CN113991117A - Preparation method of lithium iron phosphate composite material - Google Patents
Preparation method of lithium iron phosphate composite material Download PDFInfo
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- CN113991117A CN113991117A CN202111264644.8A CN202111264644A CN113991117A CN 113991117 A CN113991117 A CN 113991117A CN 202111264644 A CN202111264644 A CN 202111264644A CN 113991117 A CN113991117 A CN 113991117A
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- iron phosphate
- lithium iron
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- 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 74
- 239000002131 composite material Substances 0.000 title claims abstract description 57
- 238000002360 preparation method Methods 0.000 title claims abstract description 31
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 52
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 42
- 239000002994 raw material Substances 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 16
- 239000000463 material Substances 0.000 claims description 80
- 238000000498 ball milling Methods 0.000 claims description 71
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 50
- 238000001035 drying Methods 0.000 claims description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 35
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 34
- ATEAWHILRRXHPW-UHFFFAOYSA-J iron(2+);phosphonato phosphate Chemical compound [Fe+2].[Fe+2].[O-]P([O-])(=O)OP([O-])([O-])=O ATEAWHILRRXHPW-UHFFFAOYSA-J 0.000 claims description 34
- 238000002156 mixing Methods 0.000 claims description 34
- 239000002002 slurry Substances 0.000 claims description 34
- 229910052742 iron Inorganic materials 0.000 claims description 24
- 229910052751 metal Inorganic materials 0.000 claims description 24
- 239000002184 metal Substances 0.000 claims description 24
- 229910052698 phosphorus Inorganic materials 0.000 claims description 23
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 22
- 239000011574 phosphorus Substances 0.000 claims description 22
- 239000004576 sand Substances 0.000 claims description 22
- 238000005245 sintering Methods 0.000 claims description 22
- 239000002245 particle Substances 0.000 claims description 19
- 239000002243 precursor Substances 0.000 claims description 19
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 18
- 238000001694 spray drying Methods 0.000 claims description 18
- 229910052757 nitrogen Inorganic materials 0.000 claims description 17
- 238000001816 cooling Methods 0.000 claims description 16
- 239000011248 coating agent Substances 0.000 claims description 14
- 238000000576 coating method Methods 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 9
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 8
- 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 claims description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000004743 Polypropylene Substances 0.000 claims description 4
- 229920002472 Starch Polymers 0.000 claims description 4
- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical compound O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 claims description 4
- 239000008103 glucose Substances 0.000 claims description 4
- 229910021389 graphene Inorganic materials 0.000 claims description 4
- 238000003801 milling Methods 0.000 claims description 4
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 4
- -1 polypropylene Polymers 0.000 claims description 4
- 229920001155 polypropylene Polymers 0.000 claims description 4
- 239000008107 starch Substances 0.000 claims description 4
- 235000019698 starch Nutrition 0.000 claims description 4
- 238000000227 grinding Methods 0.000 claims description 3
- FSJSYDFBTIVUFD-SUKNRPLKSA-N (z)-4-hydroxypent-3-en-2-one;oxovanadium Chemical compound [V]=O.C\C(O)=C\C(C)=O.C\C(O)=C\C(C)=O FSJSYDFBTIVUFD-SUKNRPLKSA-N 0.000 claims description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 2
- 150000001413 amino acids Chemical class 0.000 claims description 2
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 2
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 2
- UNTBPXHCXVWYOI-UHFFFAOYSA-O azanium;oxido(dioxo)vanadium Chemical compound [NH4+].[O-][V](=O)=O UNTBPXHCXVWYOI-UHFFFAOYSA-O 0.000 claims description 2
- 239000004202 carbamide Substances 0.000 claims description 2
- 229940117975 chromium trioxide Drugs 0.000 claims description 2
- WGLPBDUCMAPZCE-UHFFFAOYSA-N chromium trioxide Inorganic materials O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims description 2
- 229940062993 ferrous oxalate Drugs 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 229910000398 iron phosphate Inorganic materials 0.000 claims description 2
- OWZIYWAUNZMLRT-UHFFFAOYSA-L iron(2+);oxalate Chemical compound [Fe+2].[O-]C(=O)C([O-])=O OWZIYWAUNZMLRT-UHFFFAOYSA-L 0.000 claims description 2
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims description 2
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 2
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 2
- SNKMVYBWZDHJHE-UHFFFAOYSA-M lithium;dihydrogen phosphate Chemical compound [Li+].OP(O)([O-])=O SNKMVYBWZDHJHE-UHFFFAOYSA-M 0.000 claims description 2
- 239000000347 magnesium hydroxide Substances 0.000 claims description 2
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 2
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 2
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 2
- 229910001930 tungsten oxide Inorganic materials 0.000 claims description 2
- 238000005303 weighing Methods 0.000 claims description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 claims 1
- 229910001936 tantalum oxide Inorganic materials 0.000 claims 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 4
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 4
- 239000010405 anode material Substances 0.000 abstract description 2
- 230000000694 effects Effects 0.000 abstract description 2
- 238000011031 large-scale manufacturing process Methods 0.000 abstract description 2
- 238000010438 heat treatment Methods 0.000 description 33
- 239000006256 anode slurry Substances 0.000 description 14
- 238000001223 reverse osmosis Methods 0.000 description 14
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 9
- 229910052744 lithium Inorganic materials 0.000 description 9
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 8
- 239000002033 PVDF binder Substances 0.000 description 7
- 239000006230 acetylene black Substances 0.000 description 7
- 229910052782 aluminium Inorganic materials 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 238000000835 electrochemical detection Methods 0.000 description 7
- 239000011888 foil Substances 0.000 description 7
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 7
- 229910052493 LiFePO4 Inorganic materials 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 4
- 229910021529 ammonia Inorganic materials 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000011651 chromium Substances 0.000 description 4
- 238000007599 discharging Methods 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 229910052721 tungsten Inorganic materials 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- 229910020056 Mg3N2 Inorganic materials 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 2
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- GAMDZJFZMJECOS-UHFFFAOYSA-N chromium(6+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Cr+6] GAMDZJFZMJECOS-UHFFFAOYSA-N 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000012983 electrochemical energy storage Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 229920000447 polyanionic polymer Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
Images
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
-
- 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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
-
- 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
Abstract
The invention relates to the field of lithium ion battery anode materials, and discloses a preparation method of a lithium iron phosphate composite material. The invention has the following advantages and effects: the lithium iron phosphate composite material prepared by the invention has excellent conductivity, tap density and electrochemical performance, and is low in carbon content, common and easily available in used raw materials, low in price, simple in process, suitable for large-scale production, high in raw material utilization rate, small in emission, environment-friendly, low in pollution and low in cost, and has a better application prospect.
Description
Technical Field
The invention relates to the technical field of lithium ion battery anode materials, in particular to a preparation method of a lithium iron phosphate composite material.
Background
The lithium ion battery is one of electrochemical energy storage batteries, has the advantages of high energy density, good cycle performance, no memory effect, low self-discharge rate and good environmental compatibility, is rapidly developed in the field of various consumer electronics products, and has strong potential in the fields of electric tools, electric automobiles and power generation and energy storage. In a series of novel compounds comprising a polyanion (XO)4 2-X ═ S, P, Si, As, Mo, W), the most prominent is lithium iron phosphate, which satisfies many key conditions As a positive electrode material for lithium batteries: the lithium ion battery can reversibly release and embed lithium at a higher voltage (3.5V), has a relatively higher gravimetric specific capacity of 170mAh/g, and can keep stable structure when the material is overcharged and overdischarged, and is compatible with most electrolyte systems. In addition, the lithium iron phosphate exists in nature as the Lilantibite, so that the lithium iron phosphate is environment-friendly, and the raw materials are rich and cheap.
Metal-carbon coating is a method for effectively improving the conductivity and electrochemical properties of lithium iron phosphate. In the preparation process of the lithium iron phosphate, the existence of metal and carbon or carbon-containing organic matters has the following functions: (1) reducing ferric iron into ferrous iron as a reducing agent or inhibiting oxidation of the ferrous iron, (2) preventing mutual contact among particles and hindering growth of the particles at high temperature, (3) improving conductivity of the material, (4) improving tap density and compaction density of the material, (5) reducing dissolution of a lithium iron phosphate positive electrode in an electrolyte, and not reducing the tap density of the material, but reducing electrochemical specific capacity of the lithium iron phosphate material by metal carbide and reducing energy density of a battery.
Disclosure of Invention
The invention aims to provide a preparation method of a lithium iron phosphate composite material, which has the effects of improving the conductivity, reducing the carbon content, improving the metal content and balancing the tap density and the electrochemical specific capacity of a lithium iron phosphate material.
The technical purpose of the invention is realized by the following technical scheme: a preparation method of a lithium iron phosphate composite material comprises the following steps:
preparing materials, namely weighing an iron source, a phosphorus source and an organic carbon source I, wherein the molar ratio of iron to phosphorus is 0.95-1:1, and the molar ratio of iron to carbon is 1: 0.1;
ball milling: taking the raw materials in the step (1), sequentially adding the raw materials into a ball mill for ball milling, adding a ball milling medium into the ball mill, and controlling ball milling: d50 of 0.5-2 μm, DmaxLess than 10 mu m to obtain ball milling slurry;
step (3), drying the double cones: taking the ball-milling slurry obtained in the step (2) to perform bipyramid drying at the temperature of 80-100 ℃;
and (4) sintering: sintering the material obtained after drying in the step (3) at high temperature of 400-700 ℃ in an inert gas protection furnace for 2-10h to prepare a precursor of the lithium iron phosphate composite material;
and (5) crushing: crushing the precursor of the lithium iron phosphate composite material, ball-milling in a dispersant medium after crushing, and controlling DmaxLess than 20 mu m to obtain precursor slurry of the lithium iron phosphate composite material;
step (6) material preparation and mixing: stirring and mixing the precursor slurry of the lithium iron phosphate composite material, lithium carbonate, a secondary organic carbon source, a nitrogen source, a metal source and a sanding medium uniformly, wherein Li: fe: p: x: the molar ratio of C is 0.98-1.03:0.95-1.0:1-1.05:0.01-0.05:1.5, X is a metal element, and C represents a carbon source;
sanding in step (7): putting the material obtained in the step (6) into a sand mill for sand milling, and controlling the sand milling granularity D50 to be 0.4-1 mu m;
step (8) spray drying: spray drying the sanded material at the temperature of 180 ℃ and 250 ℃, and controlling the drying granularity D50 to be 5-15 mu m and DmaxLess than 25 μm, and the water content is less than 4%;
and (9) sintering: sintering at the temperature of 700 ℃ and 800 ℃ for 4-15h, cooling and crushing to obtain the lithium iron phosphate material coated with the metal carbide or the metal carbonitride or the metal nitride.
The invention is further provided with: in the step (2), the feeding sequence is sequentially an iron source, a phosphorus source and an organic carbon source I.
The invention is further provided with: in the step (2), the ball-milling medium is one or more of alcohol, acetone, polyacrylonitrile and water, and the mass ratio of the raw materials and the ball-milling medium in the step (1) is 1: 2; in the step (6), the sanding medium is one or more of water, alcohol, acetone and polyacrylonitrile.
The invention is further provided with: in the step (2), the granularity of ball milling is controlled to be D50:1-4 mu m, DmaxLess than 10 μm, and in the step (7), the granularity of the sand grinding is controlled to be D50:0.4-1 μm, and D90 is less than 2 μm.
The invention is further provided with: in the step (4), the precursor of the lithium iron phosphate composite material is ferrous pyrophosphate.
The invention is further provided with: and (5) sequentially crushing the lithium iron phosphate composite material precursor by a jaw crusher and a mechanical crusher.
The invention is further provided with: in the step (2), the ball milling time is 4 h; in the step (7), the sanding time is 4 hours.
The invention is further provided with: the organic carbon source I is one or more of glucose, polypropylene, soluble starch and graphene, and the organic carbon source II is one or more of glucose, polypropylene, soluble starch and graphene; the iron source is one or more of ferrous oxalate, iron oxide red and iron powder, the phosphorus source is one or more of ammonium dihydrogen phosphate, iron phosphate and lithium dihydrogen phosphate, and the nitrogen source is one or more of urea, amino acid and nitrogen-containing organic matters; the metal source is one or more of vanadium pentoxide, nano tungsten oxide, nano chromium trioxide, nano magnesium oxide, nano magnesium hydroxide, ammonium metavanadate and vanadyl acetylacetonate.
The invention is further provided with: in the step (9), the particle size of the obtained lithium iron phosphate composite material is controlled to be D10 more than 1.0 mu m, D50:1.5-4 mu m, D90 less than 10 mu m, and DmaxLess than 30 μm and water content less than 1000 ppm.
The invention is further provided with: and (4) coating the surface of the lithium iron phosphate composite material obtained in the step (9) with a metal carbide or a metal carbonitride, wherein the C element content in the surface coating material is lower than 1%.
The invention has the beneficial effects that:
1. the lithium iron phosphate composite material prepared by the method is coated with the metal carbide and the metal carbonitride, so that the tap density and the conductivity of the lithium iron phosphate composite material are improved, and meanwhile, the lithium iron phosphate composite material has the characteristics of low carbon content and high metal content, the content of C element in the coating material is about 0.5 percent and is far lower than 1.0-1.5 percent of the content of C element in the coating material of the railway phosphate composite material in the prior art, and the prepared lithium iron phosphate composite material can well balance between tap density and electrochemical specific capacity.
2. The lithium iron phosphate composite material prepared by the invention has excellent conductivity, tap density and electrochemical performance, and is low in carbon content, common and easily available in used raw materials, low in price, simple in process, suitable for large-scale production, high in raw material utilization rate, small in emission, environment-friendly, low in pollution and low in cost, and has a better application prospect.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of a process route according to the present invention;
FIG. 2 is XRD of a lithium iron phosphate composite prepared in example 1;
FIG. 3 is an SEM image of lithium iron phosphate prepared in example 1;
FIG. 4 is a charging and discharging curve of the charging and discharging loop of the charging and discharging device of example 1;
FIG. 5 is a plot of the current draw 1C cycle for example 1;
Detailed Description
The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.
Example 1
A preparation method of a lithium iron phosphate composite material, namely VC coated with lithium iron phosphate, comprises the following steps
Step (1) preparation of materials: mixing a phosphorus source, an iron source and a carbon source according to a molar ratio of 1:1: 0.1.
Ball milling: adding the raw materials weighed in the step (1) into a ball mill, sequentially adding an iron source, a phosphorus source and an organic carbon source I, finally adding alcohol serving as a ball milling medium, wherein the mass ratio of the raw materials to the alcohol is 1:3, the rotating speed of the ball mill is 60rpm, ball milling is carried out for 4 hours, and the ball milling particle size is controlled: d50 of 0.5-2 μm, DmaxLess than 10 mu m to obtain ball milling slurry.
Step (3), drying the double cones: and (3) taking the ball-milling slurry obtained in the step (2) to perform bipyramid drying at the temperature of 95 ℃.
And (4) sintering: and (4) putting the dried material obtained in the step (3) into a nitrogen protection furnace, heating to 500 ℃ at a speed of 5 ℃/min, preserving the temperature for 2 hours, and naturally cooling to room temperature to obtain a precursor of the lithium iron phosphate composite material, namely ferrous pyrophosphate.
And (5) crushing: carrying out jaw crushing and mechanical crushing treatment on ferrous pyrophosphate, carrying out ball milling in secondary reverse osmosis pure water, and controlling DmaxLess than 20 mu m to obtain the ferrous pyrophosphate slurry.
Step (6) material preparation and mixing: mixing ferrous pyrophosphate slurry, a carbon source, a lithium source and a metal vanadium source according to the molar ratio: fe: P: Li: V: c is 0.98:1:1.01:0.02, the molar ratio of Li to C is 1:1.5, secondary reverse osmosis pure water is added as a sanding medium and is uniformly mixed by a homogenizing pump.
Sanding in step (7): squeeze into the material that step (6) obtained in the sand mill and sand, control sanding granularity D50: 0.5-1.0 μm, D90 less than 2 μm, sanding for 4 hours;
step (8) spray drying: spray drying at 220 deg.C, controlling the drying particle size D50:10 μm, DmaxLess than 25 μm, and the water content is less than 4%;
and (9) sintering: taking the material obtained in the step (8), and putting the material into nitrogen for protectionHeating to 450 deg.C at 5 deg.C/min, keeping the temperature for 2 hr, directly heating to 750 deg.C, keeping the temperature for 10 hr, cooling, crushing, and pulverizing to particle size D10 > 1.0 μm, D50:1.5-4 μm, D90 < 10 μm, and DmaxLess than 30 mu m and less than 1000ppm of water content to obtain LiFePO4Sample 1 of the/VC composite material.
And (10) uniformly mixing the prepared sample 1, acetylene black and PVDF in a mass ratio of 90:5:5, dispersing in a proper amount of NMP, continuously stirring uniformly to obtain anode slurry, coating the anode slurry on an aluminum foil, drying at 60 ℃, flattening by using a press to prepare a lithium iron phosphate anode, preparing a button cell CR2025 model, and carrying out electrochemical detection.
Example 2
A preparation method of a lithium iron phosphate composite material, namely VCN coated with lithium iron phosphate, comprises the following steps
Step (1) preparation of materials: mixing a phosphorus source, an iron source and a carbon source according to a molar ratio of 1:1: 0.1.
Ball milling: adding the raw materials weighed in the step (1) into a ball mill, sequentially adding an iron source, a phosphorus source and a carbon source, finally adding alcohol serving as a ball milling medium, wherein the mass ratio of the raw materials to the alcohol is 1:3, the rotating speed of the ball mill is 60rpm, ball milling is carried out for 4 hours, and the ball milling particle size is controlled: d50 of 0.5-2 μm, DmaxLess than 10 mu m to obtain ball milling slurry.
Step (3), drying the double cones: taking the ball-milling slurry obtained in the step (2), carrying out bipyramid drying at the temperature of 95 ℃,
and (4) sintering: and (4) putting the dried material obtained in the step (3) into a nitrogen protection furnace, heating to 500 ℃ at a speed of 5 ℃/min, preserving the temperature for 2 hours, and naturally cooling to room temperature to obtain a precursor of the lithium iron phosphate composite material, namely ferrous pyrophosphate.
And (5) crushing: carrying out jaw crushing and mechanical crushing treatment on ferrous pyrophosphate, carrying out ball milling in secondary reverse osmosis pure water, and controlling DmaxLess than 20 mu m to obtain the ferrous pyrophosphate slurry.
Step (6) material preparation and mixing: mixing the crushed ferrous pyrophosphate, a carbon source, a lithium source, a vanadium source and a nitrogen source according to the molar ratio: and adding secondary reverse osmosis pure water as a sanding medium into the mixture, and uniformly mixing the mixture by using a homogenizing pump.
Sanding in step (7): squeeze into the material that step (6) obtained in the sand mill and sand, control sanding granularity D50: 0.5-1.0 μm, D90 < 2 μm, and sanding time 4 hr.
Step (8) spray drying: spray drying at 220 deg.C, controlling the drying particle size D50:10 μm, DmaxLess than 25 μm, and the water content is less than 4%;
and (9) sintering: putting the material obtained in the step (8) into a fluidized bed reactor heated by ammonia plasma for carrying out a reaction in a maintenance way, heating the material by a heating system assisted by a plasma main heating source and a thermal resistance wire, heating the material to 450 ℃ at a speed of 5 ℃/min, keeping the temperature for 2 hours, directly heating the material to 750 ℃, keeping the temperature for 10 hours, cooling the material, crushing and crushing the material, controlling the granularity to be D10 more than 1.0 mu m, D50:1.5-4 mu m, D90 less than 10 mu m, and controlling the granularity to be D10 more than 1.0 mu mmaxLess than 30 mu m and less than 1000ppm of water content to obtain LiFePO4Sample 2 of the/VCN composite.
And (10) uniformly mixing the prepared sample 2, acetylene black and PVDF in a mass ratio of 90:5:5, dispersing in a proper amount of NMP, continuously stirring uniformly to obtain anode slurry, coating the anode slurry on an aluminum foil, drying at 60 ℃, flattening by using a press to prepare a lithium iron phosphate anode, preparing a button cell CR2025 model, and carrying out electrochemical detection.
Example 3
A preparation method of a lithium iron phosphate composite material, namely WC coated by lithium iron phosphate comprises the following steps
Step (1) preparation of materials: mixing a phosphorus source, an iron source and a carbon source according to a molar ratio of 1:1: 0.1.
Ball milling: adding the raw materials weighed in the step (1) into a ball mill, sequentially adding an iron source, a phosphorus source and a carbon source, finally adding alcohol serving as a ball milling medium, wherein the mass ratio of the raw materials to the alcohol is 1:3, the rotating speed of the ball mill is 60rpm, ball milling is carried out for 4 hours, and the ball milling particle size is controlled: d50 of 0.5-2 μm, DmaxLess than 10 mu m to obtain ball milling slurry.
Step (3), drying the double cones: and (3) taking the ball-milling slurry obtained in the step (2) to perform bipyramid drying at the temperature of 95 ℃.
And (4) sintering: and (4) putting the dried material obtained in the step (3) into a nitrogen protection furnace, heating to 500 ℃ at a speed of 5 ℃/min, preserving the temperature for 2 hours, and naturally cooling to room temperature to obtain a precursor of the lithium iron phosphate composite material, namely ferrous pyrophosphate.
And (5) crushing: carrying out jaw crushing and mechanical crushing treatment on ferrous pyrophosphate, carrying out ball milling in secondary reverse osmosis pure water, and controlling DmaxLess than 20 mu m to obtain the ferrous pyrophosphate slurry.
Step (6) material preparation and mixing: mixing the crushed ferrous pyrophosphate, a carbon source, a lithium source and a metal tungsten source according to the molar ratio: and (3) adding secondary reverse osmosis pure water serving as a sanding medium into the mixture, and uniformly mixing the mixture by using a homogenizing pump.
Sanding in step (7): squeeze into the material that step (6) obtained in the sand mill and sand, control sanding granularity D50: 0.5-1.0 μm, D90 less than 2 μm, sanding for 4 hours;
step (8) spray drying: spray drying at 220 deg.C, controlling the drying particle size D50:10 μm, DmaxLess than 25 μm, and the water content is less than 4%;
and (9) sintering: putting the material obtained in the step (8) into a nitrogen protection furnace, heating to 450 ℃ at a speed of 5 ℃/min, preserving heat for 2 hours, directly heating to 750 ℃, preserving heat for 10 hours, cooling, crushing and crushing, wherein the granularity is controlled to be D10 more than 1.0 mu m, D50 is 1.5-4 mu m, D90 is less than 10 mu m, and DmaxLess than 30 mu m and less than 1000ppm of water content to obtain LiFePO4the/WC composite sample 3.
And (10) uniformly mixing the prepared sample 2, acetylene black and PVDF in a mass ratio of 90:5:5, dispersing in a proper amount of NMP, continuously stirring uniformly to obtain anode slurry, coating the anode slurry on an aluminum foil, drying at 60 ℃, flattening by using a press to prepare a lithium iron phosphate anode, preparing a button cell CR2025 model, and carrying out electrochemical detection.
Example 4
A preparation method of a lithium iron phosphate composite material, namely a lithium iron phosphate coated WCN, comprises the following steps
Step (1) preparation of materials: mixing a phosphorus source, an iron source and a carbon source according to a molar ratio of 1:1: 0.1.
Ball milling: adding the raw materials weighed in the step (1) into a ball mill, sequentially adding an iron source, a phosphorus source and a carbon source, finally adding alcohol serving as a ball milling medium, wherein the mass ratio of the raw materials to the alcohol is 1:3, the rotating speed of the ball mill is 60rpm, ball milling is carried out for 4 hours, and the ball milling particle size is controlled: d50 of 0.5-2 μm, DmaxLess than 10 mu m to obtain ball milling slurry.
Step (3), drying the double cones: and (3) taking the ball-milling slurry obtained in the step (2) to perform bipyramid drying at the temperature of 95 ℃.
And (4) sintering: and (4) putting the dried material obtained in the step (3) into a nitrogen protection furnace, heating to 500 ℃ at a speed of 5 ℃/min, preserving the temperature for 2 hours, and naturally cooling to room temperature to obtain a precursor of the lithium iron phosphate composite material, namely ferrous pyrophosphate.
And (5) crushing: carrying out jaw crushing and mechanical crushing treatment on ferrous pyrophosphate, carrying out ball milling in secondary reverse osmosis pure water, and controlling DmaxLess than 20 mu m to obtain the ferrous pyrophosphate slurry.
Step (6) material preparation and mixing: ferrous pyrophosphate slurry, a carbon source, a lithium source and a tungsten source are mixed, wherein the molar ratio of a nitrogen source is as follows: and adding secondary reverse osmosis pure water as a sanding medium, and uniformly mixing the materials by using a homogenizing pump.
Sanding in step (7): squeeze into the material that step (6) obtained in the sand mill and sand, control sanding granularity D50: 0.5-1.0 μm, D90 less than 2 μm, sanding for 4 hours;
step (8) spray drying: spray drying at 220 deg.C, controlling drying particle size D50 at 10 μm, and water content less than 4%;
and (9) sintering: putting the material obtained in the step (8) into a fluidized bed reactor heated by ammonia plasma for carrying out a reaction in a maintenance way, heating the material by a heating system assisted by a plasma main heating source and a thermal resistance wire, heating the material to 450 ℃ at a speed of 5 ℃/min, keeping the temperature for 2 hours, directly heating the material to 750 ℃, keeping the temperature for 10 hours, cooling the material, crushing and crushing the material, controlling the granularity to be D10 more than 1.0 mu m, D50:1.5-4 mu m, D90 less than 10 mu m, and controlling the granularity to be D10 more than 1.0 mu mmaxLess than 30 mu m, the water content is controlled to be less than 1000ppm, and L is obtainediFePO4the/WCN composite sample 4 was,
and (10) uniformly mixing the prepared sample 4, acetylene black and PVDF in a mass ratio of 90:5:5, dispersing in a proper amount of NMP, continuously stirring uniformly to obtain anode slurry, coating the anode slurry on an aluminum foil, drying at 60 ℃, flattening by using a press to prepare a lithium iron phosphate anode, preparing a button cell CR2025 model, and carrying out electrochemical detection.
Example 5
Preparation method of lithium iron phosphate composite material, lithium iron phosphate coats Mg3N2Comprises the following steps
Step (1) preparation of materials: mixing a phosphorus source, an iron source and a carbon source according to a molar ratio of 1:1: 0.1.
Ball milling: adding the raw materials weighed in the step (1) into a ball mill, sequentially adding an iron source, a phosphorus source and a carbon source, finally adding alcohol serving as a ball milling medium, wherein the mass ratio of the raw materials to the alcohol is 1:3, the rotating speed of the ball mill is 60rpm, ball milling is carried out for 4 hours, and the ball milling particle size is controlled: d50 of 0.5-2 μm, DmaxLess than 10 mu m to obtain ball milling slurry.
Step (3), drying the double cones: and (3) taking the ball-milling slurry obtained in the step (2) to perform bipyramid drying at the temperature of 95 ℃.
And (4) sintering: and (4) putting the dried material obtained in the step (3) into a nitrogen protection furnace, heating to 500 ℃ at a speed of 5 ℃/min, preserving the temperature for 2 hours, and naturally cooling to room temperature to obtain a precursor of the lithium iron phosphate composite material, namely ferrous pyrophosphate.
And (5) crushing: carrying out jaw crushing and mechanical crushing treatment on ferrous pyrophosphate, carrying out ball milling in secondary reverse osmosis pure water, and controlling DmaxLess than 20 mu m to obtain the ferrous pyrophosphate slurry.
Step (6) material preparation and mixing: the molar ratio of ferrous pyrophosphate slurry to carbon source, lithium source, metal magnesium source and nitrogen source is as follows: and adding secondary reverse osmosis pure water as a sanding medium, and uniformly mixing the materials by using a homogenizing pump.
Sanding in step (7): and (3) sanding the sand mill obtained in the step (6), and controlling the sanding granularity D50: 0.5-1.0 μm, sanding for 4 hours;
step (8) spray drying: spray drying at 220 deg.C, controlling the drying particle size D50:10 μm, DmaxLess than 25 μm, and the water content is less than 4%;
and (9) sintering: putting the material obtained in the step (8) into a fluidized bed reactor heated by ammonia plasma for carrying out a reaction in a maintenance way, heating the material by a heating system assisted by a plasma main heating source and a thermal resistance wire, heating the material to 450 ℃ at a speed of 5 ℃/min, keeping the temperature for 2 hours, directly heating the material to 750 ℃, keeping the temperature for 10 hours, cooling the material, crushing and crushing the material, controlling the granularity to be D10 more than 1.0 mu m, D50:1.5-4 mu m, D90 less than 10 mu m, and controlling the granularity to be D10 more than 1.0 mu mmaxLess than 30 mu m and less than 1000ppm of water content to obtain LiFePO4/Mg3N2Sample 5.
And (10) uniformly mixing the prepared sample 5, acetylene black and PVDF in a mass ratio of 90:5:5, dispersing in a proper amount of NMP, continuously stirring uniformly to obtain anode slurry, coating the anode slurry on an aluminum foil, drying at 60 ℃, flattening by using a press to prepare a lithium iron phosphate anode, preparing a button cell CR2025 model, and carrying out electrochemical detection.
Example 6
Preparation method of lithium iron phosphate composite material, lithium iron phosphate is coated with Cr2C3Comprises the following steps
Step (1) preparation of materials: mixing a phosphorus source, an iron source and a carbon source according to a molar ratio of 1:1: 0.1.
Ball milling: adding the raw materials weighed in the step (1) into a ball mill, sequentially adding an iron source, a phosphorus source and a carbon source, finally adding alcohol serving as a ball milling medium, wherein the mass ratio of the raw materials to the alcohol is 1:3, the rotating speed of the ball mill is 60rpm, ball milling is carried out for 4 hours, and the ball milling particle size is controlled: d50 of 0.5-2 μm, DmaxLess than 10 mu m to obtain ball milling slurry.
Step (3), drying the double cones: and (3) taking the ball-milling slurry obtained in the step (2) to perform bipyramid drying at the temperature of 95 ℃.
And (4) sintering: and (4) putting the dried material obtained in the step (3) into a nitrogen protection furnace, heating to 500 ℃ at a speed of 5 ℃/min, preserving the temperature for 2 hours, and naturally cooling to room temperature to obtain a precursor of the lithium iron phosphate composite material, namely ferrous pyrophosphate.
And (5) crushing: carrying out jaw crushing and mechanical crushing treatment on ferrous pyrophosphate, carrying out ball milling in secondary reverse osmosis pure water, and controlling DmaxLess than 20 mu m to obtain the ferrous pyrophosphate slurry.
Step (6) material preparation and mixing: the mol ratio of the ferrous pyrophosphate slurry to the carbon source to the lithium source to the chromium source is as follows: and (3) adding secondary reverse osmosis pure water serving as a sanding medium into the mixture, and uniformly mixing the mixture by using a homogenizing pump.
Sanding in step (7): squeeze into the material that step (6) obtained in the sand mill and sand, control sanding granularity D50: 0.5-1.0 μm, sanding for 4 hours;
step (8) spray drying: spray drying at 220 deg.C, controlling the drying particle size D50:10 μm, DmaxLess than 25 μm, and the water content is less than 4%;
and (9) sintering: heating to 450 ℃ at the speed of 5 ℃/min, preserving heat for 2 hours, directly heating to 750 ℃, preserving heat for 10 hours, cooling, crushing and crushing to obtain LiFePO4/Cr2C3The composite material of sample 6 was prepared by the method,
and (10) uniformly mixing the prepared sample 2, acetylene black and PVDF in a mass ratio of 90:5:5, dispersing in a proper amount of NMP, continuously stirring uniformly to obtain anode slurry, coating the anode slurry on an aluminum foil, drying at 60 ℃, flattening by using a press to prepare a lithium iron phosphate anode, preparing a button cell CR2025 model, and carrying out electrochemical detection.
Example 7
A preparation method of a lithium iron phosphate composite material, namely a lithium iron phosphate coated CrCN, comprises the following steps
Step (1) preparation of materials: mixing a phosphorus source, an iron source and a carbon source according to a molar ratio of 1:1: 0.1.
Ball milling: adding the raw materials weighed in the step (1) into a ball mill, sequentially adding an iron source, a phosphorus source and a carbon source, finally adding alcohol serving as a ball milling medium, wherein the mass ratio of the raw materials to the alcohol is 1:3, the rotating speed of the ball mill is 60rpm, ball milling is carried out for 4 hours, and the ball milling particle size is controlled: d50 of 0.5-2 μm, Dmax＜10μAnd m, obtaining the ball milling slurry.
Step (3), drying the double cones: and (3) taking the ball-milling slurry obtained in the step (2) to perform bipyramid drying at the temperature of 95 ℃.
And (4) sintering: and (4) putting the dried material obtained in the step (3) into a nitrogen protection furnace, heating to 500 ℃ at a speed of 5 ℃/min, preserving the temperature for 2 hours, and naturally cooling to room temperature to obtain a precursor of the lithium iron phosphate composite material, namely ferrous pyrophosphate.
And (5) crushing: carrying out jaw crushing and mechanical crushing treatment on ferrous pyrophosphate, carrying out ball milling in secondary reverse osmosis pure water, and controlling DmaxLess than 20 mu m to obtain the ferrous pyrophosphate slurry.
Step (6) material preparation and mixing: the molar ratio of ferrous pyrophosphate slurry to carbon source, lithium source, chromium source and nitrogen source is as follows: and adding secondary reverse osmosis pure water as a sanding medium, and uniformly mixing the materials by using a homogenizing pump.
Sanding in step (7): squeeze into the material that step (6) obtained in the sand mill and sand, control sanding granularity D50: 0.5-1.0 μm, sanding for 4 hours;
step (8) spray drying: spray drying at 220 deg.C, controlling the drying particle size D50:10 μm, DmaxLess than 25 μm, and the water content is less than 4%;
and (9) sintering: taking the material obtained in the step (8), putting the material into an ammonia plasma heating fluidized bed reactor for carrying out a centering reaction, heating the material by a heating system through a plasma main heating source and a thermal resistance wire in an auxiliary manner, directly heating the material to 750 ℃ after heating the material to 450 ℃ at a speed of 5 ℃/min and preserving the temperature for 2 hours, continuously preserving the temperature for 10 hours and cooling the material, and crushing the material to obtain LiFePO4the/CrN composite sample 7 was,
and (10) uniformly mixing the prepared sample 2, acetylene black and PVDF in a mass ratio of 90:5:5, dispersing in a proper amount of NMP, continuously stirring uniformly to obtain anode slurry, coating the anode slurry on an aluminum foil, drying at 60 ℃, flattening by using a press to prepare a lithium iron phosphate anode, preparing a button cell CR2025 model, and carrying out electrochemical detection.
Table 1 shows the electrochemical properties of examples 1 to 7.
| Name (R) | O.1C/mAh/g | O.2C/mAh/g | 1.0C/mAh/g | Capacity retention/% for 80 weeks of cycles |
| Example 1 | 158.2 | 154.2 | 145.7 | 98.19 |
| Example 2 | 160.1 | 156.5 | 145.8 | 99.2 |
| Example 3 | 159.2 | 154.9 | 143.8 | 97.8 |
| Example 4 | 158.1 | 155.2 | 145.9 | 98.1 |
| Example 5 | 161.5 | 157.6 | 146.8 | 98.2 |
| Example 6 | 159.8 | 156.3 | 145.6 | 98.5 |
| Example 7 | 157.9 | 153.7 | 142.5 | 99.1 |
Table 2 is a table of tap densities for examples 1 to 7
Claims (10)
1. A preparation method of a lithium iron phosphate composite material is characterized by comprising the following steps: the method comprises the following steps:
preparing materials, namely weighing an iron source, a phosphorus source and an organic carbon source I, wherein the molar ratio of iron to phosphorus is 0.95-1:1, and the molar ratio of iron to carbon is 1: 0.1;
ball milling: taking the raw materials in the step (1), sequentially adding the raw materials into a ball mill for ball milling, adding a ball milling medium into the ball mill, and controlling ball milling: d50:0.5-2 μm, DmaxLess than 10 mu m to obtain ball milling slurry;
step (3), drying the double cones: taking the ball-milling slurry obtained in the step (2) to perform bipyramid drying at the temperature of 80-100 ℃;
and (4) sintering: sintering the material obtained after drying in the step (3) in an inert gas protection furnace at a high temperature of 400 ℃ and 700 ℃ for 2-10h to prepare a ferrous pyrophosphate precursor;
and (5) crushing: crushing the ferrous pyrophosphate precursor, ball-milling the crushed material in water, and controlling DmaxLess than 20 mu m to obtain ferrous pyrophosphate precursor slurry;
step (6) material preparation and mixing: stirring and mixing the ferrous pyrophosphate precursor slurry, lithium carbonate, a second organic carbon source, a nitrogen source, a metal source and a sand grinding medium uniformly, wherein the weight ratio of Li: fe: p: x: the molar ratio of C is 0.98-1.03:0.95-1.0:1-1.05:0.01-0.05:1.5, X is a metal element, and C represents a carbon source;
sanding in step (7): putting the material obtained in the step (6) into a sand mill for sand milling, and controlling the sand milling granularity D50 to be 0.4-1 mu m;
step (8) spray drying: spray drying the sanded material at the temperature of 180 ℃ and 250 ℃, and controlling the drying granularity D50 to be 5-15 mu m and DmaxLess than 25 μm, and the water content is less than 4%;
and (9) sintering: sintering at the temperature of 700 ℃ and 800 ℃ for 4-15h, cooling and crushing to obtain the lithium iron phosphate composite material coated with the metal carbide or the metal carbonitride.
2. The method of preparing a lithium iron phosphate composite according to claim 1, wherein: in the step (2), the feeding sequence is sequentially an iron source, a phosphorus source and an organic carbon source I.
3. The method of preparing a lithium iron phosphate composite according to claim 1, wherein: in the step (2), the ball-milling medium is one or more of alcohol, acetone, polyacrylonitrile and water, and the mass ratio of the raw materials and the ball-milling medium in the step (1) is 1: 2; in the step (6), the sanding medium is one or more of water, alcohol, acetone and polyacrylonitrile.
4. The method of preparing a lithium iron phosphate composite according to claim 1, wherein: in the step (2), the granularity of ball milling is controlled to be D50:1-4 mu m, DmaxLess than 10 μm, and in the step (7), the granularity of the sand grinding is controlled to be D50:0.4-1 μm, and D90 is less than 2 μm.
5. The method of preparing a lithium iron phosphate composite according to claim 1, wherein: in the step (4), the precursor of the lithium iron phosphate composite material is ferrous pyrophosphate.
6. The method of preparing a lithium iron phosphate composite according to claim 1, wherein: and (5) sequentially crushing the lithium iron phosphate composite material precursor by a jaw crusher and a mechanical crusher.
7. The method of preparing a lithium iron phosphate composite according to claim 1, wherein: in the step (2), the ball milling time is 4 h; in the step (7), the sanding time is 4 hours.
8. The method of preparing a lithium iron phosphate composite according to claim 1, wherein: the organic carbon source I is one or more of glucose, polypropylene, soluble starch and graphene, and the organic carbon source II is one or more of glucose, polypropylene, soluble starch and graphene; the iron source is one or more of ferrous oxalate, iron oxide red and iron powder, the phosphorus source is one or more of ammonium dihydrogen phosphate, iron phosphate and lithium dihydrogen phosphate, and the nitrogen source is one or more of urea, amino acid and nitrogen-containing organic matters; the metal source is one or more of vanadium pentoxide, nano-zirconia, nano-tungsten oxide, nano-chromium trioxide, nano-tantalum oxide, nano-magnesium hydroxide, ammonium metavanadate and vanadyl acetylacetonate.
9. The method of preparing a lithium iron phosphate composite according to claim 1Characterized in that: in the step (9), the particle size of the obtained lithium iron phosphate composite material is controlled to be D10 more than 1.0 mu m, D50:1.5-4 mu m, D90 less than 10 mu m, and DmaxLess than 30 μm and less than 1000ppm of water.
10. The method of preparing a lithium iron phosphate composite according to claim 1, wherein: and (4) coating the surface of the lithium iron phosphate composite material obtained in the step (9) with a metal carbide or a metal carbonitride, wherein the C element content in the surface coating material is lower than 1%.
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