WO2022145323A1 - Method for manufacturing vanadium lithium phosphate - Google Patents
Method for manufacturing vanadium lithium phosphate Download PDFInfo
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- WO2022145323A1 WO2022145323A1 PCT/JP2021/047758 JP2021047758W WO2022145323A1 WO 2022145323 A1 WO2022145323 A1 WO 2022145323A1 JP 2021047758 W JP2021047758 W JP 2021047758W WO 2022145323 A1 WO2022145323 A1 WO 2022145323A1
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- Prior art keywords
- vanadium
- lithium
- phosphate
- carbon
- particles
- Prior art date
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- YWJVFBOUPMWANA-UHFFFAOYSA-H [Li+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O Chemical compound [Li+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O YWJVFBOUPMWANA-UHFFFAOYSA-H 0.000 title claims abstract description 117
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 32
- 239000002245 particle Substances 0.000 claims abstract description 147
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 140
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 129
- 238000006243 chemical reaction Methods 0.000 claims abstract description 56
- 239000002131 composite material Substances 0.000 claims abstract description 51
- MCHPCGHJTDVXPP-UHFFFAOYSA-N [P].[V].[Li] Chemical compound [P].[V].[Li] MCHPCGHJTDVXPP-UHFFFAOYSA-N 0.000 claims abstract description 48
- 239000002243 precursor Substances 0.000 claims abstract description 41
- 150000002894 organic compounds Chemical class 0.000 claims abstract description 40
- 238000005979 thermal decomposition reaction Methods 0.000 claims abstract description 37
- 239000011164 primary particle Substances 0.000 claims abstract description 30
- SNKMVYBWZDHJHE-UHFFFAOYSA-M lithium;dihydrogen phosphate Chemical compound [Li+].OP(O)([O-])=O SNKMVYBWZDHJHE-UHFFFAOYSA-M 0.000 claims abstract description 26
- 239000012298 atmosphere Substances 0.000 claims abstract description 25
- 238000010438 heat treatment Methods 0.000 claims abstract description 24
- 230000002829 reductive effect Effects 0.000 claims abstract description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 9
- 239000001301 oxygen Substances 0.000 claims abstract description 9
- 239000011261 inert gas Substances 0.000 claims abstract description 7
- 239000002228 NASICON Substances 0.000 claims abstract description 5
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 90
- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical compound O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 claims description 52
- 239000002002 slurry Substances 0.000 claims description 44
- 230000001603 reducing effect Effects 0.000 claims description 34
- 238000006722 reduction reaction Methods 0.000 claims description 34
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 28
- 235000000346 sugar Nutrition 0.000 claims description 28
- 238000001694 spray drying Methods 0.000 claims description 21
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 14
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical group [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 14
- 239000011268 mixed slurry Substances 0.000 claims description 13
- 229910052720 vanadium Inorganic materials 0.000 claims description 13
- 125000004432 carbon atom Chemical group C* 0.000 claims description 12
- 238000010298 pulverizing process Methods 0.000 claims description 12
- 239000007787 solid Substances 0.000 claims description 11
- 239000003125 aqueous solvent Substances 0.000 claims description 10
- 150000001721 carbon Chemical group 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 10
- 238000001354 calcination Methods 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 229910052723 transition metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 4
- 238000000354 decomposition reaction Methods 0.000 claims description 2
- 238000002441 X-ray diffraction Methods 0.000 abstract description 21
- 239000000243 solution Substances 0.000 description 55
- 239000011163 secondary particle Substances 0.000 description 16
- 229910052744 lithium Inorganic materials 0.000 description 14
- 239000000047 product Substances 0.000 description 14
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 13
- 238000010304 firing Methods 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 229910052698 phosphorus Inorganic materials 0.000 description 12
- 239000011574 phosphorus Substances 0.000 description 12
- 125000004429 atom Chemical group 0.000 description 10
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 230000009257 reactivity Effects 0.000 description 9
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- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 4
- 229910018119 Li 3 PO 4 Inorganic materials 0.000 description 3
- 229910012258 LiPO Inorganic materials 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 229910052791 calcium Inorganic materials 0.000 description 3
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- 150000001875 compounds Chemical class 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000012467 final product Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 229910052759 nickel Inorganic materials 0.000 description 3
- 229910052758 niobium Inorganic materials 0.000 description 3
- 125000004437 phosphorous atom Chemical group 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000000790 scattering method Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- 150000003682 vanadium compounds Chemical class 0.000 description 3
- 229910052726 zirconium Inorganic materials 0.000 description 3
- OWEGMIWEEQEYGQ-UHFFFAOYSA-N 100676-05-9 Natural products OC1C(O)C(O)C(CO)OC1OCC1C(O)C(O)C(O)C(OC2C(OC(O)C(O)C2O)CO)O1 OWEGMIWEEQEYGQ-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229930091371 Fructose Natural products 0.000 description 2
- RFSUNEUAIZKAJO-ARQDHWQXSA-N Fructose Chemical compound OC[C@H]1O[C@](O)(CO)[C@@H](O)[C@@H]1O RFSUNEUAIZKAJO-ARQDHWQXSA-N 0.000 description 2
- 239000005715 Fructose Substances 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 2
- GUBGYTABKSRVRQ-PICCSMPSSA-N Maltose Natural products O[C@@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@@H]1[C@@H](CO)OC(O)[C@H](O)[C@H]1O GUBGYTABKSRVRQ-PICCSMPSSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- IIOJIAVEICKTMN-UHFFFAOYSA-K [C+4].P(=O)([O-])([O-])[O-].[V+5].[Li+] Chemical compound [C+4].P(=O)([O-])([O-])[O-].[V+5].[Li+] IIOJIAVEICKTMN-UHFFFAOYSA-K 0.000 description 2
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 2
- GLMOMDXKLRBTDY-UHFFFAOYSA-A [V+5].[V+5].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O Chemical compound [V+5].[V+5].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O GLMOMDXKLRBTDY-UHFFFAOYSA-A 0.000 description 2
- 238000000889 atomisation Methods 0.000 description 2
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 2
- GUBGYTABKSRVRQ-QUYVBRFLSA-N beta-maltose Chemical compound OC[C@H]1O[C@H](O[C@H]2[C@H](O)[C@@H](O)[C@H](O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@@H]1O GUBGYTABKSRVRQ-QUYVBRFLSA-N 0.000 description 2
- 229910052794 bromium Inorganic materials 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 229910052801 chlorine Inorganic materials 0.000 description 2
- 238000002050 diffraction method Methods 0.000 description 2
- 229910052733 gallium Inorganic materials 0.000 description 2
- 229910052732 germanium Inorganic materials 0.000 description 2
- 239000008103 glucose Substances 0.000 description 2
- 229910052735 hafnium Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052740 iodine Inorganic materials 0.000 description 2
- DMEJJWCBIYKVSB-UHFFFAOYSA-N lithium vanadium Chemical compound [Li].[V] DMEJJWCBIYKVSB-UHFFFAOYSA-N 0.000 description 2
- 239000012046 mixed solvent Substances 0.000 description 2
- 229910052762 osmium Inorganic materials 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 229910052707 ruthenium Inorganic materials 0.000 description 2
- 229910052711 selenium Inorganic materials 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 229910052712 strontium Inorganic materials 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- 229910052714 tellurium Inorganic materials 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 229910001935 vanadium oxide Inorganic materials 0.000 description 2
- 239000012002 vanadium phosphate Substances 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-M dihydrogenphosphate Chemical compound OP(O)([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-M 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 1
- 239000001177 diphosphate Substances 0.000 description 1
- XPPKVPWEQAFLFU-UHFFFAOYSA-J diphosphate(4-) Chemical compound [O-]P([O-])(=O)OP([O-])([O-])=O XPPKVPWEQAFLFU-UHFFFAOYSA-J 0.000 description 1
- 235000011180 diphosphates Nutrition 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 239000008240 homogeneous mixture Substances 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000007561 laser diffraction method Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
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- 230000005855 radiation Effects 0.000 description 1
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- 239000007921 spray Substances 0.000 description 1
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- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000012855 volatile organic compound Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/45—Phosphates containing plural metal, or metal and ammonium
-
- 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
Definitions
- the present invention relates to a method for producing lithium vanadium phosphate, which is useful as a positive electrode material for a lithium secondary battery or an all-solid-state battery.
- Lithium-ion batteries are used as batteries for mobile devices and notebook computers. Lithium-ion batteries are generally considered to be excellent in capacity and energy density. It is also expected to be used as a hybrid vehicle and an electric vehicle. When the lithium ion secondary battery is used in an automobile application, the conditions of temperature and charge / discharge current become harsher than those of the conventional one.
- Nasicon-type phosphates such as lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ) are highly safe even at high temperatures, so they are positive for lithium secondary batteries for automobile applications, all-solid-state batteries, etc. It is attracting attention as an active substance.
- Li 3 V 2 (PO 4 ) 3 lithium vanadium phosphate
- a method for producing lithium vanadium phosphate for example, a method has been proposed in which a lithium source, a vanadium compound and a phosphorus source are pulverized and mixed, the obtained homogeneous mixture is formed into pellets, and then the molded product is fired ().
- a lithium source, a vanadium compound and a phosphorus source are pulverized and mixed, the obtained homogeneous mixture is formed into pellets, and then the molded product is fired ().
- Patent Documents 1 and 2 vanadium oxide (V) is dissolved in an aqueous solution containing lithium hydroxide, a phosphorus source and carbon and / or a non-volatile organic compound are further added, and the obtained raw material mixed solution is dried.
- a method has been proposed in which a precursor is obtained and the precursor is heat-treated in an inert atmosphere to obtain a composite of Li 3 V 2 (PO 4 ) 3 and a conductive carbon material.
- Patent Document 4 mixes a lithium source, a pentavalent or tetravalent vanadium compound, a phosphorus source, and a conductive carbon material source in which carbon is generated by thermal decomposition in an aqueous solvent.
- the third step of wet pulverizing the mixture to obtain a slurry containing the pulverized product, the fourth step of spray-drying the slurry containing the pulverized product to obtain a reaction precursor, and the reaction precursor are not used.
- lithium vanadium phosphate when used as a positive electrode active material such as a lithium secondary battery for automobile applications and an all-solid-state battery, the specific surface area is low in order to improve battery performance or facilitate handling. Moreover, it may be desired that the particle size distribution is sharp.
- vanadium lithium phosphate having a high specific surface area.
- those having a sharp particle size distribution and a BET specific surface area of more than 10 m 2 / g can be obtained, but the BET specific surface area is 10 m 2 / g. It is difficult to obtain the following with a sharp particle size distribution.
- the present invention provides a method for producing vanadium lithium phosphate, which is X-ray diffractically monophasic, has a low specific surface area of 10 m 2 / g or less, and has a sharp particle distribution. To provide.
- the present invention (1) is a method for producing vanadium lithium phosphate having a NASICON structure.
- the following general formula (1) in which the average particle size of the primary particles is 2.0 ⁇ m or less: LiVOPO 4 ⁇ xH 2 O (1) (X in the formula is an integer from 0 to 2)
- Step A to prepare carbon source-adhered particles in which lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached to the surface of the particles of the lithium vanadium phosphorus composite oxide represented by.
- Step B to obtain a reaction precursor by heat-treating the carbon source-adhered particles in an oxygen-containing atmosphere.
- Step C to obtain lithium vanadium phosphate by calcining the reaction precursor at 500 to 1300 ° C. in an inert gas atmosphere or a reducing atmosphere.
- the present invention provides a method for producing lithium vanadium phosphate, which is characterized by having.
- the content of the organic compound that produces carbon by the thermal decomposition in the carbon source-adhered particles is larger than 0.6 in terms of the molar ratio (C / V) of the carbon atom to the vanadium atom.
- the present invention provides the method for producing (1) vanadium lithium phosphate, which is characterized by the above.
- the present invention (3) is characterized in that the carbon content of the reaction precursor is 0.3 to 0.6 in terms of the molar ratio (C / V) of the carbon atom to the vanadium atom (1).
- Or (2) for producing vanadium lithium phosphate is characterized in that the carbon content of the reaction precursor is 0.3 to 0.6 in terms of the molar ratio (C / V) of the carbon atom to the vanadium atom (1).
- the present invention (5) is characterized in that, in the step B, the temperature at which the carbon source-adhered particles are heat-treated is 270 to 370 ° C., which is vanadium phosphate according to any one of (1) to (4). It provides a method for producing lithium.
- the step A is A1 step of mixing vanadium pentoxide, phosphoric acid and reducing sugar in an aqueous solvent to prepare a mixed slurry (1), and A2 step of heat-treating the mixed slurry to make a solution to obtain a reduction reaction solution, and A solution containing lithium hydroxide is added to the reduction reaction solution under heating to form a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and the above.
- a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and the above.
- the present invention provides a method for producing lithium vanadium phosphate according to any one of (1) to (5), which is a step comprising the above.
- the present invention (7) is the method for producing (6) vanadium lithium phosphate, which is characterized in that the temperature at which the mixed slurry (1) is heat-treated in the A2 step is 60 to 100 ° C. It is to provide.
- the present invention (8) is the method for producing lithium vanadium phosphate according to (6) or (7), wherein the heating temperature of the reduction reaction solution is 40 to 100 ° C. in the A3 step. It is to provide.
- the mixed amount of the reduced sugar is larger than 0.6 in terms of the molar ratio (C / V) of the carbon atom in terms of carbon atom to the vanadium atom of vanadium pentoxide.
- the present invention (10) is characterized in that the average particle size of the solid content in the wet pulverized slurry (3) obtained after the A4 step is 2.0 ⁇ m or less (6) to (9). It provides a method for producing any of the vanadium lithium phosphates.
- the present invention (11) is characterized in that the reaction precursor further contains a Me source (Me represents a metal element having an atomic number of 11 or more or a transition metal element other than V) (1).
- Me source represents a metal element having an atomic number of 11 or more or a transition metal element other than V
- )-(10) Provided is a method for producing any of the vanadium lithium phosphates.
- vanadium lithium phosphate of the present invention it is possible to obtain a product having a single phase in X-ray diffraction, a BET specific surface area of 10 m 2 / g or less, a low specific surface area, and a sharp particle distribution.
- a method for producing vanadium lithium phosphate can be provided.
- the method for producing lithium vanadium phosphate of the present invention is: A method for producing lithium vanadium phosphate having a NASICON structure.
- Step B to obtain a reaction precursor by heat-treating the carbon source-adhered particles in an oxygen-containing atmosphere.
- Step C to obtain lithium vanadium phosphate by calcining the reaction precursor at 500 to 1300 ° C. in an inert gas atmosphere or a reducing atmosphere. It is a method for producing vanadium lithium phosphate, which is characterized by having.
- the method for producing vanadium lithium phosphate of the present invention is a method for producing vanadium lithium phosphate having a NASICON structure (hereinafter, simply referred to as "vanadium lithium phosphate").
- the vanadium lithium phosphate obtained by the method for producing lithium vanadium phosphate of the present invention is obtained by the following general formula (2) :.
- Li x V y (PO 4 ) 3 (2) (In the formula, x indicates 2.5 or more and 3.5 or less, and y indicates 1.8 or more and 2.2 or less.)
- the vanadium lithium phosphate represented by the above, or the vanadium lithium phosphate represented by the general formula (2) optionally represents a Me element (Me represents a metal element other than V and having an atomic number of 11 or more or a transition metal element. ) Is doped and contained in vanadium lithium phosphate.
- X in the general formula (2) is 2.5 or more and 3.5 or less, preferably 2.8 or more and 3.2 or less.
- y is 1.8 or more and 2.2 or less, preferably 1.9 or more and 2.1 or less.
- the Me element to be doped is Sr, Ba, Sc, Y, Hf, Ta, W, Ru, Os, Ag, Zn, Si, Ga, Ge, Sn, Bi. , S, Se, Te, Cl, Br, I, Na, K, Mg, Ca, Al, Mn, Co, Ni, Fe, Ti, Zr, Bi, Cr, Nb, Mo and Cu. Two or more types can be mentioned. Of these, the Me element is preferably one or more selected from Mg, Ca, Al, Mn, Co, Ni, Fe, Ti, Zr, Bi, Cr, Nb, Mo and Cu. ..
- the method for producing lithium vanadium phosphate of the present invention includes a step A, a step B, and a step C.
- Step A In step A according to the method for producing lithium vanadium phosphate of the present invention, phosphorus is applied to the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1) in which the average particle size of the primary particles is 2.0 ⁇ m or less.
- This is a step of preparing carbon source-adhered particles to which lithium dihydrogen acid (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached.
- the carbon source-adhered particles are (i) a state in which particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) having an average particle diameter of primary particles of 2.0 ⁇ m or less are monodispersed. Even if lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached to the particle surface of the monodisperse particles, or (ii) the average particle size of the primary particles is
- the lithium vanadium phosphorus composite oxide represented by the general formula (1) having a size of 2.0 ⁇ m or less forms secondary particles, and lithium dihydrogen phosphate (LiH 2 PO 4 ) and lithium dihydrogen phosphate (LiH 2 PO 4) are formed on the particle surface of the secondary particles. It may be one to which an organic compound that produces carbon by thermal decomposition is attached, or (iii) one containing both forms of (i) and (ii).
- step A lithium dihydrogen phosphate (LiH 2 PO) is placed on the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1) in which the average particle size of the primary particles is 2.0 ⁇ m or less. 4 ) And by preparing carbon source-attached particles to which an organic compound that produces carbon by thermal decomposition is attached, single-phase vanadium lithium phosphate can be obtained by X-ray diffraction with a small amount of carbon by firing in step C. It is easy to obtain vanadium lithium phosphate produced with a sharp particle distribution.
- LiH 2 PO lithium dihydrogen phosphate
- the lithium vanadium phosphorus composite oxide represented by the general formula (1) according to step A has an average particle size of primary particles of 2.0 ⁇ m or less, preferably 0.1 to 1.5 ⁇ m.
- the average particle size of the primary particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) is in the above range, coarse particles are less likely to be generated as the produced vanadium lithium phosphate, and the particle size distribution is sharp. It is easy to obtain a single-phase lithium vanadium phosphate by X-ray diffraction with a small amount of carbon.
- the average particle size of the primary particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) exceeds the above range, coarse particles are likely to be mixed as the produced vanadium lithium phosphate, and the particle size distribution. However, it becomes difficult to obtain sharp particles.
- the average particle size of the primary particles of the lithium vanadium phosphorus composite oxide is obtained as the average value of the particle size (major diameter in the Heywood diameter) of 200 arbitrarily extracted particles from the observation with a scanning electron microscope (SEM). Is.
- the lithium vanadium phosphorus composite oxide represented by the general formula (1) is a known compound, and for example, vanadium pentoxide, a phosphorus source, and an organic compound having a reducing action are pentoxide in an aqueous solvent at 60 to 100 ° C. After carrying out the reduction reaction of vanadium, a method of adding lithium hydroxide to this reduction solution and carrying out the reaction at 60 to 100 ° C., phosphoric acid, vanadium pentoxide, lithium hydroxide and an organic compound having a reducing action. (For example, see Japanese Patent Application Laid-Open No. 2010-218829) and the like, and further, by pulverizing if necessary, a general formula in which the average particle size of the primary particles is 2.0 ⁇ m or less.
- the lithium vanadium phosphorus composite oxide represented by (1) can be obtained.
- lithium dihydrogen phosphate (LiH 2 PO 4 ) is attached to the surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1).
- the lithium dihydrogen phosphate (LiH 2 PO 4 ) adhering to the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1) is partially or wholly amorphous phosphorus in step B. It becomes a compound (LiH 2 PO 4 , LiPO 3 , etc.) and lithium phosphate (Li 3 PO 4 ), and further, in step C, lithium dihydrogen phosphate (LiH 2 PO 4 ) and amorphous produced in step B.
- the phosphorus compound and / or lithium phosphate of the above reacts with the lithium vanadium phosphorus composite oxide represented by the general formula (1) to produce vanadium lithium phosphate represented by the general formula (2).
- the lithium vanadium phosphorus composite oxide represented by the general formula (1) is added to the surface of the particles by addition to lithium dihydrogen phosphate (LiH 2 PO 4 ) and heat decomposition.
- Organic compounds that generate carbon are attached.
- As an organic compound that produces carbon by thermal decomposition a part of it is removed from the system or carbon is isolated when the carbon source-adhered particles are heat-treated in step B, or the reaction precursor is fired in step C.
- carbon is isolated and converted to carbon, it is used.
- this isolated carbon becomes a component necessary for preventing the oxidation of vanadium during firing in step C.
- the organic compound that produces carbon by thermal decomposition is not particularly limited as long as it is converted to carbon through steps B and C, but is a lithium vanadium phosphorus composite oxide represented by the general formula (1).
- Organic compounds that generate carbon by thermal decomposition can be uniformly attached to the surface of the particles, and those that are soluble in an aqueous solvent are preferable, and reduced sugars are particularly preferable.
- the reducing sugar include glucose, fructose, lactose, maltose, sucrose and the like, and among these, lactose and sucrose are preferable in that a reaction precursor having excellent reactivity can be obtained.
- the organic compound having the reducing property of vanadium pentoxide for example, the reducing sugar is the reduction of vanadium pentoxide in the preferable form of the step A having the steps A1 to A5 described later. It may also be used as an agent.
- the carbon source-adhered particles are "organic having the reducing property of vanadium pentoxide and producing carbon by thermal decomposition" after being used for the reduction reaction of vanadium pentoxide.
- a reaction-converted product produced by using a compound, for example, a reducing sugar as a reducing agent for the reducing reaction of vanadium pentoxide may be attached.
- the carbon source-adhered particles have "five reduced sugars and the like" that were not used for the reduction of vanadium pentoxide as an organic compound that produces carbon by thermal decomposition.
- Organic compounds that have the reducing property of vanadium oxide and generate carbon by thermal decomposition and "the reducing property of vanadium pentoxide such as reduced sugar” that was produced by being used as a reducing agent in the reduction reaction of vanadium pentoxide.
- a reaction-converted product of an "organic compound that produces carbon by thermal decomposition” is attached.
- the amount of the organic compound that produces carbon by thermal decomposition in the carbon source-adhered particles prepared in step A is uniformly heated and decomposed on the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1).
- the molar ratio (C / V) of carbon atoms in terms of carbon atoms to the vanadium atoms in the carbon source-attached particles is that the organic compound that produces carbon adheres and the oxidation of vanadium can be suppressed in the firing of step C. , 0.6 is preferred.
- the amount of carbon attached to the organic compound that produces carbon by thermal decomposition is such that the carbon derived from the organic compound that produces carbon by thermal decomposition is oxygen in step B.
- heat treatment in the content atmosphere it is efficiently reduced and its content can be easily adjusted. It is preferably greater than 0.6 and 2.0 or less, and particularly preferably 0.7 or more and 1.7 or less.
- step A a lithium vanadium phosphorus composite oxide represented by the general formula (1) having an average particle diameter of 2.0 ⁇ m or less, lithium dihydrogen phosphate (LiH 2 PO 4 ), and carbon by thermal decomposition are obtained.
- the step of having a spray-drying treatment for spray-drying the slurry containing the organic compound containing the above is to uniformly apply phosphorus to the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1). It is preferable in that lithium dihydrogen acid (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition can be attached.
- the solvent used in the slurry containing the above is inactive, insoluble or sparingly soluble in the lithium vanadium phosphorus composite oxide represented by the general formula (1), and diphosphate. It is not particularly limited as long as it can dissolve lithium hydrogen hydrogen (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition, but it is industrially advantageous and is water, or water and an organic that is hydrophilic with water.
- a mixed solvent of the solvent is preferable.
- the average particle size of the primary particles is expressed by the general formula (1) of 2.0 ⁇ m or less.
- the lithium vanadium phosphorus composite oxide forms secondary particles, and lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition adhere to the particle surface of the secondary particles.
- the average particle size (secondary particle size) of the particles is 5 to 100 ⁇ m, preferably 10 to 50 ⁇ m, which is the average particle size obtained from SEM observation, which is easy to handle and has excellent reactivity. It is preferable from the viewpoint of The average particle diameter (secondary particle diameter) of the carbon source-attached particles is obtained as an average value of the particle diameters (major diameter in the Heywood diameter) of 200 arbitrarily extracted particles from SEM observation.
- step A a step having the following steps A1 to A5 is preferable in that a reaction precursor having industrially advantageous and excellent reactivity can be obtained. That is, as step A, vanadium pentoxide, phosphoric acid and reducing sugar are mixed in an aqueous solvent to prepare a mixed slurry (1), and step A1. A2 step of heat-treating the mixed slurry to make a solution to obtain a reduction reaction solution, A solution containing lithium hydroxide is added to the reduction reaction solution under heating to form a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and thermal decomposition.
- step A vanadium pentoxide, phosphoric acid and reducing sugar are mixed in an aqueous solvent to prepare a mixed slurry (1), and step A1.
- A3 step of preparing a slurry (2) containing an organic compound that produces carbon by A4 step of preparing the wet pulverized slurry (3) by wet pulverizing the slurry (2) with a media mill.
- the A1 step is a step of preparing a mixed slurry (1) by mixing vanadium pentoxide, phosphoric acid and a reducing sugar in an aqueous solvent.
- the mixing amount of vanadium pentoxide and phosphoric acid is the molar ratio (V / P) of V atoms in vanadium pentoxide to P atoms in phosphoric acid, which is 0.50 to 0.80, preferably 0. It is preferably .60 to 0.73 in that a single-phase lithium vanadium phosphate can be easily obtained as a final product.
- the reducing sugar according to the A1 step promotes the reduction reaction of vanadium pentoxide in the A2 step, and is a component necessary for making the reduction reaction solution obtained by performing the A2 step into a reaction solution having a good viscosity that can be stirred. It becomes. Further, the carbon source derived from the reducing sugar that was not used for reduction in the A2 step becomes a component that suppresses the oxidation of vanadium during the firing in the C step.
- Examples of the reducing sugar according to the A1 step include the above-mentioned reducing sugars, and examples thereof include glucose, fructose, lactose, maltose, and sucrose.
- lactose and sucrose are reaction precursors having excellent reactivity. Is preferable in that
- the mixing amount of the reducing sugar is the molar ratio (C / V) of the carbon atom in terms of carbon atom to the V atom in vanadium pentoxide, preferably more than 0.6 and 2.0 or less. Particularly preferably, it is 0.7 or more and 1.7 or less.
- the mixing amount of the reducing sugar in the A1 step is within the above range, it is excellent in economy, the reduction reaction solution can be made into a solution in the A2 step, and carbon source-attached particles to which the reducing sugar is uniformly adhered can be obtained. ..
- the mixing amount of the reducing sugar in the A1 step is less than the above range, it is difficult to obtain a solution in which vanadium pentoxide is reduced in the A2 step, and the amount of the reducing sugar is insufficient in the A5 step. It tends to be difficult to obtain carbon source-adhered particles to which reducing sugars are uniformly attached, and if it exceeds the above range, it takes a large amount of time to prepare the amount of reducing sugars in step B, so industrially. Not advantageous.
- the production history of vanadium pentoxide, phosphoric acid, and reducing sugars in the A1 step is not limited, but in order to produce high-purity vanadium lithium phosphate, the impurity content may be as low as possible. preferable.
- Examples of the water solvent used in the A1 step include water or a mixed solvent of water and a hydrophilic organic solvent.
- the order and mixing means for adding vanadium pentoxide, phosphoric acid and reducing sugar to the aqueous solvent are not particularly limited, and the mixed slurry (1) in which each of the above raw materials is uniformly dispersed is obtained. Will be done.
- the A2 step is an A2 step in which the mixed slurry (1) obtained in the A1 step is heat-treated to form a solution, and at least vanadium pentoxide is subjected to a reduction reaction to form a solution to obtain a reduction reaction solution.
- the present inventors have reacted with vanadium pentoxide and phosphoric acid in the presence of a reducing sugar to produce VOPO 4 or a water-containing substance thereof (for example, JP-A-2011-96640, JP-A-2011-96641). (Refer to Japanese Patent Application Laid-Open No.
- the reduction reaction solution obtained in the A2 step includes VOPO 4 or a water-containing substance thereof, excess reduced sugar, dihydrogen phosphate ion ( H2 PO 4- ) , and the like. It is considered that the ions caused by the phosphoric acid of the above are dissolved in an aqueous solvent.
- the temperature of the heat treatment in the A2 step is 60 to 100 ° C, preferably 80 to 100 ° C.
- the temperature of the heat treatment in the step A is in the above range, it can be advantageously carried out under atmospheric pressure.
- the temperature of the heat treatment in the step A is less than the above range, the reaction time becomes long, which is industrially disadvantageous, and if it exceeds the above range, a pressure vessel must be used, which is industrial. Not advantageous.
- the completion of the reduction reaction can be confirmed by visually observing that the solution becomes a deep blue transparent liquid.
- the time of the heat treatment in the A2 step is not particularly limited, and is generally 0.2 hours or more, preferably 0.5 to 4 hours. If the heat treatment is performed for a time in the above range, a satisfactory reduction reaction solution can be obtained. Can be done.
- a solution containing lithium hydroxide is added to the reduction reaction solution, and lithium vanadium phosphorus represented by the general formula (1) is added.
- This is a step of preparing a slurry (2) containing a composite oxide, lithium dihydrogen phosphate (LiH 2 PO 4 ), and an organic compound that produces carbon by thermal decomposition.
- the lithium vanadium phosphorus composite oxide represented by the general formula (1) which is precipitated by adding a solution containing lithium hydroxide to the reduction reaction solution, is a collection of plate-shaped primary particles as secondary particles.
- the body is formed, the average thickness of the plate-shaped primary particles determined by SEM observation is 1 to 20 nm, preferably 3 to 15 nm, and the average particle size of the secondary particles determined by SEM observation is 0. It is 5 to 20 ⁇ m, preferably 1 to 15 ⁇ m.
- the average thickness of the plate-shaped primary particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) and the average particle diameter of the secondary particles are 200 particles arbitrarily extracted from SEM observation. It is obtained as the average value of.
- the lithium vanadium phosphorus composite oxide represented by the general formula (1) produced in the A3 step is easily represented by the fine general formula (1) by being wet-pulverized with a media mill in the A4 step.
- the lithium vanadium phosphorus composite oxide is pulverized to obtain a slurry (2) containing a fine lithium vanadium phosphorus composite oxide represented by the general formula (1).
- the solution containing lithium hydroxide according to the A3 step is a solution in which lithium hydroxide is dissolved in water.
- the concentration of lithium hydroxide in the solution containing lithium hydroxide is 5 to 20% by mass, preferably 10 to 15% by mass.
- concentration of lithium hydroxide in the solution containing lithium hydroxide is within the above range, the operation of adding the solution to the reduction reaction solution becomes easy, and the production efficiency is controlled while controlling the heat generation associated with the addition of the solution containing lithium hydroxide. It is preferable in that it can enhance.
- the amount of the lithium hydroxide-containing solution added is 0.70, which is the molar ratio (Li / P) of the Li atom in the lithium hydroxide-containing solution to the P atom in the reduction reaction solution obtained by performing the A2 step.
- the addition amount is ⁇ 1.30, preferably 0.83 to 1.17.
- the amount of the solution containing lithium hydroxide added is within the above range, it is preferable in that single-phase vanadium lithium phosphate can be easily obtained as the final product.
- a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and thermal decomposition A solution containing lithium hydroxide is added so that the pH of the "slurry (2)" containing an organic compound that produces carbon is 3 to 7, preferably 4 to 6, particularly preferably 4 to 5.
- a single-phase lithium vanadium phosphate as a final product can be easily obtained.
- the production history of lithium hydroxide is not limited, but it is preferable that the content of impurities is as low as possible in order to produce high-purity lithium vanadium phosphate.
- the solution containing lithium hydroxide is added to the reduction reaction solution while keeping the reduction reaction solution obtained by performing the A2 step at 40 to 100 ° C., preferably 60 to 100 ° C.
- the temperature at which the solution containing lithium hydroxide is added is less than the above range, the precipitation becomes non-uniform, while if it exceeds the above range, the operability is improved by boiling the solution containing lithium hydroxide. It tends to get worse.
- the solution containing lithium hydroxide it is preferable to add the solution containing lithium hydroxide at a constant rate in that stable quality can be obtained.
- the reaction between the reduction reaction solution and lithium hydroxide is completed, so that the aging reaction can be continued if necessary.
- the temperature at which the aging reaction is carried out is preferably 40 to 100 ° C, preferably 60 to 100 ° C, in that particles having a uniform composition can be obtained.
- the aging reaction time is not particularly limited, but usually, if the aging reaction is carried out for 0.5 hours or more, a satisfactory slurry (2) can be obtained.
- the A4 step is a step of wet pulverizing the slurry (2) obtained by performing the A3 step with a media mill to prepare a wet pulverized slurry (3).
- a wet pulverized slurry (3) containing a fine lithium vanadium phosphorus composite oxide represented by the general formula (1) can be obtained.
- the reaction precursor obtained from this fine lithium vanadium phosphorus composite oxide represented by the general formula (1) has excellent reactivity, and is X-ray diffractically monophasic vanadium phosphate by firing in step C. Lithium is generated, and it becomes easy to obtain one with a sharp particle distribution.
- the solid content concentration of the slurry (2) to be wet pulverized by the media mill is 10 to 40% by mass, preferably 15 to 30% by mass, which is good in operability and also has good operability. It is preferable in that the pulverization treatment can be performed efficiently. Therefore, after performing the A3 step, it is desirable to adjust the solid content concentration so that the concentration of the slurry (2) is within the above range, if necessary, and then perform the wet pulverization treatment in the A4 step.
- the slurry (2) is wet-ground and pulverized by a media mill.
- the lithium vanadium phosphorus composite oxide represented by the general formula (1) can be pulverized more finely, so that a reaction precursor having further excellent reactivity can be obtained.
- Examples of the media mill include a bead mill, a ball mill, a paint shaker, an attritor, a sand mill, and the like, and a bead mill is preferable.
- a bead mill is used, the operating conditions and the type and size of beads may be appropriately selected according to the size and processing amount of the apparatus.
- a dispersant may be added to the slurry (2) to be wet pulverized.
- the dispersant include various surfactants, ammonium polycarboxylic acid salts and the like.
- the concentration of the dispersant in the slurry (2) to be wet-ground is preferably 0.01 to 10% by mass, preferably 0.1 to 5% by mass, from the viewpoint of obtaining a sufficient dispersion effect. ..
- the average particle size of the solid content is 2.0 ⁇ m or less, preferably 0.1 to 1.5 ⁇ m, particularly preferably 0.2 to 0 by the laser scattering / diffraction method. It is preferable to carry out the process until it reaches 5.5 ⁇ m in that a reaction precursor having excellent reactivity can be obtained.
- the A5 step is a step of spray-drying the wet pulverized slurry (3) obtained by performing the A4 step to obtain carbon source-adhered particles.
- the carbon source-attached particles obtained by performing the A5 step are the carbon source-attached particles in the form of (ii) or the above (iii) in that they serve as a reaction precursor having excellent reactivity.
- the average particle size of the primary particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) constituting the carbon source-adhered particles is the primary of the solid content in the wet pulverized slurry (3) obtained by performing the A4 step. It is about the same as the average particle size of the particles.
- a method other than the spray drying method is also known as a method for drying the liquid, but in the present invention, this drying method is adopted based on the finding that it is advantageous to select the spray drying method.
- the spray drying method in the A5 step the reduced sugar and lithium dihydrogen phosphate (LiH 2 PO) are uniformly formed on the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1). Since 4 ) is attached and a granulated product in a state in which particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) are densely packed can be obtained, a small amount of carbon is obtained by firing in step C. Therefore, it becomes easy to generate monophasic vanadium lithium phosphate by X-ray diffraction.
- the liquid is atomized by a predetermined means, and the fine droplets generated by the atomization are dried to obtain a granulated product.
- atomization of the liquid for example, there are a method using a rotating disk and a method using a pressure nozzle. Any method can be used in the A5 step.
- the relationship between the size of the droplets of the atomized slurry and the size of the particles of the pulverized product contained therein affects stable drying and the properties of the obtained dried powder. Specifically, if the size of the raw material particles of the pulverized product is too small with respect to the size of the droplets, the droplets become unstable and it becomes difficult to dry them successfully. From this point of view, the size of the atomized droplet is preferably 5 to 100 ⁇ m, particularly preferably 10 to 50 ⁇ m. It is desirable to determine the amount of slurry supplied to the spray dryer in consideration of this viewpoint.
- the drying temperature in the spray drying device shall be adjusted so that the hot air inlet temperature is adjusted to 180 to 250 ° C, preferably 200 to 240 ° C, and the powder temperature is adjusted to 90 to 150 ° C, preferably 100 to 130 ° C. However, it is preferable because it prevents the powder from absorbing moisture and facilitates the recovery of the powder.
- the carbon source-adhered particles obtained by performing the A5 step are those having x of 2 in the formula of the lithium vanadium phosphorus composite oxide represented by the general formula (1) in the X-ray diffraction analysis by drying, and the particles in the formula. It may be a mixture with water of crystallization partially removed, and the mixture is also preferably used in the present invention.
- Step B The step B according to the method for producing lithium vanadium phosphate of the present invention is a step of obtaining a reaction precursor by heat-treating the carbon source-adhered particles prepared in the step A in an oxygen atmosphere.
- step B by performing step B and adjusting the amount of carbon atoms adhering to the particle surface of the particles adhering to the carbon source, phosphoric acid having a low specific surface area and a sharp particle distribution undergoes step C. Vanadium lithium can be produced.
- the carbon content of the reaction precursor is 0.3 to 0.6, preferably 0.35 to 0.55, in terms of the molar ratio (C / V) of carbon atoms to V atoms in the reaction precursor. It is preferable to carry out the heat treatment until it becomes.
- the carbon content of the reaction precursor is in the above range, reduction in the C step occurs sufficiently, and since the carbon content is an appropriate amount, the BET specific surface area of lithium vanadium phosphate becomes low.
- the carbon content of the reaction precursor is less than the above range, the reduction in the C step is incomplete, and if it exceeds the above range, the carbon content becomes excessive and the BET specific surface area of lithium vanadium phosphate is high. Tend to be.
- step B the heat treatment is performed in an oxygen-containing atmosphere.
- the oxygen concentration in the atmosphere during the heat treatment is 5 vol% or more, particularly preferably 10 to 30 vol%, so that the organic compound that produces carbon by thermal decomposition is oxidized with high efficiency and carbon is used. It is preferable in that the content can be easily adjusted within the above range.
- the temperature of the heat treatment is preferably 270 to 370 ° C, particularly preferably 290 to 360 ° C, because the carbon content can be easily controlled. If the temperature of the heat treatment is lower than the above range, it becomes difficult to reduce the carbon atom content, and if it exceeds the above range, the carbon content decreases at once, so that it tends to be difficult to prepare the carbon content.
- step B the carbon content can be reduced as the heat treatment time becomes longer. Therefore, it is preferable to perform the heat treatment over a sufficient period of time so that the carbon content is within the above range.
- the time is 8 hours or more, the vanadium lithium phosphate obtained after the C step becomes a hard sintered body, and it becomes difficult to recover it as a powder.
- a satisfactory reaction precursor can be obtained, usually in a heat treatment time of 1 hour or more and less than 8 hours, preferably 2 to 5 hours.
- the reaction precursors obtained by performing step B are the lithium vanadium phosphorus composite oxide represented by the general formula (1) in the X-ray diffraction analysis by the heat treatment in step B, and other than that, phosphoric acid.
- lithium dihydrogen LiH 2 PO 4
- amorphous phosphorus compound LiH 2 PO 4 , LiPO 3 , etc.
- lithium phosphate Li 3 PO 4
- the step C according to the method for producing lithium vanadium phosphate of the present invention is a step of calcining the reaction precursor obtained by performing the step B at 500 to 1300 ° C. to obtain a single-phase vanadium lithium phosphate by X-ray diffraction. Is.
- the firing temperature in step C is 500 to 1300 ° C, preferably 600 to 1000 ° C. If the calcination temperature in step C is less than the above range, the calcination time until it becomes a single phase becomes long, and if it exceeds the above range, vanadium lithium phosphate is melted.
- the firing atmosphere in step C is an inert gas atmosphere or a reducing atmosphere because it prevents oxidation of vanadium and prevents melting.
- the inert gas used in the step C is not particularly limited, and examples thereof include nitrogen gas, helium gas, and argon gas.
- the firing time is not particularly limited, and if firing is generally performed for 2 hours or more, particularly 3 to 24 hours, single-phase vanadium lithium phosphate can be obtained by X-ray diffraction.
- step C the vanadium lithium phosphate obtained by firing may be subjected to a plurality of firings, if necessary.
- a Me source (Me is an atomic number other than V). 11 or more metal elements or transition metal elements are shown.)
- the Me source is contained in the carbon source-attached particles, or the carbon source-attached particles are contained.
- the following vanadium lithium phosphate is doped with a Me element to obtain a substance contained therein.
- a method of containing the Me source in the particles adhering to the carbon source a method of adding the Me source at any time between the A1 step and the A5 step before spray drying can be mentioned.
- the Me element exists in the Li-site and / and V-site of vanadium lithium phosphate represented by the general formula (2).
- Me in the Me source is a metal element or transition metal element having an atomic number of 11 or more other than V, and preferred Me elements are Sr, Ba, Sc, Y, Hf, Ta, W, Ru, Os, Ag, and the like. Zn, Si, Ga, Ge, Sn, Bi, S, Se, Te, Cl, Br, I, Na, K, Mg, Ca, Al, Mn, Co, Ni, Fe, Ti, Zr, Bi, Cr, Examples thereof include Nb, Mo, Cu and the like, and these may be used alone or in combination of two or more.
- the Me source examples include oxides having Me elements, hydroxides, halides, carbonates, nitrates, carbonates, organic acid salts and the like.
- the Me source When the Me source is mixed between the A1 step and the A5 step before the spray drying, it may be dissolved in the slurry and exist, or it may be present as a solid substance.
- Me as a solid substance in a slurry (2) containing a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition.
- a source it is preferable to use a Me source having an average particle size of 100 ⁇ m or less, preferably 0.1 to 50 ⁇ m, in that a reaction precursor having excellent reactivity can be obtained.
- the Me source is mixed before the spray drying in the A1 step to the A5 step, the mixing amount of the Me source depends on the type of the Me element to be doped, but in many cases, the slurry (2).
- the total molar ratio of V atoms to Me atoms ((Me + V) / P) with respect to the P atoms in the mixture is 0.5 to 0.80, preferably 0.60 to 0.73, and the molar ratio of Me atoms to V atoms is high.
- a mixing amount having a ratio (Me / V) of greater than 0 and 0.45 or less, preferably greater than 0 and 0.1 or less is preferable.
- the vanadium lithium phosphate obtained by performing the method for producing vanadium lithium phosphate of the present invention is a monophasic vanadium lithium phosphate in X-ray diffraction, and has a BET specific surface area of 10.0 m 2 / g. Hereinafter, it is preferably 3.0 to 8.0 m 2 / g. Further, the vanadium lithium phosphate obtained by the method for producing vanadium lithium phosphate of the present invention has an average particle size of primary particles obtained by SEM observation of 0.3 to 1.5 ⁇ m, preferably 0.4 to 1. It is preferable that the size is 2 ⁇ m and the particle size distribution is sharp.
- the carbon content of vanadium lithium phosphate obtained by the method for producing vanadium lithium phosphate of the present invention is 0.01 to 1.0% by mass, preferably 0.01 to 0.5% by mass.
- the obtained vanadium lithium phosphate may be further crushed or crushed as necessary, and further classified.
- step C it is mixed with conductive carbon or the particle surface is coated with conductive carbon and used as a vanadium lithium phosphate carbon composite. You can also do it.
- vanadium lithium phosphate obtained by the method for producing lithium vanadium phosphate of the present invention is used in a positive electrode active material such as a lithium secondary battery and an all-solid-state battery.
- step B the carbon adhering to the surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1) is reduced, and the carbon atom with respect to the vanadium atom is reduced.
- the molar ratio (C / V) of can be adjusted appropriately. Therefore, in the method for producing vanadium lithium phosphate of the present invention, the vanadium lithium phosphate obtained through the C step has a rounded particle surface. As a result, the specific surface area of vanadium lithium phosphate can be reduced in the method for producing vanadium lithium phosphate of the present invention.
- step A lithium dihydrogen phosphate (LiH 2 PO 4 ) and a lithium vanadium phosphorus composite oxide to which an organic compound that produces carbon by thermal decomposition is attached are attached.
- the average particle size of the primary particles is 2.0 ⁇ m or less, preferably 0.1 to 1.5 ⁇ m, the presence of coarse particles is extremely reduced, and therefore, vanadium lithium phosphate obtained through steps B and C.
- the particle distribution of can be sharpened.
- Example 1 ⁇ A1 process> Put 2 L of ion-exchanged water in a 5 L beaker, put 605 g of 85% phosphoric acid, 320 g of vanadium pentoxide and 96 g of lactose (milk sugar) into it, and stir at room temperature (25 ° C) to obtain an ocher-colored mixed slurry (1). Obtained.
- a lithium hydroxide solution was prepared by dissolving 220 g of lithium hydroxide / water salt in 1.5 L of ion-exchanged water. While keeping the reaction solution in the temperature range of 70 to 80 ° C., the lithium hydroxide solution was added to the reaction solution at a constant rate in 40 minutes to obtain a slurry (2) containing a precipitate. Subsequently, the slurry was allowed to cool to room temperature (25 ° C.). After sampling the precipitate, it was filtered, dried, and XRD-measured. As a result, it coincided with the peak of LiVOPO 4.2H 2O .
- the average thickness of the plate-shaped primary particles determined by SEM observation was 5 nm, and the average particle diameter of the secondary particles determined by SEM observation was 6 ⁇ m.
- the X-ray diffraction pattern of the obtained LiVOPO 4.2H 2O is shown in FIG. 1, and the SEM photograph is shown in FIGS. 2 (1000 times) and 3 (5000 times).
- the average thickness of the primary particles of LiVOPO 4.2H 2O and the average particle diameter of the secondary particles were determined as the average value of 200 arbitrarily extracted particles in SEM observation.
- the slurry (3) after wet pulverization was supplied to a spray drying device having an outlet temperature set to 120 ° C. to obtain carbon source-adhered particles.
- the average particle size (secondary particle size) obtained from the SEM observation of the carbon source-attached particles was 20 ⁇ m.
- X-ray diffraction measurement was performed using the obtained carbon source-attached particles as a radiation source, and the carbon source-attached particles contained LiVOPO 4.2H 2 O and LiH 2 PO 4 . See FIG. 4).
- the residual carbon content of the obtained carbon source-adhered particles was determined as the content of C atoms by measuring with a TOC total organic carbon meter (TOC-5000A manufactured by Shimadzu Corporation). The amount of residual carbon was 4.1% by mass.
- the average particle size (secondary particle size) of the carbon source-attached particles was determined as the average value of 200 arbitrarily extracted particles in SEM observation.
- Step B> The obtained carbon source-adhered particles were placed in a mullite saggar and heat-treated at 300 ° C. for 4 hours in an air atmosphere (oxygen concentration 20 Vol%) to obtain a reaction precursor.
- a reaction precursor As a result of X-ray diffraction analysis of the obtained reaction precursor, it was found to contain LiVOPO 4 and a trace amount of Li 3 PO 4 peak. Although no clear peak of LiH 2 PO 4 was detected by X-ray diffraction analysis, it is probable that LiH 2 PO 4 became an amorphous phosphorus compound (LiH 2 PO 4 , LiPO 3 ).
- the residual carbon content of the obtained reaction precursor was determined as the C atom content by measuring with a TOC total organic carbon meter (TOC-5000A manufactured by Shimadzu Corporation). The amount of residual carbon was 3.0% by mass.
- step B the reaction was carried out in the same manner as in Example 1 except that the heat treatment time was 2.5 hours to obtain a vanadium lithium phosphate sample. Moreover, as a result of X-ray diffraction analysis of the obtained vanadium phosphate lithium sample, it was confirmed that all of them were single-phase vanadium lithium phosphate (Li 3 V 2 (PO 4 ) 3 ) (see FIG. 6). This was used as a vanadium lithium phosphate sample.
- Example 1 A reaction was carried out in the same manner as in Example 1 except that step B was not performed to obtain a vanadium lithium phosphate sample. Moreover, as a result of X-ray diffraction analysis of the obtained vanadium phosphate lithium sample, it was confirmed that all of them were single-phase vanadium lithium phosphate (Li 3 V 2 (PO 4 ) 3 ). This was used as a vanadium lithium phosphate sample.
- the carbon content indicates the molar ratio of carbon atoms in terms of carbon atoms to V atoms in the particles attached to the carbon source, and the molar ratio of carbon atoms in terms of carbon atoms to V atoms in the reaction precursor. ..
- Example 1 Average particle size of secondary particles D 50 was determined by laser scattering / diffraction method. In addition, D 90 was also measured. Moreover, the particle size distribution map of the vanadium lithium phosphate sample obtained in Example 1 is shown in FIG. (Amount of residual carbon) It was measured with a TOC total organic carbon meter (TOC-5000A manufactured by Shimadzu Corporation).
Abstract
The purpose of the present invention is to provide a method for manufacturing vanadium lithium phosphate, said method enabling the acquisition of a product that is single-phase by X-ray diffraction, has a low specific surface area, i.e., a BET specific surface area of 10 m2/g or less and has a sharp particle distribution. A method for manufacturing vanadium lithium phosphate having a NASICON structure, said method being characterized by comprising: step A for preparing carbon source-attached particles in which lithium dihydrogen phosphate (LiH2PO4) and an organic compound capable of generating carbon upon thermal decomposition are attached to the surface of particles of lithium vanadium phosphorus composite oxide represented by general formula (1): LiVOPO4xH2O (wherein x is an integer of 0-2), the primary particles thereof having an average particle size of 2.0 μm or less; step B for heating the carbon source-attached particles in an oxygen-containing atmosphere to give a reaction precursor; and step C for baking the reaction precursor in an inert gas atmosphere or reductive atmosphere at 500-1300°C to give vanadium lithium phosphate.
Description
本発明は、リチウム二次電池や全固体電池の正極材として有用なリン酸バナジウムリチウムの製造方法に関するものである。
The present invention relates to a method for producing lithium vanadium phosphate, which is useful as a positive electrode material for a lithium secondary battery or an all-solid-state battery.
携帯機器、ノート型パソコンの電池としてリチウムイオン電池が活用されている。リチウムイオン電池は一般に容量、エネルギー密度に優れているとされている。また、ハイブリット自動車や電気自動車としての利用も期待さている。そして、リチウムイオン二次電池は自動車用途で用いられる場合、従来のものと比べて、温度や充放電電流の条件が過酷になる。
Lithium-ion batteries are used as batteries for mobile devices and notebook computers. Lithium-ion batteries are generally considered to be excellent in capacity and energy density. It is also expected to be used as a hybrid vehicle and an electric vehicle. When the lithium ion secondary battery is used in an automobile application, the conditions of temperature and charge / discharge current become harsher than those of the conventional one.
リン酸バナジウムリチウム（Ｌｉ３Ｖ２（ＰＯ４）３）等のナシコン型リン酸塩は、高温においても安全性が高くなることから、自動車用途等のリチウム二次電池、全固体電池等の正極活物質として注目されている。
Nasicon-type phosphates such as lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ) are highly safe even at high temperatures, so they are positive for lithium secondary batteries for automobile applications, all-solid-state batteries, etc. It is attracting attention as an active substance.
リン酸バナジウムリチウムの製造方法としては、例えば、リチウム源、バナジウム化合物及びリン源を粉砕混合し、得られる均一混合物をペレット状に成形し、次いでこの成形品を焼成する方法が提案されている（例えば、特許文献１及び２参照）。また、下記特許文献３には、酸化バナジウム（Ｖ）を、水酸化リチウムを含む水溶液に溶解し、さらにリン源と炭素及び／又は不揮発性有機化合物を添加し、得られる原料混合溶液を乾燥して前駆体を得、この前駆体を不活性雰囲気にて熱処理してＬｉ３Ｖ２（ＰＯ４）３と導電性炭素材料との複合体を得る方法が提案されている。
As a method for producing lithium vanadium phosphate, for example, a method has been proposed in which a lithium source, a vanadium compound and a phosphorus source are pulverized and mixed, the obtained homogeneous mixture is formed into pellets, and then the molded product is fired (). For example, see Patent Documents 1 and 2). Further, in Patent Document 3 below, vanadium oxide (V) is dissolved in an aqueous solution containing lithium hydroxide, a phosphorus source and carbon and / or a non-volatile organic compound are further added, and the obtained raw material mixed solution is dried. A method has been proposed in which a precursor is obtained and the precursor is heat-treated in an inert atmosphere to obtain a composite of Li 3 V 2 (PO 4 ) 3 and a conductive carbon material.
また、本出願人も先に、下記特許文献４で、リチウム源、５価又は４価のバナジウム化合物、リン源及び加熱分解により炭素が生じる導電性炭素材料源とを水溶媒中で混合して原料混合液を調製する第１工程と、該原料混合液を加熱して沈殿生成反応を行い、沈殿生成物を含む反応液を得る第２工程と、該沈殿生成物を含む反応液をメディアミルにより湿式粉砕処理して、粉砕処理物を含むスラリーを得る第３工程と、該粉砕処理物を含むスラリーを噴霧乾燥処理して、反応前駆体を得る第４工程と、該反応前駆体を不活性ガス雰囲気中又は還元雰囲気中で６００～１３００℃で焼成するリン酸バナジウムリチウム炭素複合体の製造方法を提案した。また、本出願人は下記特許文献５で、バナジウム化合物、リン源及び加熱分解により炭素が生じる導電性炭素材料源を水溶媒中で、好ましくは６０～１００℃で加熱処理して反応を行った後、加熱処理後の液に、更にリチウム源を添加して反応を行い、得られる反応液を噴霧乾燥して反応前駆体を得、該反応前駆体を不活性ガス雰囲気中又は還元雰囲気中で焼成してリン酸バナジウムリチウムを製造する方法等を提案した。
In addition, the applicant also first, in Patent Document 4 below, mixes a lithium source, a pentavalent or tetravalent vanadium compound, a phosphorus source, and a conductive carbon material source in which carbon is generated by thermal decomposition in an aqueous solvent. The first step of preparing the raw material mixture, the second step of heating the raw material mixture to carry out a precipitation formation reaction to obtain a reaction solution containing the precipitate product, and media milling the reaction solution containing the precipitate product. The third step of wet pulverizing the mixture to obtain a slurry containing the pulverized product, the fourth step of spray-drying the slurry containing the pulverized product to obtain a reaction precursor, and the reaction precursor are not used. We have proposed a method for producing a vanadium lithium phosphate carbon composite that is fired at 600 to 1300 ° C. in an active gas atmosphere or a reducing atmosphere. Further, in Patent Document 5 below, the applicant carried out a reaction by heat-treating a vanadium compound, a phosphorus source and a conductive carbon material source in which carbon is generated by thermal decomposition in an aqueous solvent, preferably at 60 to 100 ° C. After that, a lithium source is further added to the heat-treated liquid to carry out a reaction, and the obtained reaction liquid is spray-dried to obtain a reaction precursor, and the reaction precursor is placed in an inert gas atmosphere or a reducing atmosphere. We proposed a method for producing lithium vanadium phosphate by firing.
ここで、リン酸バナジウムリチウムを、自動車用途等のリチウム二次電池、全固体電池等の正極活物質に用いる場合に、電池性能を向上させ、或いは取り扱いを容易にするために、比表面積が低く、且つ、粒度分布がシャープなものが要望されることがある。
Here, when lithium vanadium phosphate is used as a positive electrode active material such as a lithium secondary battery for automobile applications and an all-solid-state battery, the specific surface area is low in order to improve battery performance or facilitate handling. Moreover, it may be desired that the particle size distribution is sharp.
しかしながら、上記のような、従来のリン酸バナジウムリチウムの製造方法では、高比表面積のリン酸バナジウムリチウムが得られ易い。例えば、特許文献４及び特許文献５のリン酸バナジウムリチウムの製造方法によれば、粒度分布がシャープでＢＥＴ比表面積が１０ｍ２／ｇを超えるものが得られるが、ＢＥＴ比表面積が１０ｍ２／ｇ以下のもので、粒度分布がシャープなものが得られ難い。
However, in the conventional method for producing vanadium lithium phosphate as described above, it is easy to obtain vanadium lithium phosphate having a high specific surface area. For example, according to the methods for producing vanadium lithium phosphate of Patent Documents 4 and 5, those having a sharp particle size distribution and a BET specific surface area of more than 10 m 2 / g can be obtained, but the BET specific surface area is 10 m 2 / g. It is difficult to obtain the following with a sharp particle size distribution.
従って、本発明は、Ｘ線回折的に単相であり、ＢＥＴ比表面積が１０ｍ２／ｇ以下と比表面積が低く且つ粒子分布がシャープなものを得ることができるリン酸バナジウムリチウムの製造方法を提供することにある。
Therefore, the present invention provides a method for producing vanadium lithium phosphate, which is X-ray diffractically monophasic, has a low specific surface area of 10 m 2 / g or less, and has a sharp particle distribution. To provide.
上記課題は、以下の本発明により解決される。
すなわち、本発明（１）は、ナシコン（ＮＡＳＩＣＯＮ）構造を有するリン酸バナジウムリチウムの製造方法であって、
一次粒子の平均粒子径が２．０μｍ以下である下記一般式（１）：
ＬｉＶＯＰＯ４・ｘＨ２Ｏ （１）
（式中ｘは０～２の整数）
で表されるリチウムバナジウムリン複合酸化物の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着している炭素源付着粒子を調製するＡ工程と、
該炭素源付着粒子を、酸素含有雰囲気中で加熱処理することにより、反応前駆体を得るＢ工程と、
該反応前駆体を、不活性ガス雰囲気又は還元雰囲気で５００～１３００℃で焼成し、リン酸バナジウムリチウムを得るＣ工程と、
を有することを特徴とするリン酸バナジウムリチウムの製造方法を提供するものである。 The above problem is solved by the following invention.
That is, the present invention (1) is a method for producing vanadium lithium phosphate having a NASICON structure.
The following general formula (1): in which the average particle size of the primary particles is 2.0 μm or less:
LiVOPO 4・ xH 2 O (1)
(X in the formula is an integer from 0 to 2)
Step A to prepare carbon source-adhered particles in which lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached to the surface of the particles of the lithium vanadium phosphorus composite oxide represented by. ,
Step B to obtain a reaction precursor by heat-treating the carbon source-adhered particles in an oxygen-containing atmosphere.
Step C to obtain lithium vanadium phosphate by calcining the reaction precursor at 500 to 1300 ° C. in an inert gas atmosphere or a reducing atmosphere.
The present invention provides a method for producing lithium vanadium phosphate, which is characterized by having.
すなわち、本発明（１）は、ナシコン（ＮＡＳＩＣＯＮ）構造を有するリン酸バナジウムリチウムの製造方法であって、
一次粒子の平均粒子径が２．０μｍ以下である下記一般式（１）：
ＬｉＶＯＰＯ４・ｘＨ２Ｏ （１）
（式中ｘは０～２の整数）
で表されるリチウムバナジウムリン複合酸化物の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着している炭素源付着粒子を調製するＡ工程と、
該炭素源付着粒子を、酸素含有雰囲気中で加熱処理することにより、反応前駆体を得るＢ工程と、
該反応前駆体を、不活性ガス雰囲気又は還元雰囲気で５００～１３００℃で焼成し、リン酸バナジウムリチウムを得るＣ工程と、
を有することを特徴とするリン酸バナジウムリチウムの製造方法を提供するものである。 The above problem is solved by the following invention.
That is, the present invention (1) is a method for producing vanadium lithium phosphate having a NASICON structure.
The following general formula (1): in which the average particle size of the primary particles is 2.0 μm or less:
LiVOPO 4・ xH 2 O (1)
(X in the formula is an integer from 0 to 2)
Step A to prepare carbon source-adhered particles in which lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached to the surface of the particles of the lithium vanadium phosphorus composite oxide represented by. ,
Step B to obtain a reaction precursor by heat-treating the carbon source-adhered particles in an oxygen-containing atmosphere.
Step C to obtain lithium vanadium phosphate by calcining the reaction precursor at 500 to 1300 ° C. in an inert gas atmosphere or a reducing atmosphere.
The present invention provides a method for producing lithium vanadium phosphate, which is characterized by having.
また、本発明（２）は、前記炭素源付着粒子における、前記加熱分解により炭素が生じる有機化合物の含有量が、バナジウム原子に対する炭素原子のモル比（Ｃ／Ｖ）で、０．６より大きいことを特徴とする（１）のリン酸バナジウムリチウムの製造方法を提供するものである。
Further, in the present invention (2), the content of the organic compound that produces carbon by the thermal decomposition in the carbon source-adhered particles is larger than 0.6 in terms of the molar ratio (C / V) of the carbon atom to the vanadium atom. The present invention provides the method for producing (1) vanadium lithium phosphate, which is characterized by the above.
また、本発明（３）は、前記反応前駆体の炭素含有量が、バナジウム原子に対する炭素原子のモル比（Ｃ／Ｖ）で、０．３～０．６であることを特徴とする（１）又は（２）のリン酸バナジウムリチウムの製造方法を提供するものである。
Further, the present invention (3) is characterized in that the carbon content of the reaction precursor is 0.3 to 0.6 in terms of the molar ratio (C / V) of the carbon atom to the vanadium atom (1). ) Or (2) for producing vanadium lithium phosphate.
また、本発明（４）は、前記Ａ工程は、一次粒子の平均粒子径が２．０μｍ以下の前記一般式（１）で表されるリチウムバナジウムリン複合酸化物と、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）と、前記加熱分解により炭素が生じる有機化合物と、を含有するスラリーを噴霧乾燥する噴霧乾燥処理を有する工程であることを特徴とする（１）～（３）いずれかのリン酸バナジウムリチウムの製造方法を提供するものである。
Further, in the present invention (4), in the step A, the lithium vanadium phosphorus composite oxide represented by the general formula (1) having an average particle diameter of primary particles of 2.0 μm or less and lithium dihydrogen phosphate ( Phosphorus according to any one of (1) to (3), which comprises a spray drying treatment for spray-drying a slurry containing LiH 2 PO 4 ) and an organic compound in which carbon is generated by the thermal decomposition. It provides a method for producing lithium vanadium acid.
また、本発明（５）は、前記Ｂ工程において、前記炭素源付着粒子を加熱処理する温度が、２７０～３７０℃であることを特徴とする（１）～（４）いずれかのリン酸バナジウムリチウムの製造方法を提供するものである。
Further, the present invention (5) is characterized in that, in the step B, the temperature at which the carbon source-adhered particles are heat-treated is 270 to 370 ° C., which is vanadium phosphate according to any one of (1) to (4). It provides a method for producing lithium.
また、本発明（６）は、前記Ａ工程が、
五酸化バナジウム、リン酸及び還元糖を水溶媒中で混合して混合スラリー（１）を調製するＡ１工程と、
該混合スラリーを加熱処理して溶液化し、還元反応溶液を得るＡ２工程と、
加温下に該還元反応溶液に水酸化リチウムを含有する溶液を添加して、一般式（１）で表されるリチウムバナジウムリン複合酸化物、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び前記加熱分解により炭素が生じる有機化合物を含有するスラリー（２）を調製するＡ３工程と、
該スラリー（２）をメディアミルにより湿式粉砕処理して、湿式粉砕処理スラリー（３）を調製するＡ４工程と、
該湿式粉砕処理スラリー（３）を噴霧乾燥処理して、前記炭素源付着粒子を得るＡ５工程と、
を有する工程であることを特徴とする（１）～（５）いずれかのリン酸バナジウムリチウムの製造方法を提供するものである。 Further, in the present invention (6), the step A is
A1 step of mixing vanadium pentoxide, phosphoric acid and reducing sugar in an aqueous solvent to prepare a mixed slurry (1), and
A2 step of heat-treating the mixed slurry to make a solution to obtain a reduction reaction solution, and
A solution containing lithium hydroxide is added to the reduction reaction solution under heating to form a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and the above. A3 step of preparing a slurry (2) containing an organic compound that produces carbon by thermal decomposition, and
The A4 step of preparing the wet pulverized slurry (3) by wet pulverizing the slurry (2) with a media mill.
The A5 step of spray-drying the wet pulverized slurry (3) to obtain the carbon source-adhered particles, and
The present invention provides a method for producing lithium vanadium phosphate according to any one of (1) to (5), which is a step comprising the above.
五酸化バナジウム、リン酸及び還元糖を水溶媒中で混合して混合スラリー（１）を調製するＡ１工程と、
該混合スラリーを加熱処理して溶液化し、還元反応溶液を得るＡ２工程と、
加温下に該還元反応溶液に水酸化リチウムを含有する溶液を添加して、一般式（１）で表されるリチウムバナジウムリン複合酸化物、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び前記加熱分解により炭素が生じる有機化合物を含有するスラリー（２）を調製するＡ３工程と、
該スラリー（２）をメディアミルにより湿式粉砕処理して、湿式粉砕処理スラリー（３）を調製するＡ４工程と、
該湿式粉砕処理スラリー（３）を噴霧乾燥処理して、前記炭素源付着粒子を得るＡ５工程と、
を有する工程であることを特徴とする（１）～（５）いずれかのリン酸バナジウムリチウムの製造方法を提供するものである。 Further, in the present invention (6), the step A is
A1 step of mixing vanadium pentoxide, phosphoric acid and reducing sugar in an aqueous solvent to prepare a mixed slurry (1), and
A2 step of heat-treating the mixed slurry to make a solution to obtain a reduction reaction solution, and
A solution containing lithium hydroxide is added to the reduction reaction solution under heating to form a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and the above. A3 step of preparing a slurry (2) containing an organic compound that produces carbon by thermal decomposition, and
The A4 step of preparing the wet pulverized slurry (3) by wet pulverizing the slurry (2) with a media mill.
The A5 step of spray-drying the wet pulverized slurry (3) to obtain the carbon source-adhered particles, and
The present invention provides a method for producing lithium vanadium phosphate according to any one of (1) to (5), which is a step comprising the above.
また、本発明（７）は、前記Ａ２工程において、前記混合スラリー（１）を加熱処理する温度が、６０～１００℃であることを特徴とする（６）のリン酸バナジウムリチウムの製造方法を提供するものである。
Further, the present invention (7) is the method for producing (6) vanadium lithium phosphate, which is characterized in that the temperature at which the mixed slurry (1) is heat-treated in the A2 step is 60 to 100 ° C. It is to provide.
また、本発明（８）は、前記Ａ３工程において、前記還元反応溶液の加熱温度が、４０～１００℃であることを特徴とする（６）又は（７）のリン酸バナジウムリチウムの製造方法を提供するものである。
Further, the present invention (8) is the method for producing lithium vanadium phosphate according to (6) or (7), wherein the heating temperature of the reduction reaction solution is 40 to 100 ° C. in the A3 step. It is to provide.
また、本発明（９）は、前記Ａ１工程において、前記還元糖の混合量が、五酸化バナジウムのバナジウム原子に対する炭素原子換算の炭素原子のモル比（Ｃ／Ｖ）で、０．６より大きく２．０以下であることを特徴とする（６）～（８）いずれかのリン酸バナジウムリチウムの製造方法を提供するものである。
Further, in the present invention (9), in the step A1, the mixed amount of the reduced sugar is larger than 0.6 in terms of the molar ratio (C / V) of the carbon atom in terms of carbon atom to the vanadium atom of vanadium pentoxide. Provided is a method for producing vanadium lithium phosphate according to any one of (6) to (8), which is characterized by having a value of 2.0 or less.
また、本発明（１０）は、前記Ａ４工程後に得られる前記湿式粉砕処理スラリー（３）中の固形分の平均粒子径が２．０μｍ以下であることを特徴とする（６）～（９）いずれかのリン酸バナジウムリチウムの製造方法を提供するものである。
Further, the present invention (10) is characterized in that the average particle size of the solid content in the wet pulverized slurry (3) obtained after the A4 step is 2.0 μm or less (6) to (9). It provides a method for producing any of the vanadium lithium phosphates.
また、本発明（１１）は、前記反応前駆体は、更に、Ｍｅ源（ＭｅはＶ以外の原子番号１１以上の金属元素又は遷移金属元素を示す。）を含有することを特徴とする（１）～（１０）いずれかのリン酸バナジウムリチウムの製造方法を提供するものである。
Further, the present invention (11) is characterized in that the reaction precursor further contains a Me source (Me represents a metal element having an atomic number of 11 or more or a transition metal element other than V) (1). )-(10) Provided is a method for producing any of the vanadium lithium phosphates.
本発明のリン酸バナジウムリチウムの製造方法によれば、Ｘ線回折的に単相であり、ＢＥＴ比表面積が１０ｍ２／ｇ以下と比表面積が低く且つ粒子分布がシャープなものを得ることができるリン酸バナジウムリチウムの製造方法を提供することができる。
According to the method for producing vanadium lithium phosphate of the present invention, it is possible to obtain a product having a single phase in X-ray diffraction, a BET specific surface area of 10 m 2 / g or less, a low specific surface area, and a sharp particle distribution. A method for producing vanadium lithium phosphate can be provided.
以下、本発明をその好ましい実施形態に基づき説明する。
本発明のリン酸バナジウムリチウムの製造方法は、
ナシコン（ＮＡＳＩＣＯＮ）構造を有するリン酸バナジウムリチウムの製造方法であって、
一次粒子の平均粒子径が２．０μｍ以下である下記一般式（１）：
ＬｉＶＯＰＯ４・ｘＨ２Ｏ （１）
（式中ｘは０～２の整数）
で表されるリチウムバナジウムリン複合酸化物の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着している炭素源付着粒子を調製するＡ工程と、
該炭素源付着粒子を、酸素含有雰囲気中で加熱処理することにより、反応前駆体を得るＢ工程と、
該反応前駆体を、不活性ガス雰囲気又は還元雰囲気で５００～１３００℃で焼成し、リン酸バナジウムリチウムを得るＣ工程と、
を有することを特徴とするリン酸バナジウムリチウムの製造方法である。 Hereinafter, the present invention will be described based on the preferred embodiment thereof.
The method for producing lithium vanadium phosphate of the present invention is:
A method for producing lithium vanadium phosphate having a NASICON structure.
The following general formula (1): in which the average particle size of the primary particles is 2.0 μm or less:
LiVOPO 4・ xH 2 O (1)
(X in the formula is an integer from 0 to 2)
Step A to prepare carbon source-adhered particles in which lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached to the surface of the particles of the lithium vanadium phosphorus composite oxide represented by. ,
Step B to obtain a reaction precursor by heat-treating the carbon source-adhered particles in an oxygen-containing atmosphere.
Step C to obtain lithium vanadium phosphate by calcining the reaction precursor at 500 to 1300 ° C. in an inert gas atmosphere or a reducing atmosphere.
It is a method for producing vanadium lithium phosphate, which is characterized by having.
本発明のリン酸バナジウムリチウムの製造方法は、
ナシコン（ＮＡＳＩＣＯＮ）構造を有するリン酸バナジウムリチウムの製造方法であって、
一次粒子の平均粒子径が２．０μｍ以下である下記一般式（１）：
ＬｉＶＯＰＯ４・ｘＨ２Ｏ （１）
（式中ｘは０～２の整数）
で表されるリチウムバナジウムリン複合酸化物の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着している炭素源付着粒子を調製するＡ工程と、
該炭素源付着粒子を、酸素含有雰囲気中で加熱処理することにより、反応前駆体を得るＢ工程と、
該反応前駆体を、不活性ガス雰囲気又は還元雰囲気で５００～１３００℃で焼成し、リン酸バナジウムリチウムを得るＣ工程と、
を有することを特徴とするリン酸バナジウムリチウムの製造方法である。 Hereinafter, the present invention will be described based on the preferred embodiment thereof.
The method for producing lithium vanadium phosphate of the present invention is:
A method for producing lithium vanadium phosphate having a NASICON structure.
The following general formula (1): in which the average particle size of the primary particles is 2.0 μm or less:
LiVOPO 4・ xH 2 O (1)
(X in the formula is an integer from 0 to 2)
Step A to prepare carbon source-adhered particles in which lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached to the surface of the particles of the lithium vanadium phosphorus composite oxide represented by. ,
Step B to obtain a reaction precursor by heat-treating the carbon source-adhered particles in an oxygen-containing atmosphere.
Step C to obtain lithium vanadium phosphate by calcining the reaction precursor at 500 to 1300 ° C. in an inert gas atmosphere or a reducing atmosphere.
It is a method for producing vanadium lithium phosphate, which is characterized by having.
本発明のリン酸バナジウムリチウムの製造方法は、ナシコン（ＮＡＳＩＣＯＮ）構造を有するリン酸バナジウムリチウム（以下、単に「リン酸バナジウムリチウム」と呼ぶ。）の製造方法である。
The method for producing vanadium lithium phosphate of the present invention is a method for producing vanadium lithium phosphate having a NASICON structure (hereinafter, simply referred to as "vanadium lithium phosphate").
本発明のリン酸バナジウムリチウムの製造方法を行い得られるリン酸バナジウムリチウムは、下記一般式（２）：
ＬｉｘＶｙ（ＰＯ４）３ （２）
（式中、ｘは２．５以上３．５以下、ｙは１．８以上２．２以下を示す。）
で表わされるリン酸バナジウムリチウム、あるいは、一般式（２）で表わされるリン酸バナジウムリチウムに、必要により、Ｍｅ元素（Ｍｅは、Ｖ以外の原子番号１１以上の金属元素又は遷移金属元素を示す。）がドープされて含有されているリン酸バナジウムリチウムである。 The vanadium lithium phosphate obtained by the method for producing lithium vanadium phosphate of the present invention is obtained by the following general formula (2) :.
Li x V y (PO 4 ) 3 (2)
(In the formula, x indicates 2.5 or more and 3.5 or less, and y indicates 1.8 or more and 2.2 or less.)
The vanadium lithium phosphate represented by the above, or the vanadium lithium phosphate represented by the general formula (2), optionally represents a Me element (Me represents a metal element other than V and having an atomic number of 11 or more or a transition metal element. ) Is doped and contained in vanadium lithium phosphate.
ＬｉｘＶｙ（ＰＯ４）３ （２）
（式中、ｘは２．５以上３．５以下、ｙは１．８以上２．２以下を示す。）
で表わされるリン酸バナジウムリチウム、あるいは、一般式（２）で表わされるリン酸バナジウムリチウムに、必要により、Ｍｅ元素（Ｍｅは、Ｖ以外の原子番号１１以上の金属元素又は遷移金属元素を示す。）がドープされて含有されているリン酸バナジウムリチウムである。 The vanadium lithium phosphate obtained by the method for producing lithium vanadium phosphate of the present invention is obtained by the following general formula (2) :.
Li x V y (PO 4 ) 3 (2)
(In the formula, x indicates 2.5 or more and 3.5 or less, and y indicates 1.8 or more and 2.2 or less.)
The vanadium lithium phosphate represented by the above, or the vanadium lithium phosphate represented by the general formula (2), optionally represents a Me element (Me represents a metal element other than V and having an atomic number of 11 or more or a transition metal element. ) Is doped and contained in vanadium lithium phosphate.
一般式（２）中のｘは、２．５以上３．５以下、好ましくは２．８以上３．２以下である。ｙは、１．８以上２．２以下、好ましくは１．９以上２．１以下である。
X in the general formula (2) is 2.5 or more and 3.5 or less, preferably 2.8 or more and 3.2 or less. y is 1.8 or more and 2.2 or less, preferably 1.9 or more and 2.1 or less.
リン酸バナジウムリチウムがＭｅ元素を含有する場合、ドープされるＭｅ元素は、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ｈｆ、Ｔａ、Ｗ、Ｒｕ、Ｏｓ、Ａｇ、Ｚｎ、Ｓｉ、Ｇａ、Ｇｅ、Ｓｎ、Ｂｉ、Ｓ、Ｓｅ、Ｔｅ、Ｃｌ、Ｂｒ、Ｉ、Ｎａ、Ｋ、Ｍｇ、Ｃａ、Ａｌ、Ｍｎ、Ｃｏ、Ｎｉ、Ｆｅ、Ｔｉ、Ｚｒ、Ｂｉ、Ｃｒ、Ｎｂ、Ｍｏ及びＣｕから選ばれる１種又は２種以上が挙げられる。これらのうち、Ｍｅ元素としては、Ｍｇ、Ｃａ、Ａｌ、Ｍｎ、Ｃｏ、Ｎｉ、Ｆｅ、Ｔｉ、Ｚｒ、Ｂｉ、Ｃｒ、Ｎｂ、Ｍｏ及びＣｕから選ばれる１種又は２種以上であることが好ましい。
When lithium vanadium phosphate contains a Me element, the Me element to be doped is Sr, Ba, Sc, Y, Hf, Ta, W, Ru, Os, Ag, Zn, Si, Ga, Ge, Sn, Bi. , S, Se, Te, Cl, Br, I, Na, K, Mg, Ca, Al, Mn, Co, Ni, Fe, Ti, Zr, Bi, Cr, Nb, Mo and Cu. Two or more types can be mentioned. Of these, the Me element is preferably one or more selected from Mg, Ca, Al, Mn, Co, Ni, Fe, Ti, Zr, Bi, Cr, Nb, Mo and Cu. ..
本発明のリン酸バナジウムリチウムの製造方法は、Ａ工程と、Ｂ工程と、Ｃ工程と、を有する。
The method for producing lithium vanadium phosphate of the present invention includes a step A, a step B, and a step C.
（Ａ工程）
本発明のリン酸バナジウムリチウムの製造方法に係るＡ工程は、一次粒子の平均粒子径が２．０μｍ以下である一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着している炭素源付着粒子を調製する工程である。 (Step A)
In step A according to the method for producing lithium vanadium phosphate of the present invention, phosphorus is applied to the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1) in which the average particle size of the primary particles is 2.0 μm or less. This is a step of preparing carbon source-adhered particles to which lithium dihydrogen acid (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached.
本発明のリン酸バナジウムリチウムの製造方法に係るＡ工程は、一次粒子の平均粒子径が２．０μｍ以下である一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着している炭素源付着粒子を調製する工程である。 (Step A)
In step A according to the method for producing lithium vanadium phosphate of the present invention, phosphorus is applied to the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1) in which the average particle size of the primary particles is 2.0 μm or less. This is a step of preparing carbon source-adhered particles to which lithium dihydrogen acid (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached.
なお、本発明において、炭素源付着粒子は、（ｉ）一次粒子の平均粒子径が２．０μｍ以下である一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子が単分散した状態の単分散粒子の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着したものであっても、あるいは、（ｉｉ）一次粒子の平均粒子径が２．０μｍ以下である一般式（１）で表されるリチウムバナジウムリン複合酸化物が二次粒子を形成し、該二次粒子の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着したものであっても、あるいは、（ｉｉｉ）前記（ｉ）と（ｉｉ）の両方の形態を含むものであってもよい。
In the present invention, the carbon source-adhered particles are (i) a state in which particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) having an average particle diameter of primary particles of 2.0 μm or less are monodispersed. Even if lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached to the particle surface of the monodisperse particles, or (ii) the average particle size of the primary particles is The lithium vanadium phosphorus composite oxide represented by the general formula (1) having a size of 2.0 μm or less forms secondary particles, and lithium dihydrogen phosphate (LiH 2 PO 4 ) and lithium dihydrogen phosphate (LiH 2 PO 4) are formed on the particle surface of the secondary particles. It may be one to which an organic compound that produces carbon by thermal decomposition is attached, or (iii) one containing both forms of (i) and (ii).
本発明では、Ａ工程において、一次粒子の平均粒子径が２．０μｍ以下である一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物を付着させた炭素源付着粒子を調製することにより、Ｃ工程の焼成で、少ない炭素量でＸ線回折的に単相のリン酸バナジウムリチウムが得られ易く、また、生成されるリン酸バナジウムリチウムとして粒子分布がシャープなものが得られ易くなる。
In the present invention, in step A, lithium dihydrogen phosphate (LiH 2 PO) is placed on the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1) in which the average particle size of the primary particles is 2.0 μm or less. 4 ) And by preparing carbon source-attached particles to which an organic compound that produces carbon by thermal decomposition is attached, single-phase vanadium lithium phosphate can be obtained by X-ray diffraction with a small amount of carbon by firing in step C. It is easy to obtain vanadium lithium phosphate produced with a sharp particle distribution.
Ａ工程に係る一般式（１）で表されるリチウムバナジウムリン複合酸化物は、一次粒子の平均粒子径が２．０μｍ以下、好ましくは０．１～１．５μｍである。一般式（１）で表されるリチウムバナジウムリン複合酸化物の一次粒子の平均粒子径が、上記範囲にあることにより、生成されるリン酸バナジウムリチウムとして粗粒子が生じ難くなり、粒度分布がシャープなものが得られ易く、また、少ない炭素量でＸ線回折的に単相のリン酸バナジウムリチウムが得られ易くなる。一方、一般式（１）で表されるリチウムバナジウムリン複合酸化物の一次粒子の平均粒子径が、上記範囲を超えると、生成されるリン酸バナジウムリチウムとして粗粒子が混入し易くなり、粒度分布がシャープなものが得られ難くなる。なお、リチウムバナジウムリン複合酸化物の一次粒子の平均粒子径は、走査電子顕微鏡（ＳＥＭ）観察から、任意に抽出した２００個の粒子の粒子径（Ｈｅｙｗｏｏｄ径における長径）の平均値として求められるものである。
The lithium vanadium phosphorus composite oxide represented by the general formula (1) according to step A has an average particle size of primary particles of 2.0 μm or less, preferably 0.1 to 1.5 μm. When the average particle size of the primary particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) is in the above range, coarse particles are less likely to be generated as the produced vanadium lithium phosphate, and the particle size distribution is sharp. It is easy to obtain a single-phase lithium vanadium phosphate by X-ray diffraction with a small amount of carbon. On the other hand, when the average particle size of the primary particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) exceeds the above range, coarse particles are likely to be mixed as the produced vanadium lithium phosphate, and the particle size distribution. However, it becomes difficult to obtain sharp particles. The average particle size of the primary particles of the lithium vanadium phosphorus composite oxide is obtained as the average value of the particle size (major diameter in the Heywood diameter) of 200 arbitrarily extracted particles from the observation with a scanning electron microscope (SEM). Is.
一般式（１）で表されるリチウムバナジウムリン複合酸化物は、公知の化合物であり、例えば、五酸化バナジウム、リン源及び還元作用を有する有機化合物を水溶媒中で６０～１００℃で五酸化バナジウムの還元反応を行った後、次いで、この還元溶液に、水酸化リチウムを添加して６０～１００℃で反応を行う方法、リン酸、五酸化バナジウム、水酸化リチウム及び還元作用を有する有機化合物を原料として水熱合成する方法（例えば、特開２０１０－２１８８２９号公報参照。）等が挙げられ、更に、必要により粉砕処理することにより、一次粒子の平均粒子径が２．０μｍ以下の一般式（１）で表されるリチウムバナジウムリン複合酸化物を得ることができる。
The lithium vanadium phosphorus composite oxide represented by the general formula (1) is a known compound, and for example, vanadium pentoxide, a phosphorus source, and an organic compound having a reducing action are pentoxide in an aqueous solvent at 60 to 100 ° C. After carrying out the reduction reaction of vanadium, a method of adding lithium hydroxide to this reduction solution and carrying out the reaction at 60 to 100 ° C., phosphoric acid, vanadium pentoxide, lithium hydroxide and an organic compound having a reducing action. (For example, see Japanese Patent Application Laid-Open No. 2010-218829) and the like, and further, by pulverizing if necessary, a general formula in which the average particle size of the primary particles is 2.0 μm or less. The lithium vanadium phosphorus composite oxide represented by (1) can be obtained.
Ａ工程で調製される炭素源付着粒子において、一般式（１）で表されるリチウムバナジウムリン複合酸化物に粒子表面には、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）が付着している。一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子表面に付着しているリン酸二水素リチウム（ＬｉＨ２ＰＯ４）は、Ｂ工程で、一部又は全量が非晶質のリン化合物（ＬｉＨ２ＰＯ４、ＬｉＰＯ３等）やリン酸リチウム（Ｌｉ３ＰＯ４）になり、更にＣ工程において、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）とＢ工程で生成された非晶質のリン化合物及び／又はリン酸リチウムは一般式（１）で表されるリチウムバナジウムリン複合酸化物と反応して、一般式（２）で表されるリン酸バナジウムリチウムを生成する。
In the carbon source-attached particles prepared in step A, lithium dihydrogen phosphate (LiH 2 PO 4 ) is attached to the surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1). The lithium dihydrogen phosphate (LiH 2 PO 4 ) adhering to the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1) is partially or wholly amorphous phosphorus in step B. It becomes a compound (LiH 2 PO 4 , LiPO 3 , etc.) and lithium phosphate (Li 3 PO 4 ), and further, in step C, lithium dihydrogen phosphate (LiH 2 PO 4 ) and amorphous produced in step B. The phosphorus compound and / or lithium phosphate of the above reacts with the lithium vanadium phosphorus composite oxide represented by the general formula (1) to produce vanadium lithium phosphate represented by the general formula (2).
Ａ工程で調製される炭素源付着粒子において、一般式（１）で表されるリチウムバナジウムリン複合酸化物に粒子表面には、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）に加え、加熱分解により炭素が生じる有機化合物が付着している。加熱分解により炭素が生じる有機化合物としては、Ｂ工程で炭素源付着粒子を加熱処理する際に、一部は系外に除去され、又は炭素が単離し、あるいは、Ｃ工程で反応前駆体を焼成する際に加熱分解し、炭素が単離し、炭素に変換されるものが用いられる。また、この単離した炭素は、Ｃ工程の焼成時にバナジウムの酸化の防止に必要な成分となる。
In the carbon source-adhered particles prepared in step A, the lithium vanadium phosphorus composite oxide represented by the general formula (1) is added to the surface of the particles by addition to lithium dihydrogen phosphate (LiH 2 PO 4 ) and heat decomposition. Organic compounds that generate carbon are attached. As an organic compound that produces carbon by thermal decomposition, a part of it is removed from the system or carbon is isolated when the carbon source-adhered particles are heat-treated in step B, or the reaction precursor is fired in step C. When carbon is isolated and converted to carbon, it is used. In addition, this isolated carbon becomes a component necessary for preventing the oxidation of vanadium during firing in step C.
加熱分解により炭素が生じる有機化合物としては、Ｂ工程及びＣ工程を経て、炭素に変換されるものであれば、特に制限されないが、一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子表面に、均一に加熱分解により炭素が生じる有機化合物を付着させることができる点で、水溶媒に溶解するものが好ましく、還元糖が特に好ましい。還元糖としては、例えば、グルコース、フルクトース、ラクトース、マルトース、スクロース等が挙げられ、これらのうち、ラクトース、スクロースが優れた反応性を有する反応前駆体が得られる点で、好ましい。
The organic compound that produces carbon by thermal decomposition is not particularly limited as long as it is converted to carbon through steps B and C, but is a lithium vanadium phosphorus composite oxide represented by the general formula (1). Organic compounds that generate carbon by thermal decomposition can be uniformly attached to the surface of the particles, and those that are soluble in an aqueous solvent are preferable, and reduced sugars are particularly preferable. Examples of the reducing sugar include glucose, fructose, lactose, maltose, sucrose and the like, and among these, lactose and sucrose are preferable in that a reaction precursor having excellent reactivity can be obtained.
なお、加熱分解により炭素が生じる有機化合物のうち、五酸化バナジウムの還元性を有する有機化合物、例えば、還元糖は、後述するＡ１～Ａ５工程を有するＡ工程の好ましい形態において、五酸化バナジウムの還元剤としても用いられてもよい。その場合、Ａ１～Ａ５工程を有するＡ工程では、炭素源付着粒子には、五酸化バナジウムの還元反応に用いられた後の「五酸化バナジウムの還元性を有し且つ加熱分解により炭素が生じる有機化合物」、例えば、還元糖が、五酸化バナジウムの還元反応の還元剤として使用されて生じた反応変換物が、付着していてもよい。つまり、Ａ工程が、Ａ１～Ａ５工程を有する工程の場合、炭素源付着粒子には、加熱分解により炭素が生じる有機化合物として、五酸化バナジウムの還元には使用されなかった「還元糖等の五酸化バナジウムの還元性を有し且つ加熱分解により炭素が生じる有機化合物」と、五酸化バナジウムの還元反応に還元剤として使用されて生じた「還元糖等の五酸化バナジウムの還元性を有し且つ加熱分解により炭素が生じる有機化合物」の反応変換物と、が付着している。
Among the organic compounds that generate carbon by thermal decomposition, the organic compound having the reducing property of vanadium pentoxide, for example, the reducing sugar is the reduction of vanadium pentoxide in the preferable form of the step A having the steps A1 to A5 described later. It may also be used as an agent. In that case, in the step A having the steps A1 to A5, the carbon source-adhered particles are "organic having the reducing property of vanadium pentoxide and producing carbon by thermal decomposition" after being used for the reduction reaction of vanadium pentoxide. A reaction-converted product produced by using a compound, for example, a reducing sugar as a reducing agent for the reducing reaction of vanadium pentoxide, may be attached. That is, in the case where the step A has steps A1 to A5, the carbon source-adhered particles have "five reduced sugars and the like" that were not used for the reduction of vanadium pentoxide as an organic compound that produces carbon by thermal decomposition. "Organic compounds that have the reducing property of vanadium oxide and generate carbon by thermal decomposition" and "the reducing property of vanadium pentoxide such as reduced sugar" that was produced by being used as a reducing agent in the reduction reaction of vanadium pentoxide. A reaction-converted product of an "organic compound that produces carbon by thermal decomposition" is attached.
Ａ工程で調製される炭素源付着粒子における、加熱分解により炭素が生じる有機化合物の付着量は、一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子表面に、均一に加熱分解により炭素が生じる有機化合物が付着し、Ｃ工程の焼成においてバナジウムの酸化を抑制することができる点で、炭素源付着粒子中のバナジウム原子に対する炭素原子換算の炭素原子のモル比（Ｃ／Ｖ）で、０．６より大きいことが好ましい。また、その一方で、Ａ工程で調製される炭素源付着粒子における、加熱分解により炭素が生じる有機化合物の付着量は、加熱分解により炭素が生じる有機化合物に由来する炭素が、Ｂ工程での酸素含有雰囲気中での加熱処理により、効率よく低減されて、その含有量を調整し易くなる点で、炭素源付着粒子中のバナジウム原子に対する炭素原子換算の炭素原子のモル比（Ｃ／Ｖ）で、好ましくは０．６より大きく２．０以下、特に好ましくは０．７以上１．７以下である。
The amount of the organic compound that produces carbon by thermal decomposition in the carbon source-adhered particles prepared in step A is uniformly heated and decomposed on the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1). The molar ratio (C / V) of carbon atoms in terms of carbon atoms to the vanadium atoms in the carbon source-attached particles is that the organic compound that produces carbon adheres and the oxidation of vanadium can be suppressed in the firing of step C. , 0.6 is preferred. On the other hand, in the carbon source-adhered particles prepared in step A, the amount of carbon attached to the organic compound that produces carbon by thermal decomposition is such that the carbon derived from the organic compound that produces carbon by thermal decomposition is oxygen in step B. By heat treatment in the content atmosphere, it is efficiently reduced and its content can be easily adjusted. It is preferably greater than 0.6 and 2.0 or less, and particularly preferably 0.7 or more and 1.7 or less.
Ａ工程は、一次粒子の平均粒子径が２．０μｍ以下の一般式（１）で表されるリチウムバナジウムリン複合酸化物と、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）と、加熱分解により炭素が生じる有機化合物と、を含有するスラリーを、噴霧乾燥する噴霧乾燥処理を有する工程であることが、一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子表面に、均一に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物を付着させることができる点で、好ましい。
In step A, a lithium vanadium phosphorus composite oxide represented by the general formula (1) having an average particle diameter of 2.0 μm or less, lithium dihydrogen phosphate (LiH 2 PO 4 ), and carbon by thermal decomposition are obtained. The step of having a spray-drying treatment for spray-drying the slurry containing the organic compound containing the above is to uniformly apply phosphorus to the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1). It is preferable in that lithium dihydrogen acid (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition can be attached.
一次粒子の平均粒子径が２．０μｍ以下の一般式（１）で表されるリチウムバナジウムリン複合酸化物と、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）と、加熱分解により炭素が生じる有機化合物と、を含有するスラリーで用いる溶媒としては、一般式（１）で表されるリチウムバナジウムリン複合酸化物に対して、不活性であり、且つ、不溶性又は難溶性であり、且つ、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物を溶解できるものであれば、特に制限されないが、工業的に有利となる点で、水、又は水及び水と親水性の有機溶媒の混合溶媒が好ましい。
A lithium vanadium phosphorus composite oxide represented by the general formula (1) having an average particle size of primary particles of 2.0 μm or less, lithium dihydrogen phosphate (LiH 2 PO 4 ), and an organic compound in which carbon is generated by thermal decomposition. The solvent used in the slurry containing the above is inactive, insoluble or sparingly soluble in the lithium vanadium phosphorus composite oxide represented by the general formula (1), and diphosphate. It is not particularly limited as long as it can dissolve lithium hydrogen hydrogen (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition, but it is industrially advantageous and is water, or water and an organic that is hydrophilic with water. A mixed solvent of the solvent is preferable.
また、Ａ工程で調製される炭素源付着粒子が、前記（ｉｉ）又は（ｉｉｉ）の形態の場合には、一次粒子の平均粒子径が２．０μｍ以下である一般式（１）で表されるリチウムバナジウムリン複合酸化物が二次粒子を形成し、該二次粒子の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着した炭素源付着粒子の平均粒子径（二次粒子径）は、ＳＥＭ観察から求められる平均粒子径で５～１００μｍ、好ましくは１０～５０μｍであることが、取り扱いが容易で、反応性に優れた反応前駆体となる観点から好ましい。なお、炭素源付着粒子の平均粒子径（二次粒子径）は、ＳＥＭ観察から、任意に抽出した２００個の粒子の粒子径（Ｈｅｙｗｏｏｄ径における長径）の平均値として求められるものである。
Further, when the carbon source-attached particles prepared in the step A are in the form of (ii) or (iii), the average particle size of the primary particles is expressed by the general formula (1) of 2.0 μm or less. The lithium vanadium phosphorus composite oxide forms secondary particles, and lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition adhere to the particle surface of the secondary particles. The average particle size (secondary particle size) of the particles is 5 to 100 μm, preferably 10 to 50 μm, which is the average particle size obtained from SEM observation, which is easy to handle and has excellent reactivity. It is preferable from the viewpoint of The average particle diameter (secondary particle diameter) of the carbon source-attached particles is obtained as an average value of the particle diameters (major diameter in the Heywood diameter) of 200 arbitrarily extracted particles from SEM observation.
Ａ工程としては、以下のＡ１工程～Ａ５工程を有する工程であることが、工業的に有利に優れた反応性を有する反応前駆体が得られる点で、好ましい。つまり、Ａ工程としては、五酸化バナジウム、リン酸及び還元糖を水溶媒中で混合して混合スラリー（１）を調製するＡ１工程と、
混合スラリーを加熱処理して溶液化し、還元反応溶液を得るＡ２工程と、
加温下に還元反応溶液に水酸化リチウムを含有する溶液を添加して、一般式（１）で表されるリチウムバナジウムリン複合酸化物、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物を含有するスラリー（２）を調製するＡ３工程と、
スラリー（２）をメディアミルにより湿式粉砕処理して、湿式粉砕処理スラリー（３）を調製するＡ４工程と、
湿式粉砕処理スラリー（３）を噴霧乾燥処理して、炭素源付着粒子を得るＡ５工程と、
を有する工程であることが好ましい。 As the step A, a step having the following steps A1 to A5 is preferable in that a reaction precursor having industrially advantageous and excellent reactivity can be obtained. That is, as step A, vanadium pentoxide, phosphoric acid and reducing sugar are mixed in an aqueous solvent to prepare a mixed slurry (1), and step A1.
A2 step of heat-treating the mixed slurry to make a solution to obtain a reduction reaction solution,
A solution containing lithium hydroxide is added to the reduction reaction solution under heating to form a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and thermal decomposition. A3 step of preparing a slurry (2) containing an organic compound that produces carbon by
A4 step of preparing the wet pulverized slurry (3) by wet pulverizing the slurry (2) with a media mill.
The A5 step of spray-drying the wet pulverized slurry (3) to obtain carbon source-adhered particles, and
It is preferable that the process has.
混合スラリーを加熱処理して溶液化し、還元反応溶液を得るＡ２工程と、
加温下に還元反応溶液に水酸化リチウムを含有する溶液を添加して、一般式（１）で表されるリチウムバナジウムリン複合酸化物、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物を含有するスラリー（２）を調製するＡ３工程と、
スラリー（２）をメディアミルにより湿式粉砕処理して、湿式粉砕処理スラリー（３）を調製するＡ４工程と、
湿式粉砕処理スラリー（３）を噴霧乾燥処理して、炭素源付着粒子を得るＡ５工程と、
を有する工程であることが好ましい。 As the step A, a step having the following steps A1 to A5 is preferable in that a reaction precursor having industrially advantageous and excellent reactivity can be obtained. That is, as step A, vanadium pentoxide, phosphoric acid and reducing sugar are mixed in an aqueous solvent to prepare a mixed slurry (1), and step A1.
A2 step of heat-treating the mixed slurry to make a solution to obtain a reduction reaction solution,
A solution containing lithium hydroxide is added to the reduction reaction solution under heating to form a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and thermal decomposition. A3 step of preparing a slurry (2) containing an organic compound that produces carbon by
A4 step of preparing the wet pulverized slurry (3) by wet pulverizing the slurry (2) with a media mill.
The A5 step of spray-drying the wet pulverized slurry (3) to obtain carbon source-adhered particles, and
It is preferable that the process has.
Ａ１工程は、五酸化バナジウム、リン酸及び還元糖を水溶媒中で混合して混合スラリー（１）を調製する工程である。
The A1 step is a step of preparing a mixed slurry (1) by mixing vanadium pentoxide, phosphoric acid and a reducing sugar in an aqueous solvent.
Ａ１工程において、五酸化バナジウム及びリン酸の混合量は、リン酸中のＰ原子に対する五酸化バナジウム中のＶ原子のモル比（Ｖ／Ｐ）で、０．５０～０．８０、好ましくは０．６０～０．７３であることが、最終生成物として単相のリン酸バナジウムリチウムが得られ易くなる点で、好ましい。
In the A1 step, the mixing amount of vanadium pentoxide and phosphoric acid is the molar ratio (V / P) of V atoms in vanadium pentoxide to P atoms in phosphoric acid, which is 0.50 to 0.80, preferably 0. It is preferably .60 to 0.73 in that a single-phase lithium vanadium phosphate can be easily obtained as a final product.
Ａ１工程に係る還元糖は、Ａ２工程において五酸化バナジウムの還元反応を促進し、また、Ａ２工程を行い得られる還元反応溶液が撹拌可能な良好な粘度を有する反応溶液とするのに必要な成分となる。また、Ａ２工程で還元に使用されなかった還元糖に由来する炭素源は、Ｃ工程の焼成の際に、バナジウムの酸化を抑制する成分となる。
The reducing sugar according to the A1 step promotes the reduction reaction of vanadium pentoxide in the A2 step, and is a component necessary for making the reduction reaction solution obtained by performing the A2 step into a reaction solution having a good viscosity that can be stirred. It becomes. Further, the carbon source derived from the reducing sugar that was not used for reduction in the A2 step becomes a component that suppresses the oxidation of vanadium during the firing in the C step.
Ａ１工程に係る還元糖としては、前述した還元糖が挙げられ、例えば、グルコース、フルクトース、ラクトース、マルトース、スクロース等が挙げられ、これらのうち、ラクトース、スクロースが優れた反応性を有する反応前駆体が得られる点で、好ましい。
Examples of the reducing sugar according to the A1 step include the above-mentioned reducing sugars, and examples thereof include glucose, fructose, lactose, maltose, and sucrose. Among these, lactose and sucrose are reaction precursors having excellent reactivity. Is preferable in that
Ａ１工程において、還元糖の混合量は、五酸化バナジウム中のＶ原子に対して、炭素原子換算の炭素原子のモル比（Ｃ／Ｖ）で、好ましくは０．６より大きく２．０以下、特に好ましくは０．７以上１．７以下である。Ａ１工程における還元糖の混合量が、上記範囲にあることにより、経済性に優れ、Ａ２工程での還元反応溶液の溶液化ができ、還元糖が均一に付着された炭素源付着粒子が得られる。一方、Ａ１工程における還元糖の混合量が、上記範囲未満だと、Ａ２工程において五酸化バナジウムが還元されて溶液化したものが得られ難く、また、Ａ５工程で、還元糖の量が不足し、均一に還元糖が付着した炭素源付着粒子が得られ難くなる傾向があり、また、上記範囲を超えると、Ｂ工程で還元糖の量を調製するのに多大な時間を要するため工業的に有利でない。
In the A1 step, the mixing amount of the reducing sugar is the molar ratio (C / V) of the carbon atom in terms of carbon atom to the V atom in vanadium pentoxide, preferably more than 0.6 and 2.0 or less. Particularly preferably, it is 0.7 or more and 1.7 or less. When the mixing amount of the reducing sugar in the A1 step is within the above range, it is excellent in economy, the reduction reaction solution can be made into a solution in the A2 step, and carbon source-attached particles to which the reducing sugar is uniformly adhered can be obtained. .. On the other hand, if the mixing amount of the reducing sugar in the A1 step is less than the above range, it is difficult to obtain a solution in which vanadium pentoxide is reduced in the A2 step, and the amount of the reducing sugar is insufficient in the A5 step. It tends to be difficult to obtain carbon source-adhered particles to which reducing sugars are uniformly attached, and if it exceeds the above range, it takes a large amount of time to prepare the amount of reducing sugars in step B, so industrially. Not advantageous.
Ａ１工程における、五酸化バナジウム、リン酸及び還元糖は、製造履歴は問われないが、高純度のリン酸バナジウムリチウムを製造するために、可及的に不純物含有量が少ないものであることが好ましい。
The production history of vanadium pentoxide, phosphoric acid, and reducing sugars in the A1 step is not limited, but in order to produce high-purity vanadium lithium phosphate, the impurity content may be as low as possible. preferable.
Ａ１工程で用いる水溶媒としては、水、又は水及び水と親水性の有機溶媒の混合溶媒が挙げられる。
Examples of the water solvent used in the A1 step include water or a mixed solvent of water and a hydrophilic organic solvent.
Ａ１工程において、五酸化バナジウム、リン酸及び還元糖を水溶媒へ添加する順序、混合手段は、特に制限されるものではなく、上記各原料が均一に分散した混合スラリー（１）となるように行われる。
In the A1 step, the order and mixing means for adding vanadium pentoxide, phosphoric acid and reducing sugar to the aqueous solvent are not particularly limited, and the mixed slurry (1) in which each of the above raw materials is uniformly dispersed is obtained. Will be done.
Ａ２工程は、Ａ１工程で得られる混合スラリー（１）を加熱処理して溶液化し、少なくとも五酸化バナジウムの還元反応を行って溶液化し、還元反応溶液を得るＡ２工程である。本発明者らは、五酸化バナジウムとリン酸が、還元糖の存在下に反応し、ＶＯＰＯ４或いはその含水物が生成されるので（例えば、特開２０１１－９６６４０号公報、特開２０１１－９６６４１号公報、特開２０１９－３４８７７号公報等参照）、Ａ２工程で得られる還元反応溶液は、ＶＯＰＯ４或いはその含水物と、余剰の還元糖及びリン酸二水素イオン（Ｈ２ＰＯ４
－）等のリン酸に起因したイオンが水溶媒に溶解したものであると考えている。
The A2 step is an A2 step in which the mixed slurry (1) obtained in the A1 step is heat-treated to form a solution, and at least vanadium pentoxide is subjected to a reduction reaction to form a solution to obtain a reduction reaction solution. The present inventors have reacted with vanadium pentoxide and phosphoric acid in the presence of a reducing sugar to produce VOPO 4 or a water-containing substance thereof (for example, JP-A-2011-96640, JP-A-2011-96641). (Refer to Japanese Patent Application Laid-Open No. 2019-34877, etc.), the reduction reaction solution obtained in the A2 step includes VOPO 4 or a water-containing substance thereof, excess reduced sugar, dihydrogen phosphate ion ( H2 PO 4- ) , and the like. It is considered that the ions caused by the phosphoric acid of the above are dissolved in an aqueous solvent.
Ａ２工程における加熱処理の温度は、６０～１００℃、好ましくは８０～１００℃である。Ａ工程における加熱処理の温度が、上記範囲にあることにより、大気圧下に有利に実施することができる。一方、Ａ工程における加熱処理の温度が、上記範囲未満だと、反応時間が長くなるため工業的に不利であり、また、上記範囲を超えると、加圧容器を使用しなければならず、工業的に有利でない。
The temperature of the heat treatment in the A2 step is 60 to 100 ° C, preferably 80 to 100 ° C. When the temperature of the heat treatment in the step A is in the above range, it can be advantageously carried out under atmospheric pressure. On the other hand, if the temperature of the heat treatment in the step A is less than the above range, the reaction time becomes long, which is industrially disadvantageous, and if it exceeds the above range, a pressure vessel must be used, which is industrial. Not advantageous.
Ａ２工程では、溶液が濃青色の透明な液体になることを目視で観察することにより、還元反応の終了を確認することができる。
In the A2 step, the completion of the reduction reaction can be confirmed by visually observing that the solution becomes a deep blue transparent liquid.
Ａ２工程における加熱処理の時間は、特に制限されず、一般に０．２時間以上、好ましくは０．５～４時間であり、上記範囲の時間加熱処理すれば、満足のいく還元反応溶液を得ることができる。
The time of the heat treatment in the A2 step is not particularly limited, and is generally 0.2 hours or more, preferably 0.5 to 4 hours. If the heat treatment is performed for a time in the above range, a satisfactory reduction reaction solution can be obtained. Can be done.
Ａ３工程は、Ａ２工程を得られる還元反応溶液を加温した状態に保持しながら、還元反応溶液に水酸化リチウムを含有する溶液を添加して、一般式（１）で表されるリチウムバナジウムリン複合酸化物、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物を含有するスラリー（２）を調製する工程である。
In the A3 step, while keeping the reduction reaction solution obtained in the A2 step in a heated state, a solution containing lithium hydroxide is added to the reduction reaction solution, and lithium vanadium phosphorus represented by the general formula (1) is added. This is a step of preparing a slurry (2) containing a composite oxide, lithium dihydrogen phosphate (LiH 2 PO 4 ), and an organic compound that produces carbon by thermal decomposition.
Ａ３工程において、還元反応溶液に水酸化リチウムを含有する溶液を添加することにより析出する一般式（１）で表されるリチウムバナジウムリン複合酸化物は、板状の一次粒子が二次粒子の集合体を形成しており、ＳＥＭ観察により求められる板状の一次粒子の平均の厚さが１～２０ｎｍ、好ましくは３～１５ｎｍであり、ＳＥＭ観察から求められる二次粒子の平均粒子径が０．５～２０μｍ、好ましくは１～１５μｍである。なお、一般式（１）で表されるリチウムバナジウムリン複合酸化物の板状の一次粒子の平均の厚さと、二次粒子の平均粒子径は、ＳＥＭ観察から、任意に抽出した２００個の粒子の平均値として求められるものである。
In the A3 step, the lithium vanadium phosphorus composite oxide represented by the general formula (1), which is precipitated by adding a solution containing lithium hydroxide to the reduction reaction solution, is a collection of plate-shaped primary particles as secondary particles. The body is formed, the average thickness of the plate-shaped primary particles determined by SEM observation is 1 to 20 nm, preferably 3 to 15 nm, and the average particle size of the secondary particles determined by SEM observation is 0. It is 5 to 20 μm, preferably 1 to 15 μm. The average thickness of the plate-shaped primary particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) and the average particle diameter of the secondary particles are 200 particles arbitrarily extracted from SEM observation. It is obtained as the average value of.
Ａ３工程で生成する一般式（１）で表されるリチウムバナジウムリン複合酸化物は、Ａ４工程において、メディアミルで湿式粉砕処理されることにより、容易に、微細な一般式（１）で表されるリチウムバナジウムリン複合酸化物に粉砕されて、微細な一般式（１）で表されるリチウムバナジウムリン複合酸化物を含有するスラリー（２）が得られる。
The lithium vanadium phosphorus composite oxide represented by the general formula (1) produced in the A3 step is easily represented by the fine general formula (1) by being wet-pulverized with a media mill in the A4 step. The lithium vanadium phosphorus composite oxide is pulverized to obtain a slurry (2) containing a fine lithium vanadium phosphorus composite oxide represented by the general formula (1).
Ａ３工程に係る水酸化リチウムを含有する溶液は、水酸化リチウムを水に溶解させた溶液である。
The solution containing lithium hydroxide according to the A3 step is a solution in which lithium hydroxide is dissolved in water.
水酸化リチウムを含有する溶液中の水酸化リチウム濃度は、５～２０質量％、好ましくは１０～１５質量％である。水酸化リチウムを含有する溶液中の水酸化リチウム濃度が上記範囲にあることにより、還元反応溶液への添加操作が容易となり、水酸化リチウムを含有する溶液の添加に伴う発熱を制御しながら製造効率を高めることができる点で、好ましい。
The concentration of lithium hydroxide in the solution containing lithium hydroxide is 5 to 20% by mass, preferably 10 to 15% by mass. When the concentration of lithium hydroxide in the solution containing lithium hydroxide is within the above range, the operation of adding the solution to the reduction reaction solution becomes easy, and the production efficiency is controlled while controlling the heat generation associated with the addition of the solution containing lithium hydroxide. It is preferable in that it can enhance.
水酸化リチウムを含有する溶液の添加量は、Ａ２工程を行い得られる還元反応溶液中のＰ原子に対する水酸化リチウムを含有する溶液中のＬｉ原子のモル比（Ｌｉ／Ｐ）で、０．７０～１．３０、好ましくは０．８３～１．１７となる添加量である。水酸化リチウムを含有する溶液の添加量が上記範囲にあることにより、最終生成物として単相のリン酸バナジウムリチウムが得られ易くなる点で、好ましい。また、Ａ３工程においては、水酸化リチウムを含有する溶液を添加した後の「一般式（１）で表されるリチウムバナジウムリン複合酸化物、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物を含有するスラリー（２）」のｐＨが、３～７、好ましくは４～６、特に好ましくは４～５となるように、水酸化リチウムを含有する溶液を添加することが、最終生成物として単相のリン酸バナジウムリチウムが得られ易くなる点で、好ましい。
The amount of the lithium hydroxide-containing solution added is 0.70, which is the molar ratio (Li / P) of the Li atom in the lithium hydroxide-containing solution to the P atom in the reduction reaction solution obtained by performing the A2 step. The addition amount is ~ 1.30, preferably 0.83 to 1.17. When the amount of the solution containing lithium hydroxide added is within the above range, it is preferable in that single-phase vanadium lithium phosphate can be easily obtained as the final product. Further, in the A3 step, after adding a solution containing lithium hydroxide, "a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and thermal decomposition" A solution containing lithium hydroxide is added so that the pH of the "slurry (2)" containing an organic compound that produces carbon is 3 to 7, preferably 4 to 6, particularly preferably 4 to 5. However, it is preferable in that a single-phase lithium vanadium phosphate as a final product can be easily obtained.
Ａ３工程において、水酸化リチウムは、製造履歴は問われないが、高純度のリン酸バナジウムリチウムを製造するために、可及的に不純物含有量が少ないものであることが好ましい。
In the A3 step, the production history of lithium hydroxide is not limited, but it is preferable that the content of impurities is as low as possible in order to produce high-purity lithium vanadium phosphate.
Ａ３工程では、Ａ２工程を行い得られる還元反応溶液を４０～１００℃、好ましくは６０～１００℃に保持しながら、水酸化リチウムを含有する溶液を、還元反応溶液に添加する。Ａ３工程において、水酸化リチウムを含有する溶液を添加する温度が、上記範囲未満だと、析出が不均一となり、一方、上記範囲を超えると、水酸化リチウムを含有する溶液の煮沸により操作性が悪くなる傾向がある。
In the A3 step, the solution containing lithium hydroxide is added to the reduction reaction solution while keeping the reduction reaction solution obtained by performing the A2 step at 40 to 100 ° C., preferably 60 to 100 ° C. In the A3 step, if the temperature at which the solution containing lithium hydroxide is added is less than the above range, the precipitation becomes non-uniform, while if it exceeds the above range, the operability is improved by boiling the solution containing lithium hydroxide. It tends to get worse.
また、Ａ３工程において、水酸化リチウムを含有する溶液の添加は、安定した品質のものが得られる点で、一定速度で添加することが好ましい。
Further, in the A3 step, it is preferable to add the solution containing lithium hydroxide at a constant rate in that stable quality can be obtained.
また、Ａ３工程において、水酸化リチウムを含有する溶液を添加した後、還元反応溶液と水酸化リチウムとの反応を完結させるため、必要により引き続き熟成反応を行うことができる。
Further, in the A3 step, after the solution containing lithium hydroxide is added, the reaction between the reduction reaction solution and lithium hydroxide is completed, so that the aging reaction can be continued if necessary.
熟成反応を行う温度は、４０～１００℃、好ましくは６０～１００℃であることが、均一な組成の粒子が得られる点で、好ましい。また、熟成反応時間は、特に制限されるものではないが、通常は０．５時間以上熟成反応を行えば、満足のいくスラリー（２）が得られる。
The temperature at which the aging reaction is carried out is preferably 40 to 100 ° C, preferably 60 to 100 ° C, in that particles having a uniform composition can be obtained. The aging reaction time is not particularly limited, but usually, if the aging reaction is carried out for 0.5 hours or more, a satisfactory slurry (2) can be obtained.
Ａ４工程は、Ａ３工程を行い得られたスラリー（２）をメディアミルにより湿式粉砕処理して、湿式粉砕処理スラリー（３）を調製する工程である。
The A4 step is a step of wet pulverizing the slurry (2) obtained by performing the A3 step with a media mill to prepare a wet pulverized slurry (3).
Ａ４工程を行うことにより、微細な一般式（１）で表されるリチウムバナジウムリン複合酸化物を含有する湿式粉砕処理スラリー（３）を得ることができる。この微細な一般式（１）で表されるリチウムバナジウムリン複合酸化物から得られる反応前駆体は、反応性が優れ、また、Ｃ工程の焼成で、Ｘ線回折的に単相のリン酸バナジウムリチウムが生成し、粒子分布がシャープなものが得られ易くなる。
By performing the A4 step, a wet pulverized slurry (3) containing a fine lithium vanadium phosphorus composite oxide represented by the general formula (1) can be obtained. The reaction precursor obtained from this fine lithium vanadium phosphorus composite oxide represented by the general formula (1) has excellent reactivity, and is X-ray diffractically monophasic vanadium phosphate by firing in step C. Lithium is generated, and it becomes easy to obtain one with a sharp particle distribution.
Ａ４工程において、メディアミルにより湿式粉砕の対象となるスラリー（２）の固形分濃度は、１０～４０質量％、好ましくは１５～３０質量％であることが、操作性が良好であり、また、効率的に粉砕処理を行うことができる点で、好ましい。このため、Ａ３工程を行った後、必要により、スラリー（２）の濃度が上記範囲となるように固形分濃度を調節してから、Ａ４工程において、湿式粉砕処理することが望ましい。
In the A4 step, the solid content concentration of the slurry (2) to be wet pulverized by the media mill is 10 to 40% by mass, preferably 15 to 30% by mass, which is good in operability and also has good operability. It is preferable in that the pulverization treatment can be performed efficiently. Therefore, after performing the A3 step, it is desirable to adjust the solid content concentration so that the concentration of the slurry (2) is within the above range, if necessary, and then perform the wet pulverization treatment in the A4 step.
そして、Ａ４工程では、スラリー（２）を、メディアミルにより湿式粉砕処理する。この方法を採用することで、一般式（１）で表されるリチウムバナジウムリン複合酸化物をより微細に粉砕することができるので、一層優れた反応性を有する反応前駆体を得ることができる。
Then, in the A4 process, the slurry (2) is wet-ground and pulverized by a media mill. By adopting this method, the lithium vanadium phosphorus composite oxide represented by the general formula (1) can be pulverized more finely, so that a reaction precursor having further excellent reactivity can be obtained.
メディアミルとしては、ビーズミル、ボールミル、ペイントシェーカー、アトライタ、サンドミル等が挙げられ、ビーズミルが好ましい。ビーズミルを用いる場合、運転条件やビーズの種類及び大きさは、装置のサイズや処理量に応じて適切に選択すればよい。
Examples of the media mill include a bead mill, a ball mill, a paint shaker, an attritor, a sand mill, and the like, and a bead mill is preferable. When a bead mill is used, the operating conditions and the type and size of beads may be appropriately selected according to the size and processing amount of the apparatus.
メディアミルを用いた処理を一層効率的に行う観点から、湿式粉砕の対象のスラリー（２）に分散剤を加えてもよい。分散剤としては、各種の界面活性剤、ポリカルボン酸アンモニウム塩等が挙げられる。湿式粉砕の対象のスラリー（２）中の分散剤の濃度は、０．０１～１０質量％、好ましくは０．１～５質量％であることが、十分な分散効果が得られる点で、好ましい。
From the viewpoint of more efficiently performing the treatment using the media mill, a dispersant may be added to the slurry (2) to be wet pulverized. Examples of the dispersant include various surfactants, ammonium polycarboxylic acid salts and the like. The concentration of the dispersant in the slurry (2) to be wet-ground is preferably 0.01 to 10% by mass, preferably 0.1 to 5% by mass, from the viewpoint of obtaining a sufficient dispersion effect. ..
Ａ４工程では、メディアミルを用いる湿式粉砕処理を、固形分の平均粒子径が、レーザー散乱・回折法で２．０μｍ以下、好ましくは０．１～１．５μｍ、特に好ましくは０．２～０．５μｍとなるまで行うことが、優れた反応性を有する反応前駆体が得られる点で、好ましい。
In the A4 step, in the wet pulverization treatment using a media mill, the average particle size of the solid content is 2.0 μm or less, preferably 0.1 to 1.5 μm, particularly preferably 0.2 to 0 by the laser scattering / diffraction method. It is preferable to carry out the process until it reaches 5.5 μm in that a reaction precursor having excellent reactivity can be obtained.
Ａ５工程は、Ａ４工程を行い得られる湿式粉砕処理スラリー（３）を、噴霧乾燥処理して、炭素源付着粒子を得る工程である。
The A5 step is a step of spray-drying the wet pulverized slurry (3) obtained by performing the A4 step to obtain carbon source-adhered particles.
Ａ５工程を行い得られる炭素源付着粒子は、前記（ｉｉ）又は前記（ｉｉｉ）の形態の炭素源付着粒子であることが、反応性に優れた反応前駆体となる点で、好ましい。
It is preferable that the carbon source-attached particles obtained by performing the A5 step are the carbon source-attached particles in the form of (ii) or the above (iii) in that they serve as a reaction precursor having excellent reactivity.
炭素源付着粒子を構成する一般式（１）で表されるリチウムバナジウムリン複合酸化物の一次粒子の平均粒子径は、Ａ４工程を行い得られる湿式粉砕処理スラリー（３）中の固形分の一次粒子の平均粒子径と同程度となる。
The average particle size of the primary particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) constituting the carbon source-adhered particles is the primary of the solid content in the wet pulverized slurry (3) obtained by performing the A4 step. It is about the same as the average particle size of the particles.
液の乾燥方法には噴霧乾燥法以外の方法も知られているが、本発明においては噴霧乾燥法を選択することが有利であるとの知見に基づき、この乾燥方法を採用している。詳細には、Ａ５工程において、噴霧乾燥法を用いることにより、一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子表面に、均一に還元糖及びリン酸二水素リチウム（ＬｉＨ２ＰＯ４）が付着し、また、一般式（１）で表されるリチウムバナジウムリン複合酸化物の粒子が密に詰まった状態の造粒物が得られることから、Ｃ工程の焼成で、少ない炭素量でＸ線回折的に単相のリン酸バナジウムリチウムを生成させ易くなる。
A method other than the spray drying method is also known as a method for drying the liquid, but in the present invention, this drying method is adopted based on the finding that it is advantageous to select the spray drying method. Specifically, by using the spray drying method in the A5 step, the reduced sugar and lithium dihydrogen phosphate (LiH 2 PO) are uniformly formed on the particle surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1). Since 4 ) is attached and a granulated product in a state in which particles of the lithium vanadium phosphorus composite oxide represented by the general formula (1) are densely packed can be obtained, a small amount of carbon is obtained by firing in step C. Therefore, it becomes easy to generate monophasic vanadium lithium phosphate by X-ray diffraction.
噴霧乾燥法においては、所定手段によって液を霧化し、それによって生じた微細な液滴を乾燥させることで造粒物を得る。液の霧化には、例えば、回転円盤を用いる方法と、圧力ノズルを用いる方法がある。Ａ５工程においてはいずれの方法を用いることもできる。
In the spray drying method, the liquid is atomized by a predetermined means, and the fine droplets generated by the atomization are dried to obtain a granulated product. For atomization of the liquid, for example, there are a method using a rotating disk and a method using a pressure nozzle. Any method can be used in the A5 step.
噴霧乾燥法においては、霧化されたスラリーの液滴の大きさと、それに含まれる粉砕処理物の粒子の大きさとの関係が、安定した乾燥や、得られる乾燥粉の性状に影響を与える。詳細には、液滴の大きさに対して粉砕処理物の原料粒子の大きさが小さすぎると、液滴が不安定になり、乾燥を首尾よく行いづらくなる。この観点から、霧化された液滴の大きさは、５～１００μｍが好ましく、１０～５０μｍが特に好ましい。噴霧乾燥装置へのスラリーの供給量は、この観点を考慮して決定することが望ましい。
In the spray drying method, the relationship between the size of the droplets of the atomized slurry and the size of the particles of the pulverized product contained therein affects stable drying and the properties of the obtained dried powder. Specifically, if the size of the raw material particles of the pulverized product is too small with respect to the size of the droplets, the droplets become unstable and it becomes difficult to dry them successfully. From this point of view, the size of the atomized droplet is preferably 5 to 100 μm, particularly preferably 10 to 50 μm. It is desirable to determine the amount of slurry supplied to the spray dryer in consideration of this viewpoint.
噴霧乾燥装置における乾燥温度は、熱風入口温度を１８０～２５０℃、好ましくは２００～２４０℃に調整し、粉体の温度を９０～１５０℃、好ましくは１００～１３０℃となるように調整することが、粉体の吸湿を防ぎ粉体の回収が容易になることから好ましい。
The drying temperature in the spray drying device shall be adjusted so that the hot air inlet temperature is adjusted to 180 to 250 ° C, preferably 200 to 240 ° C, and the powder temperature is adjusted to 90 to 150 ° C, preferably 100 to 130 ° C. However, it is preferable because it prevents the powder from absorbing moisture and facilitates the recovery of the powder.
Ａ５工程を行い得られる炭素源付着粒子は、乾燥により、Ｘ線回折分析において、一般式（１）で表されるリチウムバナジウムリン複合酸化物の式中のｘが２のものと、式中の結晶水の一部除去されたものとの混合物となる場合があるが、本発明では該混合物も好適に用いられる。
The carbon source-adhered particles obtained by performing the A5 step are those having x of 2 in the formula of the lithium vanadium phosphorus composite oxide represented by the general formula (1) in the X-ray diffraction analysis by drying, and the particles in the formula. It may be a mixture with water of crystallization partially removed, and the mixture is also preferably used in the present invention.
（Ｂ工程）
本発明のリン酸バナジウムリチウムの製造方法に係るＢ工程は、Ａ工程で調製した炭素源付着粒子を、酸素雰囲気で加熱処理することにより、反応前駆体を得る工程である。 (Step B)
The step B according to the method for producing lithium vanadium phosphate of the present invention is a step of obtaining a reaction precursor by heat-treating the carbon source-adhered particles prepared in the step A in an oxygen atmosphere.
本発明のリン酸バナジウムリチウムの製造方法に係るＢ工程は、Ａ工程で調製した炭素源付着粒子を、酸素雰囲気で加熱処理することにより、反応前駆体を得る工程である。 (Step B)
The step B according to the method for producing lithium vanadium phosphate of the present invention is a step of obtaining a reaction precursor by heat-treating the carbon source-adhered particles prepared in the step A in an oxygen atmosphere.
本発明では、Ｂ工程を行い、炭素源付着粒子の粒子表面に付着している炭素原子の量を調節することにより、Ｃ工程を経て、比表面積が低く、且つ、粒子分布がシャープなリン酸バナジウムリチウムを生成させることができる。
In the present invention, by performing step B and adjusting the amount of carbon atoms adhering to the particle surface of the particles adhering to the carbon source, phosphoric acid having a low specific surface area and a sharp particle distribution undergoes step C. Vanadium lithium can be produced.
Ｂ工程では、反応前駆体の炭素含有量が、反応前駆体中のＶ原子に対する炭素原子のモル比（Ｃ／Ｖ）で、０．３～０．６、好ましくは０．３５～０．５５となるまで、加熱処理を行うことが好ましい。反応前駆体の炭素含有量が、上記範囲にあることにより、Ｃ工程での還元が十分に起こり、また、炭素量が適切な量であるためリン酸バナジウムリチウムのＢＥＴ比表面積が低くなる。一方、反応前駆体の炭素含有量が、上記範囲未満だと、Ｃ工程での還元が不完全となり、また、上記範囲を超えると、炭素量が過剰となりリン酸バナジウムリチウムのＢＥＴ比表面積が高くなる傾向がある。
In step B, the carbon content of the reaction precursor is 0.3 to 0.6, preferably 0.35 to 0.55, in terms of the molar ratio (C / V) of carbon atoms to V atoms in the reaction precursor. It is preferable to carry out the heat treatment until it becomes. When the carbon content of the reaction precursor is in the above range, reduction in the C step occurs sufficiently, and since the carbon content is an appropriate amount, the BET specific surface area of lithium vanadium phosphate becomes low. On the other hand, if the carbon content of the reaction precursor is less than the above range, the reduction in the C step is incomplete, and if it exceeds the above range, the carbon content becomes excessive and the BET specific surface area of lithium vanadium phosphate is high. Tend to be.
Ｂ工程では、加熱処理を、酸素含有雰囲気下に行う。Ｂ工程において、加熱処理を行う際の雰囲気中の酸素濃度は、５ｖｏｌ％以上、特に好ましくは１０～３０ｖｏｌ％であることが、加熱分解により炭素が生じる有機化合物を高効率で酸化処理し、炭素含有量を上記範囲に調製し易くなる点で、好ましい。
In step B, the heat treatment is performed in an oxygen-containing atmosphere. In step B, the oxygen concentration in the atmosphere during the heat treatment is 5 vol% or more, particularly preferably 10 to 30 vol%, so that the organic compound that produces carbon by thermal decomposition is oxidized with high efficiency and carbon is used. It is preferable in that the content can be easily adjusted within the above range.
Ｂ工程において、加熱処理の温度は、炭素含有量の制御が容易となる点で、２７０～３７０℃が好ましく、２９０～３６０℃が特に好ましい。加熱処理の温度が、上記範囲未満では、炭素原子の含有量の低減が難しくなり、また、上記範囲を超えると、一気に炭素含有量が減るため、炭素含有量の調製が難しくなる傾向がある。
In the step B, the temperature of the heat treatment is preferably 270 to 370 ° C, particularly preferably 290 to 360 ° C, because the carbon content can be easily controlled. If the temperature of the heat treatment is lower than the above range, it becomes difficult to reduce the carbon atom content, and if it exceeds the above range, the carbon content decreases at once, so that it tends to be difficult to prepare the carbon content.
Ｂ工程では、加熱処理の時間が長くなるほど炭素含有量を少なくすることができるので、上記範囲の炭素含有量となるように十分な時間をかけて加熱処理を行うことが好ましいが、加熱処理の時間が８時間以上になると、Ｃ工程後に得られるリン酸バナジウムリチウムが硬い焼結体となって、粉体として回収することが難しくなる。Ｂ工程では、通常は、１時間以上８時間未満、好ましくは２～５時間の加熱処理の時間で、満足のいく反応前駆体を得ることができる。
In step B, the carbon content can be reduced as the heat treatment time becomes longer. Therefore, it is preferable to perform the heat treatment over a sufficient period of time so that the carbon content is within the above range. When the time is 8 hours or more, the vanadium lithium phosphate obtained after the C step becomes a hard sintered body, and it becomes difficult to recover it as a powder. In step B, a satisfactory reaction precursor can be obtained, usually in a heat treatment time of 1 hour or more and less than 8 hours, preferably 2 to 5 hours.
なお、Ｂ工程を行い得られる反応前駆体は、Ｂ工程での加熱処理により、Ｘ線回折分析において、一般式（１）で表されるリチウムバナジウムリン複合酸化物と、それ以外に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）の一部或いは全量が非晶質のリン化合物（ＬｉＨ２ＰＯ４、ＬｉＰＯ３等）及び／又はリン酸リチウム（Ｌｉ３ＰＯ４）となって含有される場合があるが、本発明では、そのようなものであっても問題なく用いることができる。
The reaction precursors obtained by performing step B are the lithium vanadium phosphorus composite oxide represented by the general formula (1) in the X-ray diffraction analysis by the heat treatment in step B, and other than that, phosphoric acid. When part or all of lithium dihydrogen (LiH 2 PO 4 ) is contained as an amorphous phosphorus compound (LiH 2 PO 4 , LiPO 3 , etc.) and / or lithium phosphate (Li 3 PO 4 ). However, in the present invention, even such a substance can be used without any problem.
（Ｃ工程）
本発明のリン酸バナジウムリチウムの製造方法に係るＣ工程は、Ｂ工程を行い得られる反応前駆体を、５００～１３００℃で焼成し、Ｘ線回折的に単相のリン酸バナジウムリチウムを得る工程である。 (C step)
The step C according to the method for producing lithium vanadium phosphate of the present invention is a step of calcining the reaction precursor obtained by performing the step B at 500 to 1300 ° C. to obtain a single-phase vanadium lithium phosphate by X-ray diffraction. Is.
本発明のリン酸バナジウムリチウムの製造方法に係るＣ工程は、Ｂ工程を行い得られる反応前駆体を、５００～１３００℃で焼成し、Ｘ線回折的に単相のリン酸バナジウムリチウムを得る工程である。 (C step)
The step C according to the method for producing lithium vanadium phosphate of the present invention is a step of calcining the reaction precursor obtained by performing the step B at 500 to 1300 ° C. to obtain a single-phase vanadium lithium phosphate by X-ray diffraction. Is.
Ｃ工程における焼成温度は、５００～１３００℃、好ましくは６００～１０００℃である。Ｃ工程における焼成温度が、上記範囲未満だと、単相になるまでの焼成時間が長くなり、また、上記範囲を超えると、リン酸バナジウムリチウムが融解する。
The firing temperature in step C is 500 to 1300 ° C, preferably 600 to 1000 ° C. If the calcination temperature in step C is less than the above range, the calcination time until it becomes a single phase becomes long, and if it exceeds the above range, vanadium lithium phosphate is melted.
Ｃ工程における焼成雰囲気は、バナジウムの酸化を防ぎ、且つ、溶融を防ぐという理由から、不活性ガス雰囲気又は還元雰囲気である。Ｃ工程で用いられる不活性ガスとしては、特に制限はなく、例えば、窒素ガス、ヘリウムガス、アルゴンガス等が挙げられる。
The firing atmosphere in step C is an inert gas atmosphere or a reducing atmosphere because it prevents oxidation of vanadium and prevents melting. The inert gas used in the step C is not particularly limited, and examples thereof include nitrogen gas, helium gas, and argon gas.
Ｃ工程において、焼成時間は特に制限されず、一般に２時間以上、特に３～２４時間焼成すれば、Ｘ線回折的に単相のリン酸バナジウムリチウムを得ることができる。
In step C, the firing time is not particularly limited, and if firing is generally performed for 2 hours or more, particularly 3 to 24 hours, single-phase vanadium lithium phosphate can be obtained by X-ray diffraction.
Ｃ工程では、焼成を行い得られるリン酸バナジウムリチウムを、必要に応じて、複数回の焼成に付してもよい。
In step C, the vanadium lithium phosphate obtained by firing may be subjected to a plurality of firings, if necessary.
本発明のリン酸バナジウムリチウムの製造方法において、リン酸バナジウムリチウムの結晶構造を安定化し、また、電池性能をいっそう向上させることを目的として、必要により、Ｍｅ源（Ｍｅは、Ｖ以外の原子番号１１以上の金属元素又は遷移金属元素を示す。）を、本発明のリン酸バナジウムリチウムの製造方法に係るＡ工程において、炭素源付着粒子中にＭｅ源を含有させるか、あるいは、炭素源付着粒子とＭｅ源を含有する混合物を調製して、該混合物を用いてＢ工程を行うことにより、反応前駆体中にＭｅ源を含有させ、次いで、Ｃ工程を行うことにより、一般式（１）で示されるリン酸バナジウムリチウムにＭｅ元素がドープされて含有されたものが得られる。具体的には、炭素源付着粒子中にＭｅ源を含有させる方法としては、Ａ１工程からＡ５工程の噴霧乾燥を行う前までの間の何れかの時期にＭｅ源を添加する方法が挙げられる。
In the method for producing vanadium lithium phosphate of the present invention, for the purpose of stabilizing the crystal structure of vanadium lithium phosphate and further improving the battery performance, if necessary, a Me source (Me is an atomic number other than V). 11 or more metal elements or transition metal elements are shown.) In the step A according to the method for producing vanadium lithium phosphate of the present invention, the Me source is contained in the carbon source-attached particles, or the carbon source-attached particles are contained. By preparing a mixture containing the above and Me source and performing step B using the mixture, the Me source is contained in the reaction precursor, and then step C is carried out, whereby the general formula (1) is used. The following vanadium lithium phosphate is doped with a Me element to obtain a substance contained therein. Specifically, as a method of containing the Me source in the particles adhering to the carbon source, a method of adding the Me source at any time between the A1 step and the A5 step before spray drying can be mentioned.
Ｍｅ元素は、一般式（２）で示されるリン酸バナジウムリチウムのＬｉサイト又は／及びＶサイトに置換されて存在する。
The Me element exists in the Li-site and / and V-site of vanadium lithium phosphate represented by the general formula (2).
Ｍｅ源中のＭｅは、Ｖ以外の原子番号１１以上の金属元素又は遷移金属元素であり、好ましいＭｅ元素としては、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ｈｆ、Ｔａ、Ｗ、Ｒｕ、Ｏｓ、Ａｇ、Ｚｎ、Ｓｉ、Ｇａ、Ｇｅ、Ｓｎ、Ｂｉ、Ｓ、Ｓｅ、Ｔｅ、Ｃｌ、Ｂｒ、Ｉ、Ｎａ、Ｋ、Ｍｇ、Ｃａ、Ａｌ、Ｍｎ、Ｃｏ、Ｎｉ、Ｆｅ、Ｔｉ、Ｚｒ、Ｂｉ、Ｃｒ、Ｎｂ、Ｍｏ、Ｃｕ等が挙げられ、これらは１種単独又は２種以上の組み合わせであってもよい。
Me in the Me source is a metal element or transition metal element having an atomic number of 11 or more other than V, and preferred Me elements are Sr, Ba, Sc, Y, Hf, Ta, W, Ru, Os, Ag, and the like. Zn, Si, Ga, Ge, Sn, Bi, S, Se, Te, Cl, Br, I, Na, K, Mg, Ca, Al, Mn, Co, Ni, Fe, Ti, Zr, Bi, Cr, Examples thereof include Nb, Mo, Cu and the like, and these may be used alone or in combination of two or more.
Ｍｅ源としては、Ｍｅ元素を有する酸化物、水酸化物、ハロゲン化物、炭酸塩、硝酸塩、炭酸塩、有機酸塩等が挙げられる。なお、Ａ１工程からＡ５工程の噴霧乾燥を行う前までの間に、Ｍｅ源を混合する場合、スラリー中に溶解させて存在させてもよく、固形物として存在させてもよい。
Examples of the Me source include oxides having Me elements, hydroxides, halides, carbonates, nitrates, carbonates, organic acid salts and the like. When the Me source is mixed between the A1 step and the A5 step before the spray drying, it may be dissolved in the slurry and exist, or it may be present as a solid substance.
一般式（１）で表されるリチウムバナジウムリン複合酸化物、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物を含有するスラリー（２）中に、固形物としてＭｅ源を存在させる場合には、平均粒子径が１００μｍ以下、好ましくは０．１～５０μｍのＭｅ源を用いることが、優れた反応性を有する反応前駆体が得られる点で、好ましい。また、Ａ１工程からＡ５工程の噴霧乾燥を行う前に、Ｍｅ源を混合する場合には、Ｍｅ源の混合量は、ドープさせるＭｅ元素の種類にもよるが、多くの場合、スラリー（２）中のＰ原子に対するＶ原子とＭｅ原子の合計のモル比（（Ｍｅ＋Ｖ）／Ｐ）が、０．５～０．８０、好ましくは０．６０～０．７３となり、Ｖ原子に対するＭｅ原子のモル比（Ｍｅ／Ｖ）が、０より大きく０．４５以下、好ましくは０より大きく０．１以下となる混合量が好ましい。
Me as a solid substance in a slurry (2) containing a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition. When a source is present, it is preferable to use a Me source having an average particle size of 100 μm or less, preferably 0.1 to 50 μm, in that a reaction precursor having excellent reactivity can be obtained. Further, when the Me source is mixed before the spray drying in the A1 step to the A5 step, the mixing amount of the Me source depends on the type of the Me element to be doped, but in many cases, the slurry (2). The total molar ratio of V atoms to Me atoms ((Me + V) / P) with respect to the P atoms in the mixture is 0.5 to 0.80, preferably 0.60 to 0.73, and the molar ratio of Me atoms to V atoms is high. A mixing amount having a ratio (Me / V) of greater than 0 and 0.45 or less, preferably greater than 0 and 0.1 or less is preferable.
このようにして、本発明のリン酸バナジウムリチウムの製造方法を行い得られるリン酸バナジウムリチウムは、Ｘ線回折的に単相のリン酸バナジウムリチウムであり、ＢＥＴ比表面積が１０．０ｍ２／ｇ以下、好ましくは３．０～８．０ｍ２／ｇであることが好ましい。また、本発明のリン酸バナジウムリチウムの製造方法を行い得られるリン酸バナジウムリチウムは、ＳＥＭ観察により求められる一次粒子の平均粒子径が、０．３～１．５μｍ、好ましくは０．４～１．２μｍであり、且つ、粒度分布がシャープなものであることが好ましい。
In this way, the vanadium lithium phosphate obtained by performing the method for producing vanadium lithium phosphate of the present invention is a monophasic vanadium lithium phosphate in X-ray diffraction, and has a BET specific surface area of 10.0 m 2 / g. Hereinafter, it is preferably 3.0 to 8.0 m 2 / g. Further, the vanadium lithium phosphate obtained by the method for producing vanadium lithium phosphate of the present invention has an average particle size of primary particles obtained by SEM observation of 0.3 to 1.5 μm, preferably 0.4 to 1. It is preferable that the size is 2 μm and the particle size distribution is sharp.
本発明のリン酸バナジウムリチウムの製造方法を行い得られるリン酸バナジウムリチウムの炭素含有量は、０．０１～１．０質量％、好ましくは０．０１～０．５質量％である。
The carbon content of vanadium lithium phosphate obtained by the method for producing vanadium lithium phosphate of the present invention is 0.01 to 1.0% by mass, preferably 0.01 to 0.5% by mass.
本発明のリン酸バナジウムリチウムの製造方法では、得られるリン酸バナジウムリチウムに対して、更に必要に応じて解砕処理、又は粉砕処理し、更に分級を行ってもよい。
In the method for producing vanadium lithium phosphate of the present invention, the obtained vanadium lithium phosphate may be further crushed or crushed as necessary, and further classified.
また、本発明のリン酸バナジウムリチウムの製造方法では、必要に応じて、Ｃ工程終了後に、導電性炭素と混合又は粒子表面を導電性炭素で被覆処理してリン酸バナジウムリチウム炭素複合体として用いることもできる。
Further, in the method for producing vanadium lithium phosphate of the present invention, if necessary, after the completion of step C, it is mixed with conductive carbon or the particle surface is coated with conductive carbon and used as a vanadium lithium phosphate carbon composite. You can also do it.
また、本発明のリン酸バナジウムリチウムの製造方法を行い得られるリン酸バナジウムリチウムは、リチウム二次電池、全固体電池等の正極活物質での用途に用いられる。
Further, vanadium lithium phosphate obtained by the method for producing lithium vanadium phosphate of the present invention is used in a positive electrode active material such as a lithium secondary battery and an all-solid-state battery.
本発明のリン酸バナジウムリチウムの製造方法では、Ｂ工程を行うことにより、一般式（１）で表されるリチウムバナジウムリン複合酸化物の表面に付着している炭素を減らし、バナジウム原子に対する炭素原子のモル比（Ｃ／Ｖ）を適切にすることができる。そのため、本発明のリン酸バナジウムリチウムの製造方法では、Ｃ工程を経て得られるリン酸バナジウムリチウムは、粒子表面が丸みを帯びた形状となる。これらのことにより、本発明のリン酸バナジウムリチウムの製造方法では、リン酸バナジウムリチウムの比表面積を低くすることができる。また、本発明のリン酸バナジウムリチウムの製造方法では、Ａ工程において、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着しているリチウムバナジウムリン複合酸化物の一次粒子の平均粒子径を、２．０μｍ以下、好ましくは０．１～１．５μｍとすることにより、粗大粒子の存在が極めて少なくなるので、Ｂ工程及びＣ工程を経て得られるリン酸バナジウムリチウムの粒子分布をシャープにすることができる。
In the method for producing vanadium lithium phosphate of the present invention, by performing step B, the carbon adhering to the surface of the lithium vanadium phosphorus composite oxide represented by the general formula (1) is reduced, and the carbon atom with respect to the vanadium atom is reduced. The molar ratio (C / V) of can be adjusted appropriately. Therefore, in the method for producing vanadium lithium phosphate of the present invention, the vanadium lithium phosphate obtained through the C step has a rounded particle surface. As a result, the specific surface area of vanadium lithium phosphate can be reduced in the method for producing vanadium lithium phosphate of the present invention. Further, in the method for producing vanadium lithium phosphate of the present invention, in step A, lithium dihydrogen phosphate (LiH 2 PO 4 ) and a lithium vanadium phosphorus composite oxide to which an organic compound that produces carbon by thermal decomposition is attached are attached. By setting the average particle size of the primary particles to 2.0 μm or less, preferably 0.1 to 1.5 μm, the presence of coarse particles is extremely reduced, and therefore, vanadium lithium phosphate obtained through steps B and C. The particle distribution of can be sharpened.
以下、本発明を実施例により詳細に説明するが、本発明はこれらの実施例に限定されるものではない。
Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.
（実施例１）
＜Ａ１工程＞
５Ｌビーカーにイオン交換水２Ｌを入れ、これに８５％リン酸６０５ｇと五酸化バナジウム３２０ｇとラクトース（乳糖）９６ｇを投入し室温（２５℃）で攪拌することにより黄土色の混合スラリー（１）を得た。 (Example 1)
<A1 process>
Put 2 L of ion-exchanged water in a 5 L beaker, put 605 g of 85% phosphoric acid, 320 g of vanadium pentoxide and 96 g of lactose (milk sugar) into it, and stir at room temperature (25 ° C) to obtain an ocher-colored mixed slurry (1). Obtained.
＜Ａ１工程＞
５Ｌビーカーにイオン交換水２Ｌを入れ、これに８５％リン酸６０５ｇと五酸化バナジウム３２０ｇとラクトース（乳糖）９６ｇを投入し室温（２５℃）で攪拌することにより黄土色の混合スラリー（１）を得た。 (Example 1)
<A1 process>
Put 2 L of ion-exchanged water in a 5 L beaker, put 605 g of 85% phosphoric acid, 320 g of vanadium pentoxide and 96 g of lactose (milk sugar) into it, and stir at room temperature (25 ° C) to obtain an ocher-colored mixed slurry (1). Obtained.
＜Ａ２工程＞
得られた混合スラリー（１）を８０℃で３時間、攪拌下に加熱し還元反応を行い、濃青色な透明な反応溶液を得た。 <A2 process>
The obtained mixed slurry (1) was heated at 80 ° C. for 3 hours under stirring to carry out a reduction reaction to obtain a deep blue transparent reaction solution.
得られた混合スラリー（１）を８０℃で３時間、攪拌下に加熱し還元反応を行い、濃青色な透明な反応溶液を得た。 <A2 process>
The obtained mixed slurry (1) was heated at 80 ° C. for 3 hours under stirring to carry out a reduction reaction to obtain a deep blue transparent reaction solution.
＜Ａ３工程＞
反応溶液を８０℃に保持したまま、次いで、水酸化リチウム・１水塩２２０ｇをイオン交換水１．５Ｌに溶解させた水酸化リチウム溶液を調製した。反応溶液を７０～８０℃の温度範囲に保持しながら、水酸化リチウム溶液を４０分で一定速度にて反応溶液に添加し、沈殿物を含むスラリー（２）を得た。続いて室温（２５℃）までスラリーを放冷した。沈殿物をサンプリング後、濾過、乾燥しＸＲＤ測定したところＬｉＶＯＰＯ４・２Ｈ２Ｏのピークと一致した。
得られたＬｉＶＯＰＯ４・２Ｈ２Ｏは、ＳＥＭ観察により求められる板状の一次粒子の平均の厚さが５ｎｍ、ＳＥＭ観察から求められる二次粒子の平均粒子径が６μｍであった。得られたＬｉＶＯＰＯ４・２Ｈ２ＯのＸ線回折図を図１に、また、ＳＥＭ写真を図２（１０００倍）及び図３（５０００倍）に示す。
なお、ＬｉＶＯＰＯ４・２Ｈ２Ｏの一次粒子の平均の厚さと、二次粒子の平均粒子径は、ＳＥＭ観察において、任意に抽出した粒子２００個の平均値として求めた。 <A3 process>
While the reaction solution was kept at 80 ° C., a lithium hydroxide solution was prepared by dissolving 220 g of lithium hydroxide / water salt in 1.5 L of ion-exchanged water. While keeping the reaction solution in the temperature range of 70 to 80 ° C., the lithium hydroxide solution was added to the reaction solution at a constant rate in 40 minutes to obtain a slurry (2) containing a precipitate. Subsequently, the slurry was allowed to cool to room temperature (25 ° C.). After sampling the precipitate, it was filtered, dried, and XRD-measured. As a result, it coincided with the peak of LiVOPO 4.2H 2O .
In the obtained LiVOPO 4.2H 2 O, the average thickness of the plate-shaped primary particles determined by SEM observation was 5 nm, and the average particle diameter of the secondary particles determined by SEM observation was 6 μm. The X-ray diffraction pattern of the obtained LiVOPO 4.2H 2O is shown in FIG. 1, and the SEM photograph is shown in FIGS. 2 (1000 times) and 3 (5000 times).
The average thickness of the primary particles of LiVOPO 4.2H 2O and the average particle diameter of the secondary particles were determined as the average value of 200 arbitrarily extracted particles in SEM observation.
反応溶液を８０℃に保持したまま、次いで、水酸化リチウム・１水塩２２０ｇをイオン交換水１．５Ｌに溶解させた水酸化リチウム溶液を調製した。反応溶液を７０～８０℃の温度範囲に保持しながら、水酸化リチウム溶液を４０分で一定速度にて反応溶液に添加し、沈殿物を含むスラリー（２）を得た。続いて室温（２５℃）までスラリーを放冷した。沈殿物をサンプリング後、濾過、乾燥しＸＲＤ測定したところＬｉＶＯＰＯ４・２Ｈ２Ｏのピークと一致した。
得られたＬｉＶＯＰＯ４・２Ｈ２Ｏは、ＳＥＭ観察により求められる板状の一次粒子の平均の厚さが５ｎｍ、ＳＥＭ観察から求められる二次粒子の平均粒子径が６μｍであった。得られたＬｉＶＯＰＯ４・２Ｈ２ＯのＸ線回折図を図１に、また、ＳＥＭ写真を図２（１０００倍）及び図３（５０００倍）に示す。
なお、ＬｉＶＯＰＯ４・２Ｈ２Ｏの一次粒子の平均の厚さと、二次粒子の平均粒子径は、ＳＥＭ観察において、任意に抽出した粒子２００個の平均値として求めた。 <A3 process>
While the reaction solution was kept at 80 ° C., a lithium hydroxide solution was prepared by dissolving 220 g of lithium hydroxide / water salt in 1.5 L of ion-exchanged water. While keeping the reaction solution in the temperature range of 70 to 80 ° C., the lithium hydroxide solution was added to the reaction solution at a constant rate in 40 minutes to obtain a slurry (2) containing a precipitate. Subsequently, the slurry was allowed to cool to room temperature (25 ° C.). After sampling the precipitate, it was filtered, dried, and XRD-measured. As a result, it coincided with the peak of LiVOPO 4.2H 2O .
In the obtained LiVOPO 4.2H 2 O, the average thickness of the plate-shaped primary particles determined by SEM observation was 5 nm, and the average particle diameter of the secondary particles determined by SEM observation was 6 μm. The X-ray diffraction pattern of the obtained LiVOPO 4.2H 2O is shown in FIG. 1, and the SEM photograph is shown in FIGS. 2 (1000 times) and 3 (5000 times).
The average thickness of the primary particles of LiVOPO 4.2H 2O and the average particle diameter of the secondary particles were determined as the average value of 200 arbitrarily extracted particles in SEM observation.
＜Ａ４工程＞
次いで、分散剤としてポリカルボン酸アンモニウム塩を２７ｇ仕込み、スラリーを攪拌しながら、直径０．５ｍｍのジルコニアビーズを仕込んだメディア攪拌型ビーズミルに供給し、湿式粉砕を行った。レーザー回折・散乱法により求められる湿式粉砕後のスラリー（３）中の固形分の平均粒子径は０．５μｍであった。また、固形分は、ＳＥＭ観察から求められる一次粒子の平均粒子径は０．５μｍであった。
なお、固形分の一次粒子の平均粒子径は、ＳＥＭ観察において、任意に抽出した粒子２００個の平均値として求めた。 <A4 process>
Next, 27 g of an ammonium polycarboxylic acid salt was charged as a dispersant, and the slurry was supplied to a media stirring type bead mill charged with zirconia beads having a diameter of 0.5 mm while stirring, and wet pulverization was performed. The average particle size of the solid content in the slurry (3) after wet pulverization determined by the laser diffraction / scattering method was 0.5 μm. As for the solid content, the average particle size of the primary particles obtained from SEM observation was 0.5 μm.
The average particle size of the primary particles having a solid content was determined as the average value of 200 arbitrarily extracted particles in SEM observation.
次いで、分散剤としてポリカルボン酸アンモニウム塩を２７ｇ仕込み、スラリーを攪拌しながら、直径０．５ｍｍのジルコニアビーズを仕込んだメディア攪拌型ビーズミルに供給し、湿式粉砕を行った。レーザー回折・散乱法により求められる湿式粉砕後のスラリー（３）中の固形分の平均粒子径は０．５μｍであった。また、固形分は、ＳＥＭ観察から求められる一次粒子の平均粒子径は０．５μｍであった。
なお、固形分の一次粒子の平均粒子径は、ＳＥＭ観察において、任意に抽出した粒子２００個の平均値として求めた。 <A4 process>
Next, 27 g of an ammonium polycarboxylic acid salt was charged as a dispersant, and the slurry was supplied to a media stirring type bead mill charged with zirconia beads having a diameter of 0.5 mm while stirring, and wet pulverization was performed. The average particle size of the solid content in the slurry (3) after wet pulverization determined by the laser diffraction / scattering method was 0.5 μm. As for the solid content, the average particle size of the primary particles obtained from SEM observation was 0.5 μm.
The average particle size of the primary particles having a solid content was determined as the average value of 200 arbitrarily extracted particles in SEM observation.
＜Ａ５工程＞
出口温度を１２０℃に設定した噴霧乾燥装置に湿式粉砕後のスラリー（３）を供給し、炭素源付着粒子を得た。
炭素源付着粒子のＳＥＭ観察から求められる平均粒子径（二次粒子径）は２０μｍであった。
得られた炭素源付着粒子を線源としてＣｕＫα線を用いてＸ線回折測定を行ったところ、該炭素源付着粒子は、ＬｉＶＯＰＯ４・２Ｈ２ＯとＬｉＨ２ＰＯ４を含むものであった
（図４参照）。
また、得られた炭素源付着粒子の残存炭素量を、ＴＯＣ全有機炭素計（島津製作所製ＴＯＣ－５０００Ａ）にて測定することによりＣ原子の含有量として求めた。残存炭素量は４．１質量％であった。
なお、炭素源付着粒子の平均粒子径（二次粒子径）は、ＳＥＭ観察において、任意に抽出した粒子２００個の平均値として求めた。 <A5 process>
The slurry (3) after wet pulverization was supplied to a spray drying device having an outlet temperature set to 120 ° C. to obtain carbon source-adhered particles.
The average particle size (secondary particle size) obtained from the SEM observation of the carbon source-attached particles was 20 μm.
X-ray diffraction measurement was performed using the obtained carbon source-attached particles as a radiation source, and the carbon source-attached particles contained LiVOPO 4.2H 2 O and LiH 2 PO 4 . See FIG. 4).
Further, the residual carbon content of the obtained carbon source-adhered particles was determined as the content of C atoms by measuring with a TOC total organic carbon meter (TOC-5000A manufactured by Shimadzu Corporation). The amount of residual carbon was 4.1% by mass.
The average particle size (secondary particle size) of the carbon source-attached particles was determined as the average value of 200 arbitrarily extracted particles in SEM observation.
出口温度を１２０℃に設定した噴霧乾燥装置に湿式粉砕後のスラリー（３）を供給し、炭素源付着粒子を得た。
炭素源付着粒子のＳＥＭ観察から求められる平均粒子径（二次粒子径）は２０μｍであった。
得られた炭素源付着粒子を線源としてＣｕＫα線を用いてＸ線回折測定を行ったところ、該炭素源付着粒子は、ＬｉＶＯＰＯ４・２Ｈ２ＯとＬｉＨ２ＰＯ４を含むものであった
（図４参照）。
また、得られた炭素源付着粒子の残存炭素量を、ＴＯＣ全有機炭素計（島津製作所製ＴＯＣ－５０００Ａ）にて測定することによりＣ原子の含有量として求めた。残存炭素量は４．１質量％であった。
なお、炭素源付着粒子の平均粒子径（二次粒子径）は、ＳＥＭ観察において、任意に抽出した粒子２００個の平均値として求めた。 <A5 process>
The slurry (3) after wet pulverization was supplied to a spray drying device having an outlet temperature set to 120 ° C. to obtain carbon source-adhered particles.
The average particle size (secondary particle size) obtained from the SEM observation of the carbon source-attached particles was 20 μm.
X-ray diffraction measurement was performed using the obtained carbon source-attached particles as a radiation source, and the carbon source-attached particles contained LiVOPO 4.2H 2 O and LiH 2 PO 4 . See FIG. 4).
Further, the residual carbon content of the obtained carbon source-adhered particles was determined as the content of C atoms by measuring with a TOC total organic carbon meter (TOC-5000A manufactured by Shimadzu Corporation). The amount of residual carbon was 4.1% by mass.
The average particle size (secondary particle size) of the carbon source-attached particles was determined as the average value of 200 arbitrarily extracted particles in SEM observation.
＜Ｂ工程＞
得られた炭素源付着粒子をムライト製匣鉢に入れ，大気雰囲気下（酸素濃度２０Ｖｏｌ％）、３００℃で４時間加熱処理して反応前駆体を得た。得られた反応前駆体をＸ線回折分析した結果、ＬｉＶＯＰＯ４と痕跡量のＬｉ３ＰＯ４ピークを含むものであった。なお、ＬｉＨ２ＰＯ４の明確なピークはＸ線回折分析で検出されなかったが、ＬｉＨ２ＰＯ４が非晶質のリン化合物（ＬｉＨ２ＰＯ４、ＬｉＰＯ３）になったものと考えられる。
また、得られた反応前駆体の残存炭素量を、ＴＯＣ全有機炭素計（島津製作所製ＴＯＣ－５０００Ａ）にて測定することによりＣ原子の含有量として求めた。残存炭素量は３．０質量％であった。 <Step B>
The obtained carbon source-adhered particles were placed in a mullite saggar and heat-treated at 300 ° C. for 4 hours in an air atmosphere (oxygen concentration 20 Vol%) to obtain a reaction precursor. As a result of X-ray diffraction analysis of the obtained reaction precursor, it was found to contain LiVOPO 4 and a trace amount of Li 3 PO 4 peak. Although no clear peak of LiH 2 PO 4 was detected by X-ray diffraction analysis, it is probable that LiH 2 PO 4 became an amorphous phosphorus compound (LiH 2 PO 4 , LiPO 3 ).
Further, the residual carbon content of the obtained reaction precursor was determined as the C atom content by measuring with a TOC total organic carbon meter (TOC-5000A manufactured by Shimadzu Corporation). The amount of residual carbon was 3.0% by mass.
得られた炭素源付着粒子をムライト製匣鉢に入れ，大気雰囲気下（酸素濃度２０Ｖｏｌ％）、３００℃で４時間加熱処理して反応前駆体を得た。得られた反応前駆体をＸ線回折分析した結果、ＬｉＶＯＰＯ４と痕跡量のＬｉ３ＰＯ４ピークを含むものであった。なお、ＬｉＨ２ＰＯ４の明確なピークはＸ線回折分析で検出されなかったが、ＬｉＨ２ＰＯ４が非晶質のリン化合物（ＬｉＨ２ＰＯ４、ＬｉＰＯ３）になったものと考えられる。
また、得られた反応前駆体の残存炭素量を、ＴＯＣ全有機炭素計（島津製作所製ＴＯＣ－５０００Ａ）にて測定することによりＣ原子の含有量として求めた。残存炭素量は３．０質量％であった。 <Step B>
The obtained carbon source-adhered particles were placed in a mullite saggar and heat-treated at 300 ° C. for 4 hours in an air atmosphere (
Further, the residual carbon content of the obtained reaction precursor was determined as the C atom content by measuring with a TOC total organic carbon meter (TOC-5000A manufactured by Shimadzu Corporation). The amount of residual carbon was 3.0% by mass.
＜Ｃ工程＞
得られた反応前駆体をＮ２雰囲気下７５０℃で４時間焼成した。次いで、焼成物を気流粉砕機で粉砕を行い、粉砕物を得た。Ｘ線回折分析した結果、単相のリン酸バナジウムリチウム（Ｌｉ３Ｖ２（ＰＯ４）３）であることを確認した（図５参照）。これをリン酸バナジウムリチウム試料とした。 <C process>
The obtained reaction precursor was calcined at 750 ° C. for 4 hours under an N 2 atmosphere. Then, the fired product was crushed by an air flow crusher to obtain a crushed product. As a result of X-ray diffraction analysis, it was confirmed that it was a single-phase lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ) (see FIG. 5). This was used as a vanadium lithium phosphate sample.
得られた反応前駆体をＮ２雰囲気下７５０℃で４時間焼成した。次いで、焼成物を気流粉砕機で粉砕を行い、粉砕物を得た。Ｘ線回折分析した結果、単相のリン酸バナジウムリチウム（Ｌｉ３Ｖ２（ＰＯ４）３）であることを確認した（図５参照）。これをリン酸バナジウムリチウム試料とした。 <C process>
The obtained reaction precursor was calcined at 750 ° C. for 4 hours under an N 2 atmosphere. Then, the fired product was crushed by an air flow crusher to obtain a crushed product. As a result of X-ray diffraction analysis, it was confirmed that it was a single-phase lithium vanadium phosphate (Li 3 V 2 (PO 4 ) 3 ) (see FIG. 5). This was used as a vanadium lithium phosphate sample.
（実施例２）
Ｂ工程において、加熱処理時間を２．５時間とする以外は、実施例１と同様に反応を行ってリン酸バナジウムリチウム試料を得た。
また、得られたリン酸バナジウムリチウム試料のＸ線回折分析した結果、何れも単相のリン酸バナジウムリチウム（Ｌｉ３Ｖ２（ＰＯ４）３）であることを確認した（図６参照）。これをリン酸バナジウムリチウム試料とした。 (Example 2)
In step B, the reaction was carried out in the same manner as in Example 1 except that the heat treatment time was 2.5 hours to obtain a vanadium lithium phosphate sample.
Moreover, as a result of X-ray diffraction analysis of the obtained vanadium phosphate lithium sample, it was confirmed that all of them were single-phase vanadium lithium phosphate (Li 3 V 2 (PO 4 ) 3 ) (see FIG. 6). This was used as a vanadium lithium phosphate sample.
Ｂ工程において、加熱処理時間を２．５時間とする以外は、実施例１と同様に反応を行ってリン酸バナジウムリチウム試料を得た。
また、得られたリン酸バナジウムリチウム試料のＸ線回折分析した結果、何れも単相のリン酸バナジウムリチウム（Ｌｉ３Ｖ２（ＰＯ４）３）であることを確認した（図６参照）。これをリン酸バナジウムリチウム試料とした。 (Example 2)
In step B, the reaction was carried out in the same manner as in Example 1 except that the heat treatment time was 2.5 hours to obtain a vanadium lithium phosphate sample.
Moreover, as a result of X-ray diffraction analysis of the obtained vanadium phosphate lithium sample, it was confirmed that all of them were single-phase vanadium lithium phosphate (Li 3 V 2 (PO 4 ) 3 ) (see FIG. 6). This was used as a vanadium lithium phosphate sample.
（比較例１）
Ｂ工程を行わないこと以外は、実施例１と同様に反応を行ってリン酸バナジウムリチウム試料を得た。
また、得られたリン酸バナジウムリチウム試料のＸ線回折分析した結果、何れも単相のリン酸バナジウムリチウム（Ｌｉ３Ｖ２（ＰＯ４）３）であることを確認した。これをリン酸バナジウムリチウム試料とした。 (Comparative Example 1)
A reaction was carried out in the same manner as in Example 1 except that step B was not performed to obtain a vanadium lithium phosphate sample.
Moreover, as a result of X-ray diffraction analysis of the obtained vanadium phosphate lithium sample, it was confirmed that all of them were single-phase vanadium lithium phosphate (Li 3 V 2 (PO 4 ) 3 ). This was used as a vanadium lithium phosphate sample.
Ｂ工程を行わないこと以外は、実施例１と同様に反応を行ってリン酸バナジウムリチウム試料を得た。
また、得られたリン酸バナジウムリチウム試料のＸ線回折分析した結果、何れも単相のリン酸バナジウムリチウム（Ｌｉ３Ｖ２（ＰＯ４）３）であることを確認した。これをリン酸バナジウムリチウム試料とした。 (Comparative Example 1)
A reaction was carried out in the same manner as in Example 1 except that step B was not performed to obtain a vanadium lithium phosphate sample.
Moreover, as a result of X-ray diffraction analysis of the obtained vanadium phosphate lithium sample, it was confirmed that all of them were single-phase vanadium lithium phosphate (Li 3 V 2 (PO 4 ) 3 ). This was used as a vanadium lithium phosphate sample.
なお、表１中、炭素含有量は、炭素源付着粒子中のＶ原子に対する炭素原子換算の炭素原子のモル比、及び反応前駆体中のＶ原子に対する炭素原子換算の炭素原子のモル比を示す。
In Table 1, the carbon content indicates the molar ratio of carbon atoms in terms of carbon atoms to V atoms in the particles attached to the carbon source, and the molar ratio of carbon atoms in terms of carbon atoms to V atoms in the reaction precursor. ..
＜リン酸バナジウムリチウム（ＬＶＰ）試料の物性評価＞
実施例及び比較例で得られたリン酸バナジウムリチウム試料について、ＢＥＴ比表面積、一次粒子の平均粒子径、二次粒子の平均粒子径、及び残存炭素量を測定した。なお、一次粒子の平均粒子径、二次粒子の平均粒子径、及び残存炭素量の測定は、下記のとおり行った。
（一次粒子の平均粒子径）
ＳＥＭ観察において、任意に抽出した粒子２００個の平均値として一次粒子の平均粒子径を求めた。また、実施例１及び比較例１で得られたリン酸バナジウムリチウム試料のＳＥＭ写真を、図７及び図８にそれぞれ示す。
（二次粒子の平均粒子径）
レーザー散乱・回折法によりＤ５０を求めた。また、併せてＤ９０も測定した。また、実施例１で得られたリン酸バナジウムリチウム試料の粒度分布図を図９に示す。
（残存炭素量）
ＴＯＣ全有機炭素計（島津製作所製ＴＯＣ－５０００Ａ）にて測定した。 <Evaluation of physical properties of lithium vanadium phosphate (LVP) sample>
For the vanadium lithium phosphate samples obtained in Examples and Comparative Examples, the BET specific surface area, the average particle size of the primary particles, the average particle size of the secondary particles, and the amount of residual carbon were measured. The average particle size of the primary particles, the average particle size of the secondary particles, and the amount of residual carbon were measured as follows.
(Average particle size of primary particles)
In the SEM observation, the average particle size of the primary particles was obtained as the average value of 200 arbitrarily extracted particles. In addition, SEM photographs of the vanadium lithium phosphate samples obtained in Example 1 and Comparative Example 1 are shown in FIGS. 7 and 8, respectively.
(Average particle size of secondary particles)
D 50 was determined by laser scattering / diffraction method. In addition, D 90 was also measured. Moreover, the particle size distribution map of the vanadium lithium phosphate sample obtained in Example 1 is shown in FIG.
(Amount of residual carbon)
It was measured with a TOC total organic carbon meter (TOC-5000A manufactured by Shimadzu Corporation).
実施例及び比較例で得られたリン酸バナジウムリチウム試料について、ＢＥＴ比表面積、一次粒子の平均粒子径、二次粒子の平均粒子径、及び残存炭素量を測定した。なお、一次粒子の平均粒子径、二次粒子の平均粒子径、及び残存炭素量の測定は、下記のとおり行った。
（一次粒子の平均粒子径）
ＳＥＭ観察において、任意に抽出した粒子２００個の平均値として一次粒子の平均粒子径を求めた。また、実施例１及び比較例１で得られたリン酸バナジウムリチウム試料のＳＥＭ写真を、図７及び図８にそれぞれ示す。
（二次粒子の平均粒子径）
レーザー散乱・回折法によりＤ５０を求めた。また、併せてＤ９０も測定した。また、実施例１で得られたリン酸バナジウムリチウム試料の粒度分布図を図９に示す。
（残存炭素量）
ＴＯＣ全有機炭素計（島津製作所製ＴＯＣ－５０００Ａ）にて測定した。 <Evaluation of physical properties of lithium vanadium phosphate (LVP) sample>
For the vanadium lithium phosphate samples obtained in Examples and Comparative Examples, the BET specific surface area, the average particle size of the primary particles, the average particle size of the secondary particles, and the amount of residual carbon were measured. The average particle size of the primary particles, the average particle size of the secondary particles, and the amount of residual carbon were measured as follows.
(Average particle size of primary particles)
In the SEM observation, the average particle size of the primary particles was obtained as the average value of 200 arbitrarily extracted particles. In addition, SEM photographs of the vanadium lithium phosphate samples obtained in Example 1 and Comparative Example 1 are shown in FIGS. 7 and 8, respectively.
(Average particle size of secondary particles)
D 50 was determined by laser scattering / diffraction method. In addition, D 90 was also measured. Moreover, the particle size distribution map of the vanadium lithium phosphate sample obtained in Example 1 is shown in FIG.
(Amount of residual carbon)
It was measured with a TOC total organic carbon meter (TOC-5000A manufactured by Shimadzu Corporation).
表２より、実施例のものは、比較例１と比べて、ＢＥＴ比表面積が小さくなっており、且つ、Ｄ５０とＤ９０の差が小さく、粒度分布がシャープなものであることが分かる。
From Table 2, it can be seen that the BET specific surface area of the example is smaller than that of the comparative example 1, the difference between D 50 and D 90 is small, and the particle size distribution is sharp.
From Table 2, it can be seen that the BET specific surface area of the example is smaller than that of the comparative example 1, the difference between D 50 and D 90 is small, and the particle size distribution is sharp.
Claims (11)
- ナシコン（ＮＡＳＩＣＯＮ）構造を有するリン酸バナジウムリチウムの製造方法であって、
一次粒子の平均粒子径が２．０μｍ以下である下記一般式（１）：
ＬｉＶＯＰＯ４・ｘＨ２Ｏ （１）
（式中ｘは０～２の整数）
で表されるリチウムバナジウムリン複合酸化物の粒子表面に、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び加熱分解により炭素が生じる有機化合物が付着している炭素源付着粒子を調製するＡ工程と、
該炭素源付着粒子を、酸素含有雰囲気中で加熱処理することにより、反応前駆体を得るＢ工程と、
該反応前駆体を、不活性ガス雰囲気又は還元雰囲気で５００～１３００℃で焼成し、リン酸バナジウムリチウムを得るＣ工程と、
を有することを特徴とするリン酸バナジウムリチウムの製造方法。 A method for producing lithium vanadium phosphate having a NASICON structure.
The following general formula (1): in which the average particle size of the primary particles is 2.0 μm or less:
LiVOPO 4・ xH 2 O (1)
(X in the formula is an integer from 0 to 2)
Step A to prepare carbon source-adhered particles in which lithium dihydrogen phosphate (LiH 2 PO 4 ) and an organic compound that produces carbon by thermal decomposition are attached to the surface of the particles of the lithium vanadium phosphorus composite oxide represented by. ,
Step B to obtain a reaction precursor by heat-treating the carbon source-adhered particles in an oxygen-containing atmosphere.
Step C to obtain lithium vanadium phosphate by calcining the reaction precursor at 500 to 1300 ° C. in an inert gas atmosphere or a reducing atmosphere.
A method for producing lithium vanadium phosphate, which comprises. - 前記炭素源付着粒子における、前記加熱分解により炭素が生じる有機化合物の含有量が、バナジウム原子に対する炭素原子のモル比（Ｃ／Ｖ）で、０．６より大きいことを特徴とする請求項１に記載のリン酸バナジウムリチウムの製造方法。 The first aspect of claim 1 is that the content of the organic compound that produces carbon by the thermal decomposition in the carbon source-adhered particles is greater than 0.6 in terms of the molar ratio (C / V) of the carbon atom to the vanadium atom. The method for producing vanadium lithium phosphate according to the above method.
- 前記反応前駆体の炭素含有量が、バナジウム原子に対する炭素原子のモル比（Ｃ／Ｖ）で、０．３～０．６であることを特徴とする請求項１又は２記載のリン酸バナジウムリチウムの製造方法。 The lithium vanadium phosphate according to claim 1 or 2, wherein the carbon content of the reaction precursor is 0.3 to 0.6 in terms of the molar ratio (C / V) of the carbon atom to the vanadium atom. Manufacturing method.
- 前記Ａ工程は、一次粒子の平均粒子径が２．０μｍ以下の前記一般式（１）で表されるリチウムバナジウムリン複合酸化物と、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）と、前記加熱分解により炭素が生じる有機化合物と、を含有するスラリーを噴霧乾燥する噴霧乾燥処理を有する工程であることを特徴とする請求項１～３いずれか１項記載のリン酸バナジウムリチウムの製造方法。 In the step A, the lithium vanadium phosphorus composite oxide represented by the general formula (1) having an average particle diameter of 2.0 μm or less, lithium dihydrogen phosphate (LiH 2 PO 4 ), and the heating are performed. The method for producing vanadium lithium phosphate according to any one of claims 1 to 3, wherein the step comprises a spray drying treatment of spray-drying a slurry containing an organic compound that produces carbon by decomposition.
- 前記Ｂ工程において、前記炭素源付着粒子を加熱処理する温度が、２７０～３７０℃であることを特徴とする請求項１～４いずれか１項記載のリン酸バナジウムリチウムの製造方法。 The method for producing lithium vanadium phosphate according to any one of claims 1 to 4, wherein in the step B, the temperature at which the carbon source-adhered particles are heat-treated is 270 to 370 ° C.
- 前記Ａ工程が、
五酸化バナジウム、リン酸及び還元糖を水溶媒中で混合して混合スラリー（１）を調製するＡ１工程と、
該混合スラリーを加熱処理して溶液化し、還元反応溶液を得るＡ２工程と、
加温下に該還元反応溶液に水酸化リチウムを含有する溶液を添加して、一般式（１）で表されるリチウムバナジウムリン複合酸化物、リン酸二水素リチウム（ＬｉＨ２ＰＯ４）及び前記加熱分解により炭素が生じる有機化合物を含有するスラリー（２）を調製するＡ３工程と、
該スラリー（２）をメディアミルにより湿式粉砕処理して、湿式粉砕処理スラリー（３）を調製するＡ４工程と、
該湿式粉砕処理スラリー（３）を噴霧乾燥処理して、前記炭素源付着粒子を得るＡ５工程と、
を有する工程であることを特徴とする請求項１～５いずれか１項記載のリン酸バナジウムリチウムの製造方法。 The step A is
A1 step of mixing vanadium pentoxide, phosphoric acid and reducing sugar in an aqueous solvent to prepare a mixed slurry (1), and
A2 step of heat-treating the mixed slurry to make a solution to obtain a reduction reaction solution, and
A solution containing lithium hydroxide is added to the reduction reaction solution under heating to form a lithium vanadium phosphorus composite oxide represented by the general formula (1), lithium dihydrogen phosphate (LiH 2 PO 4 ) and the above. A3 step of preparing a slurry (2) containing an organic compound that produces carbon by thermal decomposition, and
The A4 step of preparing the wet pulverized slurry (3) by wet pulverizing the slurry (2) with a media mill.
The A5 step of spray-drying the wet pulverized slurry (3) to obtain the carbon source-adhered particles, and
The method for producing lithium vanadium phosphate according to any one of claims 1 to 5, wherein the step comprises the above. - 前記Ａ２工程において、前記混合スラリー（１）を加熱処理する温度が、６０～１００℃であることを特徴とする請求項６記載のリン酸バナジウムリチウムの製造方法。 The method for producing lithium vanadium phosphate according to claim 6, wherein in the step A2, the temperature at which the mixed slurry (1) is heat-treated is 60 to 100 ° C.
- 前記Ａ３工程において、前記還元反応溶液の加熱温度が、４０～１００℃であることを特徴とする請求項６又は７記載のリン酸バナジウムリチウムの製造方法。 The method for producing lithium vanadium phosphate according to claim 6 or 7, wherein in the step A3, the heating temperature of the reduction reaction solution is 40 to 100 ° C.
- 前記Ａ１工程において、前記還元糖の混合量が、五酸化バナジウムのバナジウム原子に対する炭素原子換算の炭素原子のモル比（Ｃ／Ｖ）で、０．６より大きく２．０以下であることを特徴とする請求項６～８いずれか１項記載のリン酸バナジウムリチウムの製造方法。 In the A1 step, the mixed amount of the reduced sugar is the molar ratio (C / V) of carbon atoms in terms of carbon atoms to vanadium atoms of vanadium pentoxide, which is larger than 0.6 and 2.0 or less. The method for producing vanadium lithium phosphate according to any one of claims 6 to 8.
- 前記Ａ４工程後に得られる前記湿式粉砕処理スラリー（３）中の固形分の平均粒子径が２．０μｍ以下であることを特徴とする請求項６～９いずれか１項記載のリン酸バナジウムリチウムの製造方法。 The vanadium lithium phosphate according to any one of claims 6 to 9, wherein the average particle size of the solid content in the wet pulverized slurry (3) obtained after the A4 step is 2.0 μm or less. Production method.
- 前記反応前駆体は、更に、Ｍｅ源（ＭｅはＶ以外の原子番号１１以上の金属元素又は遷移金属元素を示す。）を含有することを特徴とする請求項１～１０いずれか１項記載のリン酸バナジウムリチウムの製造方法。
The one according to any one of claims 1 to 10, wherein the reaction precursor further contains a Me source (Me represents a metal element having an atomic number of 11 or more or a transition metal element other than V). A method for producing vanadium lithium phosphate.
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| JP2017160107A (en) * | 2016-03-08 | 2017-09-14 | 日本化学工業株式会社 | Method for producing lithium vanadium phosphate |
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| JP2017160107A (en) * | 2016-03-08 | 2017-09-14 | 日本化学工業株式会社 | Method for producing lithium vanadium phosphate |
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