CN117550578A - Spherical lithium iron phosphate and preparation method and application thereof - Google Patents
Spherical lithium iron phosphate and preparation method and application thereof Download PDFInfo
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- CN117550578A CN117550578A CN202311517933.3A CN202311517933A CN117550578A CN 117550578 A CN117550578 A CN 117550578A CN 202311517933 A CN202311517933 A CN 202311517933A CN 117550578 A CN117550578 A CN 117550578A
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- lithium
- iron phosphate
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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 73
- 238000002360 preparation method Methods 0.000 title abstract description 18
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 27
- 238000001354 calcination Methods 0.000 claims abstract description 27
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 27
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 26
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 20
- 238000002156 mixing Methods 0.000 claims abstract description 18
- 229910052742 iron Inorganic materials 0.000 claims abstract description 13
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 13
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 13
- 238000005507 spraying Methods 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims description 24
- PQVSTLUFSYVLTO-UHFFFAOYSA-N ethyl n-ethoxycarbonylcarbamate Chemical compound CCOC(=O)NC(=O)OCC PQVSTLUFSYVLTO-UHFFFAOYSA-N 0.000 claims description 15
- GLXDVVHUTZTUQK-UHFFFAOYSA-M lithium hydroxide monohydrate Substances [Li+].O.[OH-] GLXDVVHUTZTUQK-UHFFFAOYSA-M 0.000 claims description 15
- 229940040692 lithium hydroxide monohydrate Drugs 0.000 claims description 15
- 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 12
- 239000008103 glucose Substances 0.000 claims description 12
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 9
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 claims description 9
- 229910052808 lithium carbonate Inorganic materials 0.000 claims description 9
- 239000007921 spray Substances 0.000 claims description 9
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical group [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims description 6
- 125000002791 glucosyl group Chemical group C1([C@H](O)[C@@H](O)[C@H](O)[C@H](O1)CO)* 0.000 claims description 2
- 229910000398 iron phosphate Inorganic materials 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- 239000012530 fluid Substances 0.000 abstract description 13
- 239000000463 material Substances 0.000 abstract description 13
- 239000002245 particle Substances 0.000 abstract description 11
- 238000001694 spray drying Methods 0.000 abstract description 7
- 238000006243 chemical reaction Methods 0.000 abstract description 3
- 230000015572 biosynthetic process Effects 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 10
- 238000000498 ball milling Methods 0.000 description 8
- 239000012299 nitrogen atmosphere Substances 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 5
- 238000007599 discharging Methods 0.000 description 5
- 229910001416 lithium ion Inorganic materials 0.000 description 5
- 239000011164 primary particle Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000005955 Ferric phosphate Substances 0.000 description 4
- 229940032958 ferric phosphate Drugs 0.000 description 4
- 229910000399 iron(III) phosphate Inorganic materials 0.000 description 4
- 238000011056 performance test Methods 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 238000010532 solid phase synthesis reaction Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000012298 atmosphere Substances 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 238000009831 deintercalation Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000011163 secondary particle Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000012798 spherical particle Substances 0.000 description 2
- 238000001308 synthesis method Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/45—Phosphates containing plural metal, or metal and ammonium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/30—Particle morphology extending in three dimensions
- C01P2004/32—Spheres
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/50—Agglomerated particles
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
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- 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)
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- Organic Chemistry (AREA)
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- General Chemical & Material Sciences (AREA)
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Abstract
The invention provides spherical lithium iron phosphate and a preparation method and application thereof, belonging to the technical field of lithium batteries, and comprising the following steps: mixing a lithium source, an iron source, a carbon source and water, and calcining to obtain an intermediate lithium iron phosphate; mixing intermediate lithium iron phosphate, lithium salt, a carbon source and water, spraying and calcining to obtain the spherical lithium iron phosphate. The invention controls the LFP particle diameter to be evenly distributed between 150 and 200nm after the phase formation by the primary high-temperature reaction and controls the spherical lithium iron phosphate particle D50 to be about 7 mu m by the two-fluid spray drying. According to the embodiment, the multiplying power performance of the lithium iron phosphate battery provided by the invention is obviously improved, the 10C reaches more than 150mAh/g, and the application of the LFP material in the field of high-power supplies is widened.
Description
Technical Field
The invention relates to the technical field of lithium batteries, in particular to spherical lithium iron phosphate and a preparation method and application thereof.
Background
Currently, the synthesis methods of lithium iron phosphate include a high-temperature solid-phase method, a carbothermic reduction method, a hydrothermal (solvothermal) method, a microwave synthesis method, and the like. The high-temperature solid phase method has the defects of larger primary particles, uneven particle size, long lithium ion diffusion distance and low diffusion coefficient, and severely restricts the application of the method in a high-power supply. Therefore, the research and solving of the above problems is the direction of further research of the high temperature solid phase method. Patent CN109192953a discloses that the addition of metal oxide to modify conductivity improves the rate performance, but the stability of the crystal structure is affected to some extent, and the cycle performance of the material is deteriorated; patent CN113929070a discloses that LFP is synthesized once and metal oxide is added and modified, uniformity of primary particle size of the material is poor, rate capability of the material still has room for improvement, and cycle performance of the metal oxide after doping can be affected.
Disclosure of Invention
The invention aims to provide spherical lithium iron phosphate and a preparation method and application thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of spherical lithium iron phosphate, which comprises the following steps:
(1) Mixing a lithium source, an iron source, a carbon source and water, and calcining to obtain an intermediate lithium iron phosphate;
(2) Mixing intermediate lithium iron phosphate, lithium salt, a carbon source and water, spraying and calcining to obtain the spherical lithium iron phosphate.
Preferably, in step (1), the lithium source comprises lithium carbonate and lithium hydroxide monohydrate, and the iron source is ferric phosphate;
the mass ratio of the lithium source to the iron source is 35-45: 145-160;
the mass ratio of the lithium carbonate to the lithium hydroxide monohydrate is 20-30: 10 to 20.
Preferably, the carbon source in the step (1) is one or more of glucose, PEG and citric acid;
preferably, the mass ratio of the carbon source to the lithium source is 1 to 4:35 to 45.
Preferably, the temperature of the calcination in the step (1) is 680-750 ℃, and the heat preservation time of the calcination is 10-16 h.
Preferably, in the step (2), the mass ratio of the intermediate lithium iron phosphate, the lithium salt and the carbon source is 180-220: 0.5 to 2:3 to 5.
Preferably, in step (2), the lithium salt is lithium hydroxide monohydrate;
the carbon source is glucose.
Preferably, the feeding temperature of the spray in the step (2) is 180-220 ℃, and the discharging temperature of the spray is 90-110 ℃.
Preferably, the temperature of the calcination in the step (2) is 680-700 ℃, and the heat preservation time of the calcination is 8-10 h.
The invention also provides spherical lithium iron phosphate obtained by the preparation method.
The invention also provides application of the spherical lithium iron phosphate in a lithium battery.
The invention has the following beneficial effects
The invention provides a preparation method of spherical lithium iron phosphate, which comprises the following steps: (1) Mixing a lithium source, an iron source, a carbon source and water, and calcining to obtain an intermediate lithium iron phosphate; (2) Mixing intermediate lithium iron phosphate, lithium salt, a carbon source and water, spraying and calcining to obtain the spherical lithium iron phosphate. The invention processes and modifies the material based on the existing equipment, does not need to increase extra equipment cost, and the cycle life of the LFP material is not affected. After the primary high-temperature reaction is carried out to form a phase, the particle diameter of the LFP is controlled to be uniformly distributed between 150 and 200nm by secondary ball milling, and the spherical LFP particles D50 are controlled to be about 7 mu m by two-fluid spray drying. Under the condition of ensuring pure-phase LFP, uniform primary particle distribution can be achieved, the nano-scale regulation and control can ensure the deintercalation rate of lithium ions in the low-temperature charge and discharge process, and the electrochemical performance of the lithium ions is improved; the secondary particle spherical design ensures the internal porosity of the LFP material, and the circulation performance of the LFP material is not affected while the multiplying power is improved.
The invention also provides the spherical lithium iron phosphate prepared by the preparation method, the multiplying power performance is obviously improved, the 10C reaches more than 150mAh/g, and the application of the LFP material in the field of high-power supplies is widened.
Drawings
FIG. 1 is an SEM image of spherical lithium iron phosphate prepared according to example 1;
fig. 2 is a graph showing the discharge capacity comparison of the spherical lithium iron phosphate prepared in example 1 and comparative example 1.
Detailed Description
The invention provides a preparation method of spherical lithium iron phosphate, which comprises the following steps:
(1) Mixing a lithium source, an iron source, a carbon source and water, and calcining to obtain an intermediate lithium iron phosphate;
(2) Mixing intermediate lithium iron phosphate, lithium salt, a carbon source and water, spraying and calcining to obtain the spherical lithium iron phosphate.
In the present invention, the lithium source in step (1) comprises lithium carbonate and lithium hydroxide monohydrate, and the iron source is preferably iron phosphate.
In the invention, the mass ratio of the lithium source to the iron source is preferably 35-45: 145 to 160, more preferably 37 to 43:150 to 155, more preferably 39 to 41: 152-153.
In the invention, the mass ratio of the lithium carbonate to the lithium hydroxide monohydrate is preferably 20-30: 10 to 20, more preferably 22 to 28:12 to 18, more preferably 24 to 26:14 to 16.
In the present invention, the carbon source in step (1) is preferably one or more of glucose, PEG and citric acid.
In the present invention, the molecular weight of the PEG is 2000 or 6000.
In the present invention, the mass ratio of the carbon source to the lithium source is preferably 1 to 4:35 to 45, more preferably 2 to 3:37 to 43, more preferably 2.2 to 2.8:39 to 41.
In the present invention, the solid content of the mixture obtained by mixing the lithium source, the iron source, the carbon source and water is preferably 30 to 40%, more preferably 32 to 38%, and even more preferably 34 to 36%.
In the invention, the mixture obtained in the step (1) is mixed, and then is ground, sprayed and calcined in sequence.
In the present invention, the median particle diameter D50 after grinding is preferably 0.3 to 0.4. Mu.m, more preferably 0.32 to 0.38. Mu.m, still more preferably 0.34 to 0.36. Mu.m.
In the present invention, the calcination process in step (1) is performed under a protective atmosphere, preferably nitrogen.
In the present invention, the temperature of the calcination in the step (1) is preferably 680 to 750 ℃, more preferably 700 to 730 ℃, still more preferably 710 to 720 ℃, and the heat-retaining time of the calcination is preferably 10 to 16 hours, more preferably 11 to 15 hours, still more preferably 12 to 13 hours.
In the present invention, the mass ratio of the intermediate lithium iron phosphate, lithium salt and carbon source in step (2) is preferably 180 to 220:0.5 to 2:3 to 5, more preferably 190 to 210:1 to 1.5:3.5 to 4.5, more preferably 195 to 205:1.2 to 1.3:3.8 to 4.2.
In the present invention, the lithium salt in step (2) is preferably lithium hydroxide monohydrate and the carbon source is preferably glucose.
In the present invention, the solid content of the mixture obtained by mixing the intermediate lithium iron phosphate, lithium salt, carbon source and water in the step (2) is preferably 30 to 40%, more preferably 32 to 38%, and even more preferably 34 to 36%.
In the invention, the mixture obtained in the step (2) is subjected to ball milling and then is subjected to spraying and calcining processes.
In the present invention, the particle diameter D50 of the mixture after ball milling is preferably 0.15 to 0.20. Mu.m, more preferably 0.16 to 0.19. Mu.m, still more preferably 0.17 to 0.18. Mu.m.
In the present invention, the feeding temperature of the spray in the step (2) is preferably 180 to 220 ℃, more preferably 190 to 210 ℃, still more preferably 195 to 205 ℃, and the discharging temperature of the spray is preferably 90 to 110 ℃, more preferably 95 to 105 ℃, still more preferably 98 to 102 ℃.
In the present invention, the spray in the step (2) is a two-fluid spray, and the median particle diameter D50 of the mixture after the two-fluid spray is preferably 4 to 10. Mu.m, more preferably 5 to 9. Mu.m, still more preferably 6 to 8. Mu.m.
In the present invention, the calcination process in step (2) is performed under a protective atmosphere, preferably nitrogen.
In the present invention, the temperature of the calcination in the step (2) is preferably 680 to 700 ℃, more preferably 685 to 695 ℃, still more preferably 688 to 692 ℃, and the heat-preserving time of the calcination is preferably 8 to 10 hours, more preferably 8.5 to 9.5 hours, still more preferably 8.8 to 9.2 hours.
The invention also provides spherical lithium iron phosphate obtained by the preparation method.
The invention also provides application of the spherical lithium iron phosphate in a lithium battery.
In the present invention, the preparation materials are commercially available as known to those skilled in the art unless otherwise specified.
The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1
Mixing 150.82g of ferric phosphate, 25.12g of lithium carbonate, 14.27g of lithium hydroxide monohydrate, 2.28g of glucose and 357.48g of water, grinding to obtain a mixture with D50 of 0.351 mu m, centrifugally spray-drying the mixture, and sintering at 700 ℃ for 12 hours in a nitrogen atmosphere to obtain an intermediate lithium iron phosphate;
mixing 200.00g of intermediate lithium iron phosphate, 0.72g of lithium hydroxide monohydrate, 3.60g of glucose and 379.45g of water, ball-milling until the D50 is 0.172 mu m, spray-drying by using two fluids, wherein the feeding temperature is 201 ℃, the discharging temperature is 101 ℃, and the D50 of the mixture is 7.3 mu m after the two fluids are spray-dried; then sintering for 9h at 690 ℃ in nitrogen atmosphere; and obtaining spherical lithium iron phosphate.
SEM analysis is carried out on the spherical lithium iron phosphate prepared in example 1, as shown in FIG. 1, it can be seen from FIG. 1 that the secondary spherical particles of lithium iron phosphate have a particle diameter of 6-8 μm, a sphericity is relatively regular, the average value of primary particles forming spherical particles is 150-200 nm, and the primary particles have uniform size, which is a key factor for ensuring high-power performance of lithium iron phosphate.
Example 2
The procedure for the preparation of intermediate lithium iron phosphate was the same as in example 1, except for the preparation of spherical lithium iron phosphate.
Mixing 200.00g of intermediate lithium iron phosphate, 0.5g of lithium hydroxide monohydrate, 4.0g of glucose and 333.43g of water, ball-milling until the D50 is 0.20 mu m, spray-drying by using two fluids, wherein the feeding temperature is 182 ℃, the discharging temperature is 91 ℃, and the D50 of the mixture is 4.1 mu m after the two fluids are spray-dried; then sintering for 10 hours at 700 ℃ in nitrogen atmosphere; and obtaining spherical lithium iron phosphate.
Example 3
The procedure for the preparation of intermediate lithium iron phosphate was the same as in example 1, except for the preparation of spherical lithium iron phosphate.
Mixing 200.00g of intermediate lithium iron phosphate sample, 1.08g of lithium hydroxide monohydrate, 3.2g of glucose and 414.75g of water, ball-milling until the D50 is 0.151 mu m, spray-drying by using two fluids, wherein the feeding temperature is 219 ℃, the discharging temperature is 108 ℃, and the D50 of the mixture is 10 mu m after the two fluids are spray-dried; then sintering at 680 ℃ for 8 hours under nitrogen atmosphere; and obtaining spherical lithium iron phosphate.
Comparative example 1
An intermediate lithium iron phosphate was prepared in the manner of example 1.
Comparative example 2
150.82g of ferric phosphate, 25.37g of lithium carbonate, 14.41g of lithium hydroxide monohydrate, 3.05g of glucose and 315.94g of water are mixed and ground to obtain a mixture with D50 of 0.398 mu m, and the mixture is centrifugally spray-dried and sintered for 16 hours at 750 ℃ in a nitrogen atmosphere to obtain the intermediate lithium iron phosphate.
Comparative example 3
150.82g of ferric phosphate, 24.88g of lithium carbonate, 14.13g of lithium hydroxide monohydrate, 1.90g of glucose and 389.25g of water are mixed and ground to obtain a mixture with D50 of 0.303 mu m, and the mixture is centrifugally spray-dried and sintered for 10 hours at 680 ℃ in a nitrogen atmosphere to obtain the intermediate lithium iron phosphate.
The products obtained in examples 1 to 3 and comparative examples 1 to 3 were subjected to rate performance test at 25℃and the results are shown in Table 1:
table 1 results of rate performance test of lithium iron phosphate prepared in examples and comparative examples at 25 c
As can be seen from table 1, through the secondary ball milling and the two-fluid spraying process, the deintercalation rate of lithium ions in the charge and discharge process can be ensured, and the electrochemical performance of the lithium ions is improved; the secondary particle spherical design ensures that the internal porosity of the composite material improves the rate capability of the composite material, and meanwhile, the rate capability of the lithium iron phosphate which does not affect the cycle performance of the LFP material is obviously improved, and the rate capability of 10C reaches 151.2mAh/g.
The products obtained in examples 1 to 3 and comparative examples 1 to 3 were subjected to rate performance test at 0℃and the results are shown in Table 2:
table 2 results of rate performance test of lithium iron phosphate prepared in examples and comparative examples at 0c
As can be seen from table 2, the low-temperature rate performance of the lithium iron phosphate battery obtained by the preparation method of the invention is better, which indicates that the secondary ball milling, the two-fluid spraying process and the accurate carbon content coating can improve the low-temperature performance of the lithium iron phosphate.
The discharge capacity test is carried out on the spherical lithium iron phosphate prepared in the example 1 and the comparative example 1, and the result is shown in fig. 2, and it can be seen from fig. 2 that the rate capability, especially the 10C capacity, of the lithium iron phosphate battery obtained by the preparation method of the invention is obviously improved, and compared with the comparative example, the discharge capacity test is obviously improved.
The above method for testing electrochemical performance of lithium iron phosphate material refers to appendix F in national standard GB/T30835-2014: a method for measuring first coulombic efficiency, first reversible specific capacity and multiplying power performance.
From the above examples, the present invention provides a method for preparing spherical lithium iron phosphate, comprising the following steps: (1) Mixing a lithium source, an iron source, a carbon source and water, and calcining to obtain an intermediate lithium iron phosphate; (2) Mixing intermediate lithium iron phosphate, lithium salt, a carbon source and water, spraying and calcining to obtain the spherical lithium iron phosphate. The invention controls the LFP particle diameter to be evenly distributed between 150 and 200nm after the phase formation by the primary high-temperature reaction and controls the spherical lithium iron phosphate particle D50 to be about 7 mu m by the two-fluid spray drying. According to the embodiment, the multiplying power performance of the lithium iron phosphate battery provided by the invention is obviously improved, the 10C reaches more than 150mAh/g, and the application of the LFP material in the field of high-power supplies is widened.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A method for preparing spherical lithium iron phosphate, which is characterized by comprising the following steps:
(1) Mixing a lithium source, an iron source, a carbon source and water, and calcining to obtain an intermediate lithium iron phosphate;
(2) Mixing intermediate lithium iron phosphate, lithium salt, a carbon source and water, spraying and calcining to obtain the spherical lithium iron phosphate.
2. The method of claim 1, wherein the lithium source in step (1) comprises lithium carbonate and lithium hydroxide monohydrate and the iron source is iron phosphate;
the mass ratio of the lithium source to the iron source is 35-45: 145-160;
the mass ratio of the lithium carbonate to the lithium hydroxide monohydrate is 20-30: 10 to 20.
3. The method of claim 1 or 2, wherein the carbon source in step (1) is one or more of glucose, PEG, and citric acid;
the mass ratio of the carbon source to the lithium source is 1-4: 35 to 45.
4. The method according to claim 3, wherein the calcination temperature in step (1) is 680 to 750 ℃ and the calcination holding time is 10 to 16 hours.
5. The method according to claim 4, wherein the mass ratio of the intermediate lithium iron phosphate, lithium salt and carbon source in the step (2) is 180 to 220:0.5 to 2:3 to 5.
6. The method of claim 4 or 5, wherein the lithium salt in step (2) is lithium hydroxide monohydrate;
the carbon source is glucose.
7. The process according to claim 6, wherein the spray in step (2) is fed at a temperature of 180 to 220℃and the spray is discharged at a temperature of 90 to 110 ℃.
8. The method according to claim 7, wherein the calcination temperature in the step (2) is 680 to 700 ℃ and the calcination holding time is 8 to 10 hours.
9. The spherical lithium iron phosphate obtained by the production process according to any one of claims 1 to 8.
10. Use of the spherical lithium iron phosphate of claim 9 in a lithium battery.
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| CN102275887A (en) * | 2011-01-17 | 2011-12-14 | 横店集团东磁股份有限公司 | Preparation method of high capacity high compacted density lithium iron phosphate material and product thereof |
| CN107359336A (en) * | 2017-07-12 | 2017-11-17 | 北方奥钛纳米技术有限公司 | The preparation method and LiFePO4 and lithium ion battery of LiFePO4 |
| CN113072051A (en) * | 2021-03-26 | 2021-07-06 | 天津斯科兰德科技有限公司 | Post-treatment method of phosphate system anode material |
| CN114050259A (en) * | 2021-12-08 | 2022-02-15 | 程冲 | Preparation of single crystal high compaction lithium iron phosphate by primary reduction shaping secondary liquid phase coating method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102275887A (en) * | 2011-01-17 | 2011-12-14 | 横店集团东磁股份有限公司 | Preparation method of high capacity high compacted density lithium iron phosphate material and product thereof |
| CN107359336A (en) * | 2017-07-12 | 2017-11-17 | 北方奥钛纳米技术有限公司 | The preparation method and LiFePO4 and lithium ion battery of LiFePO4 |
| CN113072051A (en) * | 2021-03-26 | 2021-07-06 | 天津斯科兰德科技有限公司 | Post-treatment method of phosphate system anode material |
| CN114050259A (en) * | 2021-12-08 | 2022-02-15 | 程冲 | Preparation of single crystal high compaction lithium iron phosphate by primary reduction shaping secondary liquid phase coating method |
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