CN116581270A - Manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material and preparation method and application thereof - Google Patents
Manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material and preparation method and application thereof Download PDFInfo
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- CN116581270A CN116581270A CN202310692316.0A CN202310692316A CN116581270A CN 116581270 A CN116581270 A CN 116581270A CN 202310692316 A CN202310692316 A CN 202310692316A CN 116581270 A CN116581270 A CN 116581270A
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- titanium
- ferrous sulfate
- manganese
- composite material
- situ doped
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- 239000010936 titanium Substances 0.000 title claims abstract description 87
- 239000011572 manganese Substances 0.000 title claims abstract description 79
- 229910052719 titanium Inorganic materials 0.000 title claims abstract description 73
- 229910052748 manganese Inorganic materials 0.000 title claims abstract description 71
- 239000002131 composite material Substances 0.000 title claims abstract description 62
- 238000011065 in-situ storage Methods 0.000 title claims abstract description 62
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 51
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 51
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 title claims abstract description 46
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 title claims abstract description 40
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims abstract description 40
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 239000011790 ferrous sulphate Substances 0.000 claims abstract description 103
- 235000003891 ferrous sulphate Nutrition 0.000 claims abstract description 103
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims abstract description 103
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims abstract description 103
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 64
- 239000006227 byproduct Substances 0.000 claims abstract description 48
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims abstract description 39
- 235000010215 titanium dioxide Nutrition 0.000 claims abstract description 37
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 32
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 23
- 239000003513 alkali Substances 0.000 claims abstract description 20
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 20
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 19
- 238000001354 calcination Methods 0.000 claims abstract description 15
- 238000005189 flocculation Methods 0.000 claims abstract description 10
- 230000016615 flocculation Effects 0.000 claims abstract description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 64
- 238000002156 mixing Methods 0.000 claims description 36
- 238000000034 method Methods 0.000 claims description 25
- 239000002243 precursor Substances 0.000 claims description 23
- 238000006460 hydrolysis reaction Methods 0.000 claims description 20
- 238000006243 chemical reaction Methods 0.000 claims description 19
- 239000013067 intermediate product Substances 0.000 claims description 18
- 238000006722 reduction reaction Methods 0.000 claims description 18
- 238000001556 precipitation Methods 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- MECMQNITHCOSAF-UHFFFAOYSA-N manganese titanium Chemical compound [Ti].[Mn] MECMQNITHCOSAF-UHFFFAOYSA-N 0.000 claims description 14
- 238000007254 oxidation reaction Methods 0.000 claims description 13
- 239000007800 oxidant agent Substances 0.000 claims description 12
- 239000000047 product Substances 0.000 claims description 12
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 11
- 239000002253 acid Substances 0.000 claims description 11
- 229910001416 lithium ion Inorganic materials 0.000 claims description 11
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 10
- 229910052742 iron Inorganic materials 0.000 claims description 10
- 229910001448 ferrous ion Inorganic materials 0.000 claims description 9
- 230000007062 hydrolysis Effects 0.000 claims description 9
- 239000007774 positive electrode material Substances 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 8
- 239000000413 hydrolysate Substances 0.000 claims description 6
- 230000001590 oxidative effect Effects 0.000 claims description 6
- 239000012535 impurity Substances 0.000 abstract description 22
- 239000005955 Ferric phosphate Substances 0.000 abstract description 11
- 229940032958 ferric phosphate Drugs 0.000 abstract description 11
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 abstract description 11
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 abstract description 11
- 229910000399 iron(III) phosphate Inorganic materials 0.000 abstract description 11
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 abstract description 10
- 239000002994 raw material Substances 0.000 abstract description 10
- 239000010405 anode material Substances 0.000 abstract description 6
- 239000003575 carbonaceous material Substances 0.000 abstract description 3
- 230000002195 synergetic effect Effects 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 55
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 22
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 17
- 229910010710 LiFePO Inorganic materials 0.000 description 17
- 235000011114 ammonium hydroxide Nutrition 0.000 description 17
- 239000002244 precipitate Substances 0.000 description 14
- 238000005406 washing Methods 0.000 description 12
- 238000001035 drying Methods 0.000 description 11
- 238000001914 filtration Methods 0.000 description 11
- 229920002401 polyacrylamide Polymers 0.000 description 11
- 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 9
- 239000008103 glucose Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 230000035484 reaction time Effects 0.000 description 9
- 150000002500 ions Chemical class 0.000 description 8
- 230000009467 reduction Effects 0.000 description 8
- 229910052708 sodium Inorganic materials 0.000 description 8
- 239000011734 sodium Substances 0.000 description 8
- 229910010707 LiFePO 4 Inorganic materials 0.000 description 7
- 238000001816 cooling Methods 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- -1 ferric iron ions Chemical class 0.000 description 6
- 229940116007 ferrous phosphate Drugs 0.000 description 6
- 229910000155 iron(II) phosphate Inorganic materials 0.000 description 6
- SDEKDNPYZOERBP-UHFFFAOYSA-H iron(ii) phosphate Chemical compound [Fe+2].[Fe+2].[Fe+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O SDEKDNPYZOERBP-UHFFFAOYSA-H 0.000 description 6
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 6
- 229910052808 lithium carbonate Inorganic materials 0.000 description 6
- 239000011259 mixed solution Substances 0.000 description 6
- 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 5
- 238000000975 co-precipitation Methods 0.000 description 5
- 238000001878 scanning electron micrograph Methods 0.000 description 5
- 238000001179 sorption measurement Methods 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- 238000009792 diffusion process Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- WTFUTSCZYYCBAY-SXBRIOAWSA-N 6-[(E)-C-[[4-[2-(2,3-dihydro-1H-inden-2-ylamino)pyrimidin-5-yl]piperazin-1-yl]methyl]-N-hydroxycarbonimidoyl]-3H-1,3-benzoxazol-2-one Chemical compound C1C(CC2=CC=CC=C12)NC1=NC=C(C=N1)N1CCN(CC1)C/C(=N/O)/C1=CC2=C(NC(O2)=O)C=C1 WTFUTSCZYYCBAY-SXBRIOAWSA-N 0.000 description 3
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- 239000002202 Polyethylene glycol Substances 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- 229920001223 polyethylene glycol Polymers 0.000 description 3
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- 229920002538 Polyethylene Glycol 20000 Polymers 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 2
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 description 2
- 239000008394 flocculating agent Substances 0.000 description 2
- 238000003837 high-temperature calcination Methods 0.000 description 2
- 229910003002 lithium salt Inorganic materials 0.000 description 2
- 159000000002 lithium salts Chemical class 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000012798 spherical particle Substances 0.000 description 2
- 239000004408 titanium dioxide Substances 0.000 description 2
- 229920000858 Cyclodextrin Polymers 0.000 description 1
- 239000001116 FEMA 4028 Substances 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229920002873 Polyethylenimine Polymers 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000004931 aggregating effect Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- WHGYBXFWUBPSRW-FOUAGVGXSA-N beta-cyclodextrin Chemical compound OC[C@H]([C@H]([C@@H]([C@H]1O)O)O[C@H]2O[C@@H]([C@@H](O[C@H]3O[C@H](CO)[C@H]([C@@H]([C@H]3O)O)O[C@H]3O[C@H](CO)[C@H]([C@@H]([C@H]3O)O)O[C@H]3O[C@H](CO)[C@H]([C@@H]([C@H]3O)O)O[C@H]3O[C@H](CO)[C@H]([C@@H]([C@H]3O)O)O3)[C@H](O)[C@H]2O)CO)O[C@@H]1O[C@H]1[C@H](O)[C@@H](O)[C@@H]3O[C@@H]1CO WHGYBXFWUBPSRW-FOUAGVGXSA-N 0.000 description 1
- 235000011175 beta-cyclodextrine Nutrition 0.000 description 1
- 229960004853 betadex Drugs 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- YNQRWVCLAIUHHI-UHFFFAOYSA-L dilithium;oxalate Chemical compound [Li+].[Li+].[O-]C(=O)C([O-])=O YNQRWVCLAIUHHI-UHFFFAOYSA-L 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- LEAMSPPOALICQN-UHFFFAOYSA-H iron(2+);diphosphate;octahydrate Chemical compound O.O.O.O.O.O.O.O.[Fe+2].[Fe+2].[Fe+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LEAMSPPOALICQN-UHFFFAOYSA-H 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 229910001386 lithium phosphate Inorganic materials 0.000 description 1
- HQRPHMAXFVUBJX-UHFFFAOYSA-M lithium;hydrogen carbonate Chemical compound [Li+].OC([O-])=O HQRPHMAXFVUBJX-UHFFFAOYSA-M 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- RGVLTEMOWXGQOS-UHFFFAOYSA-L manganese(2+);oxalate Chemical compound [Mn+2].[O-]C(=O)C([O-])=O RGVLTEMOWXGQOS-UHFFFAOYSA-L 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- PFUVRDFDKPNGAV-UHFFFAOYSA-N sodium peroxide Chemical compound [Na+].[Na+].[O-][O-] PFUVRDFDKPNGAV-UHFFFAOYSA-N 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- 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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Composite Materials (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material, and a preparation method and application thereof, and belongs to the technical field of anode materials. The invention takes titanium white byproduct ferrous sulfate as a raw material, reduces ferric iron by using a reducing agent, removes part of titanium and other impurities by flocculation after adding alkali to obtain refined ferrous sulfate with certain manganese and titanium content, then adds phosphoric acid and alkali to oxidize to obtain ferric phosphate, finally mixes with a lithium source and a carbon source and calcines to obtain the manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material. According to the invention, manganese and titanium in the titanium white byproduct ferrous sulfate are not required to be completely removed, the titanium white byproduct ferrous sulfate is used as a doping element to be doped in situ, the preparation process is simpler, the uniform doping of a bulk phase is realized, the manganese and titanium double doping elements have a synergistic effect, and the performance of the composite material is improved. In addition, the carbon source is added to form a carbon material after calcination, so that the conductivity of the composite material is improved, and the electrochemical performance of the composite material is further improved.
Description
Technical Field
The invention relates to the technical field of positive electrode materials, in particular to a manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material, and a preparation method and application thereof.
Background
The lithium iron phosphate anode material is the most suitable energy storage type lithium ion battery anode material at present because of the advantages of no rare resources such as cobalt, nickel and the like, long cycle life, good safety and the like. In order to prepare the lithium iron phosphate positive electrode material with excellent performance, in addition to strict control of production process and equipment, strict requirements are also imposed on the purity of raw materials, such as battery-grade lithium salt, phosphoric acid, high-purity iron source and the like.
Millions of tons of byproduct ferrous sulfate are generated in the production process of titanium dioxide by the sulfuric acid method in China each year, and the ferrous sulfate contains a plurality of impurities, so that the existence of the impurities is widely considered to influence the structure and the characteristics of ferric phosphate, and further influence the performance of a battery. In order to synthesize the battery-grade anhydrous ferric phosphate, complex and complicated and high-cost procedures are required to remove impurities in raw materials, and high-temperature calcination is required to remove crystal water in ferric sulfate. On the other hand, in order to improve the performance of lithium iron phosphate, the incorporation of bulk doping elements into the crystal lattice of lithium iron phosphate during the subsequent synthesis process is an important method for improving ion transport characteristics.
Although the production and doping process of lithium iron phosphate are mature, and the conversion of titanium white byproduct ferrous sulfate to prepare lithium iron phosphate electrode materials is more, the conventional method is as follows: impurities in the byproduct ferrous sulfate are removed, then high-temperature calcination and dehydration are carried out, and doping elements are added, so that the preparation method is complex, and the uniformity of the material is still to be improved. Therefore, how to simplify the process and improve the performance of lithium iron phosphate has become a problem in the prior art.
Disclosure of Invention
The invention aims to provide a manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material, and a preparation method and application thereof. The preparation method provided by the invention is simple in process, and the prepared manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material has excellent electrochemical performance.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material, which comprises the following steps:
(1) Mixing titanium white byproduct ferrous sulfate with water and a reducing agent for reduction reaction to obtain a reducing solution;
(2) Mixing the reducing solution obtained in the step (1) with alkali, and carrying out hydrolysis reaction to obtain a hydrolysis product;
(3) Mixing the hydrolysate obtained in the step (2) with a flocculant, and performing flocculation reaction to obtain a refined ferrous sulfate solution; the mass content of manganese in the refined ferrous sulfate solution is 0.05-0.5%, and the mass content of titanium in the refined ferrous sulfate solution is 0.04-0.38%;
(4) Mixing the refined ferrous sulfate solution obtained in the step (3) with phosphoric acid and alkali, and carrying out precipitation reaction to obtain an intermediate product;
(5) Mixing the intermediate product obtained in the step (4) with an oxidant and an acid, and carrying out an oxidation reaction to obtain a precursor;
(6) And (3) mixing the precursor obtained in the step (5) with a lithium source and a carbon source, and calcining to obtain the manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material.
Preferably, in the step (1), the mass ratio of the reducing agent to the titanium white byproduct ferrous sulfate is (0.5-2): 100.
preferably, the hydrolysis reaction temperature in the step (2) is 40-70 ℃, and the hydrolysis reaction time is 1-4 h.
Preferably, the ratio of the amount of phosphoric acid in the step (4) to the amount of ferrous ion in the purified ferrous sulfate solution is (1 to 1.2): 1.
preferably, the time of the precipitation reaction in the step (4) is 0.5 to 2 hours.
Preferably, the ratio of the amount of oxidant to the amount of iron in the intermediate product in step (5) is (1.2-2.5): 1.
preferably, in the step (6), the mass ratio of the carbon source to the precursor is (7-9.5): 100.
preferably, the ratio of the amount of lithium in the lithium source of step (6) to the amount of iron in the precursor is (1.02-1.1): 1.
the invention provides the manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material prepared by the preparation method.
The invention also provides application of the manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material as a lithium ion battery anode material.
The invention provides a preparation method of a manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material, which comprises the following steps: (1) Mixing titanium white byproduct ferrous sulfate with water and a reducing agent, and carrying out a reduction reaction to obtain a reduction solution; (2) Mixing the reducing solution obtained in the step (1) with alkali, and carrying out hydrolysis reaction to obtain a hydrolysis product; (3) Mixing the hydrolysate obtained in the step (2) with a flocculant, and performing flocculation reaction to obtain a refined ferrous sulfate solution; the method comprises the steps of carrying out a first treatment on the surface of the The mass content of manganese in the refined ferrous sulfate solution is 0.05-0.5%, and the mass content of titanium in the refined ferrous sulfate solution is 0.04-0.38%; (4) Mixing the refined ferrous sulfate solution obtained in the step (3) with phosphoric acid and alkali, and carrying out precipitation reaction to obtain an intermediate product; (5) Mixing the intermediate product obtained in the step (4) with an oxidant and an acid, and carrying out an oxidation reaction to obtain a precursor; (6) And (3) mixing the precursor obtained in the step (5) with a lithium source and a carbon source, and calcining to obtain the manganese and titanium in-situ doped lithium iron phosphate. The invention takes titanium white byproduct ferrous sulfate as a raw material, realizes reduction of ferric iron by adding a reducing agent, realizes hydrolysis of titanium by adding alkali, adds a flocculating agent to remove a certain amount of Ti and other impurities to obtain refined ferrous sulfate with certain manganese and titanium content, then adds phosphoric acid and alkali to obtain manganese and titanium in-situ doped ferrous phosphate, then adds an oxidizing agent to oxidize the ferrous phosphate into ferric phosphate, finally mixes the ferric phosphate with a lithium source and a carbon source and calcines the mixture to obtain manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material, and does not need to completely remove impurities in the titanium white byproduct ferrous sulfate, but takes manganese and titanium as beneficial doping elements to obtain ferric phosphate, does not need to additionally add doping elements, has simpler preparation process, realizes uniform doping of bulk phase, has synergistic effect of manganese and titanium double doping elements, improves performance of the composite material, and forms after calcination by adding the carbon sourceThe carbon material improves the conductivity of the composite material and further improves the electrochemical performance of the composite material. The results of the examples show that the discharge capacity of the button cell assembled from the composite material prepared according to the invention is 145.2mAhg -1 The above.
Drawings
FIG. 1 is a process flow diagram of a method for preparing a manganese, titanium in-situ doped carbonaceous lithium iron phosphate composite material of the invention;
FIG. 2 shows Mn-Ti doped FePO prepared in example 1 of the present invention 4 ·2H 2 XRD pattern of O;
FIG. 3 shows Mn-Ti doped FePO prepared in example 1 of the present invention 4 ·2H 2 SEM image of O;
FIG. 4 shows Mn-and Ti-doped LiFePO prepared in example 2 of the present invention 4 XRD pattern of the/C composite;
FIG. 5 shows Mn and Ti doped LiFePO prepared in example 2 of the present invention 4 SEM image of the/C composite;
FIG. 6 shows Mn and Ti doped LiFePO prepared in example 5 of the present invention 4 SEM image of the/C composite;
FIG. 7 shows Mn and Ti doped LiFePO prepared in example 2 of the present invention 4 Charge-discharge curve graph of lithium ion battery assembled by composite material;
FIG. 8 shows Mn-Ti doped LiFePO prepared in example 5 of the invention 4 Charge-discharge curve graph of lithium ion battery assembled by composite material.
Detailed Description
The invention provides a preparation method of a manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material, which comprises the following steps:
(1) Mixing titanium white byproduct ferrous sulfate with water and a reducing agent for reduction reaction to obtain a reducing solution;
(2) Mixing the reducing solution obtained in the step (1) with alkali, and carrying out hydrolysis reaction to obtain a hydrolysis product;
(3) Mixing the hydrolysate obtained in the step (2) with a flocculant, and performing flocculation reaction to obtain a refined ferrous sulfate solution; the mass content of manganese in the refined ferrous sulfate solution is 0.05-0.5%, and the mass content of titanium in the refined ferrous sulfate solution is 0.04-0.38%;
(4) Mixing the refined ferrous sulfate solution obtained in the step (3) with phosphoric acid and alkali, and carrying out precipitation reaction to obtain an intermediate product;
(5) Mixing the intermediate product obtained in the step (4) with an oxidant and an acid, and carrying out an oxidation reaction to obtain a precursor;
(6) And (3) mixing the precursor obtained in the step (5) with a lithium source and a carbon source, and calcining to obtain the manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material.
The source of each raw material is not particularly limited unless specifically stated, and commercially available products known to those skilled in the art may be used.
The invention mixes the titanium white byproduct ferrous sulfate with water and a reducing agent for reduction reaction to obtain a reducing solution. In the invention, the reduction reaction is started after the mixing of the titanium white byproduct ferrous sulfate, water and the reducing agent is completed, and ferric iron ions in the titanium white byproduct ferrous sulfate and the reducing agent react to generate ferrous ions in the reduction reaction process.
The source of the byproduct ferrous sulfate of titanium white is not particularly limited, and the byproduct ferrous sulfate obtained in the production process of titanium white by a sulfuric acid method well known to those skilled in the art can be adopted.
In each embodiment of the invention, the mass content of each element in the titanium white byproduct ferrous sulfate is as follows: 88.5% Fe, 1.8% Mg, 4.2% Mn, 0.8% Al, 0.6% Ca, 0.9% Zn, 1.8% Ti, 0.5% Na, 0.3% Cr, 0.3% Cu and 0.3% Ni.
In the invention, the mixing of the titanium white byproduct ferrous sulfate, water and a reducing agent is preferably as follows: firstly mixing titanium white byproduct ferrous sulfate with water to obtain a mixed solution, and then adding a reducing agent.
In the present invention, the concentration of the mixed solution obtained by mixing the titanium white byproduct ferrous sulfate and water is preferably 1 to 5mol/L, more preferably 2 to 4mol/L. The concentration of the mixed solution obtained by mixing the titanium white byproduct ferrous sulfate and water is limited in the range, so that the titanium white byproduct ferrous sulfate can be more fully dissolved.
In the present invention, the reducing agent is preferably iron powder. In the invention, the mass ratio of the reducing agent to the titanium white byproduct ferrous sulfate is preferably (0.5-2): 100, more preferably (1 to 1.5): 100. in the invention, the reducing agent is used for reducing ferric iron in the byproduct ferrous sulfate of titanium white. The invention limits the mass ratio of the reducing agent and the titanium white byproduct ferrous sulfate within the above range, so that ferric iron can be reduced more fully.
In the present invention, the temperature of the reduction reaction is preferably 20 to 40 ℃, more preferably 20 to 30 ℃; the time of the reduction reaction is preferably 0.1 to 1 hour, more preferably 0.5 hour. The invention limits the temperature and time of the reduction reaction within the above ranges, so that the trivalent iron can be reduced more fully.
After the reducing solution is obtained, the reducing solution is mixed with alkali to carry out hydrolysis reaction, so that a hydrolysis product is obtained.
In the present invention, the base is preferably aqueous ammonia. In the present invention, the pH of the mixed solution of the reducing solution and the base is preferably 2 to 4, more preferably 3. The concentration and the dosage of the ammonia water are not particularly limited, and the pH value of the mixed solution obtained by mixing the reducing solution and the alkali can be ensured to be within the range.
In the present invention, the temperature of the hydrolysis reaction is preferably 40 to 70 ℃, more preferably 50 to 60 ℃; the hydrolysis reaction time is preferably 1 to 4 hours, more preferably 2 to 3 hours. In the invention, in the hydrolysis reaction process, part of titanium in the byproduct ferrous sulfate is hydrolyzed to generate precipitate. The invention limits the pH value, the hydrolysis temperature and the time of the mixed solution in the above ranges, can adjust the hydrolysis degree of titanium and ensures the titanium content in the follow-up refined ferrous sulfate.
After the hydrolysate is obtained, the hydrolysate is mixed with a flocculating agent to perform flocculation reaction to obtain a refined ferrous sulfate solution.
In the present invention, the flocculant preferably comprises polyacrylamide, sodium polyvinyl acid or polyethyleneimine.
In the invention, the mass ratio of the flocculant to the titanium white byproduct ferrous sulfate is preferably (0.02-0.15): 100, more preferably (0.05 to 0.1): 100. in the present invention, the flocculant is used for removing impurities such as precipitation and Na, zn, al, cu, ca, cr, mg generated after Ti hydrolysis.
In the present invention, the flocculation reaction time is preferably 3 to 10 minutes. The invention limits the dosage of the flocculant and the flocculation reaction time within the above ranges, can completely remove impurities in the titanium white byproduct ferrous sulfate, and ensures that the manganese and titanium contents in the refined ferrous sulfate solution are within a certain range.
After the flocculation reaction is completed, the invention preferably filters the product of the flocculation reaction to obtain a refined ferrous sulfate solution.
The filtering operation is not particularly limited in the present invention, and filtering techniques well known to those skilled in the art may be employed.
In the invention, the mass content of manganese in the refined ferrous sulfate solution is 0.05-0.5%, preferably 0.1-0.4%; the mass content of titanium in the refined ferrous sulfate solution is 0.04-0.38%, preferably 0.1-0.3%. The invention limits the mass content of manganese and titanium in the refined ferrous sulfate solution within the above range, can adjust the doping content of manganese and titanium in the prepared composite material, and forms solid solution after manganese doping, the unit cell volume and the ion diffusion channel are increased, the lithium ion diffusion rate is improved, the multiplying power performance is improved, but the manganese content is excessively oxidized to form Mn 3+ Dissolved in the electrolyte solution, resulting in a decrease in lithium intercalation capacity; titanium doping is beneficial to improving conductivity, and enables lithium iron phosphate to trend to be nano, so that an ion diffusion path is shortened, the multiplying power performance of the material is improved, but excessive Ti can lead to deformation of a unit cell, block a lithium ion transmission channel and reduce a diffusion coefficient.
When the content of manganese and titanium in the purified ferrous sulfate solution is below the above range, the present invention preferably supplements the manganese source and the titanium source. In the present invention, the manganese source is preferably manganese oxalate; the titanium source is preferably titanium dioxide. The invention has no special limitation on the amount of the manganese source and the titanium source which are added in a supplementing way, and ensures that the content of manganese and titanium in the refined ferrous sulfate solution is within the range.
After the refined ferrous sulfate solution is obtained, the refined ferrous sulfate solution is mixed with phosphoric acid and alkali to carry out precipitation reaction, so as to obtain an intermediate product.
In the present invention, the phosphoric acid is preferably phosphoric acid having a mass concentration of 85%. In the present invention, the ratio of the amounts of the substances of ferrous ions in the phosphoric acid and the purified ferrous sulfate solution is preferably (1 to 1.2): 1, more preferably (1.1 to 1.2): 1. in the present invention, the phosphoric acid and ferrous sulfate react to form ferrous phosphate. The invention limits the ratio of the amount of the substance of ferrous ions in the phosphoric acid and the refined ferrous sulfate solution within the above range, so that the ferrous ions in the ferrous phosphate can be completely reacted.
In the present invention, the base preferably includes ammonia, sodium hydroxide or potassium hydroxide.
In the present invention, the pH of the system after addition of the base is preferably 5.8 to 6.8, more preferably 6.0 to 6.6. The invention has no special limit to the addition amount of the alkali, and ensures that the pH value of the system after the alkali is added is within the range. The pH value of the system after adding alkali is limited in the range, which is favorable for the complete precipitation of ferrous ions to generate ferrous phosphate and prevents the ferrous ions from hydrolyzing to generate Fe (OH) 2 Precipitation, even Fe (OH) 3 。
In the present invention, the time of the precipitation reaction is preferably 0.5 to 2 hours, more preferably 1 to 1.5 hours. The invention limits the time of precipitation reaction within the above range, and can lead ferrous ions to be completely precipitated.
After the precipitation reaction is completed, the product of the precipitation reaction is preferably filtered, washed and dried in sequence to obtain an intermediate product.
The operation of the filtration, washing and drying is not particularly limited in the present invention, and the filtration, washing and drying techniques well known to those skilled in the art may be adopted.
In the invention, the intermediate product is Mn, tiIn-situ doped Fe 3 (PO 4 ) 2 ·8H 2 O。
After the intermediate product is obtained, the intermediate product is mixed with an oxidant and acid to perform oxidation reaction, so that a precursor is obtained.
In the present invention, the oxidizing agent preferably includes hydrogen peroxide or sodium peroxide. In the present invention, the ratio of the amount of the oxidizing agent to the amount of the iron in the intermediate product is preferably (1.2 to 2.5): 1, more preferably (1.5 to 2): 1. in the present invention, the oxidizing agent is used to oxidize the intermediate product ferrous phosphate to ferric phosphate. The invention limits the amount of the oxidizing agent to the above range, and can enable the intermediate product to be oxidized more completely.
In the present invention, the acid is preferably phosphoric acid.
In the present invention, the pH of the system after the addition of the acid is preferably 1.2 to 1.8, more preferably 1.3 to 1.6. The invention has no special limitation on the addition amount of the acid, and ensures that the pH value of the system after the acid is added is within the range. The invention limits the pH value of the system after adding acid to the above range, so that the oxidation reaction can be more fully carried out.
In the present invention, the temperature of the oxidation reaction is preferably 60 to 80 ℃, more preferably 70 ℃; the time of the oxidation reaction is preferably 0.25 to 2 hours, more preferably 0.5 to 1.5 hours. The present invention can sufficiently proceed the oxidation reaction by limiting the temperature and time of the oxidation reaction to the above-described ranges.
After the oxidation reaction is completed, the method is preferred to sequentially filter, wash and dry the products of the oxidation reaction to obtain the precursor.
The operation of the filtration, washing and drying is not particularly limited in the present invention, and the filtration, washing and drying techniques well known to those skilled in the art may be adopted.
In the invention, the precursor is manganese and titanium in-situ doped nanoscale FePO 4 ·2H 2 O。
After the precursor is obtained, the precursor is mixed with a lithium source and a carbon source and then calcined, so that the manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material is obtained.
In the present invention, the lithium source preferably includes lithium carbonate, lithium bicarbonate, or lithium oxalate.
In the present invention, the ratio of the amount of lithium in the lithium source to the amount of iron in the precursor is preferably (1.02 to 1.1): 1. the invention limits the ratio of lithium in the lithium source to the amount of iron in the precursor within the above range, and can ensure the precursor to react more fully.
In the present invention, the carbon source preferably includes polyethylene glycol 20000, glucose, or β -cyclodextrin.
In the present invention, the mass ratio of the carbon source to the precursor is preferably (7 to 9.5): 100, more preferably (7.5 to 9): 100. the invention limits the mass ratio of the carbon source and the precursor in the above range, can regulate and control the carbon content in the composite material, improves the conductivity of the composite material, and further improves the electrochemical performance of the composite material.
In the present invention, the temperature of the calcination is preferably 550 to 750 ℃, more preferably 600 to 700 ℃; the calcination time is preferably 8 to 12 hours, more preferably 9 to 11 hours. The invention limits the calcination temperature and time to the above range, and can enable the lithium source and the precursor to fully react to form lithium iron phosphate and the carbon source to fully react to form the carbon material.
After the calcination is completed, the calcined product is preferably cooled to obtain the manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material.
The cooling operation is not particularly limited in the present invention, and cooling techniques well known to those skilled in the art may be employed.
According to the invention, the reducing agent is added to reduce ferric iron, the alkali is added to hydrolyze titanium, the flocculant is added to remove a certain amount of Ti and other impurities to obtain refined ferrous sulfate with a certain manganese and titanium content, then the phosphoric acid and the alkali are added to obtain ferric phosphate, finally the ferric phosphate is mixed with the lithium source and the carbon source and then calcined to obtain the manganese and titanium in-situ doped carbon-containing ferric lithium phosphate composite material, the impurities in the titanium white byproduct ferrous sulfate are not required to be completely removed, and the doping elements are not required to be additionally added after the ferric phosphate is obtained.
The flow chart of the preparation method of the manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material is preferably shown in figure 1, and the titanium white byproduct ferrous sulfate is subjected to Fe 3+ Ion reduction, selective impurity removal under controlled conditions, in-situ Mn/Ti doping ferrous phosphate octahydrate precipitation, nano ferric phosphate dihydrate oxidation precipitation, and finally lithium salt and carbon source addition to obtain in-situ doped lithium iron phosphate anode material.
The invention provides the manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material prepared by the preparation method.
The manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material prepared by the invention has excellent electrochemical performance.
The invention also provides application of the manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material as a lithium ion battery anode material.
The application operation of the manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material as the positive electrode material of the lithium ion battery is not particularly limited, and the technical scheme of the application of the manganese and titanium doped carbon-containing lithium iron phosphate composite material as the positive electrode material of the lithium ion battery, which is well known to the person skilled in the art, is adopted.
The lithium ion battery assembled by taking the manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material as the positive electrode material has higher discharge capacity.
The technical solutions of the present invention will be clearly and completely described in the following in connection with the embodiments of the present invention. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
(1) Mixing titanium white byproduct ferrous sulfate with water to obtain ferrous sulfate solution with the concentration of 3mol/L, adding iron powder as a reducing agent (the mass ratio of the iron powder to the byproduct ferrous sulfate is 0.5:100), and reacting for 0.5h to realize complete reduction of ferric iron; adding ammonia water until the pH value is 3.0, controlling the temperature to 65 ℃, and keeping the temperature for 2 hours to hydrolyze part of titanium ions to generate precipitate; adding polyacrylamide (the mass ratio of the polyacrylamide to the byproduct ferrous sulfate is 0.05:100), removing Na, zn, al, cu, ca, cr, mg and other impurity elements by adsorption coprecipitation, and filtering impurities to obtain a refined ferrous sulfate solution with a certain amount of Mn and Ti ions, wherein the mass content of Mn is 0.15%, and the mass content of Ti is 0.24%;
(2) Adding phosphoric acid and ammonia water into the refined ferrous sulfate solution obtained in the step (1), wherein the ratio of the phosphoric acid to the Fe substance in the ferrous sulfate is 1:1, the pH value of a system after adding the ammonia water is 6.5, the reaction time is 1h, and the obtained precipitate is washed and dried to obtain Mn and Ti in-situ doped Fe 3 (PO 4 ) 2 ·8H 2 O；
(3) Fe obtained in the step (2) 3 (PO 4 ) 2 ·8H 2 Adding hydrogen peroxide to O, wherein the hydrogen peroxide and Fe 3 (PO 4 ) 2 ·8H 2 The ratio of the amount of Fe in O is 1.2:1; controlling the pH value to be 1.5 by adding phosphoric acid, reacting for 1h at 80 ℃, washing and drying the white precipitate to obtain the nano FePO 4 ·2H 2 O；
(4) In-situ doping FePO obtained in the step (3) 4 ·2H 2 O is used as a raw material and is mixed with lithium carbonate and glucose according to a proportion, wherein Li: the amount of Fe material was 1.07:1, glucose and FePO 4 ·2H 2 The mass ratio of O is 8.88:100, calcining at 700 ℃ for 10 hours, and cooling to obtain Mn and Ti in-situ doped LiFePO 4 and/C composite material.
FePO prepared in example 1 4 ·2H 2 XRD pattern of OAs shown in fig. 2, it can be seen from fig. 2 that FePO 4 ·2H 2 O is a typical monoclinic phase. FePO prepared in example 1 4 ·2H 2 The SEM image of O is shown in FIG. 3, and it can be seen from FIG. 3 that FePO 4 ·2H 2 The particle size of O is about 50nm.
Mn, ti in-situ doped LiFePO prepared in example 1 4 The carbon content of the composite/C material was 1.36% and the electrical conductivity was 2.63E -3 Scm -1 Specific surface area of 7.31m 2 g -1 。
Example 2
(1) Mixing titanium white byproduct ferrous sulfate with water to obtain ferrous sulfate solution with the concentration of 3mol/L, adding iron powder as a reducing agent (the mass ratio of the iron powder to the byproduct ferrous sulfate is 1:100), and reacting for 0.5h to realize complete reduction of ferric iron; adding ammonia water until the pH value is 3.5, controlling the temperature at 50 ℃ and keeping the temperature for 1h to hydrolyze part of titanium ions to generate precipitate; adding polyacrylamide (the mass ratio of the polyacrylamide to the byproduct ferrous sulfate is 0.03:100), removing Na, zn, al, cu, ca, cr, mg and other impurity elements by adsorption coprecipitation, and filtering impurities to obtain a refined ferrous sulfate solution with a certain amount of Mn and Ti ions, wherein the mass content of Mn is 0.28%, and the mass content of Ti is 0.35%;
(2) Adding phosphoric acid and ammonia water into the refined ferrous sulfate solution obtained in the step (1), wherein the ratio of the phosphoric acid to the Fe substance in the ferrous sulfate is 1:1, the pH value of a system after adding the ammonia water is 6.5, the reaction time is 1h, and the obtained precipitate is washed and dried to obtain Mn and Ti in-situ doped Fe 3 (PO 4 ) 2 ·8H 2 O；
(3) Fe obtained in the step (2) 3 (PO 4 ) 2 ·8H 2 Adding hydrogen peroxide to O, wherein the hydrogen peroxide and Fe 3 (PO 4 ) 2 ·8H 2 The ratio of the amount of Fe in O is 1.2:1; controlling the pH value to be 1.5 by adding phosphoric acid, reacting for 1h at 80 ℃, washing and drying the white precipitate to obtain the nano FePO 4 ·2H 2 O；
(4) In-situ doping FePO obtained in the step (3) 4 ·2H 2 O is used as a raw material and is mixed with lithium carbonate and glucose according to a proportion, wherein Li: the amount of Fe material was 1.07:1, glucose and FePO 4 ·2H 2 The mass ratio of O is 8.88:100, calcining at 700 ℃ for 10 hours, and cooling to obtain Mn and Ti in-situ doped LiFePO 4 and/C composite material.
Mn, ti in-situ doped LiFePO prepared in example 2 4 As can be seen from FIG. 4, the XRD patterns of the composite material are shown in FIG. 4, and the doping of Mn and Ti does not change LiFePO 4 And orthorhombic Pnma space group LiFePO 4 In agreement (JCDF 83-2092). Mn, ti in-situ doped LiFePO prepared in example 2 4 The SEM image of the/C composite material is shown in FIG. 5, and it can be seen from FIG. 5 that Mn and Ti are doped with LiFePO in situ 4 The composite material/C consists of micron-sized spherical particles, wherein the spherical particles are formed by aggregating small particles about 200 nm.
Mn, ti in-situ doped LiFePO prepared in example 2 4 The carbon content of the composite/C material was 1.35% and the electrical conductivity was 8.77E -3 Scm -1 Specific surface area of 8.47m 2 g -1 。
Example 3
(1) Mixing titanium white byproduct ferrous sulfate with water to obtain ferrous sulfate solution with the concentration of 3mol/L, adding iron powder as a reducing agent (the mass ratio of the iron powder to the byproduct ferrous sulfate is 1:100), and reacting for 0.5h to realize complete reduction of ferric iron; adding ammonia water until the pH value is 3.0, controlling the temperature at 55 ℃ and keeping the temperature for 4 hours to hydrolyze part of titanium ions to generate precipitate; adding polyacrylamide (the mass ratio of the polyacrylamide to the byproduct ferrous sulfate is 0.1:100), removing Na, zn, al, cu, ca, cr, mg and other impurity elements by adsorption coprecipitation, and filtering impurities to obtain a refined ferrous sulfate solution with a certain amount of Mn and Ti ions, wherein the mass content of Mn is 0.08%, and the mass content of Ti is 0.27%;
(2) Adding phosphoric acid and ammonia water into the refined ferrous sulfate solution obtained in the step (1), wherein the ratio of the phosphoric acid to the Fe substance in the ferrous sulfate is 1.1:1, the pH value of a system after adding the ammonia water is 6.2, the reaction time is 1h, and washing the obtained precipitateDrying to obtain Mn and Ti in-situ doped Fe 3 (PO 4 ) 2 ·8H 2 O；
(3) Fe obtained in the step (2) 3 (PO 4 ) 2 ·8H 2 Adding hydrogen peroxide to O, wherein the hydrogen peroxide and Fe 3 (PO 4 ) 2 ·8H 2 The ratio of the amount of Fe in O is 1.2:1; controlling the pH value to be 1.5 by adding phosphoric acid, reacting for 1h at 80 ℃, washing and drying the white precipitate to obtain the nano FePO 4 ·2H 2 O；
(4) In-situ doping FePO obtained in the step (3) 4 ·2H 2 O is used as a raw material and is mixed with lithium carbonate and glucose according to a proportion, wherein Li: the amount of Fe material was 1.07:1, glucose and FePO 4 ·2H 2 The mass ratio of O is 8.88:100, calcining at 700 ℃ for 10 hours, and cooling to obtain Mn and Ti in-situ doped LiFePO 4 and/C composite material.
Mn, ti in-situ doped LiFePO prepared in example 3 4 The carbon content of the composite positive electrode material/C is 1.4%, and the conductivity is 3.5E -3 Scm -1 Specific surface area of 7.44m 2 g -1 。
Example 4
(1) Mixing titanium white byproduct ferrous sulfate with water to obtain ferrous sulfate solution with the concentration of 3mol/L, adding iron powder as a reducing agent (the mass ratio of the iron powder to the byproduct ferrous sulfate is 1.5:100), and reacting for 0.5h to realize complete reduction of ferric iron; adding ammonia water until the pH value is 3.0, controlling the temperature at 55 ℃ and keeping the temperature for 2 hours to hydrolyze part of titanium ions to generate precipitate; adding polyacrylamide (the mass ratio of the polyacrylamide to the byproduct ferrous sulfate is 0.1:100), removing Na, zn, al, cu, ca, cr, mg and other impurity elements by adsorption coprecipitation, and filtering impurities to obtain a refined ferrous sulfate solution with a certain amount of Mn and Ti ions, wherein the mass content of Mn is 0.07%, and the mass content of Ti is 0.29%;
(2) Adding phosphoric acid and ammonia water into the refined ferrous sulfate solution obtained in the step (1), wherein the ratio of the phosphoric acid to the Fe substance in the ferrous sulfate is 1:1, and the pH value of the system after adding the ammonia water is 6.2The reaction time is 1h, and Mn and Ti in-situ doped Fe is obtained after washing and drying the obtained precipitate 3 (PO 4 ) 2 ·8H 2 O；
(3) Fe obtained in the step (2) 3 (PO 4 ) 2 ·8H 2 Adding hydrogen peroxide to O, wherein the hydrogen peroxide and Fe 3 (PO 4 ) 2 ·8H 2 The ratio of the amount of Fe in O is 1.6:1; controlling pH at 1.5 by adding phosphoric acid, reacting at 80deg.C for 1.5 hr, washing and drying to obtain nanometer FePO 4 ·2H 2 O；
(4) In-situ doping FePO obtained in the step (3) 4 ·2H 2 O is used as a raw material and is mixed with lithium carbonate and glucose according to a proportion, wherein Li: the amount of Fe material was 1.07:1, glucose and FePO 4 ·2H 2 The mass ratio of O is 8.88:100, calcining at 600 ℃ for 10 hours, and cooling to obtain Mn and Ti in-situ doped LiFePO 4 and/C composite material.
Mn, ti in-situ doped LiFePO prepared in example 4 4 The carbon content of the product of the composite positive electrode material is 1.31 percent, and the conductivity is 6.56E -4 Scm -1 Specific surface area of 6.86m 2 g -1 。
Example 5
(1) Mixing titanium white byproduct ferrous sulfate with water to obtain ferrous sulfate solution with the concentration of 3mol/L, adding iron powder as a reducing agent (the mass ratio of the iron powder to the byproduct ferrous sulfate is 1:100), and reacting for 0.5h to realize complete reduction of ferric iron; adding ammonia water until the pH value is 3.0, controlling the temperature at 50 ℃ and keeping the temperature for 1h to hydrolyze part of titanium ions to generate precipitate; adding polyacrylamide (the mass ratio of the polyacrylamide to the byproduct ferrous sulfate is 0.03:100), removing Na, zn, al, cu, ca, cr, mg and other impurity elements by adsorption coprecipitation, and filtering impurities to obtain a refined ferrous sulfate solution with a certain amount of Mn and Ti ions, wherein the mass content of Mn is 0.3%, and the mass content of Ti is 0.38%;
(2) Adding phosphoric acid and ammonia water into the refined ferrous sulfate solution obtained in the step (1), wherein the amounts of substances of Fe in the phosphoric acid and the ferrous sulfateThe ratio of the solution to the solution is 1:1, the pH value of the system is 6.5 after ammonia water is added, the reaction time is 1h, and Mn and Ti in-situ doped Fe is obtained after washing and drying the obtained precipitate 3 (PO 4 ) 2 ·8H 2 O；
(3) Fe obtained in the step (2) 3 (PO 4 ) 2 ·8H 2 Adding hydrogen peroxide to O, wherein the hydrogen peroxide and Fe 3 (PO 4 ) 2 ·8H 2 The ratio of the amount of Fe in O is 1.2:1; controlling the pH value to be 1.5 by adding phosphoric acid, reacting for 1h at 80 ℃, washing and drying the white precipitate to obtain the nano FePO 4 ·2H 2 O；
(4) In-situ doping FePO obtained in the step (3) 4 ·2H 2 Mixing the raw materials of O with lithium carbonate and polyethylene glycol PEG20000 according to a proportion, wherein Li: the amount of Fe material was 1.07:1, polyethylene glycol PEG20000 and FePO 4 ·2H 2 The mass ratio of O is 8.07:100, calcining at 700 ℃ for 10 hours, and cooling to obtain Mn and Ti in-situ doped LiFePO 4 and/C composite material.
Mn, ti in-situ doped LiFePO prepared in example 5 4 SEM of the/C composite material as shown in FIG. 6, the carbon content of the product was 1.11%, and the conductivity was 1.56E -4 Scm -1 Specific surface area of 14.33m 2 g -1 。
Application example
Mn, ti in situ co-doped LiFePO prepared in example 2 and example 5, respectively 4 the/C composite material is positive electrode, lithium metal is negative electrode, and 1MLiPF dissolved in EC (ethylene carbonate)/DMC (dimethyl carbonate)/EMC (ethyl methyl carbonate) (volume ratio 1/1/1) solvent 6 And the electrolyte is packaged in a button cell in a glove box, and is subjected to constant-current constant-voltage charge-constant-current discharge test under the multiplying power of 0.1C, and the voltage range is 2.0-3.75V. Mn, ti in-situ co-doped LiFePO prepared in example 2 and example 5 4 The charge-discharge curves of the/C composite are shown in fig. 7 and 8, respectively. Wherein Mn and Ti prepared in example 2 were co-doped with LiFePO in situ 4 Discharge capacity of 149.6 mAhg/C -1 The 3.3V platform capacity is 132.7mAhg -1 The plateau proportion is 88.7%. Real worldMn and Ti in-situ co-doped LiFePO prepared in example 5 4 Discharge capacity per C was 145.2mAhg -1 The 3.3V platform capacity is 124.1mAhg -1 The plateau proportion is 85.5%.
In conclusion, the button cell assembled by the composite material prepared by the invention has excellent electrochemical performance.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. The preparation method of the manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material comprises the following steps:
(1) Mixing titanium white byproduct ferrous sulfate with water and a reducing agent for reduction reaction to obtain a reducing solution;
(2) Mixing the reducing solution obtained in the step (1) with alkali, and carrying out hydrolysis reaction to obtain a hydrolysis product;
(3) Mixing the hydrolysate obtained in the step (2) with a flocculant, and performing flocculation reaction to obtain a refined ferrous sulfate solution; the mass content of manganese in the refined ferrous sulfate solution is 0.05-0.5%, and the mass content of titanium in the refined ferrous sulfate solution is 0.04-0.38%;
(4) Mixing the refined ferrous sulfate solution obtained in the step (3) with phosphoric acid and alkali, and carrying out precipitation reaction to obtain an intermediate product;
(5) Mixing the intermediate product obtained in the step (4) with an oxidant and an acid, and carrying out an oxidation reaction to obtain a precursor;
(6) And (3) mixing the precursor obtained in the step (5) with a lithium source and a carbon source, and calcining to obtain the manganese and titanium in-situ doped carbon-containing lithium iron phosphate composite material.
2. The method according to claim 1, wherein the mass ratio of the reducing agent to the titanium white byproduct ferrous sulfate in the step (1) is (0.5-2): 100.
3. the method according to claim 1, wherein the hydrolysis reaction in the step (2) is carried out at a temperature of 40 to 70 ℃ for a time of 1 to 4 hours.
4. The method according to claim 1, wherein the ratio of the amounts of the substances of ferrous ions in the phosphoric acid and the purified ferrous sulfate solution in the step (4) is (1 to 1.2): 1.
5. the method according to claim 1, wherein the time for the precipitation reaction in the step (4) is 0.5 to 2 hours.
6. The method according to claim 1, wherein the ratio of the amount of the oxidizing agent in the step (5) to the amount of the iron in the intermediate product is (1.2 to 2.5): 1.
7. the method according to claim 1, wherein the mass ratio of the carbon source to the precursor in the step (6) is (7 to 9.5): 100.
8. the method of claim 1, wherein the ratio of the amount of lithium in the lithium source to the amount of iron in the precursor in step (6) is (1.02-1.1): 1.
9. the manganese-titanium in-situ doped carbon-containing lithium iron phosphate composite material prepared by the preparation method of any one of claims 1 to 8.
10. The use of the manganese-titanium in-situ doped carbonaceous lithium iron phosphate composite material as a positive electrode material of a lithium ion battery according to claim 9.
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