CN112599768A - Preparation method of lithium iron phosphate material - Google Patents
Preparation method of lithium iron phosphate material Download PDFInfo
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- CN112599768A CN112599768A CN202011510738.4A CN202011510738A CN112599768A CN 112599768 A CN112599768 A CN 112599768A CN 202011510738 A CN202011510738 A CN 202011510738A CN 112599768 A CN112599768 A CN 112599768A
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- 239000000463 material Substances 0.000 title claims abstract description 131
- 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 62
- 238000002360 preparation method Methods 0.000 title claims abstract description 7
- 238000005245 sintering Methods 0.000 claims abstract description 123
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 115
- 239000002002 slurry Substances 0.000 claims abstract description 67
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 58
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 58
- 239000000203 mixture Substances 0.000 claims abstract description 49
- 238000001694 spray drying Methods 0.000 claims abstract description 44
- 238000001238 wet grinding Methods 0.000 claims abstract description 43
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 35
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 31
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 31
- 239000011574 phosphorus Substances 0.000 claims abstract description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 25
- 238000003756 stirring Methods 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 23
- 238000002156 mixing Methods 0.000 claims abstract description 22
- 239000012299 nitrogen atmosphere Substances 0.000 claims abstract description 22
- 239000002019 doping agent Substances 0.000 claims abstract description 19
- 238000007873 sieving Methods 0.000 claims abstract description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 70
- 239000002245 particle Substances 0.000 claims description 67
- 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 45
- 239000008103 glucose Substances 0.000 claims description 45
- 229910052742 iron Inorganic materials 0.000 claims description 35
- 239000002202 Polyethylene glycol Substances 0.000 claims description 29
- 229920001223 polyethylene glycol Polymers 0.000 claims description 29
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 claims description 22
- 229930006000 Sucrose Natural products 0.000 claims description 22
- 239000005720 sucrose Substances 0.000 claims description 22
- 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 claims description 16
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 15
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical group [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 9
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 9
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 8
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 8
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 8
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 6
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 6
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 6
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 5
- 229910000388 diammonium phosphate Inorganic materials 0.000 claims description 5
- 235000019838 diammonium phosphate Nutrition 0.000 claims description 5
- 239000005696 Diammonium phosphate Substances 0.000 claims description 3
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 229910044991 metal oxide Inorganic materials 0.000 claims description 3
- 150000004706 metal oxides Chemical group 0.000 claims description 3
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 235000011007 phosphoric acid Nutrition 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 229910052720 vanadium Inorganic materials 0.000 claims description 3
- 239000006012 monoammonium phosphate Substances 0.000 claims 1
- 239000011248 coating agent Substances 0.000 abstract description 10
- 238000000576 coating method Methods 0.000 abstract description 10
- 238000012545 processing Methods 0.000 abstract description 9
- 239000002994 raw material Substances 0.000 abstract description 9
- 230000000694 effects Effects 0.000 abstract description 6
- 239000010405 anode material Substances 0.000 abstract description 3
- 238000000227 grinding Methods 0.000 abstract 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 28
- 238000010438 heat treatment Methods 0.000 description 28
- 239000008367 deionised water Substances 0.000 description 15
- 229910021641 deionized water Inorganic materials 0.000 description 15
- 239000012530 fluid Substances 0.000 description 15
- 239000004576 sand Substances 0.000 description 15
- 239000007921 spray Substances 0.000 description 15
- 239000012298 atmosphere Substances 0.000 description 14
- 238000001816 cooling Methods 0.000 description 14
- 229910052757 nitrogen Inorganic materials 0.000 description 14
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 12
- 238000011068 loading method Methods 0.000 description 12
- 238000010902 jet-milling Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000004408 titanium dioxide Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 238000009826 distribution Methods 0.000 description 4
- 239000011164 primary particle Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 229910000398 iron phosphate Inorganic materials 0.000 description 3
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- NDLPOXTZKUMGOV-UHFFFAOYSA-N oxo(oxoferriooxy)iron hydrate Chemical compound O.O=[Fe]O[Fe]=O NDLPOXTZKUMGOV-UHFFFAOYSA-N 0.000 description 1
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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
- H01M4/58—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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/45—Phosphates containing plural metal, or metal and ammonium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- 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)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to the technical field of lithium battery anode materials, and discloses a preparation method of a lithium iron phosphate material, which comprises the following steps: (1) mixing iron oxide with a phosphorus source, a lithium source, a primary carbon source and a doping agent to obtain a mixture, and then adding water to stir to obtain slurry; (2) sequentially carrying out wet grinding, spray drying, primary sintering and airflow crushing on the slurry obtained in the step (1) in a nitrogen atmosphere to obtain a crushed primary sintered material; (3) mixing the crushed primary sintered material obtained in the step (2) with a secondary carbon source to obtain a mixture, and then adding water to stir to obtain slurry; (4) and (4) sequentially carrying out wet grinding, spray drying and secondary sintering in a nitrogen atmosphere on the slurry obtained in the step (3), and then sieving to obtain the lithium iron phosphate material. According to the method, iron oxide with low price is used as a raw material, pre-sintering and then grinding and sintering are adopted, the coating effect is good, and the processing performance of the battery cell end is effectively guaranteed.
Description
Technical Field
The invention relates to the technical field of lithium battery anode materials, in particular to a preparation method of a lithium iron phosphate material.
Background
Nowadays, lithium ion batteries are used more and more widely, and the technical requirements on the lithium ion batteries are higher and higher. The lithium iron phosphate material is used as the anode material, and has attracted more and more attention due to its excellent properties of environmental protection, no toxicity, high capacity and the like. With the national requirement on endurance mileage becoming higher and the demand on high-power lithium iron phosphate materials becoming more and more, the conventional treatment scheme is to select raw materials with special specifications and match with appropriate carbon coating and doping technologies to regulate and control the particle size and conductivity of the materials and improve the rate capability of the materials at present, but the requirement on the raw materials is high, particularly in the aspect of morphology, the material performance correspondingly fluctuates greatly along with the raw materials; and the effect of the conventional coating and doping method is difficult to meet the requirement, the adopted coating and doping method has higher cost, and the common high-power lithium iron phosphate material has higher difficulty in processing the battery cell, thereby increasing the use difficulty of a battery factory.
Disclosure of Invention
The invention aims to overcome the problems that the high-power lithium iron phosphate material in the prior art has high requirements on raw materials, the effect of a conventional coating and doping method is difficult to meet the requirements, and the common high-power lithium iron phosphate material has high difficulty in processing a battery cell.
In order to achieve the above object, the present invention provides a method for preparing a lithium iron phosphate material, comprising the steps of:
(1) mixing iron oxide with a phosphorus source, a lithium source, a primary carbon source and a doping agent to obtain a mixture, and then adding water to stir to obtain slurry;
(2) sequentially carrying out wet grinding, spray drying, primary sintering and airflow crushing on the slurry obtained in the step (1) in a nitrogen atmosphere to obtain a crushed primary sintered material;
(3) mixing the crushed primary sintered material obtained in the step (2) with a secondary carbon source to obtain a mixture, and then adding water to stir to obtain slurry;
(4) sequentially carrying out wet grinding, spray drying and secondary sintering in a nitrogen atmosphere on the slurry obtained in the step (3), and then sieving to obtain a lithium iron phosphate material;
wherein the temperature of the second sintering in the step (4) is higher than that of the first sintering in the step (2).
Preferably, in step (1), the phosphorus source is at least one of phosphoric acid, ammonium dihydrogen phosphate and diammonium hydrogen phosphate.
Further preferably, the molar ratio of iron in the iron oxide to phosphorus in the phosphorus source is (0.96-1): 1.
Preferably, in step (1), the lithium source is lithium carbonate and/or lithium hydroxide.
Further preferably, the molar ratio of lithium in the lithium source to iron in the iron oxide is (1.02-1.05): 1.
Preferably, the mass ratio of the amount of the primary carbon source used in step (1) to the amount of the secondary carbon source used in step (3) is 1: 1.1-1.5, wherein the total amount of the primary carbon source and the secondary carbon source is 1.5-2 wt% of the carbon content in the lithium iron phosphate material obtained in the step (4).
Preferably, the primary carbon source is selected from at least one of glucose, sucrose, polyethylene glycol and polyvinyl alcohol.
Further preferably, the secondary carbon source is selected from at least one of glucose, sucrose, polyethylene glycol and polyvinyl alcohol.
Preferably, in step (1), the dopant is a metal oxide.
Further preferably, the metal is at least one of Ti, V, Nb, and Mg.
Further preferably, the molar ratio of the dopant to the iron in the iron oxide is (0.001-0.01): 1.
Preferably, the content of the mixture in the slurry in the step (1) is 30-40 wt%.
Further preferably, the content of the mixture in the slurry in the step (3) is 30-40 wt%.
Preferably, in the step (2), the particle size D50 of the material after wet grinding is controlled to be 0.4-0.7 μm.
Further preferably, in the step (2), the inlet air temperature of the spray drying is 200-280 ℃, and the outlet air temperature of the spray drying is 90-110 ℃.
More preferably, the particle size D100 of the crushed primary sintered material is less than or equal to 60 μm.
Preferably, the temperature of the second sintering in the step (4) is 50-250 ℃ higher than that of the first sintering in the step (2).
Further preferably, the temperature of the second sintering in the step (4) is 80-150 ℃ higher than the temperature of the first sintering in the step (2).
Further preferably, the temperature of the first sintering in the step (2) is 500-600 ℃.
Further preferably, the time of the first sintering in the step (2) is 6-10h, and the pressure of the first sintering in the step (2) is 50-200 Pa.
Further preferably, the time of the second sintering in the step (4) is 6-10h, and the pressure of the second sintering in the step (4) is 50-200 Pa.
Preferably, in the step (4), the particle size D50 of the material after wet grinding is controlled to be 0.1-0.3 μm.
Further preferably, in the step (4), the inlet air temperature of the spray drying is 200-280 ℃, and the outlet air temperature of the spray drying is 90-110 ℃.
The method uses cheap ferric oxide as a raw material, and matches with a corresponding phosphorus source, a lithium source and a carbon source, the manufacturing method is stable and controllable, and a special coating mode and a doping mode are not needed in the manufacturing method, so that the raw material cost and the manufacturing cost are moderate on the whole; because of adopting pre-sintering and regrinding sintering, the shape and size of the particles can be effectively controlled, and meanwhile, the secondary sintering eliminates the interference of other factors, and the coating effect is good; the prepared lithium iron phosphate material has high power and good processing performance, and the finished product of the material is formed into a secondary ball by tightly stacking primary particles, so that the processing performance of the battery cell end is effectively ensured.
Drawings
Fig. 1 is a particle size distribution diagram of a lithium iron phosphate material prepared in example 1 of the present invention;
fig. 2 is a scanning electron microscope picture of the lithium iron phosphate material prepared in example 1 of the present invention;
fig. 3 is a scanning electron microscope picture of the lithium iron phosphate material prepared in example 1 of the present invention;
fig. 4 is a charge-discharge curve diagram of the lithium iron phosphate material prepared in example 1 of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
The invention provides a preparation method of a lithium iron phosphate material, which comprises the following steps:
(1) mixing iron oxide with a phosphorus source, a lithium source, a primary carbon source and a doping agent to obtain a mixture, and then adding water to stir to obtain slurry;
(2) sequentially carrying out wet grinding, spray drying, primary sintering and airflow crushing on the slurry obtained in the step (1) in a nitrogen atmosphere to obtain a crushed primary sintered material;
(3) mixing the crushed primary sintered material obtained in the step (2) with a secondary carbon source to obtain a mixture, and then adding water to stir to obtain slurry;
(4) sequentially carrying out wet grinding, spray drying and secondary sintering in a nitrogen atmosphere on the slurry obtained in the step (3), and then sieving to obtain a lithium iron phosphate material;
wherein the temperature of the second sintering in the step (4) is higher than that of the first sintering in the step (2).
In the invention, the iron oxide is derived from iron oxide red, and the type of the iron oxide red has no special requirement and can be selected conventionally in the field.
In the present invention, in step (1), the phosphorus source is at least one of phosphoric acid, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate. Preferably, the molar ratio of iron in the iron oxide to phosphorus in the phosphorus source is (0.96-1): 1. Specifically, the molar ratio of iron in the iron oxide to phosphorus in the phosphorus source may be 0.96:1, 0.97:1, 0.98:1, 0.99:1, or 1: 1.
In the present invention, in the step (1), the lithium source is lithium carbonate and/or lithium hydroxide. Preferably, the molar ratio of lithium in the lithium source to iron in the iron oxide is (1.02-1.05): 1. Specifically, the molar ratio of lithium in the lithium source to iron in the iron oxide can be 1.02:1, 1.03:1, 1.04:1, or 1.05: 1.
In the present invention, the primary carbon source is selected from at least one of glucose, sucrose, polyethylene glycol and polyvinyl alcohol.
In the present invention, the secondary carbon source is selected from at least one of glucose, sucrose, polyethylene glycol and polyvinyl alcohol.
In the present invention, the mass ratio of the amount of the primary carbon source used in step (1) to the amount of the secondary carbon source used in step (3) is 1: 1.1-1.5. Specifically, the mass ratio of the amount of the primary carbon source used in step (1) to the amount of the secondary carbon source used in step (3) may be 1: 1.1, 1: 1.2, 1: 1.3, 1: 1.4 or 1: 1.5.
in the invention, in the step (1), the mass ratio of the primary carbon source to the iron oxide is (0.1-0.13):1, and the carbon content in the final finished product lithium iron phosphate material is 0.2-0.5 wt% after the primary carbon source is added. Specifically, after the primary carbon source is added, the carbon content in the lithium iron phosphate material may be 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt%, or 0.5 wt%.
In the invention, the total amount of the primary carbon source and the secondary carbon source is such that the carbon content in the lithium iron phosphate material obtained in the step (4) is 1.5-2 wt%. Specifically, the carbon content in the lithium iron phosphate material may be 1.5 wt%, 1.55 wt%, 1.6 wt%, 1.65 wt%, 1.7 wt%, 1.75 wt%, 1.8 wt%, 1.85 wt%, 1.9 wt%, 1.95 wt%, or 2 wt%.
In the present invention, in the step (1), the dopant is a metal oxide.
In a preferred embodiment, the metal is at least one of Ti, V, Nb, and Mg.
In the invention, the molar ratio of the doping agent to the iron in the iron oxide is (0.001-0.01): 1. Specifically, the molar ratio of the dopant to iron in the iron oxide can be 0.001:1, 0.002:1, 0.003:1, 0.004:1, 0.005:1, 0.006:1, 0.007:1, 0.008:1, 0.009:1, or 0.01: 1.
In the invention, water is added into the mixture for stirring, the water used has no special requirement and can be a routine choice in the field, and preferably, deionized water is added into the mixture for stirring to obtain slurry.
In the invention, in the step (1), the content of the mixed material in the slurry is 30-40 wt%. Specifically, the content of the mix in the slurry may be 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, or 40 wt%.
In the invention, in the step (3), the content of the mixed material in the slurry is 30-40 wt%. Specifically, the content of the mix in the slurry may be 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, or 40 wt%.
In the method of the present invention, the equipment used for the wet grinding is not particularly required and may be conventionally selected in the art, and in a preferred embodiment, the wet grinding is performed in a high-efficiency ball mill and/or a sand mill.
In the present invention, in the step (2), the particle size D50 of the material after wet grinding is controlled to be 0.4-0.7 μm. Specifically, the particle size D50 of the wet-milled material may be 0.4 μm, 0.45 μm, 0.5 μm, 0.55 μm, 0.6 μm, 0.65 μm, or 0.7 μm.
In the method of the invention, in the step (2), the inlet air temperature of the spray drying is 200-280 ℃, and the outlet air temperature of the spray drying is 90-110 ℃. Specifically, the inlet air temperature of the spray drying can be 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃ or 280 ℃, and the outlet air temperature of the spray drying can be 90 ℃, 93 ℃, 95 ℃, 97 ℃, 100 ℃, 103 ℃, 105 ℃, 107 ℃ or 110 ℃.
In the present invention, there is no particular requirement for the equipment used for the spray drying, and may be a routine choice in the art. Preferably, the apparatus used for spray drying is a two-fluid spray apparatus.
In the present invention, the temperature of the second sintering in step (4) is 50 to 250 ℃ higher than the temperature of the first sintering in step (2). Preferably, the temperature of the second sintering in the step (4) is 80-150 ℃ higher than that of the first sintering in the step (2). Specifically, the temperature of the second sintering in the step (4) may be 80 ℃, 90 ℃, 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃ or 150 ℃ higher than the temperature of the first sintering in the step (2).
In the present invention, there is no particular requirement for the equipment used for the first sintering and the second sintering, and may be a routine choice in the art. Preferably, the equipment used for the first sintering is a rotary furnace, a roller furnace or a box furnace, and the equipment used for the second sintering is a rotary furnace, a roller furnace or a box furnace.
In the invention, in the step (2), the temperature of the first sintering is 500-600 ℃. Specifically, the temperature of the first sintering may be 500 ℃, 510 ℃, 520 ℃, 530 ℃, 540 ℃, 550 ℃, 560 ℃, 570 ℃, 580 ℃, 590 ℃ or 600 ℃.
In the invention, in the step (2), the time for the first sintering is 6-10 h. Specifically, the time for the first sintering may be 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, or 10 h.
In the invention, in the step (2), the pressure of the first sintering is 50-200 Pa. Specifically, the pressure of the first sintering may be 50Pa, 60Pa, 70Pa, 80Pa, 90Pa, 100Pa, 110Pa, 120Pa, 130Pa, 140Pa, 150Pa, 160Pa, 170Pa, 180Pa, 190Pa, or 200 Pa.
In the present invention, the pressure is a relative pressure.
In the present invention, the apparatus used for the jet milling is not particularly required and may be a conventional one in the art, and preferably, the jet milling is performed using a small jet mill.
In the present invention, in the step (2), the particle diameter D100 of the pulverized primary sintered material is not more than 60 μm.
In the present invention, in the step (4), the particle size D50 of the material after wet grinding is controlled to be 0.1-0.3 μm. Specifically, the particle size D50 of the wet-milled material may be 0.1 μm, 0.15 μm, 0.2 μm, 0.25 μm, or 0.3 μm.
In the method of the invention, in the step (4), the inlet air temperature of the spray drying is 200-280 ℃, and the outlet air temperature of the spray drying is 90-110 ℃. Specifically, the inlet air temperature of the spray drying can be 200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃ or 280 ℃, and the outlet air temperature of the spray drying can be 90 ℃, 93 ℃, 95 ℃, 97 ℃, 100 ℃, 103 ℃, 105 ℃, 107 ℃ or 110 ℃.
In the invention, in the step (4), the time of the second sintering is 6-10 h. Specifically, the time of the second sintering may be 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, or 10 h.
In the invention, in the step (4), the pressure of the second sintering is 50-200 Pa. Specifically, the pressure of the second sintering may be 50Pa, 60Pa, 70Pa, 80Pa, 90Pa, 100Pa, 110Pa, 120Pa, 130Pa, 140Pa, 150Pa, 160Pa, 170Pa, 180Pa, 190Pa, or 200 Pa.
In the present invention, in the step (4), the mesh number of the screen used is 325 mesh.
According to the method, iron oxide with low price is used as a raw material, and a corresponding phosphorus source, a lithium source and a carbon source are matched, so that the manufacturing method is stable and controllable, and a special coating mode and a doping mode are not needed in the manufacturing method, so that the raw material cost and the manufacturing cost are moderate on the whole; because of adopting pre-sintering and regrinding sintering, the shape and size of the particles can be effectively controlled, and meanwhile, the secondary sintering eliminates the interference of other factors, and the coating effect is good; the prepared lithium iron phosphate material has high power and good processing performance, and the finished product of the material is formed into a secondary ball by tightly stacking primary particles, so that the processing performance of the battery cell end is effectively ensured.
The present invention will be described in detail below by way of examples. The scope of the invention is not limited thereto.
Example 1
(1) Mixing 1000g of iron oxide with 476.6g of lithium carbonate, 1485.1g of ammonium dihydrogen phosphate, 110g of glucose, 10g of polyethylene glycol and 2.5g of titanium dioxide to obtain a mixture (the molar ratio of iron in the iron oxide to phosphorus in the phosphorus source is 0.97:1, the molar ratio of lithium in the lithium source to iron in the iron oxide is 1.03:1, the molar ratio of a doping agent to iron in the iron oxide is 0.0025:1, and the mass ratio of the total mass of glucose and polyethylene glycol to the mass of iron oxide is 0.12: 1), then adding deionized water, and stirring for 30min to obtain a slurry, wherein the content of the mixture in the slurry is 35 wt%;
(2) transferring the slurry obtained in the step (1) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.4 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 220 deg.C and outlet air temperature of 100 deg.C, loading into sagger, placing in box-type atmosphere furnace, carrying out first sintering in nitrogen atmosphere, introducing nitrogen for 3.5h before heating, heating at a rate of 2.5 ℃/min, first sintering at a temperature of 600 ℃, first sintering for 6h under a pressure of 100Pa, naturally cooling the material to 75 ℃ along with the furnace after sintering, taking out, then, carrying out jet milling by using a small jet mill to obtain a milled primary sintering material, wherein the grain diameter D100 of the milled primary sintering material is 35 mu m;
(3) mixing the crushed primary sintered material obtained in the step (2) with 100g of glucose and 60g of polyethylene glycol to obtain a mixture, adding deionized water, and stirring for 30min to obtain slurry, wherein the content of the mixture in the slurry is 40 wt%;
(4) transferring the slurry obtained in the step (3) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.15 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 220 deg.C and outlet air temperature of 100 deg.C, loading into sagger, placing in box-type atmosphere furnace, performing second sintering in nitrogen atmosphere, introducing nitrogen for 3.5h before heating, heating at a rate of 2.5 deg.C/min, sintering at 700 deg.C for 6h under a pressure of 100Pa, naturally cooling to 75 deg.C with the furnace after sintering, then sieving the mixture by a 325-mesh sieve to obtain a lithium iron phosphate material, wherein the carbon content in the lithium iron phosphate material is 1.65 percent by weight, the particle size D10 is 1.52 mu m, the particle size D50 is 5.65 mu m, and the particle size D90 is 8.96 mu m;
wherein the ratio of the total mass of glucose and polyethylene glycol in step (1) to the total mass of glucose and polyethylene glycol in step (3) is 1: 1.33;
in the step (1), glucose and polyethylene glycol are added so that the content of carbon in the lithium iron phosphate material is 0.25% by weight.
Example 2
(1) Mixing 1000g of iron oxide with 305.9g of lithium hydroxide, 1500.6g of ammonium dihydrogen phosphate, 80g of glucose, 30g of sucrose and 5g of magnesium oxide to obtain a mixture (the molar ratio of iron in the iron oxide to phosphorus in the phosphorus source is 0.96:1, the molar ratio of lithium in the lithium source to iron in the iron oxide is 1.02:1, the molar ratio of a doping agent to iron in the iron oxide is 0.01:1, and the mass ratio of the total mass of glucose and sucrose to the mass of the iron oxide is 0.11: 1), adding deionized water, and stirring for 30min to obtain a slurry, wherein the content of the mixture in the slurry is 30 wt%;
(2) transferring the slurry obtained in the step (1) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.5 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 200 deg.C and outlet air temperature of 90 deg.C, loading into sagger, placing in box-type atmosphere furnace, performing first sintering in nitrogen atmosphere, introducing nitrogen for 4h before heating, heating at a rate of 2.5 deg.C/min, sintering at 550 deg.C for 6h under 100Pa, naturally cooling to 70 deg.C with the furnace after sintering, then, carrying out jet milling by adopting a small jet mill to obtain a milled primary sintering material, wherein the grain diameter D100 of the milled primary sintering material is 40 mu m;
(3) mixing the crushed primary sintered material obtained in the step (2) with 100g of glucose and 60g of polyethylene glycol to obtain a mixture, adding deionized water, and stirring for 30min to obtain slurry, wherein the content of the mixture in the slurry is 30 wt%;
(4) transferring the slurry obtained in the step (3) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.1 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 280 deg.C and outlet air temperature of 110 deg.C, loading into sagger, placing into box-type atmosphere furnace, performing second sintering in nitrogen atmosphere, introducing nitrogen for 3.5h before heating, heating at 2.5 deg.C/min, sintering at 650 deg.C for 7h under 100Pa, naturally cooling to 70 deg.C, then sieving the mixture by a 325-mesh sieve to obtain a lithium iron phosphate material, wherein the carbon content in the lithium iron phosphate material is 1.5 percent by weight, the particle size D10 is 1.95 mu m, the particle size D50 is 6.10 mu m, and the particle size D90 is 9.20 mu m;
wherein the ratio of the total mass of glucose and sucrose in step (1) to the total mass of glucose and polyethylene glycol in step (3) is 1: 1.45 of;
in the step (1), glucose and sucrose are added so that the content of carbon in the lithium iron phosphate material is 0.2 wt%.
Example 3
(1) Mixing 1000g of iron oxide with 485.8g of lithium carbonate, 1705g of diammonium phosphate, 80g of glucose, 40g of sucrose and 5.0g of titanium dioxide to obtain a mixture (the molar ratio of iron in the iron oxide to phosphorus in a phosphorus source is 0.97:1, the molar ratio of lithium in the lithium source to iron in the iron oxide is 1.05:1, the molar ratio of a doping agent to iron in the iron oxide is 0.005:1, and the mass ratio of the total mass of the glucose and the sucrose to the mass of the iron oxide is 0.12: 1), then adding deionized water, and stirring for 30min to obtain a slurry, wherein the content of the mixture in the slurry is 40 wt%;
(2) transferring the slurry obtained in the step (1) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.5 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 280 deg.C and outlet air temperature of 110 deg.C, loading into sagger, placing into box-type atmosphere furnace, performing first sintering in nitrogen atmosphere, introducing nitrogen for 4h before heating, heating at a rate of 2.5 deg.C/min, sintering at 600 deg.C for 8h under 100Pa, naturally cooling to 70 deg.C with the furnace after sintering, then, carrying out jet milling by using a small jet mill to obtain a milled primary sintering material, wherein the grain diameter D100 of the milled primary sintering material is 42 microns;
(3) mixing the crushed primary sintered material obtained in the step (2) with 120g of glucose and 60g of polyethylene glycol to obtain a mixture, adding deionized water, and stirring for 30min to obtain slurry, wherein the content of the mixture in the slurry is 35 wt%;
(4) transferring the slurry obtained in the step (3) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.2 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 200 deg.C and outlet air temperature of 90 deg.C, loading into sagger, placing in box-type atmosphere furnace, performing second sintering in nitrogen atmosphere, introducing nitrogen for 3.5h before heating, heating at a rate of 2.5 deg.C/min, sintering at 700 deg.C for 10h under 100Pa, naturally cooling to 70 deg.C with the furnace after sintering, then sieving the mixture by a 325-mesh sieve to obtain a lithium iron phosphate material, wherein the carbon content in the lithium iron phosphate material is 2 wt%, the particle size D10 is 1.35 mu m, the particle size D50 is 5.95 mu m, and the particle size D90 is 8.6 mu m;
wherein the ratio of the total mass of glucose and sucrose in step (1) to the total mass of glucose and polyethylene glycol in step (3) is 1: 1.5;
in the step (1), glucose and sucrose are added so that the content of carbon in the lithium iron phosphate material is 0.35% by weight.
Example 4
(1) Mixing 1000g of iron oxide with 481.2g of lithium carbonate, 1470g of ammonium dihydrogen phosphate, 100g of glucose, 20g of polyethylene glycol and 5.0g of titanium dioxide to obtain a mixture (the molar ratio of iron in the iron oxide to phosphorus in a phosphorus source is 0.98:1, the molar ratio of lithium in the lithium source to iron in the iron oxide is 1.04:1, the molar ratio of a doping agent to iron in the iron oxide is 0.005:1, and the mass ratio of the total mass of glucose and polyethylene glycol to the mass of iron oxide is 0.12: 1), then adding deionized water, and stirring for 30min to obtain a slurry, wherein the content of the mixture in the slurry is 33 wt%;
(2) transferring the slurry obtained in the step (1) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.4 mu m after the wet grinding, then spray drying with two-fluid spray equipment at air inlet temperature of 250 deg.C and air outlet temperature of 100 deg.C, loading into sagger, placing in box-type atmosphere furnace, performing first sintering in nitrogen atmosphere, introducing nitrogen for 4h before heating, heating at a rate of 2.5 deg.C/min, sintering at 570 deg.C for 8h under 100Pa, naturally cooling to 70 deg.C with the furnace after sintering, then, carrying out jet milling by using a small jet mill to obtain a milled primary sintering material, wherein the grain diameter D100 of the milled primary sintering material is 35 mu m;
(3) mixing the crushed primary sintered material obtained in the step (2) with 100g of glucose and 40g of polyethylene glycol to obtain a mixture, adding deionized water, and stirring for 30min to obtain slurry, wherein the content of the mixture in the slurry is 37 wt%;
(4) transferring the slurry obtained in the step (3) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.2 mu m after the wet grinding, then spray drying with two-fluid spray equipment at air inlet temperature of 250 deg.C and air outlet temperature of 100 deg.C, loading into sagger, placing in box-type atmosphere furnace, carrying out second sintering in nitrogen atmosphere, introducing nitrogen for 3.5h before heating, heating at 2.5 deg.C/min, sintering at 650 deg.C for 8h under 100Pa, naturally cooling to 75 deg.C, then sieving the mixture by a 325-mesh sieve to obtain a lithium iron phosphate material, wherein the carbon content in the lithium iron phosphate material is 1.75 percent by weight, the particle size D10 is 1.63 mu m, the particle size D50 is 6.6 mu m, and the particle size D90 is 9.2 mu m;
wherein the ratio of the total mass of glucose and polyethylene glycol in step (1) to the total mass of glucose and polyethylene glycol in step (3) is 1: 1.17;
in the step (1), glucose and polyethylene glycol are added so that the content of carbon in the lithium iron phosphate material is 0.2 wt%.
Example 5
(1) Mixing 1000g of iron oxide with 485.8g of lithium carbonate, 1653.9g of diammonium phosphate, 100g of glucose, 30g of sucrose and 1.0g of titanium dioxide to obtain a mixture (the molar ratio of iron in the iron oxide to phosphorus in a phosphorus source is 1:1, the molar ratio of lithium in the lithium source to iron in the iron oxide is 1.05:1, the molar ratio of a doping agent to iron in the iron oxide is 0.001:1, and the mass ratio of the total mass of the glucose and the sucrose to the mass of the iron oxide is 0.13: 1), adding deionized water, and stirring for 30min to obtain a slurry, wherein the content of the mixture in the slurry is 40 wt%;
(2) transferring the slurry obtained in the step (1) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.7 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 280 deg.C and outlet air temperature of 110 deg.C, loading into sagger, placing into box-type atmosphere furnace, carrying out first sintering in nitrogen atmosphere, introducing nitrogen for 4h before heating, heating at a rate of 2.5 ℃/min, sintering at 500 ℃ for 10h, sintering at 200Pa, naturally cooling to 70 ℃ along with the furnace after sintering, then, carrying out jet milling by adopting a small jet mill to obtain a milled primary sintering material, wherein the grain diameter D100 of the milled primary sintering material is 60 microns;
(3) mixing the crushed primary sintered material obtained in the step (2) with 100g of glucose and 43g of polyethylene glycol to obtain a mixture, adding deionized water, and stirring for 30min to obtain slurry, wherein the content of the mixture in the slurry is 35 wt%;
(4) transferring the slurry obtained in the step (3) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.3 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 200 deg.C and outlet air temperature of 90 deg.C, loading into sagger, placing in box-type atmosphere furnace, performing second sintering in nitrogen atmosphere, introducing nitrogen for 3.5h before heating, heating at 2.5 deg.C/min, sintering at 650 deg.C for 10h under 50Pa, naturally cooling to 70 deg.C with the furnace after sintering, then, screening the mixture by a 325-mesh screen to obtain a lithium iron phosphate material, wherein the carbon content in the lithium iron phosphate material is 2 wt%, the particle size D10 is 1.85 mu m, the particle size D50 is 5.94 mu m, and the particle size D90 is 8.83 mu m;
wherein the ratio of the total mass of glucose and sucrose in step (1) to the total mass of glucose and polyethylene glycol in step (3) is 1: 1.1;
in the step (1), glucose and sucrose are added so that the content of carbon in the lithium iron phosphate material is 0.5 wt%.
Example 6
(1) Mixing 1000g of iron oxide with 305.9g of lithium hydroxide, 1500.6g of ammonium dihydrogen phosphate, 80g of glucose, 30g of sucrose and 5g of magnesium oxide to obtain a mixture (the molar ratio of iron in the iron oxide to phosphorus in the phosphorus source is 0.96:1, the molar ratio of lithium in the lithium source to iron in the iron oxide is 1.02:1, the molar ratio of a doping agent to iron in the iron oxide is 0.01:1, and the mass ratio of the total mass of glucose and sucrose to the mass of the iron oxide is 0.11: 1), adding deionized water, and stirring for 30min to obtain a slurry, wherein the content of the mixture in the slurry is 30 wt%;
(2) transferring the slurry obtained in the step (1) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.5 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 220 deg.C and outlet air temperature of 90 deg.C, loading into sagger, placing in box-type atmosphere furnace, carrying out first sintering in nitrogen atmosphere, introducing nitrogen for 4h before heating, heating at a rate of 2.5 ℃/min, at a temperature of 540 ℃ for first sintering, for a time of 10h, at a pressure of 50Pa, naturally cooling the material to 70 ℃ along with the furnace after sintering, taking out, then, carrying out jet milling by adopting a small jet mill to obtain a milled primary sintering material, wherein the grain diameter D100 of the milled primary sintering material is 40 mu m;
(3) mixing the crushed primary sintered material obtained in the step (2) with 100g of glucose and 60g of polyethylene glycol to obtain a mixture, adding deionized water, and stirring for 30min to obtain slurry, wherein the content of the mixture in the slurry is 30 wt%;
(4) transferring the slurry obtained in the step (3) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.1 mu m after the wet grinding, then spray drying with two-fluid spray equipment at inlet air temperature of 240 deg.C and outlet air temperature of 100 deg.C, loading into sagger, placing into box-type atmosphere furnace, performing second sintering in nitrogen atmosphere, introducing nitrogen for 3.5h before heating, heating at 2.5 deg.C/min, sintering at 655 deg.C for 6h under 200Pa, naturally cooling to 70 deg.C, then sieving the mixture by a 325-mesh sieve to obtain a lithium iron phosphate material, wherein the carbon content in the lithium iron phosphate material is 1.5 percent by weight, the particle size D10 is 1.87 mu m, the particle size D50 is 5.69 mu m, and the particle size D90 is 9.69 mu m;
wherein the ratio of the total mass of glucose and sucrose in step (1) to the total mass of glucose and polyethylene glycol in step (3) is 1: 1.45 of;
in the step (1), glucose and sucrose are added so that the content of carbon in the lithium iron phosphate material is 0.20 wt%.
Example 7
The method of example 4 was carried out, except that in step (4), the temperature of the second sintering was 620 ℃, and a lithium iron phosphate material was obtained, in which the carbon content was 1.80 wt%, the particle diameter D10 was 1.62 μm, D50 was 6.4 μm, and D90 was 9.6 μm.
Example 8
The procedure of example 5 was followed, except that in step (4), the temperature of the second sintering was 750 ℃ to obtain a lithium iron phosphate material having a carbon content of 1.9% by weight, a particle diameter D10 of 1.90 μm, a D50 of 6.12 μm, and a D90 of 9.3 μm.
Comparative example 1
The preparation method of the lithium iron phosphate material by using the prior art comprises the following specific operations:
(1) mixing 1000g of iron phosphate with 252.3g of lithium carbonate, 90g of glucose, 30g of polyethylene glycol and 2.6g of titanium dioxide to obtain a mixture (the molar ratio of lithium in a lithium source to iron in the iron phosphate is 1.03:1, and the molar ratio of a dopant to iron in the iron phosphate is 0.005:1), adding deionized water, and stirring for 30min to obtain a slurry, wherein the content of the mixture in the slurry is 30 wt%;
(2) and (2) transferring the slurry obtained in the step (1) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.3 mu m after the wet grinding, then performing spray drying by adopting a two-fluid spray device, wherein the inlet air temperature of the spray drying is 220 ℃, the outlet air temperature of the spray drying is 100 ℃, then placing the spray-dried material into a sagger, sintering the sagger in a box-type atmosphere furnace in the nitrogen atmosphere, introducing 4h of nitrogen before heating, the heating rate is 2.5 ℃/min, the sintering temperature is 700 ℃, the sintering time is 8h, the sintering pressure is 100Pa, naturally cooling the material to 70 ℃ along with the furnace after sintering, taking out the material, and then passing through a 325-mesh screen to obtain the lithium iron phosphate material, wherein the carbon content of the lithium iron phosphate material is 1.85 weight percent, the particle size D10 is 1.68 mu m, the D50 is 6.8 mu m, and the D90 is 9.5 mu m.
Comparative example 2
(1) Mixing 1000g of iron oxide with 476.6g of lithium carbonate, 1485.1g of ammonium dihydrogen phosphate, 180g of glucose, 50g of polyethylene glycol and 2.5g of titanium dioxide to obtain a mixture (the molar ratio of iron in the iron oxide to phosphorus in the phosphorus source is 0.97:1, the molar ratio of lithium in the lithium source to iron in the iron oxide is 1.03:1, the molar ratio of a doping agent to iron in the iron oxide is 0.0025:1, and the mass ratio of the total mass of glucose and polyethylene glycol to the mass of iron oxide is 0.23: 1), then adding deionized water, and stirring for 30min to obtain a slurry, wherein the content of the mixture in the slurry is 35 wt%;
(2) and (2) transferring the slurry obtained in the step (1) into a 1L sand mill for wet grinding, controlling the particle size D50 of the material to be 0.3 mu m after the wet grinding, then performing spray drying by adopting a two-fluid spray device, wherein the inlet air temperature of the spray drying is 220 ℃, the outlet air temperature of the spray drying is 100 ℃, then putting the spray-dried material into a sagger, sintering in a box-type atmosphere furnace, sintering in a nitrogen atmosphere, introducing 3.5h of nitrogen before heating, the heating rate is 2.5 ℃/min, the sintering temperature is 700 ℃, the sintering time is 6h, the sintering pressure is 100Pa, naturally cooling the material to 70 ℃ along with the furnace after sintering, taking out, and then screening by a 325-mesh screen to obtain the lithium iron phosphate material, wherein the content of carbon in the lithium iron phosphate material is 1.65 weight percent, the particle size D10 is 2.23 mu m, the D50 is 6.85 mu m, and the D90 is 10.5 mu m.
Comparative example 3
The process was carried out as described in example 1, except that in step (4), the temperature of the second sintering was 600 ℃ to obtain a lithium iron phosphate material having a carbon content of 1.70 wt%, a particle diameter D10 of 1.75 μm, a particle diameter D50 of 6.2 μm, and a particle diameter D90 of 8.4 μm.
Comparative example 4
The process was carried out as described in example 1, except that in step (4), the temperature of the second sintering was 550 ℃ to obtain a lithium iron phosphate material having a carbon content of 1.75 wt%, a particle diameter D10 of 1.6 μm, a particle diameter D50 of 5.9 μm, and a particle diameter D90 of 8.1 μm.
Test example 1
The particle size distribution of the lithium iron phosphate material prepared in example 1 is detected by a laser particle size tester, the particle size distribution diagram is shown in fig. 1, the particle size distribution is in a single peak state, the peak value is about 6 μm, and no obvious small particle size peak (fine powder) or large particle size peak (coarse powder) exists, so that the processing performance is facilitated.
Test example 2
The scanning electron microscope is used for observing the lithium iron phosphate material prepared in the embodiment 1, the scanning electron microscope images of which are shown in fig. 2 and fig. 3, and the scanning electron microscope images can show that the primary particles of the prepared lithium iron phosphate material are within 100nm, and meanwhile, the particles are round, the contact among the particles is tight, the particle morphology is good, the lithium iron phosphate material is beneficial to the diffusion and the conductivity of Li ions, and the rate capability can be ensured to the maximum extent.
Test example 3
The button cell is manufactured according to the GB/T30835-.
Test example 4
The physicochemical properties and electrochemical properties of the lithium iron phosphate materials prepared in examples 1-8 and comparative examples 1-4 were tested according to the GB/T30835-.
TABLE 1
TABLE 2
As can be seen from the results in tables 1 and 2, the specific surface area of the lithium iron phosphate material prepared in the examples is 10-15m2The lithium iron phosphate material has high tap density, which indicates that the solidity of the secondary spheres of the material is high and the gaps among the particles are small under the condition that the primary particles of the material are small, thereby being beneficial to improving the processing performance and the energy density, and the gram volume is still high under the condition of high rate, fully reflecting the good rate performance of the material, having high power and good coating effect, and being particularly suitable for high-power batteries.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A preparation method of a lithium iron phosphate material is characterized by comprising the following steps:
(1) mixing iron oxide with a phosphorus source, a lithium source, a primary carbon source and a doping agent to obtain a mixture, and then adding water to stir to obtain slurry;
(2) sequentially carrying out wet grinding, spray drying, primary sintering and airflow crushing on the slurry obtained in the step (1) in a nitrogen atmosphere to obtain a crushed primary sintered material;
(3) mixing the crushed primary sintered material obtained in the step (2) with a secondary carbon source to obtain a mixture, and then adding water to stir to obtain slurry;
(4) sequentially carrying out wet grinding, spray drying and secondary sintering in a nitrogen atmosphere on the slurry obtained in the step (3), and then sieving to obtain a lithium iron phosphate material;
wherein the temperature of the second sintering in the step (4) is higher than that of the first sintering in the step (2).
2. The method of claim 1, wherein in step (1), the source of phosphorus is at least one of phosphoric acid, monoammonium phosphate, and diammonium phosphate;
preferably, the molar ratio of iron in the iron oxide to phosphorus in the phosphorus source is (0.96-1): 1.
3. The method according to claim 1, wherein, in step (1), the lithium source is lithium carbonate and/or lithium hydroxide;
preferably, the molar ratio of lithium in the lithium source to iron in the iron oxide is (1.02-1.05): 1.
4. The method according to claim 1, wherein the mass ratio of the amount of the primary carbon source used in step (1) to the amount of the secondary carbon source used in step (3) is 1: 1.1-1.5, wherein the total amount of the primary carbon source and the secondary carbon source is 1.5-2 wt% of the carbon content in the lithium iron phosphate material obtained in the step (4).
5. The method according to claim 1 or 4, wherein the primary carbon source is selected from at least one of glucose, sucrose, polyethylene glycol and polyvinyl alcohol;
preferably, the secondary carbon source is selected from at least one of glucose, sucrose, polyethylene glycol and polyvinyl alcohol.
6. The method according to claim 1, wherein in step (1), the dopant is a metal oxide;
preferably, the metal is at least one of Ti, V, Nb, and Mg;
preferably, the molar ratio of the dopant to the iron in the iron oxide is (0.001-0.01): 1.
7. The method according to claim 1, wherein the content of the mixed material in the slurry in the step (1) is 30-40 wt%;
preferably, the content of the mixture in the slurry in the step (3) is 30-40 wt%.
8. The method as claimed in claim 1, wherein in the step (2), the particle size D50 of the wet-milled material is controlled to be 0.4-0.7 μm;
preferably, the inlet air temperature of the spray drying is 200-280 ℃, and the outlet air temperature of the spray drying is 90-110 ℃;
preferably, the particle size D100 of the crushed primary sintering material is less than or equal to 60 mu m.
9. The method of claim 1, wherein the temperature of the second sintering in step (4) is 50-250 ℃ higher than the temperature of the first sintering in step (2);
preferably, the temperature of the second sintering in the step (4) is 80-150 ℃ higher than that of the first sintering in the step (2);
preferably, the temperature of the first sintering in the step (2) is 500-600 ℃;
preferably, the time of the first sintering in the step (2) is 6-10h, and the pressure of the first sintering in the step (2) is 50-200 Pa;
preferably, the time of the second sintering in the step (4) is 6-10h, and the pressure of the second sintering in the step (4) is 50-200 Pa.
10. The method as claimed in claim 1, wherein in the step (4), the particle size D50 of the material after wet grinding is controlled to be 0.1-0.3 μm;
preferably, the inlet air temperature of the spray drying is 200-280 ℃, and the outlet air temperature of the spray drying is 90-110 ℃.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115403020A (en) * | 2022-09-07 | 2022-11-29 | 佛山市德方纳米科技有限公司 | Preparation method of lithium iron phosphate material |
| CN115465849A (en) * | 2022-09-26 | 2022-12-13 | 佛山市德方纳米科技有限公司 | Phosphate-series positive electrode material and preparation method and application thereof |
| CN115924876A (en) * | 2022-12-29 | 2023-04-07 | 蜂巢能源科技股份有限公司 | Method for preparing lithium iron phosphate anode material |
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| CN102969502A (en) * | 2012-11-26 | 2013-03-13 | 厦门钨业股份有限公司 | Preparation method of high-vibration-compaction low-specific-surface-area lithium iron phosphate made by positive pole material |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115231543A (en) * | 2022-08-02 | 2022-10-25 | 湖北融通高科先进材料有限公司 | Preparation method of multi-carbon-coated high-compaction lithium iron manganese phosphate |
| CN115403020A (en) * | 2022-09-07 | 2022-11-29 | 佛山市德方纳米科技有限公司 | Preparation method of lithium iron phosphate material |
| CN115403020B (en) * | 2022-09-07 | 2024-03-12 | 佛山市德方纳米科技有限公司 | Preparation method of lithium iron phosphate material |
| CN115465849A (en) * | 2022-09-26 | 2022-12-13 | 佛山市德方纳米科技有限公司 | Phosphate-series positive electrode material and preparation method and application thereof |
| CN115465849B (en) * | 2022-09-26 | 2024-05-10 | 佛山市德方纳米科技有限公司 | Phosphate positive electrode material and preparation method and application thereof |
| CN115924876A (en) * | 2022-12-29 | 2023-04-07 | 蜂巢能源科技股份有限公司 | Method for preparing lithium iron phosphate anode material |
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