲ ＩＩＩ）を用いて調べた。実施例１～２９で得た粒子は、いずれも斜方晶のオリビン型Ｌｉ2ＳｉＯ4（Ｋ．Ｚａｇｈｉｂ　ｅｔ　ａｌ．，　Ｊｏｕｒｎａｌ　ｏｆ　Ｐｏｗｅｒ　Ｓｏｕｒｃｅｓ，　１６０，　１３８１－１３８６，　２００６　および　Ｒ．Ｄｏｍｉｎｋｏ　ｅｔ　ａｌ．，　Ｅｌｅｃｔｒｏｃｈｅｍｉｓｔｒｙ　Ｃｏｍｍｕｎｉｃａｔｉｏｎｓ，　８，　２１７－２２２　（２００６）参照）に類似した回折パターンを示した。この結果から、ケイ酸－バナジン酸化合物粒子が結晶であり、かつ、Ａ2ＭＳｉＯ4結晶のＳｉの一部がＶに置換された固溶体結晶からなることが確認できた。よって、ｘが０．８≦ｘ＜１である場合には、Ａ2ＭＳｉＯ4結晶のＳｉの一部がＶに置換された固溶体結晶が得られることが確認できた。
　実施例１、２、３、および４で得た各結晶のＸ線回折パターンを、それぞれ図１の（ａ）、（ｂ）、（ｃ）、および（ｄ）に示す。また、実施例５、６、７、および８で得た各結晶のＸ線回折パターンを、それぞれ図２の（ａ）、（ｂ）、（ｃ）、および（ｄ）に、実施例１６、１７、１８、および１９で得た各結晶のＸ線回折パターンを、それぞれ図３の（ａ）、（ｂ）、（ｃ）、および（ｄ）に、示す。 (X-ray diffraction)
The mineral phase of the obtained silicic acid-vanadic acid compound particles was examined using an X-ray diffraction apparatus (manufactured by Rigaku Corporation, apparatus name: RINT TTR III). The particles obtained in Examples 1 to 29 are all orthorhombic olivine-type Li 2 SiO 4 (K. Zaghib et al., Journal of Power Sources, 160, 1361-1386, 2006 and R. Dominko et al. , Electrochemistry Communications, 8, 217-222 (2006)). From this result, it was confirmed that the silicic acid-vanadic acid compound particles were crystals and consisted of solid solution crystals in which a part of Si in the A 2 MSiO 4 crystals was substituted with V. Therefore, when x is 0.8 ≦ x <1, it was confirmed that a solid solution crystal in which a part of Si of the A 2 MSiO 4 crystal was substituted with V was obtained.
The X-ray diffraction patterns of the crystals obtained in Examples 1, 2, 3, and 4 are shown in FIGS. 1 (a), (b), (c), and (d), respectively. In addition, the X-ray diffraction patterns of the crystals obtained in Examples 5, 6, 7, and 8 are shown in FIGS. 2 (a), (b), (c), and (d), respectively. The X-ray diffraction patterns of the crystals obtained in 17, 18 and 19 are shown in FIGS. 3 (a), (b), (c) and (d), respectively.
（粒度分布）
　実施例２および６で得たケイ酸－バナジン酸化合物の粒径分布を、レーザ回折／散乱式粒度分布測定装置（堀場製作所社製、装置名：ＬＡ－９２０）で測定した。体積換算のメディアン径は、それぞれ０．１２μｍ（実施例２）、０．１３μｍ（実施例６）であった。さらに、比表面積を比表面積測定装置（島津製作所社製、装置名：ＡＳＡＰ２０２０）で測定したところ、２３ｍ2／ｇ（実施例２）、２１ｍ2／ｇ（実施例６）であった。 (Particle size distribution)
The particle size distribution of the silicic acid-vanadic acid compounds obtained in Examples 2 and 6 was measured with a laser diffraction / scattering particle size distribution measuring apparatus (manufactured by Horiba, Ltd., apparatus name: LA-920). The median diameters in terms of volume were 0.12 μm (Example 2) and 0.13 μm (Example 6), respectively. Furthermore, it was 23 m < 2 > / g (Example 2) and 21 m < 2 > / g (Example 6) when the specific surface area was measured with the specific surface area measuring apparatus (Shimadzu Corporation make, apparatus name: ASAP2020).
（組成分析）
　得られたケイ酸－バナジン酸化合物粒子の化学組成を測定した。まず、粒子を２．５ｍｏｌ／ＬのＫＯＨ溶液で１２０℃にて加熱密閉分解し、分解液を塩酸酸性下で乾固した。次に、塩酸酸性溶液として濾過した後、濾液および残渣を得た。濾液中のＳｉ、Ｖ、Ｐ、Ｂ、Ａｌ、Ｆｅ、Ｍｎ、Ｃｏ、およびＮｉは、誘導結合発光分光分析装置（セイコーインスツル社製、装置名：ＳＶＳ３１００）を用いて定量した。濾液中のＬｉおよびＮａは原子吸光光度計（日立ハイテクノロジーズ社製、装置名：Ｚ－２３１０）を用いて定量した。Ｓｉ、Ｖ、Ｐ、Ｂ、Ａｌ、Ｆｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｌｉ、およびＮａの定量値から、ＳｉＯ2、Ｖ2Ｏ5、Ｐ2Ｏ5、Ｂ2Ｏ3、Ａｌ2Ｏ3、ＦｅＯ、ＭｎＯ、ＣｏＯ、ＮｉＯ、Ｌｉ2Ｏ、およびＮａ2Ｏの量をそれぞれ算出した。さらに、残渣は灰化した後、フッ酸－硫酸で分解処理し、この処理による重量減少をＳｉＯ2量とした。全ＳｉＯ2量は、重量減少値から算出される量と濾液中のＳｉＯ2量の合量とした。実施例１～４、実施例１６～１９、実施例２２～２４、および実施例２７～３０で得たケイ酸－バナジン酸化合物粒子の化学組成の定量値を、表２に示す。 (Composition analysis)
The chemical composition of the resulting silicic acid-vanadic 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. Si, V, P, B, Al, Fe, Mn, Co, and Ni in the filtrate were quantified using an inductively coupled emission spectroscopic analyzer (manufactured by Seiko Instruments Inc., apparatus name: SVS3100). Li and Na in the filtrate were quantified using an atomic absorption photometer (manufactured by Hitachi High-Technologies Corporation, apparatus name: Z-2310). From the quantitative values of Si, V, P, B, Al, Fe, Mn, Co, Ni, Li, and Na, SiO 2 , V 2 O 5 , P 2 O 5 , B 2 O 3 , Al 2 O 3 , The amounts of FeO, MnO, CoO, NiO, Li 2 O, and Na 2 O were calculated. 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 value and the amount of SiO 2 in the filtrate. Table 2 shows the quantitative values of the chemical compositions of the silicic acid-vanadic acid compound particles obtained in Examples 1 to 4, Examples 16 to 19, Examples 22 to 24, and Examples 27 to 30.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
［実施例４１～４４］
　実施例１、２、３、および４で溶融、冷却、粗粉砕して得られた粗粉砕物とカーボンブラックとを、粗粉砕物とカーボンブラック中の炭素量との質量比で９：１となるように混合し、実施例１と同様にして遊星ミルを用いて粉砕した。各実施例における炭素含有粉砕物をＡｒガス中にて７００℃および８００℃の２種類の温度で８時間加熱し、－２００℃／時間の速度で冷却（空冷）して、ケイ酸－バナジン酸化合物粒子を得た。得られたケイ酸－バナジン酸化合物粒子のＸ線回折パターンは、それぞれ実施例１、２、３、および４のそれとほぼ一致した。 [Examples 41 to 44]
The coarsely pulverized product obtained by melting, cooling, and coarsely pulverizing in Examples 1, 2, 3, and 4 and carbon black were 9: 1 in mass ratio of the coarsely pulverized product and the amount of carbon in the carbon black. The mixture was mixed and ground in the same manner as in Example 1 using a planetary mill. 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-vanadic acid. Compound particles were obtained. The X-ray diffraction patterns of the resulting silicic acid-vanadic acid compound particles almost coincided with those of Examples 1, 2, 3, and 4, respectively.
　実施例４１および４４において、７００℃で８時間加熱し、－２００℃／時間の速度で冷却（空冷）して得たケイ酸－バナジン酸化合物の炭素含有量を、炭素分析装置（堀場製作所社製、装置名：ＥＭＩＡ－９２０Ｖ）で測定したところ、それぞれ９．８質量％（実施例４１）、９．６質量％（実施例４４）であった。また、実施例４１および４４において、７００℃で８時間加熱し、－２００℃／時間の速度で冷却（空冷）して得たケイ酸－バナジン酸化合物粒子の比表面積を測定したところ、それぞれ２５ｍ2／ｇ（実施例４１）、２８ｍ2／ｇ（実施例４４）であった。 In Examples 41 and 44, the carbon content of the silicic acid-vanadic acid compound 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, Ltd.). Product, device name: EMIA-920V), which were 9.8 mass% (Example 41) and 9.6 mass% (Example 44), respectively. In Examples 41 and 44, the specific surface areas of the silicic acid-vanadic acid compound particles obtained by heating at 700 ° C. for 8 hours and cooling (air cooling) at a rate of −200 ° C./hour were measured. 2 / g (Example 41) and 28 m 2 / g (Example 44).
［実施例４５～４６］
　実施例２および６で溶融、冷却、粗粉砕して得られた粗粉砕物とカーボンブラックとシュークロース水溶液とを、粗粉砕物とカーボンブラック中の炭素量とシュークロース中の炭素量との質量比で、０．９０：０．０５：０．０５となるように混合し、実施例４１と同様にして、粉砕、加熱し、空冷して、ケイ酸－バナジン酸化合物粒子を得た。得られたケイ酸－バナジン酸化合物のＸ線回折パターンは、それぞれ実施例２および６のそれとほぼ一致した。 [Examples 45 to 46]
The coarsely pulverized product obtained by melting, cooling, and coarsely pulverizing in Examples 2 and 6, carbon black, and the sucrose aqueous solution, the mass of the coarsely pulverized product, the carbon amount in carbon black, and the carbon amount in sucrose. The mixture was mixed so that the ratio was 0.90: 0.05: 0.05, and pulverized, heated and air-cooled in the same manner as in Example 41 to obtain silicic acid-vanadic acid compound particles. The X-ray diffraction patterns of the obtained silicic acid-vanadic acid compounds almost coincided with those of Examples 2 and 6, respectively.
　実施例４５および４６において、７００℃で８時間加熱し、－２００℃／時間の速度で冷却（空冷）して得たケイ酸－バナジン酸化合物の炭素含有量を、炭素分析装置（堀場製作所社製、装置名：ＥＭＩＡ－９２０Ｖ）で測定したところ、それぞれ７．１質量％（実施例４５）、７．０質量％（実施例４６）であった。また、比表面積を測定したところ、それぞれ４８ｍ2／ｇ（実施例４５）、５３ｍ2／ｇ（実施例４６）であった。 In Examples 45 and 46, the carbon content of the silicic acid-vanadic acid compound 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, Ltd.). Product, device name: EMIA-920V), which were 7.1% by mass (Example 45) and 7.0% by mass (Example 46), respectively. The measured specific surface area, respectively 48m 2 / g (Example 45), was 53m 2 / g (Example 46).
［比較例１］
　溶融物の組成がＬｉ2Ｏ、ＦｅＯ、ＳｉＯ2、Ｖ2Ｏ5換算量（単位：モル％）で、３２．６％、４６．５％、１８．６％、および２．３％となるように、炭酸リチウム（Ｌｉ2ＣＯ3）、四酸化三鉄（Ｆｅ3Ｏ4）、二酸化ケイ素（ＳｉＯ2）、および酸化バナジウム（Ｖ2Ｏ5）をそれぞれ秤量し、乾式で混合・粉砕して原料調合物を得た。原料調合物を実施例１と同様に加熱したが、溶融できなかった。該原料調合物の組成は、式（１）において、ａ＝１、ｂ＝２、ｘ＝０．８に相当する。 [Comparative Example 1]
The composition of the melt is 32.6%, 46.5%, 18.6%, and 2.3% in terms of Li 2 O, FeO, SiO 2 , and V 2 O 5 (unit: mol%). Lithium carbonate (Li 2 CO 3 ), triiron tetroxide (Fe 3 O 4 ), silicon dioxide (SiO 2 ), and vanadium oxide (V 2 O 5 ) were weighed, mixed and pulverized in a dry manner. The raw material formulation was obtained. The raw material formulation was heated as in Example 1, but could not be melted. The composition of the raw material formulation corresponds to a = 1, b = 2, and x = 0.8 in the formula (1).
［実施例４７～５２：Ｌｉイオン二次電池用正極および評価用電池の製造例］
　実施例１、２、３、４、６および２３において、７００℃で８時間加熱し、－２００℃／時間の速度で冷却（空冷）して得たケイ酸－バナジン酸化合物粒子と、２０質量％のショ糖溶液とを、粉砕物とショ糖中の炭素量との質量比が９５：５となるように混合、粉砕し、Ｎ2ガス中にて６００℃で２時間加熱し、冷却後に粉砕して活物質を得た。該活物質とポリフッ化ビニリデン樹脂（結着剤）とアセチレンブラック（導電材）とを、質量比で８５：５：１０の比率となるように秤量し、Ｎ－メチルピロリドン（溶媒）中で均一になるまで混合してスラリーを調製した。次いで、該スラリーをバーコーターで厚さ３０μｍのアルミニウム箔に塗布した。これを空気中にて１２０℃で乾燥させて溶媒を除去した後、ロールプレスで塗工層を圧密化した後、幅１０ｍｍ×長さ４０ｍｍの短冊状に切り出した。 [Examples 47 to 52: Production Examples of Positive Electrode for Li-ion Secondary Battery and Evaluation Battery]
In Examples 1, 2, 3, 4, 6 and 23, silicic acid-vanadic acid compound particles obtained by heating at 700 ° C. for 8 hours and cooling (air cooling) at a rate of −200 ° C./hour, and 20 mass % Sucrose solution was mixed and pulverized so that the mass ratio of the pulverized product to the amount of carbon in the sucrose was 95: 5, heated in N 2 gas at 600 ° C. for 2 hours, and after cooling The active material was obtained by grinding. 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 μm 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.
　塗工層は短冊状アルミニウム箔の先端１０×１０ｍｍの部分を残して剥離し、これを電極とした。得られた電極のロールプレス後の塗工層厚は２０μｍであった。得られた電極は１５０℃で真空乾燥した後、精製アルゴンガスが満たされたグローブボックス中に搬入し、ニッケルメッシュにリチウム箔を圧着した対極と多孔質ポリエチレンフィルム製セパレータを介して対向させ、さらに両側をポリエチレン板で挟んで固定した。 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 μm. The obtained electrode was vacuum-dried at 150 ° C., then carried into a glove box filled with purified argon gas, and opposed to a counter electrode made by pressure bonding a lithium foil to a nickel mesh with a porous polyethylene film separator, Both sides were fixed with a polyethylene plate.
　対向電極をポリエチレン製ビーカに入れ、六フッ化リン酸リチウムをエチレンカーボネートとエチルメチルカーボネートとの混合溶媒（１：１体積比）に１ｍｏｌ／Ｌの濃度で溶解した非水電解液を注入して充分に含浸させた。電解液含浸後の電極をビーカから取り出し、アルミニウムラミネートフィルム袋に入れ、リード線部を取り出して封止して半電池を構成した。この半電池の特性を以下のようにして測定した。 The counter electrode was put in a polyethylene beaker, and a nonaqueous electrolyte solution in which lithium hexafluorophosphate was dissolved in a mixed solvent of ethylene carbonate and ethyl methyl carbonate (1: 1 volume ratio) at a concentration of 1 mol / L was injected. Fully impregnated. The electrode after impregnation with the electrolytic solution was taken out from the beaker, put in an aluminum laminate film bag, the lead wire part was taken out and sealed to form a half battery. The characteristics of this half-cell were measured as follows.
（Ｌｉイオン二次電池用正極の充放電特性評価）
　得られた半電池を６０℃の恒温槽に入れ、定電流充放電試験機（北斗電工社製、装置名：ＨＪ２０１Ｂ）に接続して充放電試験を行った。電流密度は電極活物質の質量（導電材と結着剤とを除いた質量）当たりの電流値を１０ｍＡ／ｇとして充放電を行った。充電終止電位はＬｉ対極基準で４．５Ｖとし、終止電圧に到達後即座に放電を開始した。放電終止電圧はＬｉ対極基準で１．５Ｖとした。この充放電サイクルを３サイクル繰り返した。３サイクル目の放電容量は、それぞれ１５０ｍＡｈ／ｇ（実施例４７）、１５２ｍＡｈ／ｇ（実施例４８）、１４８ｍＡｈ／ｇ（実施例４９）、１４５ｍＡｈ／ｇ（実施例５０）、１５５ｍＡｈ／ｇ（実施例５１）、２４５ｍＡｈ／ｇ（実施例５２）であった。 (Charge / discharge characteristic evaluation of positive electrode for Li ion secondary battery)
The obtained half-cell was placed in a constant temperature bath at 60 ° C. and connected to a constant current charge / discharge tester (manufactured by Hokuto Denko Co., Ltd., device name: HJ201B) to conduct a charge / discharge test. The current density was charged / discharged with the current value per mass of the electrode active material (the mass excluding the conductive material and the binder) being 10 mA / g. The end-of-charge potential was 4.5 V with respect to the Li counter electrode, and discharge was started immediately after reaching the end voltage. The end-of-discharge voltage was 1.5 V with respect to the Li counter electrode. This charge / discharge cycle was repeated three times. The discharge capacities at the third cycle were 150 mAh / g (Example 47), 152 mAh / g (Example 48), 148 mAh / g (Example 49), 145 mAh / g (Example 50), and 155 mAh / g (implemented), respectively. Example 51) and 245 mAh / g (Example 52).
　本発明のケイ酸－バナジン酸化合物の製造方法は、ケイ酸－バナジン酸化合物の組成や粒径の制御がしやすく、製造しやすいので有用である。得られたケイ酸－バナジン酸化合物は、二次電池用正極材料さらには二次電池に適用して有用である。本発明のケイ酸－リン酸化合物を正極材料として用いた二次電池は、プラグインハイブリッド自動車や電気自動車に搭載する二次電池として、また、電力貯蔵用の蓄電池として有用である。

　なお、２０１０年１２月２２日に出願された日本特許出願２０１０－２８５６８０号の明細書、特許請求の範囲、図面及び要約書の全内容をここに引用し、本発明の明細書の開示として、取り入れるものである。 The method for producing a silicic acid-vanadic acid compound of the present invention is useful because the composition and particle size of the silicic acid-vanadic acid compound can be easily controlled and produced. The obtained silicic acid-vanadic acid compound is useful when applied to a positive electrode material for a secondary battery and further to 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.

The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2010-285680 filed on December 22, 2010 are cited herein as disclosure of the specification of the present invention. Incorporated.

Claims (15)

  1. 　式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物の製造方法であって、
    　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d2　　　（Ｂ）
    （式中、ＡはＬｉ、Ｎａ、およびＫからなる群より選ばれる少なくとも１種の元素である。ＭはＦｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、およびＺｎからなる群より選ばれる少なくとも１種の元素である。ＸはＰ、Ｂ、およびＡｌからなる群より選ばれる少なくとも１種の元素である。ｆは０．８＜ｆ＜２．４、ｂは０．７≦ｂ≦１．３、ｃは０＜ｃ≦１、ｘは０．６＜ｘ＜１であり、ｄ２はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。）
    　元素Ａ、元素Ｍ、Ｓｉ、Ｖ、および元素Ｘを含む原料を、元素Ａ、元素Ｍ、Ｓｉ、Ｖ、および元素Ｘのモル比が式（Ｂ）で表されるモル比となるように調整してなる原料調合物を加熱して溶融物を得る工程、
    　前記溶融物を冷却し固化物を得る冷却工程、
    　前記固化物を粉砕し粉砕物を得る粉砕工程、および
    　前記粉砕物を加熱してケイ酸化合物を得る加熱工程、
    　をこの順に実施することを特徴とするケイ酸化合物の製造方法。     A method for producing a silicic acid-vanadic acid compound having a composition represented by the formula (B):
    A f M b Si x (V c X 1-c ) 1-x O 4 + d2 (B)
    (In the formula, A is at least one element selected from the group consisting of Li, Na, and K. M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 <f <2.4, b is 0.7 ≦ b ≦ 1.3, c is 0 <c ≦ 1, x is 0.6 <x <1, and d2 is a number depending on the valence N of X, f, b, c, x, and M.)
    The raw material containing element A, element M, Si, V, and element X is adjusted so that the molar ratio of element A, element M, Si, V, and element X is the molar ratio represented by formula (B) Heating the raw material formulation to obtain a melt,
    A cooling step of cooling the melt to obtain a solidified product,
    A pulverization step of pulverizing the solidified product to obtain a pulverized product, and a heating step of heating the pulverized product to obtain a silicate compound.
    Are carried out in this order. A method for producing a silicic acid compound.
  2. 　下式（Ａ）で表される組成を有する溶融物を得る溶融工程、
    　前記溶融物を冷却して固化物を得る冷却工程、
    　前記固化物を粉砕して粉砕物を得る粉砕工程、および
    　前記粉砕物を加熱して、下式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物を得る加熱工程、をこの順に実施する請求項１に記載のケイ酸－バナジン酸化合物の製造方法。
    　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d1　　　（Ａ）
    （式中、ＡはＬｉ、Ｎａ、およびＫからなる群より選ばれる少なくとも１種の元素である。ＭはＦｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、およびＺｎからなる群より選ばれる少なくとも１種の元素である。ＸはＰ、Ｂ、およびＡｌからなる群より選ばれる少なくとも１種の元素である。ｆは０．８＜ｆ＜２．４、ｂは０．７≦ｂ≦１．３、ｃは０＜ｃ≦１、ｘは０．６＜ｘ＜１であり、ｄ１はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎ’に依存する数であり、加熱工程後にｄ２となる数である。）
    　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d2　　　（Ｂ）
    （式中、Ａ、Ｍ、Ｘ、ｆ、ｂ、ｃ、およびｘは前記と同じ意味を示し、ｄ２はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。）     A melting step for obtaining a melt having a composition represented by the following formula (A):
    A cooling step of cooling the melt to obtain a solidified product,
    A pulverization step of pulverizing the solidified product to obtain a pulverized product, and a heating step of heating the pulverized product to obtain a silicic acid-vanadic acid compound having a composition represented by the following formula (B) are performed in this order: The method for producing a silicic acid-vanadic acid compound according to claim 1.
    A f M b Si x (V c X 1-c ) 1-x O 4 + d1 (A)
    (In the formula, A is at least one element selected from the group consisting of Li, Na, and K. M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 <f <2.4, b is 0.7 ≦ b ≦ 1.3, c is 0 <c ≦ 1, x is 0.6 <x <1, d1 is a number depending on the valence N ′ of X, f, b, c, x, and M, and d2 after the heating step Is a number.)
    A f M b Si x (V c X 1-c ) 1-x O 4 + d2 (B)
    (In the formula, A, M, X, f, b, c, and x have the same meaning as described above, and d2 is a number that depends on the valence N of X, f, b, c, x, and M. .)
  3. 　前記式（Ａ）で表される組成を有する溶融物が、下式（１）で表される組成を有する溶融物であり、前記式（Ｂ）で表される組成を有するケイ酸－バナジン酸化合物が、下式（２）で表される組成を有するケイ酸－バナジン酸化合物である、請求項２に記載のケイ酸－バナジン酸化合物の製造方法。
    　Ａ1+x+aＭbＳｉx（ＶcＸ1-c）1-xＯ4+d11　　　（１）
    　Ａ1+x+aＭbＳｉx（ＶcＸ1-c）1-xＯ4+d12　　　（２）
    （式中、Ａ、Ｍ、Ｘ、ｂ、ｃ、およびｘは前記と同じ意味を示し、ａは－１．０≦ａ≦０．６であり、ｄ１１はＸ、ａ、ｂ、ｃ、ｘ、およびＭの価数Ｎ’に依存する数であり、加熱工程後にｄ１２となる数であり、ｄ１２はＸ、ａ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。）     The melt having the composition represented by the formula (A) is a melt having the composition represented by the following formula (1), and the silicic acid-vanadic acid having the composition represented by the formula (B) The method for producing a silicic acid-vanadic acid compound according to claim 2, wherein the compound is a silicic acid-vanadic acid compound having a composition represented by the following formula (2).
    A 1 + x + a M b Si x (V c X 1-c ) 1-x O 4 + d11 (1)
    A 1 + x + a M b Si x (V c X 1-c ) 1-x O 4 + d12 (2)
    (Wherein A, M, X, b, c, and x have the same meaning as described above, a is −1.0 ≦ a ≦ 0.6, and d11 is X, a, b, c, x , And a number that depends on the valence N ′ of M, and is a number that becomes d12 after the heating step, and d12 is a number that depends on the valence N of X, a, b, c, x, and M. )
  4. 　前記溶融工程が、
    　元素Ａが、Ａの炭酸塩、Ａの炭酸水素塩、Ａの水酸化物、Ａのケイ酸塩、Ａのバナジン酸塩、Ａの塩化物、Ａの硝酸塩、Ａの硫酸塩、およびＡの有機酸塩からなる群より選ばれる少なくとも１種（ただし、該少なくとも１種の一部または全部は、それぞれ水和塩を形成していてもよい。）として含まれ、
    　元素Ｍが、Ｍの酸化物、Ｍのオキシ水酸化物、Ｍの水酸化物、Ｍのケイ酸塩、Ｍのバナジン酸塩、金属Ｍ、Ｍの塩化物、Ｍの硝酸塩、Ｍの硫酸塩、およびＭの有機酸塩からなる群より選ばれる少なくとも１種として含まれ、
    　Ｓｉが、酸化ケイ素、Ａのケイ酸塩、Ｍのケイ酸塩、ケイ酸バナジウム、およびケイ素のアルコキシドからなる群より選ばれる少なくとも１種として含まれ、
    　Ｖが、酸化バナジウム、Ａのバナジン酸塩、Ｍのバナジン酸塩、バナジン酸アンモニウム、ケイ酸バナジウム、塩化バナジウム、およびオキシ硫酸バナジウムからなる群より選ばれる少なくとも１種として含まれる、
    　原料調合物を加熱して、前記溶融物を得る工程である、請求項１～３のいずれか一項に記載のケイ酸－バナジン酸化合物の製造方法。     The melting step is
    Element A is A carbonate, A bicarbonate, A hydroxide, A silicate, A vanadate, A chloride, A nitrate, A sulfate, and A And at least one selected from the group consisting of organic acid salts (however, at least one of the at least one kind may each form a hydrated salt),
    Element M is M oxide, M oxyhydroxide, M hydroxide, M silicate, M vanadate, metal M, M chloride, M nitrate, M sulfate And at least one selected from the group consisting of organic acid salts of M,
    Si is included as at least one selected from the group consisting of silicon oxide, A silicate, M silicate, vanadium silicate, and silicon alkoxide,
    V is included as at least one selected from the group consisting of vanadium oxide, A vanadate, M vanadate, ammonium vanadate, vanadium silicate, vanadium chloride, and vanadium oxysulfate.
    The method for producing a silicic acid-vanadic acid compound according to any one of claims 1 to 3, wherein the melt is obtained by heating a raw material formulation.
  5. 　前記原料調合物が、さらに元素Ｘを、酸化リン、リン酸、リン酸アンモニウム、リン酸水素アンモニウム、Ａのリン酸塩、Ａのリン酸水素塩、Ｍのリン酸塩、酸化ホウ素、ホウ酸、Ａのホウ酸塩、Ｍのホウ酸塩、酸化アルミニウム、およびオキシ水酸化アルミニウムからなる群より選ばれる少なくとも１種として含む、請求項４に記載のケイ酸－バナジン酸化合物の製造方法。 The raw material preparation further contains element X in the form of phosphorus oxide, phosphoric acid, ammonium phosphate, ammonium hydrogen phosphate, A phosphate, A hydrogen phosphate, M phosphate, boron oxide, boric acid. The method for producing a silicic acid-vanadic acid compound according to claim 4, comprising at least one selected from the group consisting of borate of A, borate of M, aluminum borate, aluminum oxide, and aluminum oxyhydroxide.
  6. 　元素ＡがＬｉである、請求項１～５のいずれか一項に記載のケイ酸－バナジン酸化合物の製造方法。 The method for producing a silicic acid-vanadic acid compound according to any one of claims 1 to 5, wherein the element A is Li.
  7. 　元素ＭがＦｅおよびＭｎからなる群より選ばれる少なくとも１種である、請求項１～６のいずれか一項に記載のケイ酸－バナジン酸化合物の製造方法。 The method for producing a silicic acid-vanadic acid compound according to any one of claims 1 to 6, wherein the element M is at least one selected from the group consisting of Fe and Mn.
  8. 　前記冷却工程において、冷却速度を－１×１０3℃／秒～－１×１０10℃／秒とする、請求項１～７のいずれか一項に記載のケイ酸－バナジン酸化合物の製造方法。 The method for producing a silicic acid-vanadic acid compound according to any one of claims 1 to 7, wherein in the cooling step, a cooling rate is set to -1 x 10 3 ° C / sec to -1 x 10 10 ° C / sec. .
  9. 　前記粉砕工程において、前記固化物に、有機化合物および炭素粉末からなる群より選ばれる少なくとも１種の炭素源を含ませ、かつ該炭素源中の炭素換算量（質量）が、固化物の質量と、該炭素源中の炭素換算量（質量）との合計質量に対して０．１～２０質量％である、請求項１～８のいずれか一項に記載のケイ酸－バナジン酸化合物の製造方法。 In the pulverization step, the solidified product contains at least one carbon source selected from the group consisting of an organic compound and carbon powder, and a carbon equivalent amount (mass) in the carbon source is equal to the mass of the solidified product. The production of a silicic acid-vanadic acid compound according to any one of claims 1 to 8, wherein the content is 0.1 to 20% by mass relative to a total mass with respect to a carbon equivalent amount (mass) in the carbon source. Method.
  10. 　前記加熱工程を５００～１，０００℃に加熱することにより行う、請求項１～９のいずれか一項に記載のケイ酸－バナジン酸化合物の製造方法。 The method for producing a silicic acid-vanadic acid compound according to any one of claims 1 to 9, wherein the heating step is performed by heating to 500 to 1,000 ° C.
  11. 　前記式（１）で表される組成を有する溶融物が、下式（１Ａ）で表される組成を有する溶融物であり、前記式（２）で表される組成を有するケイ酸－バナジン酸化合物が、下式（２Ａ）で表される組成を有するオリビン型結晶粒子を含むケイ酸－バナジン酸化合物である、請求項２～１０のいずれか一項に記載のケイ酸－バナジン酸化合物の製造方法。
    　Ｌｉ1+x+a（ＦｅyＭｎ1-y）bＳｉxＶ1-xＯ4+d11　　　（１Ａ）
    　Ｌｉ1+x+a（ＦｅyＭｎ1-y）bＳｉxＶ1-xＯ4+d12　　　（２Ａ）
    （式中、ａ、ｂ、ｄ１１、ｄ１２、およびｘは前記と同じ意味を示し、ｙは０≦ｙ≦１である。）     The melt having the composition represented by the formula (1) is a melt having the composition represented by the following formula (1A), and the silicic acid-vanadic acid having the composition represented by the formula (2) The silicic acid-vanadic acid compound according to any one of claims 2 to 10, wherein the compound is a silicic acid-vanadic acid compound containing olivine type crystal particles having a composition represented by the following formula (2A): Production method.
    Li 1 + x + a (Fe y Mn 1-y ) b Si x V 1-x O 4 + d11 (1A)
    Li 1 + x + a (Fe y Mn 1-y ) b Si x V 1-x O 4 + d12 (2A)
    (Wherein a, b, d11, d12, and x have the same meaning as described above, and y is 0 ≦ y ≦ 1.)
  12. 　請求項１～１１のいずれか一項に記載の製造方法によってケイ酸－バナジン酸化合物を得て、次に、該ケイ酸－バナジン酸化合物を二次電池用正極材料として用いて二次電池用正極を製造することを特徴とする二次電池用正極の製造方法。 A silicic acid-vanadic acid compound is obtained by the production method according to any one of claims 1 to 11, and then the silicic acid-vanadic acid compound is used as a positive electrode material for a secondary battery. A method for producing a positive electrode for a secondary battery, comprising producing a positive electrode.
  13. 　請求項１２に記載の製造方法で二次電池用正極を得て、次に、該二次電池用正極を用いて二次電池を製造することを特徴とする二次電池の製造方法。 A method for producing a secondary battery, comprising: obtaining a positive electrode for a secondary battery by the production method according to claim 12, and then producing a secondary battery using the positive electrode for the secondary battery.
  14. 　下式（Ｂ）で表される組成を有することを特徴とするケイ酸－バナジン酸化合物。
    　ＡfＭbＳｉx（ＶcＸ1-c）1-xＯ4+d2　　　（Ｂ）
    （式中、ＡはＬｉ、Ｎａ、およびＫからなる群より選ばれる少なくとも１種の元素である。ＭはＦｅ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、およびＺｎからなる群より選ばれる少なくとも１種の元素である。ＸはＰ、Ｂ、およびＡｌからなる群より選ばれる少なくとも１種の元素である。ｆは０．８＜ｆ＜２．４、ｂは０．７≦ｂ≦１．３、ｃは０＜ｃ≦１、ｘは０．６＜ｘ＜１であり、ｄ２はＸ、ｆ、ｂ、ｃ、ｘ、およびＭの価数Ｎに依存する数である。）     A silicic acid-vanadic acid compound having a composition represented by the following formula (B):
    A f M b Si x (V c X 1-c ) 1-x O 4 + d2 (B)
    (In the formula, A is at least one element selected from the group consisting of Li, Na, and K. M is at least one element selected from the group consisting of Fe, Mn, Co, Ni, Cu, and Zn. X is at least one element selected from the group consisting of P, B, and Al, f is 0.8 <f <2.4, b is 0.7 ≦ b ≦ 1.3, c is 0 <c ≦ 1, x is 0.6 <x <1, and d2 is a number depending on the valence N of X, f, b, c, x, and M.)
  15. 　下式（２Ａ）で表される組成を有することを特徴とするケイ酸－バナジン酸化合物。
    　Ｌｉ1+x+a（ＦｅyＭｎ1-y）bＳｉxＶ1-xＯ4+d12　　　（２Ａ）
    （式中、ａは－１．０≦ａ≦０．４、ｂは０．７≦ｂ≦１．３、ｘは０．６＜ｘ＜１、ｙは０≦ｙ≦１であり、ｄ１２はａ、ｂ、ｘ、およびＦｅyＭｎ1-yの平均価数Ｎに依存する数である。）     A silicic acid-vanadic acid compound having a composition represented by the following formula (2A):
    Li 1 + x + a (Fe y Mn 1-y ) b Si x V 1-x O 4 + d12 (2A)
    (Where a is −1.0 ≦ a ≦ 0.4, b is 0.7 ≦ b ≦ 1.3, x is 0.6 <x <1, y is 0 ≦ y ≦ 1, d12 Is a number that depends on the average valence N of a, b, x, and Fe y Mn 1-y .)
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JP2014207157A (en) * 2013-04-15 2014-10-30 日本電気硝子株式会社 Positive electrode material for electricity storage device and method for producing the same
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