WO2011138964A1 - (silicic acid)-(phosphoric acid) compound, positive electrode for secondary battery, and process for production of secondary battery - Google Patents

(silicic acid)-(phosphoric acid) compound, positive electrode for secondary battery, and process for production of secondary battery Download PDF

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Publication number
WO2011138964A1
WO2011138964A1 PCT/JP2011/060602 JP2011060602W WO2011138964A1 WO 2011138964 A1 WO2011138964 A1 WO 2011138964A1 JP 2011060602 W JP2011060602 W JP 2011060602W WO 2011138964 A1 WO2011138964 A1 WO 2011138964A1
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silicic acid
phosphoric acid
atom
compound
group
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PCT/JP2011/060602
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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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Priority to JP2012513832A priority Critical patent/JPWO2011138964A1/en
Priority to CN2011800227700A priority patent/CN102884017A/en
Publication of WO2011138964A1 publication Critical patent/WO2011138964A1/en

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    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a silicic acid-phosphoric acid compound, a positive electrode for a secondary battery, and a method for producing a secondary battery.
  • lithium ion secondary batteries have been widely used as power sources for portable electronic devices such as mobile phones and laptop computers, and portable power tools.
  • Application of a lithium ion secondary battery as a power source for an electric vehicle is desired, and attempts have been made to increase the capacity of the positive electrode material of the lithium ion secondary battery in order to realize the application to a power source for an electric vehicle.
  • olivine-type phosphate compounds represented by olivine-type lithium iron phosphate (LiFePO 4 ) ( LiMPO 4 and M are transition metal elements) have attracted attention, and their production methods are being studied.
  • Patent Document 1 Li a M 1 (2 -b) M 2 b Si c P 3-c O 12 (0 ⁇ b ⁇ 2,0 ⁇ c ⁇ 3, a is selected to balance the formula
  • a silicon phosphate compound represented by the following formula has been proposed: the number of Li atoms is greater than 0, and M 1 and M 2 are the same or different transition metal elements. It has been suggested that a portion of PO 4 which is a polyanion is replaced with SiO 2 .
  • Patent Document 2 a mixture containing a transition metal atom M oxide such as Li 2 O and Fe 2 O 3 and P 2 O 5 is melted, and the resulting melt is quenched to obtain a precursor glass. After the formation, the precursor glass is baked to deposit LiFePO 4 crystals, LiMn x Fe 1-x PO 4 crystals (0 ⁇ x ⁇ 1), etc., thereby producing a positive electrode material for a secondary battery. It is described to do.
  • a transition metal atom M oxide such as Li 2 O and Fe 2 O 3 and P 2 O 5
  • Patent Document 1 Since the manufacturing method described in Patent Document 1 is manufactured by reacting raw materials, the manufacturing process is complicated and the manufacturing cost increases. Moreover, although manufacture of the silicon phosphate compound is suggested, the example actually manufactured is not described in the Example. In the production method described in Patent Document 2, it is difficult to control the composition of the silicic acid-phosphoric acid compound particles. Also, be contained Nb 2 O 5, V 2 O 5, SiO 2, Sb 2 O 3 and Bi 2 O 3 or the like for the purpose of improving the vitrification, the molar ratio of P 2 O 5 in terms of oxide Since it has a relatively high glass composition, the upper limit of the heating temperature for melting the raw material is limited to a temperature at which P does not evaporate. For this reason, there existed a problem that manufacturing conditions were restrict
  • An object of the present invention is to provide a method that makes it easy to control the composition of a silicic acid-phosphoric acid compound and that is easy to manufacture. According to the method of the present invention, a method for producing a silicic acid-phosphoric acid compound having excellent battery characteristics and reliability at low cost and efficiently can be provided. Furthermore, this invention provides the manufacturing method of the positive electrode for secondary batteries which is excellent in a battery characteristic and reliability, and a secondary battery.
  • the present invention is the following [1] to [15].
  • the oxide equivalent amount of each atom when it becomes a melt (unit: Mol%) 15% ⁇ A 2 O ⁇ 30%, 35% ⁇ MO ⁇ 55%, 15% ⁇ SiO 2 ⁇ 50%, 1% ⁇ P 2 O 5 ⁇ 18%, 0.8 ⁇ A 2 O / (0.5SiO 2 + P 2 O 5 ) ⁇ 1.2, 0.8 ⁇ A 2 O / 0.5MO ⁇ 1.2, Heating the raw material formulation to obtain a melt, Cooling the melt to obtain a solidified product, A step of pulverizing the solidified product to obtain a pulverized product, and a heating step of heating the pulverized product to obtain a silicic
  • Atom M is selected from the group consisting of M oxide, M oxyhydroxide, M metal, M phosphate, M chloride, M nitrate, M sulfate, and M organic salt
  • At least one Si is a silicate of A selected from the group consisting of silicon oxide, A 2 SiO 3 and A 4 SiO 4 (where A is the same kind of atom as described above), and MSiO 3 and M 2 SiO 4 M silicate selected from the group consisting of (wherein M is the same kind of atom as described above), and included as at least one selected from the group consisting of:
  • P is at least one selected from the group consisting of phosphorus oxide, ammonium phosphate, ammonium hydrogen phosphate, phosphoric acid, polyphosphoric acid, phospho
  • the silicic acid-phosphoric acid compound having the composition represented by the formula (1) is a crystal particle of a compound having the composition represented by the following formula (2): [1] to [3] A method for producing a silicic acid-phosphoric acid compound.
  • the solidified product includes at least one carbon source selected from the group consisting of an organic compound and a carbon-based conductive active material, and the amount of the carbon source is determined based on the amount of the solidified product and carbon.
  • the silicic acid-phosphoric acid of [1] to [7], wherein the ratio of the carbon conversion amount (mass) to the total mass with the carbon conversion amount (mass) in the source is 0.1 to 20% by mass A method for producing a compound.
  • the conductive carbonaceous layer may be 0.1 to 20% by mass of the silicic acid-phosphoric acid compound particles based on the total mass of the silicic acid-phosphoric acid compound and the conductive carbonaceous layer.
  • the silicic acid-phosphoric acid compound according to [12] which is contained on the surface of the particle or the interparticle interface.
  • [14] Obtaining a silicic acid-phosphoric acid compound by the production method of [1] to [11], and producing a secondary battery positive electrode using the silicic acid-phosphoric acid compound as a positive electrode material for a secondary battery. The manufacturing method of the positive electrode for secondary batteries characterized by these.
  • a method for producing a secondary battery comprising obtaining a positive electrode for a secondary battery by the production method of [14], and then producing a secondary battery using the positive electrode for a secondary battery.
  • the method for producing a silicic acid-phosphoric acid compound of the present invention provides a method for efficiently producing a silicic acid-phosphoric acid compound using an inexpensive raw material and a simple technique.
  • a silicic acid-phosphoric acid compound having a desired composition can be produced efficiently. Therefore, by using the silicic acid-phosphoric acid compound obtained by the present invention, a positive electrode for secondary batteries and a secondary battery excellent in battery characteristics and reliability can be produced.
  • the present invention also provides a silicic acid-phosphoric acid compound that is excellent in battery characteristics and reliability.
  • FIG. 3 is a diagram showing an X-ray diffraction pattern of silicic acid-phosphoric acid compound particles produced in Examples 1, 3 and 6.
  • FIG. 4 is a view showing an X-ray diffraction pattern of silicic acid-phosphoric acid compound particles produced in Examples 13 and 14.
  • A represents at least one atom selected from the group consisting of Li, Na and K.
  • A represents an atom of the above three alkali metal elements.
  • A may consist of a combination of two or more atoms.
  • M represents at least one atom selected from the group consisting of Fe, Mn, Co and Ni.
  • M represents an atom of the above four transition metal elements. M may consist of a combination of two or more atoms.
  • chemical formulas, such as Formula (1), Formula (2), Formula (3) represent an average composition.
  • a crystal having an olivine structure is hereinafter referred to as an olivine crystal, and a particle containing the olivine crystal is also referred to as an olivine crystal particle.
  • the olivine-type crystal particle may partially include a crystal structure other than the olivine-type crystal structure, or may partially include an amorphous structure. It is preferable that substantially all of the olivine type crystal particles are made of olivine type crystals.
  • step (1) In the method for producing a silicic acid-phosphoric acid compound of the present invention, the following step (1), step (2), step (3), and step (4) are performed in this order. Other steps may be performed before, between and after the steps (1) to (4) as long as each step is not affected.
  • Step (1) at least one atom A selected from the group consisting of Li, Na and K; at least one atom M selected from the group consisting of Fe, Mn, Co and Ni;
  • the oxide equivalent amount (unit: mol%) of the content of each atom when it becomes a product is 15% ⁇ A 2 O ⁇ 30%, 35% ⁇ MO ⁇ 55%, 15% ⁇ SiO 2 ⁇ 50% 1% ⁇ P 2 O 5 ⁇ 18%, 0.8 ⁇ A 2 O / (0.5SiO 2 + P 2 O 5 ) ⁇ 1.2, 0.8 ⁇ A 2 O / 0.5MO ⁇ 1 .2.
  • Step (2) Heating the raw material formulation to obtain a melt
  • Step (3) pulverizing the solidified product to obtain a pulverized product
  • Step (4) A step of heating the pulverized product to obtain a silicic acid-phosphoric acid compound having a composition represented by the formula (1).
  • step (1) since it can be melted in a wide composition range by forming a melt having the above composition in step (1), the following step (2), step (3), and step (4) are performed. As a result, a silicic acid-phosphoric acid compound having a desired composition represented by the formula (1) can be obtained. Accordingly, it is possible to produce a silicic acid-phosphoric acid compound having a composition not described in Patent Document 1.
  • the composition has a relatively low molar ratio of P 2 O 5 in terms of oxide, the material cost can be reduced. Moreover, since the upper limit of the heating temperature at the time of melting a raw material formulation rises, a melting temperature range can be expanded and it becomes easy to manufacture. Hereinafter, each step will be specifically described.
  • step (1) first, at least one atom A selected from the group consisting of Li, Na and K, at least one atom M selected from the group consisting of Fe, Mn, Co and Ni, Si and (Wherein at least one selected from the group consisting of atom A, atom M, Si and P is included as an oxide), and an oxide having a content of each atom when it becomes a melt
  • the conversion amount (unit: mol%) is 15% ⁇ A 2 O ⁇ 30%, 35% ⁇ MO ⁇ 55%, 15% ⁇ SiO 2 ⁇ 50%, 1% ⁇ P 2 O 5 ⁇ 18%,
  • a raw material formulation having 0.8 ⁇ A 2 O / (0.5SiO 2 + P 2 O 5 ) ⁇ 1.2 and 0.8 ⁇ A 2 O / 0.5MO ⁇ 1.2 is obtained.
  • the raw material formulation is heated to obtain a melt.
  • the raw material preparation Before the raw material preparation is heated, it may be mixed, pulverized and heated to obtain a melt.
  • the raw material preparation may be manufactured after each raw material has been pulverized in advance.
  • the raw material mixture is mixed and pulverized using a ball mill, a jet mill, a planetary mill or the like in a dry or wet manner. A dry method is preferable in that it is not necessary to remove the dispersion medium.
  • melt has a composition satisfying 15% ⁇ A 2 O ⁇ 30%, 35% ⁇ MO ⁇ 55%, 15% ⁇ SiO 2 ⁇ 50%, and 1% ⁇ P 2 O 5 ⁇ 18% This is preferable because the product can be easily melted.
  • MO is 55% or more
  • SiO 2 is 15% or less
  • P 2 O 5 is 1% or less
  • MO is 35% or less
  • dissolves means that a raw material formulation melt
  • the melt further has a composition satisfying 18% ⁇ A 2 O ⁇ 25%, 40% ⁇ MO ⁇ 50%, 17% ⁇ SiO 2 ⁇ 38%, and 1% ⁇ P 2 O 5 ⁇ 18%.
  • the desired silicic acid-phosphoric acid compound can be obtained, which is particularly preferable.
  • the melt is not limited to those consisting only of atoms A, atoms M, silicon (Si), phosphorus (P), and oxygen (O), but from Ti, V, B, Al, Ca, Cu, Mg, and Zn. It may contain at least one atom X selected from the group consisting of By containing the atom X, the raw material preparation can be easily melted.
  • the content of atoms X (the total amount in the case of a plurality of atoms) is 0.1 to 5% in terms of oxide content (unit: mol%) of the content of each atom when it becomes a melt. preferable.
  • atoms A, atoms M, Si and P are converted into oxides (unit: mol%) of the content of each atom when it becomes a melt, and 15% ⁇ A 2 O ⁇ 30% 35% ⁇ MO ⁇ 55%, 15% ⁇ SiO 2 ⁇ 50%, 1% ⁇ P 2 O 5 ⁇ 18%, 0.8 ⁇ A 2 O / (0.5SiO 2 + P 2 O 5 ) ⁇
  • the raw materials are selected and mixed so that a melt satisfying 1.2, 0.8 ⁇ A 2 O / 0.5MO ⁇ 1.2 is obtained.
  • the raw material is a compound containing atom A, a compound containing atom M, a compound containing Si, a compound containing P, or a compound containing atom X as necessary.
  • A may be at least one atom selected from the group consisting of Li, Na and K. However, since it is suitable as a positive electrode material for a secondary battery, it is preferable to make Li essential. It is particularly preferred.
  • the silicic acid-phosphoric acid compound containing Li can increase the capacity per unit volume (mass) of the secondary battery.
  • Compounds containing an atom A include A carbonate (A 2 CO 3 ), A bicarbonate (AHCO 3 ), A hydroxide (AOH), A phosphate and hydrogen phosphate (A t H 3 ⁇ t PO 4 , 0 ⁇ t ⁇ 3), A nitrate (ANO 3 ), A chloride (ACl), A sulfate (A 2 SO 4 ), A acetate (CH 3 COOA) ) And A oxalate ((COOA) 2 ), and at least one selected from the group consisting of (COOA) 2 ) (however, these compounds may each form a hydrate salt).
  • a 2 CO 3 or AHCO 3 is particularly preferable because it is inexpensive and easy to handle.
  • ⁇ Compound containing atom M> M may be at least one atom selected from the group consisting of Fe, Mn, Co and Ni.
  • the silicic acid-phosphoric acid compound is applied to the positive electrode material for secondary batteries, it is preferable to use at least one atom selected from the group consisting of Fe and Mn as M from the viewpoint of cost.
  • Fe is particularly preferable because the theoretical capacity of the positive electrode material for a secondary battery is easily developed. From the viewpoint of increasing the operating voltage, at least one atom selected from the group consisting of Co and Ni is preferable.
  • 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
  • Oxyhydroxide (MO (OH)) of element M metal M, M phosphate (M 3 (PO 4 ) 2 , MPO 4 ), M chloride, M nitrate, M sulfate, M At least one selected from the group consisting of organic salts and the like is preferred.
  • Fe 3 O 4 , Fe 2 O 3 , MnO 2 , Co 3 O 4 or NiO is more preferable because it is inexpensive and easy to handle.
  • Fe 3 O 4 , Fe 2 O 3 or MnO 2 is particularly preferred.
  • silicate of A selected from the group consisting of silicon oxide (SiO 2 ), A 2 SiO 3 and A 4 SiO 4 (where A is the same kind of atom as described above), And at least one selected from the group consisting of M silicates selected from the group consisting of MSiO 3 and M 2 SiO 4 (wherein M is the same type of atom as described above).
  • SiO 2 is particularly preferable from the viewpoint of inexpensiveness.
  • the compound containing Si may be crystalline or amorphous.
  • NH 4 H 2 PO 4 , (NH 4 ) 2 HPO 4 , A phosphate or P 2 O 5 is particularly preferable because it is inexpensive and easy to handle.
  • a suitable combination of a compound containing atom A as a raw material formulation, a compound containing atom M, a compound containing Si, and a compound containing P is: Compounds containing atom A are A carbonate (A 2 CO 3 ), bicarbonate (AHCO 3 ), A hydroxide (AOH), A phosphate and hydrogen phosphate (A t H 3 -T PO 4 , 0 ⁇ t ⁇ 3), A nitrate (ANO 3 ), A chloride (ACl), A sulfate (A 2 SO 4 ), A acetate (CH 3 COOA), and At least one selected from the group consisting of oxalates of A (however, these compounds may each form a hydrate salt); A compound containing an atom M is an oxide 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), M Oxyhydr
  • the compound containing atom A is a carbonate of A (A 2 CO 3 ) or a bicarbonate (AHCO 3 );
  • the compound containing the atom M is an oxide 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) or M Oxyhydroxide (MO (OH)) of
  • the compound containing Si is silicon oxide (SiO 2 ),
  • the combination in which the compound containing P is ammonium hydrogen phosphate ((NH 4 ) 2 HPO 4 , NH 4 H 2 PO 4 ).
  • the composition of the raw material formulation corresponds theoretically to the composition of the melt obtained from the raw material formulation.
  • this raw material formulation there are components that are easily lost due to volatilization etc. during melting, such as Li, P, etc., so the composition of the resulting melt is determined by each element calculated from the amount of each raw material charged. May be slightly different from the oxide equivalent amount (unit: mol%).
  • the purity of the raw material in a raw material formulation is not specifically limited, The range which does not reduce a desired characteristic is preferable.
  • the purity excluding the water of hydration is preferably 99% or more, particularly preferably 99.9% or more.
  • the particle size of the raw material is not particularly limited as long as it is within a range in which a uniform melt can be obtained by melting.
  • the container used for heating is preferably made of alumina, carbon, silicon carbide, zirconium boride, titanium boride, boron nitride, platinum or platinum containing rhodium, but refractory bricks should be used. You can also. Furthermore, it is preferable to attach a lid to the container in order to prevent volatilization and evaporation.
  • Heating is preferably performed using a resistance heating furnace, a high frequency induction furnace or a plasma arc furnace.
  • the electric resistance furnace is particularly preferably an electric furnace provided with a heating element made of a metal such as a nichrome alloy, silicon carbide, or molybdenum silicide.
  • the temperature at which the raw material mixture is heated and melted is preferably 1,250 ° C. to 1,550 ° C., particularly preferably 1,350 ° C. to 1,500 ° C.
  • the time for heating and melting the raw material preparation is preferably 0.2 to 2 hours, particularly preferably 0.5 to 2 hours. If the melting time is not less than the lower limit of the above range, the uniformity of the melt will be sufficient, and if it is not more than the upper limit, the raw material components will not easily evaporate.
  • step (2) the melt obtained in step (1) is rapidly cooled to around room temperature (20 to 25 ° C.) to obtain a solidified product.
  • the solidified product preferably contains an amorphous part.
  • the amorphous part it is softer than the crystalline part and thus easily pulverized, and the material diffusion in the amorphous part is fast, so that the reactivity can be increased. It becomes easy to control the composition of the silicic acid-phosphoric acid compound.
  • the product can be prevented from being agglomerated, and the particle size of the product can be easily controlled.
  • the amorphous part is preferably 80 to 100% by mass of the solidified product.
  • the amorphous part prefferably be in this range because the solidified product is easily pulverized and the reactivity is increased.
  • the wear of the cooling device is remarkably accelerated, and the burden of the subsequent step (3) is increased.
  • the cooling of the melt is preferably performed in an inert gas or a reducing gas because the equipment is simple. According to this cooling method, an amorphous substance can be obtained more easily.
  • the cooling rate is preferably not less than -1 ⁇ 10 3 °C / sec, -1 ⁇ 10 4 °C / sec or more is particularly preferable.
  • a temperature change per unit time (ie, cooling rate) in the case of cooling is indicated by a negative value
  • a temperature change per unit time in case of heating ie, the heating rate
  • the 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.
  • 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.
  • a fiber-like solidified material can be obtained by winding a fiber-like solidified material (long fiber) continuously from the melt with a drum that rotates at high speed, or by using a spinner that rotates at high speed and has pores on the side walls. You may use the method of obtaining (short fiber). If these apparatuses are used, the melt is effectively cooled, and a solidified product having a high purity and a uniform chemical composition can be obtained.
  • a cooling method there is also a method in which the melt is directly poured into water, but this method is difficult to control, it is difficult to obtain an amorphous material, the solidified product becomes a lump, and the disadvantage of requiring a lot of labor for grinding 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 solidified product 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.
  • Step (3) is a step of pulverizing the solidified product obtained in step (2) to obtain a pulverized product.
  • the solidified product may contain at least one carbon source selected from the group consisting of an organic compound and a carbon-based conductive active material.
  • the solidified product may be pulverized after containing the carbon source.
  • the solidified product may be pulverized in advance and then mixed with the carbon source.
  • the solidified product and the carbon source may be pulverized in advance. You may mix.
  • the carbon source has an action of preventing oxidation and promoting reduction in the steps (3) and (4).
  • the carbon source is mixed with the solidified product and pulverized to uniformly coat the surface of the solidified product or exists at the interface between the solidified products
  • a silicic acid-phosphate compound was used as the positive electrode material of the secondary battery.
  • the conductive material can be a positive electrode material.
  • the mixing / pulverization is preferably performed by a dry or wet method using a ball mill, a jaw crusher, a jet mill, a planetary mill or the like.
  • a carbon source when included, it is preferable to pulverize in a wet manner in order to uniformly disperse the carbon source on the surface of the pulverized product.
  • the carbon source is an organic compound
  • wet pulverization using a dispersion medium capable of dissolving the organic compound is preferable.
  • the subsequent step (4) is preferably performed after the dispersion medium is removed by sedimentation, filtration, drying under reduced pressure, drying by heating, and the like.
  • the average particle diameter of the pulverized product is preferably 1 nm to 100 ⁇ m, more preferably 10 nm to 10 ⁇ m, and particularly preferably 10 nm to 1 ⁇ m in terms of volume median diameter in order to increase conductivity when applied to a positive electrode material for a secondary battery.
  • the average particle size is not less than the lower limit of the above range, because the pulverized products are not sintered together in the subsequent step (4) and the particle size is not too large. Moreover, since it is less than the upper limit of the said range, the heating temperature and time of the following process (4) can be reduced, it is preferable.
  • Organic compound at least one selected from the group consisting of saccharides, amino acids, peptides, aldehydes and ketones is preferable, and saccharides, amino acids and peptides are particularly preferable.
  • sugars include monosaccharides such as glucose, fructose, and galactose; oligosaccharides such as sucrose, maltose, cellobiose, and trehalose; polysaccharides such as invert sugar, dextrin, amylose, amylopectin, and cellulose; and similar substances such as ascorbic acid. Can be mentioned. Monosaccharides and oligosaccharides are preferred because of their strong reducing properties.
  • 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.
  • organic compounds having a reducing functional group such as an aldehyde group or a ketone group are also included.
  • the organic compound specifically, glucose, sucrose, glucose-fructose invert sugar, caramel, starch, pregelatinized starch, carboxymethylcellulose and the like are preferable.
  • Carbon-based conductive active material As the carbon-based conductive active material, carbon black, graphite, acetylene black, carbon fiber, amorphous carbon and the like are preferable. By including the carbon-based conductive active material at the time of mixing and pulverizing the solidified product, it is not necessary to separately provide a step of mixing the carbon-based conductive active material after producing the silicic acid-phosphate compound in step (4). . Furthermore, by including the carbon-based conductive active material together with the organic compound when the formulation is pulverized, the distribution of the carbon-based conductive active material in the silicic acid-phosphate compound powder becomes uniform, and the organic compound or its thermal decomposition The contact area with the object (carbide) increases. This makes it possible to increase the binding force of the carbon-based conductive active material to the silicic acid-phosphoric acid compound.
  • 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 mass% is particularly preferred.
  • Step (4) is a step of obtaining a silicic acid-phosphoric acid compound having a composition represented by formula (1), preferably crystal grains thereof.
  • Step (4) preferably includes crystal nucleation and grain growth of the pulverized product. Further, when at least one selected from the group consisting of an organic compound and a carbon-based conductive active material is included in the previous pulverization step, the resulting silicic acid-phosphoric acid compound, preferably on the surface of the crystal particles. It is preferably a step of bonding at least one selected from an organic compound, a carbon-based conductive active material, and a reactant thereof. When the step (3) is performed by a wet method, the dispersion medium may be removed at the same time as the heating and firing.
  • a part of 0.3 to 15 mol% of the atom M may be substituted with an element having a valence of +2 or +3.
  • Ti, V, B, Al, Ca, Cu, Mg, and Zn are mentioned.
  • the silicic acid-phosphoric acid compound particles represented by the formula (1) are a compound having a composition represented by the formula (2) and are crystalline particles because they can be manufactured at low cost.
  • Li x (Fe b Mn 1-b ) y Si a P 1-a O z (2) In the formula, x, y, z and a are respectively the same numerical values as above, and b is 0 ⁇ b ⁇ 1.
  • the silicic acid-phosphoric acid compound particles represented by the above formula (2) are compounds having the composition represented by the formula (3), a material that exhibits good characteristics can be produced at low cost. Particularly preferred. LiFe b Mn 1-b Si a P 1-a O z (3) (In the formula, z, a and b are respectively the same numerical values as described above.)
  • A +1 valence
  • M +2 valence
  • Si +4 valence
  • Step (4) is preferably performed in an inert gas or a reducing gas.
  • 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 container containing the reducing agent for example, graphite
  • the pulverized material is loaded in the heating furnace, reduction of M ions in the pulverized material (for example, change from M 3+ to M 2+ ). Can be promoted.
  • a silicic acid-phosphoric acid compound having a composition represented by the formula (1) can be obtained with good reproducibility.
  • the heating temperature is preferably 500 to 1,000 ° C, particularly preferably 600 to 900 ° C.
  • the heating temperature is 1,000 ° C. or less, the pulverized product is difficult to melt and the crystal diameter and particle diameter can be easily controlled.
  • a silicic acid-phosphoric acid compound having an appropriate crystallinity, particle size, particle size distribution, and the like, preferably crystal particles thereof can be easily obtained.
  • Step (4) may be performed at a constant temperature or by changing the 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 a desired particle diameter.
  • the heating time (holding time depending on the heating temperature) is preferably 1 to 72 hours in consideration of a desired particle size.
  • 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, more preferably 1 to 10% by volume of the reducing gas 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 cooling rate in the cooling is preferably ⁇ 30 ° C./hour to ⁇ 300 ° C./hour.
  • the cooling rate is preferably ⁇ 30 ° C./hour to ⁇ 300 ° C./hour.
  • the cooling may be left to cool to room temperature. Cooling is preferably performed in an inert gas or a reducing gas.
  • the organic compound or carbon-based conductive active material adhering to the surface of the pulverized product in the step (3) can bind to the particle surface of the silicic acid-phosphate compound generated in the step (4) and function as a conductive material.
  • the organic compound is thermally decomposed in the step (4), and at least a part of the organic compound becomes a carbide to function as a conductive material.
  • the thermal decomposition of the organic compound is preferably performed at 400 ° C. or lower, and the carbonization is preferably performed at 600 ° C. or lower. When pyrolysis is performed at 600 ° C.
  • the volume change associated with the pyrolysis reaction can be reduced, so that the carbide and the carbon-based conductive active material can be used as a conductive carbonaceous layer. It can bond uniformly and firmly to the surface of the acid-phosphate compound particles or the interface between the silicic acid-phosphate compound particles.
  • the particles of silicic acid-phosphoric acid compound further contain a conductive carbonaceous layer, and 0.1 to 20% by mass with respect to the total mass of the silicic acid-phosphoric acid compound and the conductive carbonaceous layer.
  • the conductive carbonaceous layer is preferably contained on the surface of the particles or at the interface between the particles, and particularly preferably 2 to 10% by mass.
  • silicic acid-phosphate compound having a composition represented by the formula (1) is produced.
  • the silicic acid-phosphoric acid compound is preferably a particle, more preferably a crystal particle, and particularly preferably an olivine type crystal particle.
  • the particles include both primary particles and secondary particles.
  • a carbon source is included in the solidified product
  • a conductive material based on an organic compound or a carbon-based conductive active material is uniformly and firmly formed on the surface simultaneously with the formation of crystal particles of a silicic acid-phosphoric acid compound. Combined materials can be produced.
  • This powder material is suitable for a positive electrode material for a secondary battery.
  • secondary particles When secondary particles are present in the obtained silicic acid-phosphate compound particles and the powder material containing the same, they may be crushed and pulverized to the extent that the primary particles are not destroyed.
  • the crystal particles preferably have an orthorhombic crystal system and do not include crystals composed of cristobalite and phosphoric acid M.
  • the average particle size of the silicic acid-phosphoric acid compound particles 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 powder of silicic acid-phosphoric acid compound particles 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 powder consisting of phosphoric acid compound is preferably 0.2 ⁇ 200m 2 / g, 1 ⁇ 200m 2 / g is particularly preferred.
  • the specific surface area can be measured by, for example, a specific surface area measuring apparatus using a nitrogen adsorption method.
  • the crystal particles are preferably composed only of primary particles.
  • the method for producing a silicic acid-phosphoric acid compound of the present invention is excellent in manufacturability and composition controllability of the silicic acid-phosphoric acid compound, an olivine-type silicic acid-phosphoric acid compound can be produced at low cost and efficiently. it can.
  • the manufacturability of the silicic acid-phosphoric acid compound crystal particles can be enhanced. Further, it is possible to obtain silicic acid-phosphoric acid compound crystal particles having excellent chemical composition and uniform particle diameter and high crystallinity.
  • a positive electrode for a secondary battery can be produced using the silicic acid-phosphate compound obtained by the production method of the present invention as a positive electrode material for a secondary battery.
  • the silicic acid-phosphoric acid compound of the present invention is used as a positive electrode material for a secondary battery, when the atom M is, for example, Fe and / or Mn, these divalent / trivalent redox reactions are utilized for charging and discharging, Works.
  • the crystalline particles of silicic acid-phosphoric acid compound obtained by the production method of the present invention have high crystallinity, and therefore, when applied to a positive electrode material for a secondary battery, suppresses functional deterioration during repeated use. Can do. Therefore, it is possible to provide a secondary battery positive electrode excellent in battery characteristics and reliability at low cost.
  • 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-phosphoric acid compound obtained by the manufacturing method of the present invention is used.
  • a silicic acid-phosphoric acid compound powder may be added to a known binder (polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, ethylene propylene diene polymer, styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluorine if necessary.
  • the mixed powder thus obtained may be press-molded on a support made of stainless steel or filled in a metal container.
  • the mixed powder is mixed with an organic solvent (N-methylpyrrolidone, toluene, cyclohexane, dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran.
  • organic solvent N-methylpyrrolidone, toluene, cyclohexane, dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran.
  • a metal substrate such as aluminum, nickel, stainless steel, or copper can also be employed.
  • a secondary battery By using the silicic acid-phosphoric acid compound obtained by the production method of the present invention as a positive electrode material for a secondary battery, 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 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 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 non-aqueous electrolyte lithium ion secondary battery is preferable.
  • the secondary battery manufacturing method of the present invention by applying the secondary battery positive electrode obtained by the secondary battery positive electrode manufacturing method of the present invention to the secondary battery positive electrode, characteristics and reliability can be improved. An excellent secondary battery can be obtained.
  • Examples 1 to 14 Lithium carbonate (Li 2 CO 3 ), so that the composition of the melt is a Li 2 O, FeO, MnO, SiO 2 and P 2 O 5 conversion amount (unit: mol%), and the ratio shown in Table 1 respectively.
  • Triiron tetroxide (Fe 3 O 4 ), manganese dioxide (MnO 2 ), silicon dioxide (SiO 2 ), and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) were weighed, mixed and pulverized in a dry process. A raw material formulation was obtained.
  • the obtained raw material mixture was filled in a platinum crucible containing 20% by mass of rhodium.
  • the crucible was placed in an electric furnace (model name: NH-3035, manufactured by Motoyama) equipped with a heating element made of molybdenum silicide.
  • the electric furnace was heated at a rate of 300 ° C./hour and heated at 1,350 to 1,450 ° C. for 0.5 hour while flowing N 2 gas at a flow rate of 1 L / min. Each melt was obtained after confirming that it became transparent visually.
  • composition analysis The chemical composition of the resulting silicic acid-phosphoric acid compound particles was measured. First, silicic acid-phosphoric acid compound particles were decomposed by heating and sealing with a 2.5 mol / L NaOH solution at 120 ° C., and the decomposed solution was dried to dryness under hydrochloric acid acidity and filtered again as hydrochloric acid acidic solution. A residue was obtained. Fe, Mn, Si, and P in the filtrate use an inductively coupled emission spectroscopic analyzer (manufactured by Seiko Instruments Inc., apparatus name: SPS3100), and Li in the filtrate uses an atomic absorption photometer (manufactured by Hitachi High-Technologies Corporation, apparatus name). : Z-2310).
  • Example 15 With respect to the flaky solidified product obtained in Example 3, carbon black and glucose (aqueous solution) are mixed so that the mass ratio of the solidified product, carbon black and glucose is 90: 2.5: 2.5. Added to. Next, using a ball made of zirconia, it was pulverized in a dry manner to obtain a pulverized product.
  • the obtained pulverized product was heated at 800 ° C. for 8 hours in Ar gas in the same manner as in Example 3.
  • the chemical composition of the obtained particles was measured in the same manner as in Example 3.
  • the chemical composition was Li 0.99 Fe 0.98 Si 0.63 P 0.37 O 3.66 .
  • the carbon content of the obtained particles was measured using a carbon analyzer (manufactured by Horiba, Ltd., apparatus name: EMIA-920A), it was 2.8% based on the C mass.
  • grains was 1.4 micrometers in median diameter of volume conversion.
  • Example 16 Manufacture of positive electrode for Li ion secondary battery and evaluation battery
  • the carbon-containing particles obtained in Example 15 were used as active materials, and these, polyvinylidene fluoride resin as a binder, and acetylene black as a conductive material were weighed so as to have a mass ratio of 85: 5: 10.
  • N-methylpyrrolidone was mixed well as a solvent to prepare a slurry.
  • the slurry was applied to an aluminum foil having a thickness of 30 ⁇ m with a bar coater.
  • the solvent was removed by drying at 120 ° C. in the air, and then the coating layer was consolidated by a roll press and cut into strips each having a width of 10 mm and a length of 40 mm.
  • 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 in which lithium foil was pressure-bonded 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 these half cells were measured as follows.
  • This charge / discharge cycle was repeated 10 cycles.
  • the discharge capacity at the fifth cycle of the half cell using the active material of Example 15 was 128 mAh / g. Further, the charge / discharge cycle was repeated 10 cycles in the same manner at 60 ° C.
  • the discharge capacity at the fifth cycle was 148 mAh / g.
  • Lithium carbonate (5%, 60%, 30%, 5%) in terms of Li 2 O, FeO, SiO 2 and P 2 O 5 equivalent amounts (unit: mol%), respectively, Li 2 CO 3 ), triiron tetroxide (Fe 3 O 4 ), silicon dioxide (SiO 2 ), and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) are weighed, mixed and pulverized in a dry process, A raw material formulation was obtained. Although it melted at 1,450 ° C. in the same manner as in Example 1, a complete melt could not be obtained.
  • Example 1 a silicic acid-phosphoric acid compound having a desired composition could be produced efficiently. Further, it was confirmed in Example 16 that the produced silicic acid-phosphoric acid compound had excellent characteristics as a positive electrode material for a secondary battery and further as a secondary battery.
  • the method for producing a silicic acid-phosphoric acid compound of the present invention is useful because the composition of the silicic acid-phosphoric acid compound can be easily controlled and produced.
  • the obtained silicic acid-phosphoric acid compound is useful when applied to a positive electrode material for a secondary battery and further to a secondary battery.

Abstract

Disclosed is a process for producing a (silicic acid)-(phosphoric acid) compound, which enables the production of the (silicic acid)-(phosphoric acid) compound that has excellent battery properties and excellent reliability at low cost and with high efficiency. A (silicic acid)-(phosphoric acid) compound having a chemical composition represented by the following formula: AxMySiaP1-aOz (0.8 < x < 1.2, 0. 8< y < 1.2 and 0.35 ≤ a ≤ 0.95) can be produced by solidifying a molten material by cooling, milling the solidified product, and heating the milled product, wherein the molten material is produced by heating a raw material preparation which comprises at least one atom (A) selected from the group consisting of Li, Na and K, at least one atom (M) selected from the group consisting of Fe, Mn, Co and Ni, Si and P and which contains these atoms in amounts that are expressed in terms of the following oxide contents (mol%): 15% < A2O < 30%, 35% < MO < 55%, 15% < SiO2 < 50% and 1% < P2O5 < 18%, wherein the A2O/(0.5SiO2+P2O5) ratio is 0.8 to 1.2 exclusive and the A2O/0.5MO ratio is 0.8 to 1.2 exclusive.

Description

ケイ酸－リン酸化合物、二次電池用正極、および二次電池の製造方法Silicic acid-phosphoric acid compound, positive electrode for secondary battery, and method for producing secondary battery
　本発明は、ケイ酸－リン酸化合物、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-phosphoric acid compound, a positive electrode for a secondary battery, and a method for producing a secondary battery.
　近年、携帯電話やノート型パソコン等の携帯型電子機器、携帯型電動工具等の電源として、リチウムイオン二次電池が広汎に使用されている。リチウムイオン二次電池の電気自動車用電源としての適用が望まれており、電気自動車用電源への適用を実現するために、リチウムイオン二次電池の正極材料の高容量化が試みられている。 In recent years, lithium ion secondary batteries have been widely used as power sources for portable electronic devices such as mobile phones and laptop computers, and portable power tools. Application of a lithium ion secondary battery as a power source for an electric vehicle is desired, and attempts have been made to increase the capacity of the positive electrode material of the lithium ion secondary battery in order to realize the application to a power source for an electric vehicle.
　リチウムイオン二次電池の次世代の正極材料として、資源面、安全面、コスト面、安定性等の観点から、オリビン型リン酸鉄リチウム（ＬｉＦｅＰＯ４）に代表されるオリビン型のリン酸化合物（ＬｉＭＰＯ４、Ｍは遷移金属元素）が注目されており、その製造方法が検討されている。 As a next-generation cathode material for lithium ion secondary batteries, from the viewpoint of resources, safety, cost, stability, etc., olivine-type phosphate compounds represented by olivine-type lithium iron phosphate (LiFePO 4 ) ( LiMPO 4 and M are transition metal elements) have attracted attention, and their production methods are being studied.
　特許文献１には、ＬｉａＭ１ （２－ｂ）Ｍ２ ｂＳｉｃＰ３－ｃＯ１２（０≦ｂ≦２、０＜ｃ＜３、ａは該式を均衡するように選択された０より大きいＬｉ原子数であって、Ｍ１、Ｍ２は、同じまたは異なる遷移金属元素である。）で表されるリン酸ケイ素化合物が提案されている。ポリアニオンであるＰＯ４の一部をＳｉＯ２で置換することが示唆されている。 Patent Document 1, Li a M 1 (2 -b) M 2 b Si c P 3-c O 12 (0 ≦ b ≦ 2,0 <c <3, a is selected to balance the formula In addition, a silicon phosphate compound represented by the following formula has been proposed: the number of Li atoms is greater than 0, and M 1 and M 2 are the same or different transition metal elements. It has been suggested that a portion of PO 4 which is a polyanion is replaced with SiO 2 .
　特許文献２には、Ｌｉ２ＯとＦｅ２Ｏ３等の遷移金属原子Ｍの酸化物とＰ２Ｏ５とを含有する混合物を溶融し、得られた溶融物を急冷して前駆体ガラスを形成した後、該前駆体ガラスを焼成して、ＬｉＦｅＰＯ４の結晶やＬｉＭｎｘＦｅ１－ｘＰＯ４の結晶（０＜ｘ＜１）等を析出させることによって、二次電池用正極材料を製造することが記載されている。 In Patent Document 2, a mixture containing a transition metal atom M oxide such as Li 2 O and Fe 2 O 3 and P 2 O 5 is melted, and the resulting melt is quenched to obtain a precursor glass. After the formation, the precursor glass is baked to deposit LiFePO 4 crystals, LiMn x Fe 1-x PO 4 crystals (0 <x <1), etc., thereby producing a positive electrode material for a secondary battery. It is described to do.
特表２００２－５１９８３６号公報Special table 2002-519836 gazette 特開２００９－０８７９３３号公報JP 2009-087933 A
　特許文献１に記載された製造方法は、原料を反応させて製造することから、製造工程が複雑で、製造コストがかさむ。また、リン酸ケイ素化合物の製造は示唆はされているが、実施例には実際に製造した例が記載されていない。
　特許文献２に記載された製造方法は、ケイ酸－リン酸化合物粒子の組成制御が難しい。また、ガラス化を向上させる目的でＮｂ２Ｏ５、Ｖ２Ｏ５、ＳｉＯ２、Ｓｂ２Ｏ３およびＢｉ２Ｏ３等を含有させても、酸化物換算でＰ２Ｏ５のモル比率が相対的に高いガラス組成を有していることから、原料を溶融させる加熱温度の上限が、Ｐが蒸発しない温度に制限される。このため、製造条件が制限されるという問題があった。 Since the manufacturing method described in Patent Document 1 is manufactured by reacting raw materials, the manufacturing process is complicated and the manufacturing cost increases. Moreover, although manufacture of the silicon phosphate compound is suggested, the example actually manufactured is not described in the Example.
In the production method described in Patent Document 2, it is difficult to control the composition of the silicic acid-phosphoric acid compound particles. Also, be contained Nb 2 O 5, V 2 O 5, SiO 2, Sb 2 O 3 and Bi 2 O 3 or the like for the purpose of improving the vitrification, the molar ratio of P 2 O 5 in terms of oxide Since it has a relatively high glass composition, the upper limit of the heating temperature for melting the raw material is limited to a temperature at which P does not evaporate. For this reason, there existed a problem that manufacturing conditions were restrict | limited.
　本発明の目的は、ケイ酸－リン酸化合物の組成制御をしやすくかつ、製造しやすい方法を提供することにある。本発明の方法によれば、電池特性や信頼性に優れるケイ酸－リン酸化合物を安価にかつ効率的に製造する方法を提供できる。さらに本発明は、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の製造方法を提供する。 An object of the present invention is to provide a method that makes it easy to control the composition of a silicic acid-phosphoric acid compound and that is easy to manufacture. According to the method of the present invention, a method for producing a silicic acid-phosphoric acid compound having excellent battery characteristics and reliability at low cost and efficiently can be provided. Furthermore, this invention provides the manufacturing method of the positive electrode for secondary batteries which is excellent in a battery characteristic and reliability, and a secondary battery.
　本発明は、下記［１］～［１５］の発明である。 The present invention is the following [1] to [15].
［１］　Ｌｉ、ＮａおよびＫからなる群から選ばれる少なくとも１種の原子Ａと、Ｆｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選ばれる少なくとも１種の原子Ｍと、ＳｉおよびＰと、を含み（ただし、原子Ａ、原子Ｍ、ＳｉおよびＰからなる群から選ばれる少なくとも１種は酸化物として含まれる。）、溶融物になったときの各原子の含有量の酸化物換算量（単位：モル％）が、
　１５％＜Ａ２Ｏ＜３０％、
　３５％＜ＭＯ＜５５％、
　１５％＜ＳｉＯ２＜５０％、
　１％＜Ｐ２Ｏ５＜１８％、であり、
　０．８＜Ａ２Ｏ／（０．５ＳｉＯ２＋Ｐ２Ｏ５）＜１．２、
　０．８＜Ａ２Ｏ／０．５ＭＯ＜１．２、
であ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工程、
　前記固化物を粉砕し粉砕物を得る工程、および
　前記粉砕物を加熱して下式（１）で表される組成を有するケイ酸－リン酸化合物を得る加熱工程、
を含むことを特徴とするケイ酸－リン酸化合物の製造方法。
　ＡｘＭｙＳｉａＰ１－ａＯｚ　　　　（１）
（式中、ＡおよびＭは、それぞれ前記と同じ種類の原子であり、ｘ、ｙおよびａは、０．８＜ｘ＜１．２、０．８＜ｙ＜１．２、０．３５≦ａ≦０．９５であり、ｚは、ｘ、ｙ、ａおよびＭの価数Ｎに依存する数である。）
［２］　Ｌｉ、ＮａおよびＫからなる群から選ばれる少なくとも１種の原子Ａと、Ｆｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選ばれる少なくとも１種の原子Ｍと、ＳｉおよびＰ（ただし、原子Ａ、原子Ｍ、ＳｉおよびＰからなる群から選ばれる少なくとも１種は酸化物として含まれる。）と、を含む原料調合物を加熱して、各原子の含有量の酸化物換算量（単位：モル％）が、
　１５％＜Ａ２Ｏ＜３０％、
　３５％＜ＭＯ＜５５％、
　１５％＜ＳｉＯ２＜５０％、
　１％＜Ｐ２Ｏ５＜１８％、であり、
　０．８＜Ａ２Ｏ／（０．５ＳｉＯ２＋Ｐ２Ｏ５）＜１．２、
　０．８＜Ａ２Ｏ／０．５ＭＯ＜１．２、
である溶融物を得る工程
　前記溶融物を冷却し固化物を得る工程、
　前記固化物を粉砕し粉砕物を得る工程、および
　前記粉砕物を加熱して下式（１）で表される組成を有するケイ酸－リン酸化合物を得る工程、
を含むケイ酸－リン酸化合物の製造方法。
　ＡｘＭｙＳｉａＰ１－ａＯｚ　　　　（１）
（式中、ＡおよびＭは、それぞれ前記と同じ種類の原子であり、ｘ、ｙおよびａは、０．８＜ｘ＜１．２、０．８＜ｙ＜１．２、０．３５≦ａ≦０．９５であり、ｚは、ｘ、ｙ、ａおよびＭの価数Ｎに依存する数である。）
［３］　前記原料調合物中に含まれる原子Ａが、Ａの炭酸塩、Ａの炭酸水素塩、Ａの水酸化物、Ａのリン酸塩およびリン酸水素塩、Ａの硝酸塩、Ａの塩化物、Ａの硫酸塩、Ａの酢酸塩、およびＡのシュウ酸塩からなる群から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。）として含まれ、
　原子Ｍが、Ｍの酸化物、Ｍのオキシ水酸化物、Ｍの金属、Ｍのリン酸塩、Ｍの塩化物、Ｍの硝酸塩、Ｍの硫酸塩、およびＭの有機塩からなる群から選ばれる少なくとも１種として含まれ、
　Ｓｉが、酸化ケイ素、Ａ２ＳｉＯ３およびＡ４ＳｉＯ４からなる群から選ばれるＡのケイ酸塩（ただし、Ａは前記と同じ種類の原子である。）、ならびにＭＳｉＯ３およびＭ２ＳｉＯ４からなる群から選ばれるＭのケイ酸塩（ただし、Ｍは前記と同じ種類の原子である。）、からなる群から選ばれる少なくとも１種として含まれ、
　Ｐが、酸化リン、リン酸アンモニウム、リン酸水素アンモニウム、リン酸、ポリリン酸、亜リン酸、次亜リン酸、Ａのリン酸塩、およびＭのリン酸塩からなる群から選ばれる少なくとも１種として含まれる、［１］または［２］のケイ酸－リン酸化合物の製造方法。
［４］　前記原子ＡがＬｉである、［１］～［３］のケイ酸－リン酸化合物の製造方法。
［５］　前記原子ＭがＦｅおよびＭｎからなる群から選ばれる少なくとも１種である、［１］～［４］のケイ酸－リン酸化合物の製造方法。
［６］　前記式（１）で表される組成を有するケイ酸－リン酸化合物が、下式（２）で表される組成を有する化合物の結晶粒子である、［１］～［３］のケイ酸－リン酸化合物の製造方法。
　Ｌｉｘ（ＦｅｂＭｎ１－ｂ）ｙＳｉａＰ１－ａＯｚ　　　　（２）
（式中、ｘ、ｙ、ｚおよびａは、それぞれ前記と同じ数値であり、ｂは０≦ｂ≦１である。）
［７］　前記式（２）で表される組成を有する化合物の結晶粒子が、下式（３）で表される組成を有する化合物の結晶粒子である、［６］のケイ酸－リン酸化合物の製造方法。
　ＬｉＦｅｂＭｎ１－ｂＳｉａＰ１－ａＯｚ　　　　（３）
（式中、ｚ、ａおよびｂは前記と同じ数値である。）
［８］　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系導電活物質からなる群から選択される少なくとも１種の炭素源を含ませ、かつ該炭素源の量は、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％となる量である、［１］～［７］のケイ酸－リン酸化合物の製造方法。
［９］　前記固化物を得る工程において、冷却速度が、－１０3℃／秒～－１０10℃／秒である、［１］～［８］のケイ酸－リン酸化合物の製造方法。
［１０］　前記固化物が、非晶質部分を含む固体状化合物である、［１］～［９］のケイ酸－リン酸化合物の製造方法。
［１１］　前記ケイ酸－リン酸化合物を得る工程を不活性ガス中または還元ガス中で、５００℃～１，０００℃で行う、［１］～［１０］のケイ酸－リン酸化合物の製造方法。 [1] including at least one atom A selected from the group consisting of Li, Na and K, at least one atom M selected from the group consisting of Fe, Mn, Co and Ni, and Si and P (However, at least one selected from the group consisting of atom A, atom M, Si, and P is included as an oxide.) The oxide equivalent amount of each atom when it becomes a melt (unit: Mol%)
15% <A 2 O <30%,
35% <MO <55%,
15% <SiO 2 <50%,
1% <P 2 O 5 <18%,
0.8 <A 2 O / (0.5SiO 2 + P 2 O 5 ) <1.2,
0.8 <A 2 O / 0.5MO <1.2,
Heating the raw material formulation to obtain a melt,
Cooling the melt to obtain a solidified product,
A 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-phosphoric acid compound having a composition represented by the following formula (1):
A process for producing a silicic acid-phosphoric acid compound, comprising:
A x M y Si a P 1 -a O z (1)
(In the formula, A and M are the same kind of atoms as described above, and x, y and a are 0.8 <x <1.2, 0.8 <y <1.2, 0.35 ≦ a ≦ 0.95, and z is a number depending on the valence N of x, y, a and M.)
[2] At least one atom A selected from the group consisting of Li, Na and K, at least one atom M selected from the group consisting of Fe, Mn, Co and Ni, and Si and P (provided that And at least one selected from the group consisting of A, atoms M, Si and P is included as an oxide.), And an oxide equivalent amount (unit: Mol%)
15% <A 2 O <30%,
35% <MO <55%,
15% <SiO 2 <50%,
1% <P 2 O 5 <18%,
0.8 <A 2 O / (0.5SiO 2 + P 2 O 5 ) <1.2,
0.8 <A 2 O / 0.5MO <1.2,
Obtaining a melt that is a step of cooling the melt to obtain a solidified product,
Pulverizing the solidified product to obtain a pulverized product, and heating the pulverized product to obtain a silicic acid-phosphoric acid compound having a composition represented by the following formula (1):
A method for producing a silicic acid-phosphoric acid compound comprising:
A x M y Si a P 1 -a O z (1)
(In the formula, A and M are the same kind of atoms as described above, and x, y and a are 0.8 <x <1.2, 0.8 <y <1.2, 0.35 ≦ a ≦ 0.95, and z is a number depending on the valence N of x, y, a and M.)
[3] The atom A contained in the raw material preparation is A carbonate, A bicarbonate, A hydroxide, A phosphate and hydrogen phosphate, A nitrate, A chloride. At least one selected from the group consisting of a product, sulfate of A, acetate of A, and oxalate of A (provided that a part or all of the one or more forms a hydrate salt, respectively) May be included),
Atom M is selected from the group consisting of M oxide, M oxyhydroxide, M metal, M phosphate, M chloride, M nitrate, M sulfate, and M organic salt Included as at least one
Si is a silicate of A selected from the group consisting of silicon oxide, A 2 SiO 3 and A 4 SiO 4 (where A is the same kind of atom as described above), and MSiO 3 and M 2 SiO 4 M silicate selected from the group consisting of (wherein M is the same kind of atom as described above), and included as at least one selected from the group consisting of:
P is at least one selected from the group consisting of phosphorus oxide, ammonium phosphate, ammonium hydrogen phosphate, phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphorous acid, A phosphate, and M phosphate A method for producing a silicic acid-phosphoric acid compound of [1] or [2], which is contained as a seed.
[4] The method for producing a silicic acid-phosphoric acid compound of [1] to [3], wherein the atom A is Li.
[5] The method for producing a silicic acid-phosphoric acid compound of [1] to [4], wherein the atom M is at least one selected from the group consisting of Fe and Mn.
[6] The silicic acid-phosphoric acid compound having the composition represented by the formula (1) is a crystal particle of a compound having the composition represented by the following formula (2): [1] to [3] A method for producing a silicic acid-phosphoric acid compound.
Li x (Fe b Mn 1-b ) y Si a P 1-a O z (2)
(In the formula, x, y, z and a are respectively the same numerical values as above, and b is 0 ≦ b ≦ 1.)
[7] The silicic acid-phosphate compound of [6], wherein the crystal grains of the compound having the composition represented by the formula (2) are the crystal grains of the compound having the composition represented by the following formula (3) Manufacturing method.
LiFe b Mn 1-b Si a P 1-a O z (3)
(In the formula, z, a and b are the same numerical values as described above.)
[8] In the pulverization step, the solidified product includes at least one carbon source selected from the group consisting of an organic compound and a carbon-based conductive active material, and the amount of the carbon source is determined based on the amount of the solidified product and carbon. The silicic acid-phosphoric acid of [1] to [7], wherein the ratio of the carbon conversion amount (mass) to the total mass with the carbon conversion amount (mass) in the source is 0.1 to 20% by mass A method for producing a compound.
[9] The method for producing a silicic acid-phosphate compound according to [1] to [8], wherein in the step of obtaining the solidified product, a cooling rate is −10 3 ° C./second to −10 10 ° C./second.
[10] The method for producing a silicic acid-phosphoric acid compound according to any one of [1] to [9], wherein the solidified product is a solid compound containing an amorphous part.
[11] The production of the silicic acid-phosphoric acid compound of [1] to [10], wherein the step of obtaining the silicic acid-phosphoric acid compound is performed in an inert gas or a reducing gas at 500 ° C. to 1,000 ° C. Method.
［１２］　下式（１）で表される組成を有することを特徴とするケイ酸－リン酸化合物。
　ＡｘＭｙＳｉａＰ１－ａＯｚ　　　　（１）
（式中、ＡはＬｉ、ＮａおよびＫからなる群から選ばれる少なくとも１種の原子、ＭはＦｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選ばれる少なくとも１種の原子であり、ｘ、ｙおよびａは、０．８＜ｘ＜１．２、０．８＜ｙ＜１．２、０．３５≦ａ≦０．９５であり、ｚは、ｘ、ｙ、ａおよびＭの価数Ｎに依存する数である。） [12] A silicic acid-phosphoric acid compound having a composition represented by the following formula (1):
A x M y Si a P 1 -a O z (1)
Wherein A is at least one atom selected from the group consisting of Li, Na and K, M is at least one atom selected from the group consisting of Fe, Mn, Co and Ni, and x, y and a is 0.8 <x <1.2, 0.8 <y <1.2, 0.35 ≦ a ≦ 0.95, and z is the valence N of x, y, a, and M. Depends on the number.)
［１３］　前記ケイ酸－リン酸化合物の粒子が、該ケイ酸－リン酸化合物と導電性炭素質層との合計質量に対して、０．１～２０質量％の導電性炭素質層を、該粒子の表面または粒子間界面に含有する、［１２］のケイ酸－リン酸化合物。
［１４］　［１］～［１１］の製造方法でケイ酸－リン酸化合物を得て、該ケイ酸―リ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] The conductive carbonaceous layer may be 0.1 to 20% by mass of the silicic acid-phosphoric acid compound particles based on the total mass of the silicic acid-phosphoric acid compound and the conductive carbonaceous layer. The silicic acid-phosphoric acid compound according to [12], which is contained on the surface of the particle or the interparticle interface.
[14] Obtaining a silicic acid-phosphoric acid compound by the production method of [1] to [11], and producing a secondary battery positive electrode using the silicic acid-phosphoric acid compound as a positive electrode material for a secondary battery. The manufacturing method of the positive electrode for secondary batteries characterized by these.
［１５］　［１４］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。 [15] A method for producing a secondary battery, comprising obtaining a positive electrode for a secondary battery by the production method of [14], and then producing a secondary battery using the positive electrode for a secondary battery.
　本発明のケイ酸－リン酸化合物の製造方法によれば、安価な原料と簡便な手法とを用いてケイ酸－リン酸化合物を効率的に製造する方法が提供される。本発明の製造方法は、ケイ酸－リン酸化合物の組成の制御がしやすいため、所望の組成を有するケイ酸－リン酸化合物を効率的に製造できる。したがって、本発明により得られるケイ酸－リ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電池用正極および二次電池が製造できる。
　また本発明によれば、電池特性や信頼性に優れるケイ酸－リン酸化合物が提供される。 The method for producing a silicic acid-phosphoric acid compound of the present invention provides a method for efficiently producing a silicic acid-phosphoric acid compound using an inexpensive raw material and a simple technique. In the production method of the present invention, since the composition of the silicic acid-phosphoric acid compound is easily controlled, a silicic acid-phosphoric acid compound having a desired composition can be produced efficiently. Therefore, by using the silicic acid-phosphoric acid compound obtained by the present invention, a positive electrode for secondary batteries and a secondary battery excellent in battery characteristics and reliability can be produced.
The present invention also provides a silicic acid-phosphoric acid compound that is excellent in battery characteristics and reliability.
実施例１、３および６で製造したケイ酸－リン酸化合物粒子のＸ線回折パターンを示す図である。FIG. 3 is a diagram showing an X-ray diffraction pattern of silicic acid-phosphoric acid compound particles produced in Examples 1, 3 and 6. 実施例１３および１４で製造したケイ酸－リン酸化合物粒子のＸ線回折パターンを示す図である。FIG. 4 is a view showing an X-ray diffraction pattern of silicic acid-phosphoric acid compound particles produced in Examples 13 and 14.
　以下の説明において、Ａは、Ｌｉ、ＮａおよびＫからなる群から選択される少なくとも１種の原子を表す。Ａは、上記３種のアルカリ金属元素の原子を表す。Ａは２種以上の原子の組み合わせからなっていてもよい。Ｍは、Ｆｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選択される少なくとも１種の原子を表す。Ｍは、上記４種の遷移金属元素の原子を表す。Ｍは２種以上の原子の組み合わせからなっていてもよい。なお、式（１）、式（２）、式（３）等の化学式は平均組成を表す。
　また、オリビン型構造の結晶を以下オリビン型結晶といい、オリビン型結晶を含む粒子を以下オリビン型結晶粒子ともいう。オリビン型結晶粒子は、オリビン型結晶構造以外の結晶構造を部分的に含んでいてもよく、非結晶構造を部分的に含んでいてもよい。オリビン型結晶粒子としては、その実質的にすべてがオリビン型結晶からなっていることが好ましい。 In the following description, A represents at least one atom selected from the group consisting of Li, Na and K. A represents an atom of the above three alkali metal elements. A may consist of a combination of two or more atoms. M represents at least one atom selected from the group consisting of Fe, Mn, Co and Ni. M represents an atom of the above four transition metal elements. M may consist of a combination of two or more atoms. In addition, chemical formulas, such as Formula (1), Formula (2), Formula (3), represent an average composition.
A crystal having an olivine structure is hereinafter referred to as an olivine crystal, and a particle containing the olivine crystal is also referred to as an olivine crystal particle. The olivine-type crystal particle may partially include a crystal structure other than the olivine-type crystal structure, or may partially include an amorphous structure. It is preferable that substantially all of the olivine type crystal particles are made of olivine type crystals.
［ケイ酸－リン酸化合物の製造方法］
　本発明のケイ酸－リン酸化合物の製造方法は、以下の工程（１）、工程（２）、工程（３）、および工程（４）を、この順に行う。（１）～（４）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。
　工程（１）：Ｌｉ、ＮａおよびＫからなる群から選ばれる少なくとも１種の原子Ａ；Ｆｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選ばれる少なくとも１種の原子Ｍ；ＳｉおよびＰを含み、溶融物になったときの各原子の含有量の酸化物換算量（単位：モル％）が、１５％＜Ａ２Ｏ＜３０％、３５％＜ＭＯ＜５５％、１５％＜ＳｉＯ２＜５０％、１％＜Ｐ２Ｏ５＜１８％であり、０．８＜Ａ２Ｏ／（０．５ＳｉＯ２＋Ｐ２Ｏ５）＜１．２、０．８＜Ａ２Ｏ／０．５ＭＯ＜１．２、である原料調合物を加熱して溶融物を得る工程、
　工程（２）：前記溶融物を冷却し固化物を得る工程、
　工程（３）：前記固化物を粉砕し粉砕物を得る工程、
　工程（４）：前記粉砕物を加熱して式（１）で表される組成を有するケイ酸－リン酸化合物を得る工程。 [Method for producing silicic acid-phosphoric acid compound]
In the method for producing a silicic acid-phosphoric acid compound of the present invention, the following step (1), step (2), step (3), and step (4) are performed in this order. Other steps may be performed before, between and after the steps (1) to (4) as long as each step is not affected.
Step (1): at least one atom A selected from the group consisting of Li, Na and K; at least one atom M selected from the group consisting of Fe, Mn, Co and Ni; The oxide equivalent amount (unit: mol%) of the content of each atom when it becomes a product is 15% <A 2 O <30%, 35% <MO <55%, 15% <SiO 2 <50% 1% <P 2 O 5 <18%, 0.8 <A 2 O / (0.5SiO 2 + P 2 O 5 ) <1.2, 0.8 <A 2 O / 0.5MO <1 .2. Heating the raw material formulation to obtain a melt,
Step (2): a step of cooling the melt to obtain a solidified product,
Step (3): pulverizing the solidified product to obtain a pulverized product,
Step (4): A step of heating the pulverized product to obtain a silicic acid-phosphoric acid compound having a composition represented by the formula (1).
　本発明の製造方法において、工程（１）で上記組成の溶融物にすることで、広い組成範囲で溶融させることができるため、続く工程（２）、工程（３）、および工程（４）を経て、所望の式（１）で表される組成を有するケイ酸－リン酸化合物を得ることができる。したがって、特許文献１に記載されていない組成のケイ酸－リン酸化合物の製造が可能となる。 In the production method of the present invention, since it can be melted in a wide composition range by forming a melt having the above composition in step (1), the following step (2), step (3), and step (4) are performed. As a result, a silicic acid-phosphoric acid compound having a desired composition represented by the formula (1) can be obtained. Accordingly, it is possible to produce a silicic acid-phosphoric acid compound having a composition not described in Patent Document 1.
　本発明の製造方法において、酸化物換算でＰ２Ｏ５のモル比率が相対的に低い組成を有していることから、材料コストを低減できる。また、原料調合物を溶融させる際の加熱温度の上限が上昇するため、溶融温度範囲を広げられ、製造しやすくなる。
　以下、各工程について具体的に説明する。 In the production method of the present invention, since the composition has a relatively low molar ratio of P 2 O 5 in terms of oxide, the material cost can be reduced. Moreover, since the upper limit of the heating temperature at the time of melting a raw material formulation rises, a melting temperature range can be expanded and it becomes easy to manufacture.
Hereinafter, each step will be specifically described.
（工程（１））
　工程（１）では、まず、Ｌｉ、ＮａおよびＫからなる群から選ばれる少なくとも１種の原子Ａと、Ｆｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選ばれる少なくとも１種の原子Ｍと、ＳｉおよびＰと、を含み（ただし、原子Ａ、原子Ｍ、ＳｉおよびＰからなる群から選ばれる少なくとも１種は酸化物として含まれる。）、溶融物になったときの各原子の含有量の酸化物換算量（単位：モル％）が、１５％＜Ａ２Ｏ＜３０％、３５％＜ＭＯ＜５５％、１５％＜ＳｉＯ２＜５０％、１％＜Ｐ２Ｏ５＜１８％であり、０．８＜Ａ２Ｏ／（０．５ＳｉＯ２＋Ｐ２Ｏ５）＜１．２、０．８＜Ａ２Ｏ／０．５ＭＯ＜１．２、である原料調合物を得る。続いて該原料調合物を加熱して、溶融物を得る。原料調合物を加熱する前に混合・粉砕し、加熱して、溶融物を得てもよい。また、各原料を予め粉砕してから、原料調合物を製造してもよい。原料調合物の混合・粉砕は、ボールミル、ジェットミル、遊星ミル等を用い、乾式または湿式で行う。分散媒の除去が不要である点で、乾式が好ましい。 (Process (1))
In the step (1), first, at least one atom A selected from the group consisting of Li, Na and K, at least one atom M selected from the group consisting of Fe, Mn, Co and Ni, Si and (Wherein at least one selected from the group consisting of atom A, atom M, Si and P is included as an oxide), and an oxide having a content of each atom when it becomes a melt The conversion amount (unit: mol%) is 15% <A 2 O <30%, 35% <MO <55%, 15% <SiO 2 <50%, 1% <P 2 O 5 <18%, A raw material formulation having 0.8 <A 2 O / (0.5SiO 2 + P 2 O 5 ) <1.2 and 0.8 <A 2 O / 0.5MO <1.2 is obtained. Subsequently, the raw material formulation is heated to obtain a melt. Before the raw material preparation is heated, it may be mixed, pulverized and heated to obtain a melt. Alternatively, the raw material preparation may be manufactured after each raw material has been pulverized in advance. The raw material mixture is mixed and pulverized using a ball mill, a jet mill, a planetary mill or the like in a dry or wet manner. A dry method is preferable in that it is not necessary to remove the dispersion medium.
　溶融物が１５％＜Ａ２Ｏ＜３０％、３５％＜ＭＯ＜５５％、１５％＜ＳｉＯ２＜５０％、および１％＜Ｐ２Ｏ５＜１８％を満たす組成であると、原料調合物を容易に溶融することができるので好ましい。Ａ２Ｏが１５％以下、ＭＯが５５％以上、ＳｉＯ２が１５％以下またはＰ２Ｏ５が１％以下の場合には、原料調合物を溶融するのが困難となる。一方、Ａ２Ｏが３０％以上、ＭＯが３５％以下、ＳｉＯ２が５０％以上またはＰ２Ｏ５が１８％以上の場合には、目的とするケイ酸－リン酸化合物を得ることが困難となる。なお、ここで溶融するとは、原料調合物が融解し、目視で透明な状態となることをいう。 If the melt has a composition satisfying 15% <A 2 O <30%, 35% <MO <55%, 15% <SiO 2 <50%, and 1% <P 2 O 5 <18% This is preferable because the product can be easily melted. When A 2 O is 15% or less, MO is 55% or more, SiO 2 is 15% or less, or P 2 O 5 is 1% or less, it is difficult to melt the raw material preparation. On the other hand, when A 2 O is 30% or more, MO is 35% or less, SiO 2 is 50% or more, or P 2 O 5 is 18% or more, it is difficult to obtain the target silicic acid-phosphate compound. It becomes. In addition, it melt | dissolves here means that a raw material formulation melt | dissolves and it will be in a transparent state visually.
　溶融物は、さらに、１８％＜Ａ２Ｏ＜２５％、４０％＜ＭＯ＜５０％、１７％＜ＳｉＯ２＜３８％、および１％＜Ｐ２Ｏ５＜１８％を満たす組成であると、目的とするケイ酸－リン酸化合物を得ることができるので、特に好ましい。 The melt further has a composition satisfying 18% <A 2 O <25%, 40% <MO <50%, 17% <SiO 2 <38%, and 1% <P 2 O 5 <18%. The desired silicic acid-phosphoric acid compound can be obtained, which is particularly preferable.
　また、０．８＜Ａ２Ｏ／（０．５ＳｉＯ２＋Ｐ２Ｏ５）＜１．２および０．８＜Ａ２Ｏ／０．５ＭＯ＜１．２を満たす組成であると、式（１）で表される組成を有するケイ酸－リン酸化合物を得ることができるので好ましい。 Further, when the composition satisfies 0.8 <A 2 O / (0.5SiO 2 + P 2 O 5 ) <1.2 and 0.8 <A 2 O / 0.5MO <1.2, the formula (1 It is preferable because a silicic acid-phosphoric acid compound having a composition represented by
　溶融物は、原子Ａ、原子Ｍ、ケイ素（Ｓｉ）、リン（Ｐ）、および酸素（Ｏ）のみからなるものに限らず、Ｔｉ、Ｖ、Ｂ、Ａｌ、Ｃａ、Ｃｕ、Ｍｇ、およびＺｎからなる群から選ばれる少なくとも１種の原子Ｘを含んでいてもよい。原子Ｘを含有させることで、原料調合物を溶融しやすくすることができる。原子Ｘの含有量（複数の原子の場合には合計量）は、溶融物になったときの各原子の含有量の酸化物換算量（単位：モル％）が、０．１～５％が好ましい。 The melt is not limited to those consisting only of atoms A, atoms M, silicon (Si), phosphorus (P), and oxygen (O), but from Ti, V, B, Al, Ca, Cu, Mg, and Zn. It may contain at least one atom X selected from the group consisting of By containing the atom X, the raw material preparation can be easily melted. The content of atoms X (the total amount in the case of a plurality of atoms) is 0.1 to 5% in terms of oxide content (unit: mol%) of the content of each atom when it becomes a melt. preferable.
　原料調合物は、原子Ａ、原子Ｍ、ＳｉおよびＰを、溶融物になったときの各原子の含有量の酸化物換算量（単位：モル％）が、１５％＜Ａ２Ｏ＜３０％、３５％＜ＭＯ＜５５％、１５％＜ＳｉＯ２＜５０％、１％＜Ｐ２Ｏ５＜１８％であり、０．８＜Ａ２Ｏ／（０．５ＳｉＯ２＋Ｐ２Ｏ５）＜１．２、０．８＜Ａ２Ｏ／０．５ＭＯ＜１．２である溶融物を得られるように、原料を選択して混合する。原料は、原子Ａを含む化合物、原子Ｍを含む化合物、Ｓｉを含む化合物、Ｐを含む化合物、必要に応じて原子Ｘを含む化合物である。 In the raw material formulation, atoms A, atoms M, Si and P are converted into oxides (unit: mol%) of the content of each atom when it becomes a melt, and 15% <A 2 O <30% 35% <MO <55%, 15% <SiO 2 <50%, 1% <P 2 O 5 <18%, 0.8 <A 2 O / (0.5SiO 2 + P 2 O 5 ) < The raw materials are selected and mixed so that a melt satisfying 1.2, 0.8 <A 2 O / 0.5MO <1.2 is obtained. The raw material is a compound containing atom A, a compound containing atom M, a compound containing Si, a compound containing P, or a compound containing atom X as necessary.
＜原子Ａを含む化合物＞
　Ａは、Ｌｉ、ＮａおよびＫからなる群から選択される少なくとも１種の原子であればよいが、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－リン酸化合物は、二次電池の単位体積（質量）当たりの容量を高くできる。 <Compound containing atom A>
A may be at least one atom selected from the group consisting of Li, Na and K. However, since it is suitable as a positive electrode material for a secondary battery, it is preferable to make Li essential. It is particularly preferred. The silicic acid-phosphoric acid compound containing Li can increase the capacity per unit volume (mass) of the secondary battery.
　原子Ａを含む化合物としては、Ａの炭酸塩（Ａ２ＣＯ３）、Ａの炭酸水素塩（ＡＨＣＯ３）、Ａの水酸化物（ＡＯＨ）、Ａのリン酸塩およびリン酸水素塩（ＡｔＨ３－ｔＰＯ４、０＜ｔ≦３）、Ａの硝酸塩（ＡＮＯ３）、Ａの塩化物（ＡＣｌ）、Ａの硫酸塩（Ａ２ＳＯ４）、Ａの酢酸塩（ＣＨ３ＣＯＯＡ）、およびＡのシュウ酸塩（（ＣＯＯＡ）２）からなる群から選ばれる少なくとも１種（ただし、これらの化合物は、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、安価かつ取扱いが容易な点で、Ａ２ＣＯ３またはＡＨＣＯ３が特に好ましい。 Compounds containing an atom A include A carbonate (A 2 CO 3 ), A bicarbonate (AHCO 3 ), A hydroxide (AOH), A phosphate and hydrogen phosphate (A t H 3−t PO 4 , 0 <t ≦ 3), A nitrate (ANO 3 ), A chloride (ACl), A sulfate (A 2 SO 4 ), A acetate (CH 3 COOA) ) And A oxalate ((COOA) 2 ), and at least one selected from the group consisting of (COOA) 2 ) (however, these compounds may each form a hydrate salt). Among these, A 2 CO 3 or AHCO 3 is particularly preferable because it is inexpensive and easy to handle.
＜原子Ｍを含む化合物＞
　ＭはＦｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選択される少なくとも１種の原子であればよい。ケイ酸－リン酸化合物を二次電池用正極材料に適用する場合、コストの点から、ＭとしてはＦｅおよびＭｎからなる群から選択される少なくとも１種の原子を用いるのが好ましい。二次電池用正極材料の理論容量を発現し易くなる点から、Ｆｅが特に好ましい。作動電圧を高くする点からは、ＣｏおよびＮｉからなる群から選択される少なくとも１種の原子が好ましい。 <Compound containing atom M>
M may be at least one atom selected from the group consisting of Fe, Mn, Co and Ni. In the case where the silicic acid-phosphoric acid compound is applied to the positive electrode material for secondary batteries, it is preferable to use at least one atom selected from the group consisting of Fe and Mn as M from the viewpoint of cost. Fe is particularly preferable because the theoretical capacity of the positive electrode material for a secondary battery is easily developed. From the viewpoint of increasing the operating voltage, at least one atom selected from the group consisting of Co and Ni is preferable.
　原子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）、元素Ｍのオキシ水酸化物（ＭＯ（ＯＨ））、金属Ｍ、Ｍのリン酸塩（Ｍ３（ＰＯ４）２、ＭＰＯ４）、Ｍの塩化物、Ｍの硝酸塩、Ｍの硫酸塩、Ｍの有機塩等からなる群から選ばれる少なくとも１種が好ましい。なかでも、安価かつ取扱いが容易な点で、Ｆｅ３Ｏ４、Ｆｅ２Ｏ３、ＭｎＯ２、Ｃｏ３Ｏ４またはＮｉＯがより好ましい。Ｆｅ３Ｏ４、Ｆｅ２Ｏ３またはＭｎＯ２が特に好ましい。 As the compound containing the atom M, 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), Oxyhydroxide (MO (OH)) of element M, metal M, M phosphate (M 3 (PO 4 ) 2 , MPO 4 ), M chloride, M nitrate, M sulfate, M At least one selected from the group consisting of organic salts and the like is preferred. Among these, Fe 3 O 4 , Fe 2 O 3 , MnO 2 , Co 3 O 4 or NiO is more preferable because it is inexpensive and easy to handle. Fe 3 O 4 , Fe 2 O 3 or MnO 2 is particularly preferred.
＜Ｓｉを含む化合物＞
　Ｓｉを含む化合物としては、酸化ケイ素（ＳｉＯ２）、Ａ２ＳｉＯ３およびＡ４ＳｉＯ４からなる群から選ばれるＡのケイ酸塩（ただし、Ａは前記と同じ種類の原子である。）、ならびにＭＳｉＯ３およびＭ２ＳｉＯ４からなる群から選ばれるＭのケイ酸塩（ただし、Ｍは前記と同じ種類の原子である。）からなる群から選ばれる少なくとも１種が好ましい。なかでも、安価な点で、ＳｉＯ２が特に好ましい。なお、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。 <Compound containing Si>
As the compound containing Si, silicate of A selected from the group consisting of silicon oxide (SiO 2 ), A 2 SiO 3 and A 4 SiO 4 (where A is the same kind of atom as described above), And at least one selected from the group consisting of M silicates selected from the group consisting of MSiO 3 and M 2 SiO 4 (wherein M is the same type of atom as described above). Of these, SiO 2 is particularly preferable from the viewpoint of inexpensiveness. Note that the compound containing Si may be crystalline or amorphous.
＜Ｐを含む化合物＞
　Ｐを含む化合物としては、酸化リン（Ｐ２Ｏ５）、リン酸アンモニウム（（ＮＨ４）３ＰＯ４）、リン酸水素アンモニウム（（ＮＨ４）２ＨＰＯ４、ＮＨ４Ｈ２ＰＯ４）、リン酸（Ｈ３ＰＯ４）、ポリリン酸（Ｈ（ｎ＋２）ＰｎＯ（３ｎ＋１））、亜リン酸（Ｈ３ＰＯ３）、次亜リン酸（Ｈ３ＰＯ２）、Ａのリン酸塩、およびＭのリン酸塩等からなる群から選ばれる少なくとも１種が好ましい。なかでも、安価かつ取扱いが容易な点で、ＮＨ４Ｈ２ＰＯ４、（ＮＨ４）２ＨＰＯ４、Ａのリン酸塩またはＰ２Ｏ５が特に好ましい。 <Compound containing P>
As the compound containing P, phosphorus oxide (P 2 O 5 ), ammonium phosphate ((NH 4 ) 3 PO 4 ), ammonium hydrogen phosphate ((NH 4 ) 2 HPO 4 , NH 4 H 2 PO 4 ), Phosphoric acid (H 3 PO 4 ), polyphosphoric acid (H (n + 2) P n O (3n + 1) ), phosphorous acid (H 3 PO 3 ), hypophosphorous acid (H 3 PO 2 ), A phosphate And at least one selected from the group consisting of M phosphates and the like. Among these, NH 4 H 2 PO 4 , (NH 4 ) 2 HPO 4 , A phosphate or P 2 O 5 is particularly preferable because it is inexpensive and easy to handle.
　原料調合物として原子Ａを含む化合物、原子Ｍを含む化合物、Ｓｉを含む化合物、およびＰを含む化合物の好適な組み合わせは、
　原子Ａを含む化合物が、Ａの炭酸塩（Ａ２ＣＯ３）、炭酸水素塩（ＡＨＣＯ３）、Ａの水酸化物（ＡＯＨ）、Ａのリン酸塩およびリン酸水素塩（ＡｔＨ３－ｔＰＯ４、０＜ｔ≦３）、Ａの硝酸塩（ＡＮＯ３）、Ａの塩化物（ＡＣｌ）、Ａの硫酸塩（Ａ２ＳＯ４）、Ａの酢酸塩（ＣＨ３ＣＯＯＡ）、およびＡのシュウ酸塩からなる群から選ばれる少なくとも１種（ただし、これらの化合物は、それぞれ水和塩を形成していてもよい。）であり、
　原子Ｍを含む化合物が、Ｍの酸化物（ＦｅＯ、Ｆｅ３Ｏ４、Ｆｅ２Ｏ３、ＭｎＯ、Ｍｎ２Ｏ３、ＭｎＯ２、ＣｏＯ、Ｃｏ３Ｏ４、Ｃｏ２Ｏ３、ＮｉＯ）、Ｍのオキシ水酸化物（ＭＯ（ＯＨ））、金属Ｍ、Ｍのリン酸塩（Ｍ３（ＰＯ４）２、ＭＰＯ４）、Ｍの塩化物、Ｍの硝酸塩、Ｍの硫酸塩、およびＭの有機塩からなる群から選ばれる少なくとも１種であり、
　Ｓｉを含む化合物が、酸化ケイ素（ＳｉＯ２）、Ａ２ＳｉＯ３およびＡ４ＳｉＯ４からなる群から選ばれるＡのケイ酸塩（ただし、Ａは前記と同じ種類の原子である。）、ならびにＭＳｉＯ３およびＭ２ＳｉＯ４からなる群から選ばれるＭのケイ酸塩（ただし、Ｍは前記と同じ種類の原子である。）からなる群から選ばれる少なくとも１種であり、そして、
　Ｐを含む化合物が、酸化リン（Ｐ２Ｏ５）、リン酸アンモニウム（（ＮＨ４）３ＰＯ４）、リン酸水素アンモニウム（（ＮＨ４）２ＨＰＯ４、ＮＨ４Ｈ２ＰＯ４）、リン酸（Ｈ３ＰＯ４）、ポリリン酸（Ｈ（ｎ＋２）ＰｎＯ（３ｎ＋１））、亜リン酸（Ｈ３ＰＯ３）、次亜リン酸（Ｈ３ＰＯ２）、およびＡのリン酸塩、およびＭのリン酸塩からなる群から選ばれる少なくとも１種である、組み合わせである。
　より好ましくは、
　原子Ａを含む化合物が、Ａの炭酸塩（Ａ２ＣＯ３）または炭酸水素塩（ＡＨＣＯ３）であり、
　原子Ｍを含む化合物が、Ｍの酸化物（ＦｅＯ、Ｆｅ３Ｏ４、Ｆｅ２Ｏ３、ＭｎＯ、Ｍｎ２Ｏ３、ＭｎＯ２、ＣｏＯ、Ｃｏ３Ｏ４、Ｃｏ２Ｏ３、ＮｉＯ）またはＭのオキシ水酸化物（ＭＯ（ＯＨ））であり、
　Ｓｉを含む化合物が、酸化ケイ素（ＳｉＯ２）であり、
　Ｐを含む化合物が、リン酸水素アンモニウム（（ＮＨ４）２ＨＰＯ４、ＮＨ４Ｈ２ＰＯ４）である、組み合わせである。 A suitable combination of a compound containing atom A as a raw material formulation, a compound containing atom M, a compound containing Si, and a compound containing P is:
Compounds containing atom A are A carbonate (A 2 CO 3 ), bicarbonate (AHCO 3 ), A hydroxide (AOH), A phosphate and hydrogen phosphate (A t H 3 -T PO 4 , 0 <t ≦ 3), A nitrate (ANO 3 ), A chloride (ACl), A sulfate (A 2 SO 4 ), A acetate (CH 3 COOA), and At least one selected from the group consisting of oxalates of A (however, these compounds may each form a hydrate salt);
A compound containing an atom M is an oxide 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), M Oxyhydroxide (MO (OH)), metal M, M phosphate (M 3 (PO 4 ) 2 , MPO 4 ), M chloride, M nitrate, M sulfate, and M At least one selected from the group consisting of organic salts,
A compound containing Si is a silicate of A selected from the group consisting of silicon oxide (SiO 2 ), A 2 SiO 3 and A 4 SiO 4 (wherein A is the same kind of atom as described above), and And at least one selected from the group consisting of M silicates selected from the group consisting of MSiO 3 and M 2 SiO 4 (wherein M is the same type of atom as described above), and
Compounds containing P are phosphorous oxide (P 2 O 5 ), ammonium phosphate ((NH 4 ) 3 PO 4 ), ammonium hydrogen phosphate ((NH 4 ) 2 HPO 4 , NH 4 H 2 PO 4 ), phosphorus Acid (H 3 PO 4 ), polyphosphoric acid (H (n + 2) P n O (3n + 1) ), phosphorous acid (H 3 PO 3 ), hypophosphorous acid (H 3 PO 2 ), and A phosphate And a combination which is at least one selected from the group consisting of M phosphates.
More preferably,
The compound containing atom A is a carbonate of A (A 2 CO 3 ) or a bicarbonate (AHCO 3 );
The compound containing the atom M is an oxide 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) or M Oxyhydroxide (MO (OH)) of
The compound containing Si is silicon oxide (SiO 2 ),
The combination in which the compound containing P is ammonium hydrogen phosphate ((NH 4 ) 2 HPO 4 , NH 4 H 2 PO 4 ).
　原料調合物の組成は、原則として、当該原料調合物から得られる溶融物の組成と理論上対応するものである。ただし、この原料調合物中には、溶融中に揮発等により失われやすい成分、例えばＬｉ、Ｐ等が存在するため、得られる溶融物の組成は、各原料の仕込み量から計算される各元素の含有量の酸化物換算量（単位：モル％）と若干相違する場合がある。 In principle, the composition of the raw material formulation corresponds theoretically to the composition of the melt obtained from the raw material formulation. However, in this raw material formulation, there are components that are easily lost due to volatilization etc. during melting, such as Li, P, etc., so the composition of the resulting melt is determined by each element calculated from the amount of each raw material charged. May be slightly different from the oxide equivalent amount (unit: mol%).
　原料調合物中の原料の純度は特に限定されないが、所望の特性を低下させない範囲が好ましい。水和水を除いた純度が９９％以上であるのが好ましく、純度９９．９％以上が特に好ましい。また、溶融して均一な溶融物が得られる範囲であれば、上記原料の粒度も特に限定されない。 Although the purity of the raw material in a raw material formulation is not specifically limited, The range which does not reduce a desired characteristic is preferable. The purity excluding the water of hydration is preferably 99% or more, particularly preferably 99.9% or more. Further, the particle size of the raw material is not particularly limited as long as it is within a range in which a uniform melt can be obtained by melting.
　加熱に用いる容器は、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、チッ化ホウ素製、白金製またはロジウムを含む白金製が好ましいが、耐火物系煉瓦を用いることもできる。さらに、揮散および蒸発防止のために、容器に蓋を装着することが好ましい。 The container used for heating is preferably made of alumina, carbon, silicon carbide, zirconium boride, titanium boride, boron nitride, platinum or platinum containing rhodium, but refractory bricks should be used. You can also. Furthermore, it is preferable to attach a lid to the container in order to prevent volatilization and evaporation.
　加熱は抵抗加熱炉、高周波誘導炉またはプラズマアーク炉を用いて行うことが好ましい。抵抗加熱炉は、ニクロム合金等の金属製、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が特に好ましい。 Heating is preferably performed using a resistance heating furnace, a high frequency induction furnace or a plasma arc furnace. The electric resistance furnace is particularly preferably an electric furnace provided with a heating element made of a metal such as a nichrome alloy, silicon carbide, or molybdenum silicide.
＜溶融条件＞
　原料調合物を加熱して溶融させる温度は、１，２５０℃～１，５５０℃が好ましく、１，３５０℃～１，５００℃が特に好ましい。溶融させる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、上限値以下であると原料の揮発がしにくくなる。
　また、原料調合物を加熱して溶融させる時間は０．２～２時間が好ましく、０．５～２時間が特に好ましい。溶融させる時間が上記範囲の下限値以上であると溶融物の均一性が充分になり、上限値以下であると原料成分が揮発しにくい。 <Melting conditions>
The temperature at which the raw material mixture is heated and melted is preferably 1,250 ° C. to 1,550 ° C., particularly preferably 1,350 ° C. to 1,500 ° C. When the melting temperature is not less than the lower limit of the above range, melting becomes easy, and when it is not more than the upper limit, the raw material is hardly volatilized.
The time for heating and melting the raw material preparation is preferably 0.2 to 2 hours, particularly preferably 0.5 to 2 hours. If the melting time is not less than the lower limit of the above range, the uniformity of the melt will be sufficient, and if it is not more than the upper limit, the raw material components will not easily evaporate.
（工程（２））
　工程（２）では、工程（１）で得られた溶融物を急速に室温付近（２０～２５℃）まで冷却して固化物を得る。固化物は、非晶質部分を含むことが好ましい。非晶質部分を含むことにより、結晶質部分に比べて柔らかいので粉砕しやすく、また非晶質部分中の物質拡散は速いので、反応性を高めることができる。ケイ酸－リン酸化合物の組成を制御しやすくなる。さらに、後工程の工程（４）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。非晶質部分は固化物の８０～１００質量％であるのが好ましい。非晶質部分が該範囲であると、固化物が粉砕しやすく、反応性が高まるので好ましい。結晶質部分を多く含むと粒状またはフレーク状の固化物を得ることが困難となる。また、冷却機器の損耗を著しく早め、さらに、その後の工程（３）の負担が大きくなる。 (Process (2))
In step (2), the melt obtained in step (1) is rapidly cooled to around room temperature (20 to 25 ° C.) to obtain a solidified product. The solidified product preferably contains an amorphous part. By including the amorphous part, it is softer than the crystalline part and thus easily pulverized, and the material diffusion in the amorphous part is fast, so that the reactivity can be increased. It becomes easy to control the composition of the silicic acid-phosphoric acid compound. Furthermore, in the post-process (4), the product can be prevented from being agglomerated, and the particle size of the product can be easily controlled. The amorphous part is preferably 80 to 100% by mass of the solidified product. It is preferable for the amorphous part to be in this range because the solidified product is easily pulverized and the reactivity is increased. When a large amount of crystalline part is contained, it becomes difficult to obtain a granular or flaky solidified product. Further, the wear of the cooling device is remarkably accelerated, and the burden of the subsequent step (3) is increased.
　溶融物の冷却は、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。該冷却方法によれば、非晶質物をより簡便に得ることができる。
　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。 The cooling of the melt is preferably performed in an inert gas or a reducing gas because the equipment is simple. According to this cooling method, an amorphous substance can be obtained more easily.
The cooling rate 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.
　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。さらに、高速で回転するドラムにより、溶融物から連続的にファイバー状の固化物（長繊維）を巻き取る方法や、高速で回転し側壁に細孔を設けたスピナーを用いてファイバー状の固化物（短繊維）を得る方法を用いてもよい。これらの装置を用いれば、溶融物を効果的に冷却して、高純度で化学組成が均一な固化物が得られる。
　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。 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. In addition, a fiber-like solidified material can be obtained by winding a fiber-like solidified material (long fiber) continuously from the melt with a drum that rotates at high speed, or by using a spinner that rotates at high speed and has pores on the side walls. You may use the method of obtaining (short fiber). If these apparatuses are used, the melt is effectively cooled, and a solidified product having a high purity and a uniform chemical composition can be obtained.
In addition, as a cooling method, there is also a method in which the melt is directly poured into water, but this method is difficult to control, it is difficult to obtain an amorphous material, the solidified product becomes a lump, and the disadvantage of requiring a lot of labor for grinding 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.
　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を上記の上限値以下とすることにより、続く工程（３）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 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. By setting the average thickness and the average diameter to be equal to or less than the above upper limit values, it is possible to reduce the time and labor of the subsequent step (3) and increase the crystallization efficiency. 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.
（工程（３））
　工程（３）は、工程（２）で得た固化物を粉砕して粉砕物を得る工程である。固化物に有機化合物および炭素系導電活物質からなる群から選択される少なくとも１種の炭素源を含ませてもよい。固化物に炭素源を含ませてから粉砕してもよく、また、固化物を予め粉砕してから炭素源を含ませて混合してもよく、固化物と炭素源をそれぞれ予め粉砕してから混合してもよい。該炭素源は、工程（３）および工程（４）における酸化防止、還元促進の作用を有する。炭素源は、固化物に混合されて粉砕され、固化物の表面を均一に被覆したり、固化物間の界面に存在するため、ケイ酸－リン酸化合物を二次電池の正極材料に用いた場合に正極材料の導電材となり得る。 (Process (3))
Step (3) is a step of pulverizing the solidified product obtained in step (2) to obtain a pulverized product. The solidified product may contain at least one carbon source selected from the group consisting of an organic compound and a carbon-based conductive active material. The solidified product may be pulverized after containing the carbon source. Alternatively, the solidified product may be pulverized in advance and then mixed with the carbon source. The solidified product and the carbon source may be pulverized in advance. You may mix. The carbon source has an action of preventing oxidation and promoting reduction in the steps (3) and (4). Since the carbon source is mixed with the solidified product and pulverized to uniformly coat the surface of the solidified product or exists at the interface between the solidified products, a silicic acid-phosphate compound was used as the positive electrode material of the secondary battery. In some cases, the conductive material can be a positive electrode material.
　混合・粉砕はボールミル、ジョークラシャー、ジェットミル、遊星ミル等を用い、乾式または湿式で行うのが好ましい。特に炭素源を含ませる場合には、炭素源を粉砕物の表面に均一に分散させる上で、湿式で粉砕することが好ましい。特に炭素源が有機化合物の場合、該有機化合物を溶解しうる分散媒を使用した湿式粉砕が好ましい。 The mixing / pulverization is preferably performed by a dry or wet method using a ball mill, a jaw crusher, a jet mill, a planetary mill or the like. In particular, when a carbon source is included, it is preferable to pulverize in a wet manner in order to uniformly disperse the carbon source on the surface of the pulverized product. In particular, when the carbon source is an organic compound, wet pulverization using a dispersion medium capable of dissolving the organic compound is preferable.
　湿式粉砕する際の分散媒としては、水あるいはエタノール、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。水は安価な点で特に好ましい。なお、混合・粉砕を湿式で行った場合には、続く工程（４）は、分散媒を沈降、濾過、減圧乾燥、加熱乾燥等で除去した後に実施するのが好ましい。 As a dispersion medium for wet pulverization, water or an organic solvent such as ethanol, isopropyl alcohol, acetone, hexane, or toluene can be used. Water is particularly preferred because of its low cost. In addition, when mixing and pulverization are performed in a wet manner, the subsequent step (4) is preferably performed after the dispersion medium is removed by sedimentation, filtration, drying under reduced pressure, drying by heating, and the like.
　粉砕物の平均粒径は、二次電池用正極材料に適用した場合に導電性を高めるために、体積換算のメディアン径で１ｎｍ～１００μｍが好ましく、１０ｎｍ～１０μｍがより好ましく、１０ｎｍ～１μｍが特に好ましい。平均粒径が上記範囲の下限値以上であると、続く工程（４）で粉砕物同士が焼結して粒径が大きくなりすぎることがなく、好ましい。また上記範囲の上限値以下であると、続く工程（４）の加熱温度や時間を低減できるために好ましい。 The average particle diameter of the pulverized product is preferably 1 nm to 100 μm, more preferably 10 nm to 10 μm, and particularly preferably 10 nm to 1 μm in terms of volume median diameter in order to increase conductivity when applied to a positive electrode material for a secondary battery. preferable. It is preferable that the average particle size is not less than the lower limit of the above range, because the pulverized products are not sintered together in the subsequent step (4) and the particle size is not too large. Moreover, since it is less than the upper limit of the said range, the heating temperature and time of the following process (4) can be reduced, it is preferable.
＜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、アルデヒド類およびケトン類からなる群から選択される少なくとも１種が好ましく、糖類、アミノ酸類、ペプチド類が特に好ましい。糖類としては、グルコース、フラクトース、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、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、セルロース等の多糖類およびアスコルビン酸等のこれらの類縁物質が挙げられる。単糖類およびオリゴ糖は還元性が強くて好ましい。
　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。さらに、アルデヒド基やケトン基等の還元性の官能基を有する有機化合物も挙げられる。
　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 and ketones is preferable, and saccharides, amino acids and peptides are particularly preferable. Examples of sugars include monosaccharides such as glucose, fructose, and galactose; oligosaccharides such as sucrose, maltose, cellobiose, and trehalose; polysaccharides such as invert sugar, dextrin, amylose, amylopectin, and cellulose; and similar substances such as ascorbic acid. Can be mentioned. Monosaccharides and oligosaccharides are preferred because of their strong reducing properties.
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. Furthermore, organic compounds having a reducing functional group such as an aldehyde group or a ketone group are also included.
As the organic compound, specifically, glucose, sucrose, glucose-fructose invert sugar, caramel, starch, pregelatinized starch, carboxymethylcellulose and the like are preferable.
＜炭素系導電活物質＞
　炭素系導電活物質としては、カーボンブラック、グラファイト、アセチレンブラック、カーボンファイバおよびアモルファスカーボン等が好ましい。炭素系導電活物質を固化物の混合・粉砕時に含ませることによって、工程（４）でケイ酸－リン酸化合物を製造した後に、炭素系導電活物質を混合する工程を別途に設ける必要がなくなる。さらに、炭素系導電活物質を有機化合物と共に調合物の粉砕時に含ませることによって、ケイ酸－リン酸化合物の粉末内での炭素系導電活物質の分布が均一となり、また有機化合物またはその熱分解物（炭化物）との接触面積が大きくなる。これによって、炭素系導電活物質のケイ酸－リン酸化合物に対する結合力を高めることが可能となる。 <Carbon-based conductive active material>
As the carbon-based conductive active material, carbon black, graphite, acetylene black, carbon fiber, amorphous carbon and the like are preferable. By including the carbon-based conductive active material at the time of mixing and pulverizing the solidified product, it is not necessary to separately provide a step of mixing the carbon-based conductive active material after producing the silicic acid-phosphate compound in step (4). . Furthermore, by including the carbon-based conductive active material together with the organic compound when the formulation is pulverized, the distribution of the carbon-based conductive active material in the silicic acid-phosphate compound powder becomes uniform, and the organic compound or its thermal decomposition The contact area with the object (carbide) increases. This makes it possible to increase the binding force of the carbon-based conductive active material to the silicic acid-phosphoric acid compound.
　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。炭素源を上記範囲の下限値以上にすることにより、ケイ酸－リ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。上記範囲の上限値以下にすることにより、ケイ酸－リン酸化合物を二次電池用正極材料として用いる場合に、二次電池用正極材料としての特性を高いまま保持できる。 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 mass% is particularly preferred. By setting the carbon source to be equal to or higher than the lower limit of the above range, it is possible to sufficiently increase the conductivity when the silicic acid-phosphoric acid compound is used as a positive electrode material for a secondary battery. By setting it to the upper limit of the above range or less, when the silicic acid-phosphoric acid compound is used as the positive electrode material for the secondary battery, the characteristics as the positive electrode material for the secondary battery can be kept high.
（工程（４））
　工程（４）は、式（１）で表される組成を有するケイ酸－リン酸化合物、好ましくはその結晶粒子を得る工程である。 (Process (4))
Step (4) is a step of obtaining a silicic acid-phosphoric acid compound having a composition represented by formula (1), preferably crystal grains thereof.
　工程（４）は、粉砕物の結晶核生成および粒成長を含むことが好ましい。また、前の粉砕工程において有機化合物および炭素系導電活物質からなる群から選択される少なくとも１種を含ませた場合には、得られるケイ酸－リン酸化合物、好ましくはその結晶粒子の表面に有機化合物、炭素系導電活物質およびこれらの反応物から選択される少なくとも１種を結合させる工程であることが好ましい。工程（３）を湿式で行った場合には、分散媒の除去を加熱焼成時に同時に行ってもよい。 Step (4) preferably includes crystal nucleation and grain growth of the pulverized product. Further, when at least one selected from the group consisting of an organic compound and a carbon-based conductive active material is included in the previous pulverization step, the resulting silicic acid-phosphoric acid compound, preferably on the surface of the crystal particles. It is preferably a step of bonding at least one selected from an organic compound, a carbon-based conductive active material, and a reactant thereof. When the step (3) is performed by a wet method, the dispersion medium may be removed at the same time as the heating and firing.
　式（１）中、ｘ、ｙおよびａが０．８＜ｘ＜１．２、０．８＜ｙ＜１．２および０．３５≦ａ≦０．９５を満たし、Ｎ＝＋２であると、ケイ酸－リン酸化合物粒子を二次電池用正極材料に適用した場合、良好な特性を発現するので、好ましい。ｚの値は、ｘ＝１、ｙ＝１、Ｎ＝＋２、ａ＝０．５の場合、３．７５である。
　また、式（１）中、性能向上のため、原子Ｍの一部０．３～１５モル％を＋２価または＋３価の価数をとりうる元素で置換してもよい。例えば、Ｔｉ、Ｖ、Ｂ、Ａｌ、Ｃａ、Ｃｕ、ＭｇおよびＺｎが挙げられる。 In the formula (1), x, y and a satisfy 0.8 <x <1.2, 0.8 <y <1.2 and 0.35 ≦ a ≦ 0.95, and N = + 2 In the case where the silicic acid-phosphoric acid compound particles are applied to the positive electrode material for a secondary battery, good characteristics are exhibited, which is preferable. The value of z is 3.75 when x = 1, y = 1, N = + 2, and a = 0.5.
In the formula (1), in order to improve the performance, a part of 0.3 to 15 mol% of the atom M may be substituted with an element having a valence of +2 or +3. For example, Ti, V, B, Al, Ca, Cu, Mg, and Zn are mentioned.
　また、式（１）で表されるケイ酸－リン酸化合物粒子が、式（２）で表される組成を有する化合物であり、かつ結晶粒子であると、安価に製造できるので、好ましい。
　Ｌｉｘ（ＦｅｂＭｎ１－ｂ）ｙＳｉａＰ１－ａＯｚ　　　（２）
（式中、ｘ、ｙ、ｚおよびａは、それぞれ前記と同じ数値であり、ｂは０≦ｂ≦１である。） Further, it is preferable that the silicic acid-phosphoric acid compound particles represented by the formula (1) are a compound having a composition represented by the formula (2) and are crystalline particles because they can be manufactured at low cost.
Li x (Fe b Mn 1-b ) y Si a P 1-a O z (2)
(In the formula, x, y, z and a are respectively the same numerical values as above, and b is 0 ≦ b ≦ 1.)
　さらに、上記式（２）で表されるケイ酸－リン酸化合物粒子が、式（３）で表される組成を有する化合物であると、良好な特性を発現する材料を安価に製造できるので、特に好ましい。
　ＬｉＦｅｂＭｎ１－ｂＳｉａＰ１－ａＯｚ　　　（３）
（式中、ｚ、ａおよびｂは、それぞれ前記と同じ数値である。） Furthermore, since the silicic acid-phosphoric acid compound particles represented by the above formula (2) are compounds having the composition represented by the formula (3), a material that exhibits good characteristics can be produced at low cost. Particularly preferred.
LiFe b Mn 1-b Si a P 1-a O z (3)
(In the formula, z, a and b are respectively the same numerical values as described above.)
　式（１）において、Ａは＋１価、Ｍは＋２価、Ｓｉは＋４価、およびＰは＋５価が、安定な価数であるので、電荷バランスの点から、Ｚ＝｛ｘ＋２ｙ＋４ａ＋５（１－ａ）｝／２の関係を有することが好ましい。 In the formula (1), A is +1 valence, M is +2 valence, Si is +4 valence, and P is +5 valence, which is a stable valence. Therefore, Z = {x + 2y + 4a + 5 (1-a )} / 2.
＜加熱条件＞
　工程（４）は、不活性ガス中または還元ガス中で行うのが好ましい。
　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イオンの還元（例えばＭ3+からＭ2＋への変化）を促進することができる。これによって、式（１）で表される組成を有するケイ酸－リン酸化合物を再現性よく得ることができる。 <Heating conditions>
Step (4) is preferably performed in an inert gas or a reducing gas.
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 the container containing the reducing agent (for example, graphite) and the pulverized material is loaded in the heating furnace, reduction of M ions in the pulverized material (for example, change from M 3+ to M 2+ ). Can be promoted. Thereby, a silicic acid-phosphoric acid compound having a composition represented by the formula (1) can be obtained with good reproducibility.
　加熱温度は、５００～１，０００℃が好ましく、６００～９００℃が特に好ましい。加熱温度が１，０００℃以下であると、粉砕物が融解しにくく、結晶径や粒子径を制御しやすい。また、該加熱温度範囲であると、適度な結晶性、粒子径、粒度分布等を有するケイ酸－リン酸化合物、好ましくはその結晶粒子が得られやすくなる。 The heating temperature is preferably 500 to 1,000 ° C, particularly preferably 600 to 900 ° C. When the heating temperature is 1,000 ° C. or less, the pulverized product is difficult to melt and the crystal diameter and particle diameter can be easily controlled. In addition, when the heating temperature is within the above range, a silicic acid-phosphoric acid compound having an appropriate crystallinity, particle size, particle size distribution, and the like, preferably crystal particles thereof can be easily obtained.
　工程（４）は一定温度で保持しても、多段階に温度を変化させて行ってもよい。加熱温度を高くするほど、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。 Step (4) may be performed at a constant temperature or by changing the temperature in multiple stages. As 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 a desired particle diameter.
The heating time (holding time depending on the heating temperature) is preferably 1 to 72 hours in consideration of a desired particle size.
　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から選ばれる少なくとも１種の不活性ガスを９９体積％以上含むガスをいう。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ガスをいう。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、全気体体積中に還元性を有するガスが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, more preferably 1 to 10% by volume of the reducing gas 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.
　工程（４）の加熱が終了した後、通常は室温まで冷却する。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、生成物が結晶質粒子である場合は、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 in step (4) is completed, 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 crystalline particles, 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.
　工程（３）で粉砕物の表面に付着した有機化合物や炭素系導電活物質は、工程（４）で生成したケイ酸－リン酸化合物の粒子表面に結合して導電材として機能し得る。有機化合物は工程（４）で熱分解され、さらに少なくとも一部が炭化物となって導電材として機能し得る。有機化合物の熱分解は４００℃以下で行うことが好ましく、炭化は６００℃以下で行うことが好ましい。熱分解を６００℃以下で行うと、炭素系導電活物質の炭化に加えて、熱分解反応に伴う体積変化を小さくできるため、炭化物および炭素系導電活物質が、導電性炭素質層として、ケイ酸－リン酸化合物の粒子表面またはケイ酸－リン酸化合物粒子間の界面に均一かつ強固に結合できる。
　ケイ酸－リン酸化合物の粒子が、さらに導電性炭素質層を含有し、かつ、ケイ酸－リン酸化合物と導電性炭素質層との合計質量に対して、０．１～２０質量％の導電性炭素質層を、該粒子の表面または粒子間界面に含有するのが好ましく、２～１０質量％含有するのが特に好ましい。 The organic compound or carbon-based conductive active material adhering to the surface of the pulverized product in the step (3) can bind to the particle surface of the silicic acid-phosphate compound generated in the step (4) and function as a conductive material. The organic compound is thermally decomposed in the step (4), and at least a part of the organic compound becomes a carbide to function as a conductive material. The thermal decomposition of the organic compound is preferably performed at 400 ° C. or lower, and the carbonization is preferably performed at 600 ° C. or lower. When pyrolysis is performed at 600 ° C. or lower, in addition to carbonization of the carbon-based conductive active material, the volume change associated with the pyrolysis reaction can be reduced, so that the carbide and the carbon-based conductive active material can be used as a conductive carbonaceous layer. It can bond uniformly and firmly to the surface of the acid-phosphate compound particles or the interface between the silicic acid-phosphate compound particles.
The particles of silicic acid-phosphoric acid compound further contain a conductive carbonaceous layer, and 0.1 to 20% by mass with respect to the total mass of the silicic acid-phosphoric acid compound and the conductive carbonaceous layer. The conductive carbonaceous layer is preferably contained on the surface of the particles or at the interface between the particles, and particularly preferably 2 to 10% by mass.
　上述した工程（１）～（４）の各工程を経ることによって、式（１）で表される組成を有するケイ酸－リン酸化合物が製造される。該ケイ酸－リン酸化合物は粒子であることが好ましく、結晶粒子であることがより好ましく、オリビン型結晶粒子であることが特に好ましい。 Through the steps (1) to (4) described above, a silicic acid-phosphate compound having a composition represented by the formula (1) is produced. The silicic acid-phosphoric acid compound is preferably a particle, more preferably a crystal particle, and particularly preferably an olivine type crystal particle.
　該粒子としては、一次粒子および二次粒子の双方を含む。また、固化物に炭素源を含ませた場合には、ケイ酸－リン酸化合物の結晶粒子の生成と同時に、その表面に有機化合物や炭素系導電活物質に基づく導電材を均一にかつ強固に結合させた材料を製造することができる。この粉末材料は二次電池用正極材料に好適である。得られたケイ酸－リン酸化合物の粒子やそれを含む粉末材料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。
　結晶粒子は、その結晶系が斜方晶系であり、クリストバライトおよびリン酸Ｍからなる結晶が含まれないことが好ましい。 The particles include both primary particles and secondary particles. In addition, when a carbon source is included in the solidified product, a conductive material based on an organic compound or a carbon-based conductive active material is uniformly and firmly formed on the surface simultaneously with the formation of crystal particles of a silicic acid-phosphoric acid compound. Combined materials can be produced. This powder material is suitable for a positive electrode material for a secondary battery. When secondary particles are present in the obtained silicic acid-phosphate compound particles and the powder material containing the same, they may be crushed and pulverized to the extent that the primary particles are not destroyed.
The crystal particles preferably have an orthorhombic crystal system and do not include crystals composed of cristobalite and phosphoric acid M.
　本発明のケイ酸－リン酸化合物の粒子の平均粒径は、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－リン酸化合物粒子の粉末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－リン酸化合物からなる粉末の比表面積は、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－リン酸化合物からなる粉末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。なお、結晶粒子は一次粒子のみからなることが好ましい。 The average particle size of the silicic acid-phosphoric acid compound particles 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 powder of silicic acid-phosphoric acid compound particles 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 powder consisting of phosphoric acid 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 powder made of silicic acid-phosphoric 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. The crystal particles are preferably composed only of primary particles.
　本発明のケイ酸－リン酸化合物の製造方法は、ケイ酸－リン酸化合物の製造性や組成制御性に優れるため、オリビン型ケイ酸－リン酸化合物を安価にかつ効率的に製造することができる。特に、ケイ酸－リン酸化合物の結晶粒子の製造性を高めることができる。さらに、化学組成や粒子径の均一性に優れ、かつ高い結晶性を有するケイ酸－リン酸化合物の結晶粒子を得ることができる。 Since the method for producing a silicic acid-phosphoric acid compound of the present invention is excellent in manufacturability and composition controllability of the silicic acid-phosphoric acid compound, an olivine-type silicic acid-phosphoric acid compound can be produced at low cost and efficiently. it can. In particular, the manufacturability of the silicic acid-phosphoric acid compound crystal particles can be enhanced. Further, it is possible to obtain silicic acid-phosphoric acid compound crystal particles having excellent chemical composition and uniform particle diameter and high crystallinity.
［二次電池用正極の製造方法］
　本発明の製造方法により得られたケイ酸－リン酸化合物を、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できる。
　本発明のケイ酸－リン酸化合物を二次電池用正極材料として用いると、原子Ｍが例えばＦｅおよびまたはＭｎの場合は、これらの２価／３価のレドックス反応を充放電に利用して、作用する。 [Method for producing positive electrode for secondary battery]
A positive electrode for a secondary battery can be produced using the silicic acid-phosphate compound obtained by the production method of the present invention as a positive electrode material for a secondary battery.
When the silicic acid-phosphoric acid compound of the present invention is used as a positive electrode material for a secondary battery, when the atom M is, for example, Fe and / or Mn, these divalent / trivalent redox reactions are utilized for charging and discharging, Works.
　本発明の製造方法により得られたケイ酸－リン酸化合物の結晶粒子は高い結晶性を有しているため、二次電池用正極材料に適用した際に、繰返し使用における機能低下を抑制することができる。したがって、電池特性や信頼性に優れる二次電池用正極を安価に提供することが可能となる。 The crystalline particles of silicic acid-phosphoric acid compound obtained by the production method of the present invention have high crystallinity, and therefore, when applied to a positive electrode material for a secondary battery, suppresses functional deterioration during repeated use. Can do. Therefore, it is possible to provide a secondary battery positive electrode excellent in battery characteristics and reliability at low cost.
　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－リ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、ケイ酸－リン酸化合物の粉末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、得られた混合粉末をステンレス鋼製等の支持体上に圧着成形したり、金属製容器に充填すればよい。また、例えば、該混合粉末を有機溶剤（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）と混合して得られたスラリーをアルミニウム、ニッケル、ステンレス、または銅等の金属基板上に塗布する等の方法も採用できる。 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-phosphoric acid compound obtained by the manufacturing method of the present invention is used. For example, a silicic acid-phosphoric acid compound powder may be added to a known binder (polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, ethylene propylene diene polymer, styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluorine if necessary. After mixing with rubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose, etc.) and, if necessary, known conductive materials (acetylene black, carbon, graphite, natural graphite, artificial graphite, needle coke, etc.) The mixed powder thus obtained may be press-molded on a support made of stainless steel or filled in a metal container. Further, for example, the mixed powder is mixed with an organic solvent (N-methylpyrrolidone, toluene, cyclohexane, dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran. And the like, and a slurry obtained by mixing with a metal substrate such as aluminum, nickel, stainless steel, or copper can also be employed.
［二次電池の製造方法］
　本発明の製造方法により得られたケイ酸－リン酸化合物を、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。 [Method for producing secondary battery]
By using the silicic acid-phosphoric acid compound obtained by the production method of the present invention as a positive electrode material for a secondary battery, 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.
　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、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 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 non-aqueous electrolyte lithium ion secondary battery is preferable.
　本発明の二次電池の製造方法によれば、本発明の二次電池用正極の製造方法により得られた二次電池用正極を二次電池の正極に適用することにより、特性や信頼性に優れる二次電池とすることができる。 According to the secondary battery manufacturing method of the present invention, by applying the secondary battery positive electrode obtained by the secondary battery positive electrode manufacturing method of the present invention to the secondary battery positive electrode, characteristics and reliability can be improved. An excellent secondary battery can be obtained.
　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１～１４］
（工程（１））
　溶融物の組成がＬｉ２Ｏ、ＦｅＯ、ＭｎＯ、ＳｉＯ２およびＰ２Ｏ５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）、四酸化三鉄（Ｆｅ３Ｏ４）、二酸化マンガン（ＭｎＯ２）、二酸化ケイ素（ＳｉＯ２）、およびリン酸二水素アンモニウム（ＮＨ４Ｈ２ＰＯ４）をそれぞれ秤量し、乾式で混合・粉砕し、原料調合物を得た。 [Examples 1 to 14]
(Process (1))
Lithium carbonate (Li 2 CO 3 ), so that the composition of the melt is a Li 2 O, FeO, MnO, SiO 2 and P 2 O 5 conversion amount (unit: mol%), and the ratio shown in Table 1 respectively. Triiron tetroxide (Fe 3 O 4 ), manganese dioxide (MnO 2 ), silicon dioxide (SiO 2 ), and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) were weighed, mixed and pulverized in a dry process. A raw material formulation was obtained.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　得られた原料調合物を、ロジウムを２０質量％含む白金製るつぼに充填した。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、型式名：ＮＨ－３０３５）の中に入れた。該電気炉を、流量１Ｌ／分でＮ２ガスを流通しつつ、３００℃／時間の速度で昇温し、１，３５０～１，４５０℃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。 The obtained raw material mixture was filled in a platinum crucible containing 20% by mass of rhodium. Next, the crucible was placed in an electric furnace (model name: NH-3035, manufactured by Motoyama) equipped with a heating element made of molybdenum silicide. The electric furnace was heated at a rate of 300 ° C./hour and heated at 1,350 to 1,450 ° C. for 0.5 hour while flowing N 2 gas at a flow rate of 1 L / min. Each melt was obtained after confirming that it became transparent visually.
（工程（２））
　次に、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って、溶融物を－１×１０５℃／秒で冷却し、フレーク状の固化物を得た。得られた固化物はガラス状物質であった。各例で得たフレーク状固化物の厚さをマイクロメータで測定したところ、５０～１５０μｍであった。 (Process (2))
Next, the melt is cooled at −1 × 10 5 ° C./sec by passing the melt in the crucible through a stainless steel double roller having a diameter of about 15 cm and rotating at 400 revolutions per minute to obtain a flaky solidified product. It was. The obtained solidified product was a glassy substance. The thickness of the flaky solidified material obtained in each example was measured with a micrometer and found to be 50 to 150 μm.
（工程（３））
　得られたフレーク状固化物を軽く手で揉み粗粉砕した後、乳棒および乳鉢を用い、粗粉砕した。さらに、粉砕媒体をジルコニア製のボールとし、遊星ミルを用いて乾式で混合・粉砕して粉砕物を得た。実施例１の粉砕物の粒子径をレーザ回折／散乱式粒度分布測定装置（堀場製作所社製、装置名：ＬＡ－９５０）を用いて測定したところ、体積換算のメディアン径で、１．７μｍであった。 (Process (3))
The obtained flaky solidified product was lightly kneaded and coarsely pulverized, and then coarsely pulverized using a pestle and mortar. Further, the pulverization medium was made into balls made of zirconia and mixed and pulverized by a dry method using a planetary mill to obtain a pulverized product. When the particle diameter of the pulverized product of Example 1 was measured using a laser diffraction / scattering particle size distribution measuring apparatus (manufactured by Horiba, Ltd., apparatus name: LA-950), the volume-converted median diameter was 1.7 μm. there were.
（工程（４））
　ふるい後の実施例１～１４の粉砕物を３体積％Ｈ２－Ａｒガス中にて、７００℃で８時間加熱することによって、それぞれ式（１）で表される組成を有するケイ酸－リン酸化合物粒子を得た。さらに、各例において、各粉砕物を３体積％Ｈ2－Ａｒガス中にて、６００℃×８時間の加熱により、また８００℃×８時間の加熱により、いずれの温度においてもそれぞれ上記７００℃×８時間の加熱の場合と同様の式（１）で表される組成を有するケイ酸－リン酸化合物粒子を得た。その７００℃で加熱して得られたケイ酸－リン酸化合物粒子の平均粒径は、体積換算のメディアン径で、４．４μｍ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、１．４ｍ２／ｇであった。 (Process (4))
By heating the pulverized materials of Examples 1 to 14 after sieving in 3% by volume of H 2 —Ar gas at 700 ° C. for 8 hours, silicate-phosphorus having a composition represented by formula (1), respectively. Acid compound particles were obtained. Further, in each example, each pulverized product was heated at 600 ° C. for 8 hours and heated at 800 ° C. for 8 hours in 3% by volume H 2 —Ar gas. Silica-phosphate compound particles having a composition represented by the same formula (1) as in the case of × 8 hours of heating were obtained. The average particle diameter of the silicic acid-phosphoric acid compound particles obtained by heating at 700 ° C. was 4.4 μm in terms of volume median diameter. Furthermore, it was 1.4 m < 2 > / g 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－リン酸化合物粒子の化学組成を測定した。まず、ケイ酸－リン酸化合物粒子を２．５ｍｏｌ／ＬのＮａＯＨ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、再び塩酸酸性溶液とし濾過した後、濾液および残渣を得た。濾液中のＦｅ、Ｍｎ、ＳｉおよびＰは誘導結合発光分光分析装置（セイコーインスツルメンツ社製、装置名：ＳＰＳ３１００）を用い、また濾液中のＬｉ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。測定したＦｅ、Ｍｎ、Ｓｉ、ＰおよびＬｉ含量から、ＦｅＯ、ＭｎＯ、ＳｉＯ２、Ｐ２Ｏ５およびＬｉ２Ｏを算出した。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含量とした。なお、全ＳｉＯ２含量は、この値と誘導結合発光分光分析装置によって同定したＳｉＯ２含量との合量とした。実施例１～１４において、８００℃で８時間加熱して得られたケイ酸－リン酸化合物粒子について、これらの定量値から求めた粒子の化学組成を表２に示す。 (Composition analysis)
The chemical composition of the resulting silicic acid-phosphoric acid compound particles was measured. First, silicic acid-phosphoric acid compound particles were decomposed by heating and sealing with a 2.5 mol / L NaOH solution at 120 ° C., and the decomposed solution was dried to dryness under hydrochloric acid acidity and filtered again as hydrochloric acid acidic solution. A residue was obtained. Fe, Mn, Si, and P in the filtrate use an inductively coupled emission spectroscopic analyzer (manufactured by Seiko Instruments Inc., apparatus name: SPS3100), and Li in the filtrate uses an atomic absorption photometer (manufactured by Hitachi High-Technologies Corporation, apparatus name). : Z-2310). From the measured Fe, Mn, Si, P and Li contents, FeO, MnO, SiO 2 , P 2 O 5 and Li 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 SiO 2 content. The total SiO 2 content was the total of this value and the SiO 2 content identified by the inductively coupled emission spectrometer. Table 2 shows the chemical composition of the particles obtained from these quantitative values of the silicic acid-phosphate compound particles obtained by heating at 800 ° C. for 8 hours in Examples 1 to 14.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
（Ｘ線回折）
　得られたケイ酸－リ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　ＴＴＲIII）を用いて調べた。その結果、実施例１～１４の粒子はいずれも斜方晶と考えられる結晶からなり、クリストバライト、リン酸鉄およびリン酸マンガンは同定されなかった。参考のために実施例１、３、６、１３および１４において、８００℃で８時間加熱して得られたケイ酸－リン酸化合物粒子のＸ線回折パターンをそれぞれ図１のａ）、ｂ）およびｃ）、図２のａ）およびｂ）にそれぞれ示す。 (X-ray diffraction)
The mineral phase of the obtained silicic acid-phosphate compound particles was examined using an X-ray diffraction apparatus (manufactured by Rigaku Corporation, apparatus name: RINT TTRIII). As a result, all the particles of Examples 1 to 14 consisted of crystals considered to be orthorhombic, and cristobalite, iron phosphate and manganese phosphate were not identified. For reference, X-ray diffraction patterns of silicic acid-phosphoric acid compound particles obtained in Examples 1, 3, 6, 13 and 14 by heating at 800 ° C. for 8 hours are shown in FIGS. And c), and a) and b) of FIG. 2, respectively.
［実施例１５］
　実施例３で得られたフレーク状の固化物に対して、カーボンブラックとグルコース（水溶液）とを、固化物とカーボンブラックとグルコースとの質量比が９０：２．５：２．５となるように添加した。次いで、ジルコニア製のボールを用い、乾式で粉砕し粉砕物を得た。 [Example 15]
With respect to the flaky solidified product obtained in Example 3, carbon black and glucose (aqueous solution) are mixed so that the mass ratio of the solidified product, carbon black and glucose is 90: 2.5: 2.5. Added to. Next, using a ball made of zirconia, it was pulverized in a dry manner to obtain a pulverized product.
　得られた粉砕物を実施例３同様に、Ａｒガス中にて、８００℃で８時間加熱した。得られた粒子の化学組成を実施例３同様に測定した。その結果、化学組成は、Ｌｉ０．９９Ｆｅ０．９８Ｓｉ０．６３Ｐ０．３７Ｏ３．６６であった。さらに、得られた粒子の炭素含有量を、炭素分析装置（堀場製作所社製、装置名：ＥＭＩＡ－９２０Ａ）を用いて測定したところ、Ｃ質量基準で２．８％であった。また、得られた粒子の平均粒径は、体積換算のメディアン径で、１．４μｍであった。 The obtained pulverized product was heated at 800 ° C. for 8 hours in Ar gas in the same manner as in Example 3. The chemical composition of the obtained particles was measured in the same manner as in Example 3. As a result, the chemical composition was Li 0.99 Fe 0.98 Si 0.63 P 0.37 O 3.66 . Furthermore, when the carbon content of the obtained particles was measured using a carbon analyzer (manufactured by Horiba, Ltd., apparatus name: EMIA-920A), it was 2.8% based on the C mass. Moreover, the average particle diameter of the obtained particle | grains was 1.4 micrometers in median diameter of volume conversion.
［実施例１６］
（Ｌｉイオン二次電池用正極および評価用電池の製造）
　実施例１５で得られた炭素含有の粒子を活物質とし、これらと結着剤としてポリフッ化ビニリデン樹脂と導電材としてアセチレンブラックとを、質量比で８５：５：１０の比率となるように秤量し、Ｎ－メチルピロリドンを溶媒としてよく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で厚さ３０μｍのアルミニウム箔に塗布した。空気中で１２０℃で乾燥させて溶媒を除去し、次いで、ロールプレスで塗工層を圧密化し、それぞれ幅１０ｍｍ×長さ４０ｍｍの短冊状に切り出した。 [Example 16]
(Manufacture of positive electrode for Li ion secondary battery and evaluation battery)
The carbon-containing particles obtained in Example 15 were used as active materials, and these, polyvinylidene fluoride resin as a binder, and acetylene black as a conductive material were weighed so as to have a mass ratio of 85: 5: 10. Then, N-methylpyrrolidone was mixed well as a solvent to prepare a slurry. Next, the slurry was applied to an aluminum foil having a thickness of 30 μm with a bar coater. The solvent was removed by drying at 120 ° C. in the air, and then the coating layer was consolidated by a roll press and cut into strips each having a width of 10 mm and a length of 40 mm.
　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 in which lithium foil was pressure-bonded 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。これら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 these half cells 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２５℃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８５ｍＡ／ｇとして充放電を行った。充電終止電位はＬｉ対極基準で４．２Ｖ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２．０Ｖとした。この充放電サイクルを１０サイクル繰り返した。実施例１５の活物質を用いた半電池の５サイクル目の放電容量は、１２８ｍＡｈ／ｇであった。さらに、６０℃で同様にして充放電サイクルを１０サイクル繰り返した。５サイクル目の放電容量は、１４８ｍＡｈ／ｇ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 25 ° 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 85 mA / g. The end-of-charge potential was 4.2 V with respect to the Li counter electrode, and discharge was started immediately after reaching the end-of-voltage. The end-of-discharge voltage was set to 2.0 V based on the Li counter electrode. This charge / discharge cycle was repeated 10 cycles. The discharge capacity at the fifth cycle of the half cell using the active material of Example 15 was 128 mAh / g. Further, the charge / discharge cycle was repeated 10 cycles in the same manner at 60 ° C. The discharge capacity at the fifth cycle was 148 mAh / g.
［比較例１］
　溶融物の組成が、Ｌｉ２Ｏ、ＦｅＯ、ＳｉＯ２およびＰ２Ｏ５換算量（単位：モル％）で、それぞれ、５％、６０％、３０％、５％となるように、炭酸リチウム（Ｌｉ２ＣＯ３）、四酸化三鉄（Ｆｅ３Ｏ４）、ニ酸化ケイ素（ＳｉＯ２）およびリン酸ニ水素アンモニウム（ＮＨ４Ｈ２ＰＯ４）をそれぞれ秤量し、乾式で混合・粉砕し、原料調合物を得た。１，４５０℃で実施例１と同様に溶融したが、完全な溶融物を得ることができなかった。 [Comparative Example 1]
Lithium carbonate (5%, 60%, 30%, 5%) in terms of Li 2 O, FeO, SiO 2 and P 2 O 5 equivalent amounts (unit: mol%), respectively, Li 2 CO 3 ), triiron tetroxide (Fe 3 O 4 ), silicon dioxide (SiO 2 ), and ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ) are weighed, mixed and pulverized in a dry process, A raw material formulation was obtained. Although it melted at 1,450 ° C. in the same manner as in Example 1, a complete melt could not be obtained.
　実施例１～１５では、所望の組成のケイ酸－リン酸化合物を効率的に製造することができた。また、製造されたケイ酸－リン酸化合物は、二次電池用正極材料、さらには二次電池として優れた特性を有することを実施例１６において確認した。 In Examples 1 to 15, a silicic acid-phosphoric acid compound having a desired composition could be produced efficiently. Further, it was confirmed in Example 16 that the produced silicic acid-phosphoric acid compound had excellent characteristics as a positive electrode material for a secondary battery and further as a secondary battery.
　本発明のケイ酸－リン酸化合物の製造方法は、ケイ酸－リン酸化合物の組成制御をしやすくかつ、製造しやすいので有用である。得られたケイ酸－リン酸化合物は、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。
　なお、２０１０年５月６日に出願された日本特許出願２０１０－１０６７７２号の明細書、特許請求の範囲、図面およ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-phosphoric acid compound of the present invention is useful because the composition of the silicic acid-phosphoric acid compound can be easily controlled and produced. The obtained silicic acid-phosphoric acid compound is useful when applied to a positive electrode material for a secondary battery and further to a secondary battery.
The entire content of the specification, claims, drawings and abstract of Japanese Patent Application No. 2010-106762 filed on May 6, 2010 is cited here as the disclosure of the specification of the present invention. Incorporated.

Claims (15)

  1. 　Ｌｉ、ＮａおよびＫからなる群から選ばれる少なくとも１種の原子Ａと、Ｆｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選ばれる少なくとも１種の原子Ｍと、ＳｉおよびＰと、を含み（ただし、原子Ａ、原子Ｍ、ＳｉおよびＰからなる群から選ばれる少なくとも１種は酸化物として含まれる。）、溶融物になったときの各原子の含有量の酸化物換算量（単位：モル％）が、
    　１５％＜Ａ２Ｏ＜３０％、
    　３５％＜ＭＯ＜５５％、
    　１５％＜ＳｉＯ２＜５０％、
    　１％＜Ｐ２Ｏ５＜１８％、であり、
    　０．８＜Ａ２Ｏ／（０．５ＳｉＯ２＋Ｐ２Ｏ５）＜１．２、
    　０．８＜Ａ２Ｏ／０．５ＭＯ＜１．２、
    であ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工程、
    　前記固化物を粉砕し粉砕物を得る工程、および
    　前記粉砕物を加熱して下式（１）で表される組成を有するケイ酸－リン酸化合物を得る工程、
    を含むことを特徴とするケイ酸－リン酸化合物の製造方法。
    　ＡｘＭｙＳｉａＰ１－ａＯｚ　　　　（１）
    （式中、ＡおよびＭは、それそれ前記と同じ種類の原子であり、ｘ、ｙおよびａは、０．８＜ｘ＜１．２、０．８＜ｙ＜１．２、０．３５≦ａ≦０．９５であり、ｚは、ｘ、ｙ、ａおよびＭの価数Ｎに依存する数である。）     Including at least one atom A selected from the group consisting of Li, Na and K, at least one atom M selected from the group consisting of Fe, Mn, Co and Ni, and Si and P (wherein At least one selected from the group consisting of atom A, atom M, Si and P is included as an oxide.), Oxide equivalent amount (unit: mol%) of the content of each atom when it becomes a melt But,
    15% <A 2 O <30%,
    35% <MO <55%,
    15% <SiO 2 <50%,
    1% <P 2 O 5 <18%,
    0.8 <A 2 O / (0.5SiO 2 + P 2 O 5 ) <1.2,
    0.8 <A 2 O / 0.5MO <1.2,
    Heating the raw material formulation to obtain a melt,
    Cooling the melt to obtain a solidified product,
    Pulverizing the solidified product to obtain a pulverized product, and heating the pulverized product to obtain a silicic acid-phosphoric acid compound having a composition represented by the following formula (1):
    A process for producing a silicic acid-phosphoric acid compound, comprising:
    A x M y Si a P 1 -a O z (1)
    (In the formula, A and M are the same kind of atoms as described above, and x, y, and a are 0.8 <x <1.2, 0.8 <y <1.2, 0.35, respectively. ≦ a ≦ 0.95, and z is a number depending on the valence N of x, y, a and M.)
  2. 　Ｌｉ、ＮａおよびＫからなる群から選ばれる少なくとも１種の原子Ａと、Ｆｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選ばれる少なくとも１種の原子Ｍと、ＳｉおよびＰ（ただし、原子Ａ、原子Ｍ、ＳｉおよびＰからなる群から選ばれる少なくとも１種は酸化物として含まれる。）と、を含む原料調合物を加熱して、各原子の含有量の酸化物換算量（単位：モル％）が、
    　１５％＜Ａ２Ｏ＜３０％、
    　３５％＜ＭＯ＜５５％、
    　１５％＜ＳｉＯ２＜５０％、
    　１％＜Ｐ２Ｏ５＜１８％、であり、
    　０．８＜Ａ２Ｏ／（０．５ＳｉＯ２＋Ｐ２Ｏ５）＜１．２、
    　０．８＜Ａ２Ｏ／０．５ＭＯ＜１．２、
    である溶融物を得る工程、
    　前記溶融物を冷却し固化物を得る工程、
    　前記固化物を粉砕し粉砕物を得る工程、および
    　前記粉砕物を加熱して下式（１）で表される組成を有するケイ酸－リン酸化合物を得る工程、
    を含むケイ酸－リン酸化合物の製造方法。
    　ＡｘＭｙＳｉａＰ１－ａＯｚ　　　　（１）
    （式中、ＡおよびＭは、それぞれ前記と同じ種類の原子であり、ｘ、ｙおよびａは、０．８＜ｘ＜１．２、０．８＜ｙ＜１．２、０．３５≦ａ≦０．９５であり、ｚは、ｘ、ｙ、ａおよびＭの価数Ｎに依存する数である。）     At least one atom A selected from the group consisting of Li, Na and K; at least one atom M selected from the group consisting of Fe, Mn, Co and Ni; and Si and P (provided that atom A, atom And at least one selected from the group consisting of M, Si, and P is included as an oxide.), And an oxide equivalent amount (unit: mol%) of the content of each atom But,
    15% <A 2 O <30%,
    35% <MO <55%,
    15% <SiO 2 <50%,
    1% <P 2 O 5 <18%,
    0.8 <A 2 O / (0.5SiO 2 + P 2 O 5 ) <1.2,
    0.8 <A 2 O / 0.5MO <1.2,
    Obtaining a melt which is
    Cooling the melt to obtain a solidified product,
    Pulverizing the solidified product to obtain a pulverized product, and heating the pulverized product to obtain a silicic acid-phosphoric acid compound having a composition represented by the following formula (1):
    A method for producing a silicic acid-phosphoric acid compound comprising:
    A x M y Si a P 1 -a O z (1)
    (In the formula, A and M are the same kind of atoms as described above, and x, y and a are 0.8 <x <1.2, 0.8 <y <1.2, 0.35 ≦ a ≦ 0.95, and z is a number depending on the valence N of x, y, a and M.)
  3. 　前記原料調合物中に含まれる原子Ａが、Ａの炭酸塩、Ａの炭酸水素塩、Ａの水酸化物、Ａのリン酸塩およびリン酸水素塩、Ａの硝酸塩、Ａの塩化物、Ａの硫酸塩、Ａの酢酸塩、およびＡのシュウ酸塩からなる群から選ばれる少なくとも１種（ただし、これらの化合物は、それぞれ水和塩を形成していてもよい。）として含まれ、
    　原子Ｍが、Ｍの酸化物、Ｍのオキシ水酸化物、Ｍの金属、Ｍのリン酸塩、Ｍの塩化物、Ｍの硝酸塩、Ｍの硫酸塩、およびＭの有機塩からなる群から選ばれる少なくとも１種として含まれ、
    　Ｓｉが、酸化ケイ素、Ａ２ＳｉＯ３およびＡ４ＳｉＯ４からなる群から選ばれるＡのケイ酸塩（ただし、Ａは前記と同じ種類の原子である。）、ならびにＭＳｉＯ３およびＭ２ＳｉＯ４からなる群から選ばれるＭのケイ酸塩（ただし、Ｍは前記と同じ種類の原子である。）、からなる群から選ばれる少なくとも１種として含まれ、
    　Ｐが、酸化リン、リン酸アンモニウム、リン酸水素アンモニウム、リン酸、ポリリン酸、亜リン酸、次亜リン酸、Ａのリン酸塩、およびＭのリン酸塩からなる群から選ばれる少なくとも１種として含まれる、請求項１または２に記載のケイ酸－リン酸化合物の製造方法。     Atoms A contained in the raw material formulation are A carbonate, A bicarbonate, A hydroxide, A phosphate and hydrogen phosphate, A nitrate, A chloride, A And at least one selected from the group consisting of A sulfate, A acetate, and A oxalate (however, these compounds may each form a hydrate salt),
    Atom M is selected from the group consisting of M oxide, M oxyhydroxide, M metal, M phosphate, M chloride, M nitrate, M sulfate, and M organic salt Included as at least one
    Si is a silicate of A selected from the group consisting of silicon oxide, A 2 SiO 3 and A 4 SiO 4 (where A is the same kind of atom as described above), and MSiO 3 and M 2 SiO 4 M silicate selected from the group consisting of (wherein M is the same kind of atom as described above), and included as at least one selected from the group consisting of:
    P is at least one selected from the group consisting of phosphorus oxide, ammonium phosphate, ammonium hydrogen phosphate, phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphorous acid, A phosphate, and M phosphate The method for producing a silicic acid-phosphate compound according to claim 1 or 2, which is contained as a seed.
  4. 　前記原子ＡがＬｉである、請求項１～３のいずれか一項に記載のケイ酸－リン酸化合物の製造方法。 The method for producing a silicic acid-phosphate compound according to any one of claims 1 to 3, wherein the atom A is Li.
  5. 　前記原子ＭがＦｅおよびＭｎからなる群から選ばれる少なくとも１種である、請求項１～４のいずれか一項に記載のケイ酸－リン酸化合物の製造方法。 The method for producing a silicic acid-phosphate compound according to any one of claims 1 to 4, wherein the atom M is at least one selected from the group consisting of Fe and Mn.
  6. 　前記式（１）で表される組成を有するケイ酸－リン酸化合物が、下式（２）で表される組成を有する化合物の結晶粒子である、請求項１～３のいずれか一項に記載のケイ酸－リン酸化合物の製造方法。
    　Ｌｉｘ（ＦｅｂＭｎ１－ｂ）ｙＳｉａＰ１－ａＯｚ　　　　（２）
    （式中、ｘ、ｙ、ｚおよびａは、それぞれ前記と同じ数値であり、ｂは０≦ｂ≦１である。）     The silicic acid-phosphoric acid compound having a composition represented by the formula (1) is a crystal particle of a compound having a composition represented by the following formula (2): A process for producing the silicic acid-phosphoric acid compound as described.
    Li x (Fe b Mn 1-b ) y Si a P 1-a O z (2)
    (In the formula, x, y, z and a are respectively the same numerical values as above, and b is 0 ≦ b ≦ 1.)
  7. 　前記式（２）で表される組成を有する化合物の結晶粒子が、下式（３）で表される組成を有する化合物の結晶粒子である、請求項６に記載のケイ酸－リン酸化合物の製造方法。
    　ＬｉＦｅｂＭｎ１－ｂＳｉａＰ１－ａＯｚ　　　　（３）
    （式中、ｚ、ａおよびｂは、それぞれ前記と同じ数値である。）     The crystal particle of the compound having the composition represented by the formula (2) is a crystal particle of a compound having the composition represented by the following formula (3): Production method.
    LiFe b Mn 1-b Si a P 1-a O z (3)
    (In the formula, z, a and b are respectively the same numerical values as described above.)
  8. 　前記粉砕物を得る工程において、前記固化物に、有機化合物および炭素系導電活物質からなる群から選択される少なくとも１種の炭素源を含ませ、かつ該炭素源の量は、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％となる量である、請求項１～７のいずれか一項に記載のケイ酸－リン酸化合物の製造方法。 In the step of obtaining the pulverized product, the solidified product includes at least one carbon source selected from the group consisting of an organic compound and a carbon-based conductive active material, and the amount of the carbon source is determined based on the amount of the solidified product and carbon. The amount according to any one of claims 1 to 7, wherein the ratio of the carbon equivalent (mass) to the total mass with the carbon equivalent (mass) in the source is 0.1 to 20% by mass. A method for producing a silicic acid-phosphoric acid compound.
  9. 　前記固化物を得る工程において、冷却速度が、－１０3℃／秒～－１０10℃／秒である、請求項１～８のいずれか一項に記載のケイ酸－リン酸化合物の製造方法。 The method for producing a silicic acid-phosphate compound according to any one of claims 1 to 8, wherein in the step of obtaining the solidified product, a cooling rate is from -10 3 ° C / second to -10 10 ° C / second. .
  10. 　前記固化物が、非晶質部分を含む固体状化合物である、請求項１～９のいずれか一項記載のケイ酸－リン酸化合物の製造方法。 The method for producing a silicic acid-phosphoric acid compound according to any one of claims 1 to 9, wherein the solidified product is a solid compound containing an amorphous part.
  11. 　前記ケイ酸－リン酸化合物を得る工程を不活性ガス中または還元ガス中で、５００℃～１，０００℃で行う、請求項１～１０のいずれか一項に記載のケイ酸－リン酸化合物の製造方法。 The silicic acid-phosphoric acid compound according to any one of claims 1 to 10, wherein the step of obtaining the silicic acid-phosphoric acid compound is performed in an inert gas or a reducing gas at 500 ° C to 1,000 ° C. Manufacturing method.
  12. 　下式（１）で表される組成を有することを特徴とするケイ酸－リン酸化合物。
    　ＡｘＭｙＳｉａＰ１－ａＯｚ　　　　（１）
    （式中、ＡはＬｉ、ＮａおよびＫからなる群から選ばれる少なくとも１種の原子、ＭはＦｅ、Ｍｎ、ＣｏおよびＮｉからなる群から選ばれる少なくとも１種の原子であり、ｘ、ｙおよびａは、０．８＜ｘ＜１．２、０．８＜ｙ＜１．２、０．３５≦ａ≦０．９５であり、ｚは、ｘ、ｙ、ａおよびＭの価数Ｎに依存する数である。）     A silicic acid-phosphoric acid compound having a composition represented by the following formula (1):
    A x M y Si a P 1 -a O z (1)
    Wherein A is at least one atom selected from the group consisting of Li, Na and K, M is at least one atom selected from the group consisting of Fe, Mn, Co and Ni, and x, y and a is 0.8 <x <1.2, 0.8 <y <1.2, 0.35 ≦ a ≦ 0.95, and z is the valence N of x, y, a, and M. Depends on the number.)
  13. 　前記ケイ酸－リン酸化合物の粒子が、該ケイ酸－リン酸化合物と導電性炭素質層との合計質量に対して、０．１～２０質量％の導電性炭素質層を、該粒子の表面または粒子間界面に含有する、請求項１２に記載のケイ酸－リン酸化合物。 The particles of the silicic acid-phosphoric acid compound comprise 0.1 to 20% by mass of the conductive carbonaceous layer based on the total mass of the silicic acid-phosphoric acid compound and the conductive carbonaceous layer. The silicic acid-phosphoric acid compound according to claim 12, which is contained on the surface or the interparticle interface.
  14. 　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－リン酸化合物を得て、次に、該ケイ酸―リ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-phosphoric acid compound is obtained by the production method according to any one of claims 1 to 11, and then the silicic acid-phosphoric acid compound is used as a positive electrode material for a secondary battery. The manufacturing method of the positive electrode for secondary batteries characterized by manufacturing a positive electrode for batteries.
  15. 　請求項１４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 14, and then producing a secondary battery using the positive electrode for the secondary battery.
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