WO2025000793A1 - Lithium iron phosphate positive electrode material, and preparation method therefor and use thereof - Google Patents
Lithium iron phosphate positive electrode material, and preparation method therefor and use thereof Download PDFInfo
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- WO2025000793A1 WO2025000793A1 PCT/CN2023/128477 CN2023128477W WO2025000793A1 WO 2025000793 A1 WO2025000793 A1 WO 2025000793A1 CN 2023128477 W CN2023128477 W CN 2023128477W WO 2025000793 A1 WO2025000793 A1 WO 2025000793A1
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- WIPO (PCT)
- Prior art keywords
- lithium
- iron phosphate
- positive electrode
- electrode material
- preparation
- Prior art date
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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 75
- 239000007774 positive electrode material Substances 0.000 title claims abstract description 56
- 238000002360 preparation method Methods 0.000 title claims abstract description 24
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 39
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 39
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 30
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims abstract description 28
- 238000005245 sintering Methods 0.000 claims abstract description 23
- 229910000398 iron phosphate Inorganic materials 0.000 claims abstract description 22
- VAKIVKMUBMZANL-UHFFFAOYSA-N iron phosphide Chemical compound P.[Fe].[Fe].[Fe] VAKIVKMUBMZANL-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000007788 liquid Substances 0.000 claims abstract description 16
- 229920002239 polyacrylonitrile Polymers 0.000 claims abstract description 15
- 238000002156 mixing Methods 0.000 claims abstract description 11
- 238000000034 method Methods 0.000 claims abstract description 10
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 18
- 229910001416 lithium ion Inorganic materials 0.000 claims description 18
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 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
- 239000002245 particle Substances 0.000 claims description 11
- 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
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- TUSDEZXZIZRFGC-UHFFFAOYSA-N 1-O-galloyl-3,6-(R)-HHDP-beta-D-glucose Natural products OC1C(O2)COC(=O)C3=CC(O)=C(O)C(O)=C3C3=C(O)C(O)=C(O)C=C3C(=O)OC1C(O)C2OC(=O)C1=CC(O)=C(O)C(O)=C1 TUSDEZXZIZRFGC-UHFFFAOYSA-N 0.000 claims description 6
- 239000001263 FEMA 3042 Substances 0.000 claims description 6
- 239000005955 Ferric phosphate Substances 0.000 claims description 6
- LRBQNJMCXXYXIU-PPKXGCFTSA-N Penta-digallate-beta-D-glucose Natural products OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-PPKXGCFTSA-N 0.000 claims description 6
- 229940032958 ferric phosphate Drugs 0.000 claims description 6
- 229910000399 iron(III) phosphate Inorganic materials 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 238000001694 spray drying Methods 0.000 claims description 6
- LRBQNJMCXXYXIU-NRMVVENXSA-N tannic acid Chemical compound OC1=C(O)C(O)=CC(C(=O)OC=2C(=C(O)C=C(C=2)C(=O)OC[C@@H]2[C@H]([C@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)[C@@H](OC(=O)C=3C=C(OC(=O)C=4C=C(O)C(O)=C(O)C=4)C(O)=C(O)C=3)O2)OC(=O)C=2C=C(OC(=O)C=3C=C(O)C(O)=C(O)C=3)C(O)=C(O)C=2)O)=C1 LRBQNJMCXXYXIU-NRMVVENXSA-N 0.000 claims description 6
- 229940033123 tannic acid Drugs 0.000 claims description 6
- 235000015523 tannic acid Nutrition 0.000 claims description 6
- 229920002258 tannic acid Polymers 0.000 claims description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims description 5
- 239000011574 phosphorus Substances 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 239000000463 material Substances 0.000 abstract description 7
- 238000005056 compaction Methods 0.000 abstract description 4
- 229910003481 amorphous carbon Inorganic materials 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 239000007772 electrode material Substances 0.000 abstract description 2
- 239000004576 sand Substances 0.000 description 9
- 239000012300 argon atmosphere Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 7
- 239000003792 electrolyte Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 239000012298 atmosphere Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 3
- 239000002033 PVDF binder Substances 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000010406 cathode material Substances 0.000 description 3
- 239000002270 dispersing agent Substances 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- -1 lithium hexafluorophosphate Chemical compound 0.000 description 3
- 238000003760 magnetic stirring Methods 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 101001121408 Homo sapiens L-amino-acid oxidase Proteins 0.000 description 2
- 101000827703 Homo sapiens Polyphosphoinositide phosphatase Proteins 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 102100026388 L-amino-acid oxidase Human genes 0.000 description 2
- 102100023591 Polyphosphoinositide phosphatase Human genes 0.000 description 2
- 101100012902 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) FIG2 gene Proteins 0.000 description 2
- 101100233916 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) KAR5 gene Proteins 0.000 description 2
- 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 description 2
- 229930006000 Sucrose Natural products 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000005720 sucrose Substances 0.000 description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000007704 transition Effects 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- 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
-
- 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
-
- 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
-
- 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
- C01P2006/80—Compositional purity
-
- 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
Definitions
- the present invention relates to the technical field of electrode materials, and in particular to a lithium iron phosphate positive electrode material and a preparation method and application thereof.
- ternary cathode materials have problems such as releasing oxygen and thermal instability during phase transition. Therefore, ternary cathodes are accompanied by significant safety issues.
- the energy density of lithium iron phosphate cathodes is lower than that of ternary cathodes, it has high safety performance and good cycle stability. Because of this, lithium iron phosphate cathodes have also ushered in new developments in recent years.
- the problem of poor intrinsic conductivity of lithium iron phosphate makes it impossible to fully exert its capacity, resulting in incomplete capacity release of lithium iron phosphate cathode materials, low energy density, and poor cycle performance. Therefore, to improve the energy density and cycle life of lithium iron phosphate batteries, the conductivity of lithium iron phosphate materials must first be improved.
- the current industrial method usually uses carbon coating to improve the conductivity of lithium iron phosphate, generally using glucose or sucrose as the carbon source. Studies have shown that when the temperature reaches the melting point of glucose or sucrose, they will adhere to the surface of the lithium iron phosphate precursor. During high-temperature sintering, the carbon source inhibits the grain growth of lithium iron phosphate and forms a carbon coating layer. This method can effectively improve the conductivity of lithium iron phosphate and is conducive to the infiltration of the electrolyte. However, after too much amorphous carbon is compounded with lithium iron phosphate, the compaction density will be greatly reduced, resulting in a decrease in the energy density of the battery.
- the purpose of the present invention is to provide a lithium iron phosphate positive electrode material and a preparation method and application thereof.
- the lithium iron phosphate positive electrode material prepared by the preparation method of the present invention has high compaction density and high specific capacity.
- the present invention provides a method for preparing a lithium iron phosphate positive electrode material, comprising the following steps: mixing iron phosphate, a lithium source and a carbon source After that, sintering is performed to obtain the lithium iron phosphate positive electrode material; the carbon source includes liquid polyacrylonitrile; the sintering temperature is 750-810°C, and is not 750°C.
- the lithium source includes lithium carbonate and/or lithium hydroxide; the molar ratio of the iron in the iron phosphate, the phosphorus in the iron phosphate and the lithium in the lithium source is 1:1:(1-1.05).
- the carbon source also includes glucose and/or tannic acid.
- the mass of the carbon source accounts for 5-15% of the total mass of the iron phosphate and the lithium source.
- the mass of the liquid polyacrylonitrile is 2-12% of the total mass of the iron phosphate and the lithium source.
- the mass of the glucose is 3-12% of the total mass of the iron phosphate and the lithium source; the mass of the tannic acid is 1-3% of the total mass of the iron phosphate and the lithium source.
- the particle size of the mixture obtained by mixing is ⁇ 300 nm; and the sintering time is 3 to 24 hours.
- the present invention also provides a lithium iron phosphate positive electrode material prepared by the preparation method described in the above technical solution, wherein the lithium iron phosphate positive electrode material contains carbon and iron phosphide.
- the carbon content in the lithium iron phosphate positive electrode material is 0.5-2.5 wt %; the iron phosphide content in the lithium iron phosphate positive electrode material is 0.2-2 wt %.
- the present invention also provides the use of the lithium iron phosphate positive electrode material described in the above technical solution in a lithium ion battery.
- the present invention provides a method for preparing a lithium iron phosphate positive electrode material, comprising the following steps: mixing iron phosphate, a lithium source and a carbon source, and sintering to obtain the lithium iron phosphate positive electrode material;
- the carbon source includes liquid polyacrylonitrile;
- the sintering temperature is 750-810°C, and is not 750°C.
- the present invention introduces liquid polyacrylonitrile as a carbon source, which can produce iron phosphide at a lower sintering temperature, and then prepare a lithium iron phosphate positive electrode material containing iron phosphide; since iron phosphide has a higher electrical conductivity, the amount of carbon source can be reduced to a certain extent to reduce the content of amorphous carbon in the lithium iron phosphate material, thereby increasing the compaction density of the lithium iron phosphate material, and then increasing its electrochemical specific capacity.
- the preparation method of the present invention is simple, easy to operate, excellent in performance, and suitable for large-scale mass production.
- FIG. 1 is an XRD diagram of the lithium iron phosphate positive electrode material described in Example 3.
- FIG. 2 is an XRD diagram of the lithium iron phosphate positive electrode material described in Comparative Example 1.
- FIG. 3 is an XRD diagram of the lithium iron phosphate positive electrode material described in Comparative Example 2.
- FIG. 4 is a SEM image of the lithium iron phosphate positive electrode material described in Example 3.
- FIG5 is a cycle stability curve of the lithium-ion CR2032 button cell described in Example 3 at a current density of 1C.
- FIG6 is a diagram of the first cycle charge and discharge voltage of the lithium-ion CR2032 button battery described in Example 3.
- the present invention provides a method for preparing a lithium iron phosphate positive electrode material, comprising the following steps: mixing iron phosphate, a lithium source and a carbon source, and sintering to obtain the lithium iron phosphate positive electrode material; the carbon source comprises liquid polyacrylonitrile; and the sintering temperature is 750-810°C, and is not 750°C.
- the ferric phosphate serves as both an iron source and a phosphorus source.
- the lithium source preferably includes lithium carbonate and/or lithium hydroxide.
- the present invention has no special limitation on the amount of the lithium carbonate and lithium hydroxide, and they can be mixed in any ratio.
- the carbon source includes liquid polyacrylonitrile.
- the carbon source also preferably includes glucose and/or tannic acid; when the carbon source is two or more of the above specific options, the present invention has no special restrictions on the ratio of the above specific substances.
- the molar ratio of the iron in the ferric phosphate, the phosphorus in the ferric phosphate, and the lithium in the lithium source is preferably 1:1:(1 to 1.05).
- the mass of the carbon source preferably accounts for 5-15% of the total mass of the iron phosphate and the lithium source, and more preferably 8-12%.
- the mass of the liquid polyacrylonitrile is preferably 2-12% of the total mass of the iron phosphate and the lithium source, more preferably 4-10%, and most preferably 6-8%.
- the mass of the glucose is preferably 3-12% of the total mass of the iron phosphate and the lithium source, more preferably 5-10%, and most preferably 6-8%.
- the mass of the tannic acid is preferably 1 to 3% of the total mass of the iron phosphate and the lithium source, more preferably 1.5 to 2.5%, and most preferably 1.8 to 2.2%.
- the mixing method is preferably sand grinding; the sand grinding is preferably wet sand grinding;
- the sanding medium used in the wet sanding is preferably one or more of water, ethanol and methanol; when the sanding medium is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and they can be mixed in any ratio.
- the present invention does not have any special restrictions on the amount of the sanding medium, and the amount familiar to those skilled in the art can be used.
- the present invention does not have any special restrictions on the conditions of the sanding, and the conditions familiar to those skilled in the art can be used.
- the method Before the sintering, the method also includes: spray drying the mixture obtained by mixing; the spray drying temperature is preferably 100-300°C, more preferably 150-250°C, and most preferably 180-220°C; the spray drying time is preferably 1-6h, more preferably 2-5h, and most preferably 2-3h.
- the particle size of the mixture obtained after the mixing is preferably ⁇ 300 nm.
- the sintering is preferably carried out in a reducing atmosphere or a protective atmosphere;
- the reducing atmosphere is preferably an argon-hydrogen mixed gas, and the volume ratio of argon and hydrogen in the argon-hydrogen mixed gas is preferably 95:5;
- the protective atmosphere is preferably argon.
- the sintering temperature is 750-810°C, preferably 750-800°C, and more preferably 770-790°C;
- the sintering time is preferably 3-24h, more preferably 5-20h, and most preferably 10-15h.
- the present invention also provides a lithium iron phosphate positive electrode material prepared by the preparation method described in the above technical solution, wherein the lithium iron phosphate positive electrode material contains carbon and iron phosphide.
- the carbon content in the lithium iron phosphate positive electrode material is preferably 0.5-2.5wt%, more preferably 0.8-2.2wt%, more preferably 1.0-1.8wt%;
- the iron phosphide content in the lithium iron phosphate positive electrode material is preferably 0.2-2wt%, more preferably 0.4-1.6wt%, most preferably 0.6-1.2wt%.
- the particle size of the lithium iron phosphate positive electrode material is preferably 300 to 800 nm.
- the present invention also provides the application of the lithium iron phosphate cathode material described in the above technical solution in a lithium ion battery.
- the present invention does not have any special limitation on the method of the application, and the method well known to those skilled in the art can be used.
- lithium iron phosphate positive electrode material provided by the present invention and its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
- the lithium iron phosphate positive electrode material, conductive carbon black and polyvinylidene fluoride were mixed in a mass ratio of 100:3.5:3, and N-methylpyrrolidone was used as a dispersant. After magnetic stirring for 8 hours, the obtained slurry was coated on aluminum foil, dried at 70° C. for 12 hours, and vacuum dried at 80° C. for 12 hours to obtain the positive electrode sheet of the battery.
- a lithium-ion CR2032 button cell was assembled.
- the counter electrode was a metallic lithium sheet
- the lithium hexafluorophosphate electrolyte was the electrolyte of the lithium-ion CR2032 button cell
- the battery separator was Celgard 2400.
- the assembled lithium-ion CR2032 button battery was subjected to charge and discharge tests on a blue dot test system.
- the authorized charge and discharge specific capacities of the lithium-ion CR2032 button battery were 160.8mAh ⁇ g -1 and 156mAh ⁇ g -1 , respectively; and the cycle stability was good.
- the lithium iron phosphate positive electrode material, conductive carbon black and polyvinylidene fluoride were mixed in a mass ratio of 100:3.5:3, and N-methylpyrrolidone was used as a dispersant. After magnetic stirring for 8 hours, the obtained slurry was coated on aluminum foil, dried at 70° C. for 12 hours, and vacuum dried at 80° C. for 12 hours to obtain the positive electrode sheet of the battery.
- a lithium-ion CR2032 button cell was assembled.
- the counter electrode was a metallic lithium sheet
- the lithium hexafluorophosphate electrolyte was the electrolyte of the lithium-ion CR2032 button cell
- the battery separator was Celgard 2400.
- the assembled lithium-ion CR2032 button battery was subjected to charge and discharge tests on a blue dot test system.
- the authorized charge and discharge specific capacities of the lithium-ion CR2032 button battery were 154.7mAh ⁇ g -1 and 150.1mAh ⁇ g -1 , respectively; and the cycle stability was good.
- FIG1 is an XRD diagram of the lithium iron phosphate positive electrode material.
- the lithium iron phosphate positive electrode material prepared according to the conditions of Example 1 has a carbon content of about 1.34 wt % and contains about 0.5 wt % of iron phosphide.
- FIG4 is a SEM image of the lithium iron phosphate positive electrode material. It can be seen from FIG4 that the lithium iron phosphate positive electrode material prepared according to the conditions of Example 1 has relatively uniform particles, and the particle size is all below 500 nm.
- the lithium iron phosphate positive electrode material, conductive carbon black and polyvinylidene fluoride are mixed in a mass ratio of 100:3.5:3, and N-methylpyrrolidone is used as a dispersant. After magnetic stirring for 8 hours, the obtained slurry is coated on aluminum foil, dried at 70°C for 12 hours, and vacuum dried at 80°C for 12 hours to obtain the positive electrode sheet of the battery.
- a lithium-ion CR2032 button cell was assembled.
- the counter electrode was a metallic lithium sheet
- the lithium hexafluorophosphate electrolyte was the electrolyte of the lithium-ion CR2032 button cell
- the battery separator was Celgard 2400.
- the assembled lithium-ion CR2032 button cell was subjected to charge and discharge tests on a Blue Dot test system.
- the first cycle charge and discharge specific capacities of the lithium-ion CR2032 button cell were 159.8mAh ⁇ g -1 and 153.9mAh ⁇ g -1 , respectively; the cycle stability was good, and the capacity retention rate after 100 cycles at a current density of 1C was 93.4%, as shown in FIG5 .
- FIG6 is a graph of the first charge and discharge voltage of the lithium-ion CR2032 button cell, from which it can be seen that the lithium iron phosphate positive electrode prepared according to Example 1 has a higher gram capacity and a smaller polarization voltage in the first charge and discharge cycle, indicating that optimizing the carbon content and the iron phosphide content plays a key role in improving the electrochemical performance of the lithium iron phosphate positive electrode.
- lithium iron phosphate positive electrode material carbon content of about 1.31wt%, iron phosphide content of 0, and particle size of about 350nm. It shows that lithium iron phosphate positive electrode material containing iron phosphide cannot be prepared without adding liquid polyacrylonitrile.
- FIG2 is an XRD diagram of the lithium iron phosphate positive electrode material.
- the lithium iron phosphate positive electrode material prepared according to the conditions of Comparative Example 1 (without adding liquid acrylonitrile) does not contain iron phosphide components.
- the difference is that the sintering temperature is 750°C, and a lithium iron phosphate positive electrode material (carbon content is about 1.5wt%, iron phosphide content is 0, and particle size is about 360nm) is obtained. It shows that if the sintering temperature is too low, a lithium iron phosphate positive electrode material containing iron phosphide cannot be obtained.
- FIG3 is an XRD diagram of the lithium iron phosphate positive electrode material.
- the lithium iron phosphate positive electrode material prepared according to the conditions of Comparative Example 2 sining at 750° C. does not contain iron phosphide.
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Abstract
Description
本申请要求于2023年06月26日提交中国专利局、申请号为202310754083.2、发明名称为“一种磷酸铁锂正极材料及其制备方法和应用”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。This application claims the priority of the Chinese patent application filed with the China Patent Office on June 26, 2023, with application number 202310754083.2 and invention name “A lithium iron phosphate positive electrode material, preparation method and application thereof”, the entire contents of which are incorporated by reference in this application.
本发明涉及电极材料技术领域，尤其涉及一种磷酸铁锂正极材料及其制备方法和应用。The present invention relates to the technical field of electrode materials, and in particular to a lithium iron phosphate positive electrode material and a preparation method and application thereof.
近些年来，电动汽车产业高速发展，三元动力电池由于能量密度高的优点，在动力电池市场占据重要的份额，但三元正极材料具有在相转变过程中释放氧气和热不稳定等问题，因此，三元正极伴随着显著的安全问题，磷酸铁锂正极虽然能量密度较三元正极低，但安全性能高，循环稳定性好。正因为如此，磷酸铁锂正极近年来也迎来了全新的发展。然而，磷酸铁锂本征导电性差的问题使得它的容量无法完全发挥出来，导致磷酸铁锂正极材料容量释放不完全，能量密度低，循环性能差。因此，要提高磷酸铁锂电池的能量密度和循环寿命，首先得提高磷酸铁锂材料的导电率。In recent years, the electric vehicle industry has developed rapidly. Due to the advantage of high energy density, ternary power batteries occupy an important share in the power battery market. However, ternary cathode materials have problems such as releasing oxygen and thermal instability during phase transition. Therefore, ternary cathodes are accompanied by significant safety issues. Although the energy density of lithium iron phosphate cathodes is lower than that of ternary cathodes, it has high safety performance and good cycle stability. Because of this, lithium iron phosphate cathodes have also ushered in new developments in recent years. However, the problem of poor intrinsic conductivity of lithium iron phosphate makes it impossible to fully exert its capacity, resulting in incomplete capacity release of lithium iron phosphate cathode materials, low energy density, and poor cycle performance. Therefore, to improve the energy density and cycle life of lithium iron phosphate batteries, the conductivity of lithium iron phosphate materials must first be improved.
目前产业化方法通常是利用碳包覆来提高磷酸铁锂的导电率，一般采用葡萄糖或者蔗糖作为碳源。研究表明，当温度达到葡萄糖或者蔗糖的熔点后，他们会粘附在磷酸铁锂前驱体的表面，高温烧结时，碳源抑制磷酸铁锂的晶粒长大，同时形成碳包覆层。这种方法能够有效提高磷酸铁锂的导电率，且有利于电解液的浸润。但是过多的无定形碳与磷酸铁锂复合之后，压实密度会大大降低，导致电池的能量密度降低。The current industrial method usually uses carbon coating to improve the conductivity of lithium iron phosphate, generally using glucose or sucrose as the carbon source. Studies have shown that when the temperature reaches the melting point of glucose or sucrose, they will adhere to the surface of the lithium iron phosphate precursor. During high-temperature sintering, the carbon source inhibits the grain growth of lithium iron phosphate and forms a carbon coating layer. This method can effectively improve the conductivity of lithium iron phosphate and is conducive to the infiltration of the electrolyte. However, after too much amorphous carbon is compounded with lithium iron phosphate, the compaction density will be greatly reduced, resulting in a decrease in the energy density of the battery.
发明内容Summary of the invention
本发明的目的在于提供一种磷酸铁锂正极材料及其制备方法和应用。利用本发明所述的制备方法制备得到的磷酸铁锂正极材料压实密度高，比容量高。The purpose of the present invention is to provide a lithium iron phosphate positive electrode material and a preparation method and application thereof. The lithium iron phosphate positive electrode material prepared by the preparation method of the present invention has high compaction density and high specific capacity.
为了实现上述发明目的，本发明提供以下技术方案：本发明提供了一种磷酸铁锂正极材料的制备方法，包括以下步骤：将磷酸铁、锂源和碳源混合 后，进行烧结，得到所述磷酸铁锂正极材料；所述碳源包括液态聚丙烯腈；所述烧结的温度为750～810℃，且不为750℃。In order to achieve the above-mentioned invention object, the present invention provides the following technical solutions: The present invention provides a method for preparing a lithium iron phosphate positive electrode material, comprising the following steps: mixing iron phosphate, a lithium source and a carbon source After that, sintering is performed to obtain the lithium iron phosphate positive electrode material; the carbon source includes liquid polyacrylonitrile; the sintering temperature is 750-810°C, and is not 750°C.
优选的，所述锂源包括碳酸锂和/或氢氧化锂；所述磷酸铁中的铁、所述磷酸铁中的磷和所述锂源中的锂的摩尔比为1:1:(1～1.05)。Preferably, the lithium source includes lithium carbonate and/or lithium hydroxide; the molar ratio of the iron in the iron phosphate, the phosphorus in the iron phosphate and the lithium in the lithium source is 1:1:(1-1.05).
优选的，所述碳源还包括葡萄糖和/或单宁酸。Preferably, the carbon source also includes glucose and/or tannic acid.
优选的，所述碳源的质量占所述磷酸铁和锂源总质量的5～15％。Preferably, the mass of the carbon source accounts for 5-15% of the total mass of the iron phosphate and the lithium source.
优选的，所述液态聚丙烯腈的质量为所述磷酸铁和锂源总质量的2～12％。Preferably, the mass of the liquid polyacrylonitrile is 2-12% of the total mass of the iron phosphate and the lithium source.
优选的，所述葡萄糖的质量为所述磷酸铁和锂源总质量的3～12％；所述单宁酸的质量为所述磷酸铁和锂源总质量的1～3％。Preferably, the mass of the glucose is 3-12% of the total mass of the iron phosphate and the lithium source; the mass of the tannic acid is 1-3% of the total mass of the iron phosphate and the lithium source.
优选的，所述混合得到的混合物的粒径≤300nm；所述烧结的时间为3～24h。Preferably, the particle size of the mixture obtained by mixing is ≤300 nm; and the sintering time is 3 to 24 hours.
本发明还提供了上述技术方案所述的制备方法制备得到的磷酸铁锂正极材料，所述磷酸铁锂正极材料中含有碳和磷化铁。The present invention also provides a lithium iron phosphate positive electrode material prepared by the preparation method described in the above technical solution, wherein the lithium iron phosphate positive electrode material contains carbon and iron phosphide.
优选的，所述磷酸铁锂正极材料中的碳含量为0.5～2.5wt％；所述磷酸铁锂正极材料中的磷化铁含量为0.2～2wt％。Preferably, the carbon content in the lithium iron phosphate positive electrode material is 0.5-2.5 wt %; the iron phosphide content in the lithium iron phosphate positive electrode material is 0.2-2 wt %.
本发明还提供了上述技术方案所述的磷酸铁锂正极材料在锂离子电池中的应用。The present invention also provides the use of the lithium iron phosphate positive electrode material described in the above technical solution in a lithium ion battery.
本发明提供了一种磷酸铁锂正极材料的制备方法，包括以下步骤：将磷酸铁、锂源和碳源混合后，进行烧结，得到所述磷酸铁锂正极材料；所述碳源包括液态聚丙烯腈；所述烧结的温度为750～810℃，且不为750℃。本发明引入液态聚丙烯腈作为碳源，可以实现在较低的烧结温度下产生磷化铁，进而制备得到含有磷化铁的磷酸铁锂正极材料；由于磷化铁具有较高的电导率，因此，在一定程度上可以降低碳源的用量，以减少磷酸铁锂材料中无定形碳的含量，从而提高磷酸铁锂材料的压实密度，进而提高其电化学比容量。同时，本发明所述制备方法简单，操作方便，性能优异，适合大规模量产。The present invention provides a method for preparing a lithium iron phosphate positive electrode material, comprising the following steps: mixing iron phosphate, a lithium source and a carbon source, and sintering to obtain the lithium iron phosphate positive electrode material; the carbon source includes liquid polyacrylonitrile; the sintering temperature is 750-810°C, and is not 750°C. The present invention introduces liquid polyacrylonitrile as a carbon source, which can produce iron phosphide at a lower sintering temperature, and then prepare a lithium iron phosphate positive electrode material containing iron phosphide; since iron phosphide has a higher electrical conductivity, the amount of carbon source can be reduced to a certain extent to reduce the content of amorphous carbon in the lithium iron phosphate material, thereby increasing the compaction density of the lithium iron phosphate material, and then increasing its electrochemical specific capacity. At the same time, the preparation method of the present invention is simple, easy to operate, excellent in performance, and suitable for large-scale mass production.
图1为实施例3所述磷酸铁锂正极材料的XRD图。FIG. 1 is an XRD diagram of the lithium iron phosphate positive electrode material described in Example 3.
图2为对比例1所述磷酸铁锂正极材料的XRD图。 FIG. 2 is an XRD diagram of the lithium iron phosphate positive electrode material described in Comparative Example 1.
图3为对比例2所述磷酸铁锂正极材料的XRD图。FIG. 3 is an XRD diagram of the lithium iron phosphate positive electrode material described in Comparative Example 2.
图4为实施例3所述磷酸铁锂正极材料的SEM图。FIG. 4 is a SEM image of the lithium iron phosphate positive electrode material described in Example 3.
图5为实施例3所述锂离子CR2032扣式电池在1C电流密度下的循环稳定性曲线。FIG5 is a cycle stability curve of the lithium-ion CR2032 button cell described in Example 3 at a current density of 1C.
图6为实施例3所述锂离子CR2032扣式电池首圈充放电电压图。FIG6 is a diagram of the first cycle charge and discharge voltage of the lithium-ion CR2032 button battery described in Example 3.
本发明提供了一种磷酸铁锂正极材料的制备方法，包括以下步骤：将磷酸铁、锂源和碳源混合后，进行烧结，得到所述磷酸铁锂正极材料；所述碳源包括液态聚丙烯腈；所述烧结的温度为750～810℃，且不为750℃。The present invention provides a method for preparing a lithium iron phosphate positive electrode material, comprising the following steps: mixing iron phosphate, a lithium source and a carbon source, and sintering to obtain the lithium iron phosphate positive electrode material; the carbon source comprises liquid polyacrylonitrile; and the sintering temperature is 750-810°C, and is not 750°C.
在本发明中，若无特殊说明，所有制备原料均为本领域技术人员熟知的市售产品。In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.
在本发明中，所述磷酸铁既作为铁源又作为磷源。In the present invention, the ferric phosphate serves as both an iron source and a phosphorus source.
在本发明中，所述锂源优选包括碳酸锂和/或氢氧化锂；当所述锂源为碳酸锂和氢氧化锂时，本发明对所述碳酸锂和氢氧化锂的用量没有任何特殊的限定，按任意配比进行混合即可。In the present invention, the lithium source preferably includes lithium carbonate and/or lithium hydroxide. When the lithium source is lithium carbonate and lithium hydroxide, the present invention has no special limitation on the amount of the lithium carbonate and lithium hydroxide, and they can be mixed in any ratio.
在本发明中，所述碳源包括液态聚丙烯腈。在本发明中，所述碳源还优选包括葡萄糖和/或单宁酸；当所述碳源为上述具体选择中的两种以上时，本发明对上述具体物质的配比没有任何特殊的限定。In the present invention, the carbon source includes liquid polyacrylonitrile. In the present invention, the carbon source also preferably includes glucose and/or tannic acid; when the carbon source is two or more of the above specific options, the present invention has no special restrictions on the ratio of the above specific substances.
在本发明中，所述磷酸铁中的铁、所述磷酸铁中的磷和所述锂源中的锂的摩尔比优选为1:1:(1～1.05)。In the present invention, the molar ratio of the iron in the ferric phosphate, the phosphorus in the ferric phosphate, and the lithium in the lithium source is preferably 1:1:(1 to 1.05).
在本发明中，所述碳源的质量优选占所述磷酸铁和锂源总质量的5～15％，更优选为8～12％。In the present invention, the mass of the carbon source preferably accounts for 5-15% of the total mass of the iron phosphate and the lithium source, and more preferably 8-12%.
在本发明中，所述液态聚丙烯腈的质量优选为所述磷酸铁和锂源总质量的2～12％，更优选为4～10％，最优选为6～8％。In the present invention, the mass of the liquid polyacrylonitrile is preferably 2-12% of the total mass of the iron phosphate and the lithium source, more preferably 4-10%, and most preferably 6-8%.
在本发明中，所述葡萄糖的质量优选为所述磷酸铁和锂源总质量的3～12％，更优选为5～10％，最优选为6～8％。In the present invention, the mass of the glucose is preferably 3-12% of the total mass of the iron phosphate and the lithium source, more preferably 5-10%, and most preferably 6-8%.
在本发明中，所述单宁酸的质量优选为所述磷酸铁和锂源总质量的1～3％，更优选为1.5～2.5％，最优选为1.8～2.2％。In the present invention, the mass of the tannic acid is preferably 1 to 3% of the total mass of the iron phosphate and the lithium source, more preferably 1.5 to 2.5%, and most preferably 1.8 to 2.2%.
在本发明中，所述混合的方式优选为砂磨；所述砂磨优选为湿法砂磨； 所述湿法砂磨采用的砂磨介质优选为水、乙醇和甲醇中的一种或几种；当所述砂磨介质为上述具体选择中的两种以上时，本发明对上述具体物质的配比没有任何特殊的限定，按任意配比进行混合即可。本发明对所述砂磨介质的用量没有任何特殊的限定，采用本领域技术人员熟知的用量即可。本发明对所述砂磨的条件没有任何特殊的限定，采用本领域技术人员熟知的条件进行即可。In the present invention, the mixing method is preferably sand grinding; the sand grinding is preferably wet sand grinding; The sanding medium used in the wet sanding is preferably one or more of water, ethanol and methanol; when the sanding medium is two or more of the above specific selections, the present invention does not have any special restrictions on the ratio of the above specific substances, and they can be mixed in any ratio. The present invention does not have any special restrictions on the amount of the sanding medium, and the amount familiar to those skilled in the art can be used. The present invention does not have any special restrictions on the conditions of the sanding, and the conditions familiar to those skilled in the art can be used.
所述烧结前还包括：将所述混合得到的混合物进行喷雾干燥；所述喷雾干燥的温度优选为100～300℃，更优选为150～250℃，最优选为180～220℃；所述喷雾干燥的时间优选为1～6h，更优选为2～5h，最优选为2～3h。Before the sintering, the method also includes: spray drying the mixture obtained by mixing; the spray drying temperature is preferably 100-300°C, more preferably 150-250°C, and most preferably 180-220°C; the spray drying time is preferably 1-6h, more preferably 2-5h, and most preferably 2-3h.
在本发明中，所述混合后得到的混合物的粒径优选≤300nm。In the present invention, the particle size of the mixture obtained after the mixing is preferably ≤300 nm.
在本发明中，所述烧结优选在还原气氛或保护气氛中进行；所述还原气氛优选为氩氢混合气，所述氩氢混合气中的氩气和氢气的体积比优选为95:5；所述保护气氛优选为氩气。在本发明中，所述烧结的温度为750～810℃，优选为750～800℃，更优选为770～790℃；时间优选为3～24h，更优选为5～20h，最优选为10～15h。In the present invention, the sintering is preferably carried out in a reducing atmosphere or a protective atmosphere; the reducing atmosphere is preferably an argon-hydrogen mixed gas, and the volume ratio of argon and hydrogen in the argon-hydrogen mixed gas is preferably 95:5; the protective atmosphere is preferably argon. In the present invention, the sintering temperature is 750-810°C, preferably 750-800°C, and more preferably 770-790°C; the sintering time is preferably 3-24h, more preferably 5-20h, and most preferably 10-15h.
本发明还提供了上述技术方案所述的制备方法制备得到的磷酸铁锂正极材料，所述磷酸铁锂正极材料中含有碳和磷化铁。The present invention also provides a lithium iron phosphate positive electrode material prepared by the preparation method described in the above technical solution, wherein the lithium iron phosphate positive electrode material contains carbon and iron phosphide.
在本发明中，所述磷酸铁锂正极材料中的碳含量优选为0.5～2.5wt％，更优选为0.8～2.2wt％，更优选为1.0～1.8wt％；所述磷酸铁锂正极材料中的磷化铁含量优选为0.2～2wt％，更优选为0.4～1.6wt％，最优选为0.6～1.2wt％。In the present invention, the carbon content in the lithium iron phosphate positive electrode material is preferably 0.5-2.5wt%, more preferably 0.8-2.2wt%, more preferably 1.0-1.8wt%; the iron phosphide content in the lithium iron phosphate positive electrode material is preferably 0.2-2wt%, more preferably 0.4-1.6wt%, most preferably 0.6-1.2wt%.
在本发明中，所述磷酸铁锂正极材料的粒径优选为300～800nm。In the present invention, the particle size of the lithium iron phosphate positive electrode material is preferably 300 to 800 nm.
本发明还提供了上述技术方案所述的磷酸铁锂正极材料在锂离子电池中的应用。本发明对所述应用的方法没有任何特殊的限定，采用本领域技术人员熟知的方法进行即可。The present invention also provides the application of the lithium iron phosphate cathode material described in the above technical solution in a lithium ion battery. The present invention does not have any special limitation on the method of the application, and the method well known to those skilled in the art can be used.
下面结合实施例对本发明提供的磷酸铁锂正极材料及其制备方法和应用进行详细的说明，但是不能把它们理解为对本发明保护范围的限定。The lithium iron phosphate positive electrode material provided by the present invention and its preparation method and application are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
实施例1Example 1
将1.4kg磷酸铁、0.349kg碳酸锂、87g葡萄糖、122g液态聚丙烯腈和4.1L去离子水混合，转移到砂磨机中砂磨3h，220℃喷雾干燥2h后，在氩 气气氛下800℃烧结10h，得到磷酸铁锂正极材料(含碳量约为1.34wt％，磷化铁的含量约为0.5wt％，粒径为350nm)。1.4 kg of ferric phosphate, 0.349 kg of lithium carbonate, 87 g of glucose, 122 g of liquid polyacrylonitrile and 4.1 L of deionized water were mixed and transferred to a sand mill for 3 h. After spray drying at 220 °C for 2 h, the mixture was heated to 40 °C and then dried under argon atmosphere. The material was sintered at 800° C. for 10 h in a gas atmosphere to obtain a lithium iron phosphate positive electrode material (with a carbon content of about 1.34 wt %, an iron phosphide content of about 0.5 wt %, and a particle size of 350 nm).
按照100:3.5:3的质量比，将所述磷酸铁锂正极材料、导电炭黑和聚偏氟乙烯混合，以N-甲基吡咯烷酮为分散剂，磁力搅拌8h后，将得到的浆料涂布在铝箔上，70℃干燥12h，80℃真空干燥12h，得到电池的正极极片。The lithium iron phosphate positive electrode material, conductive carbon black and polyvinylidene fluoride were mixed in a mass ratio of 100:3.5:3, and N-methylpyrrolidone was used as a dispersant. After magnetic stirring for 8 hours, the obtained slurry was coated on aluminum foil, dried at 70° C. for 12 hours, and vacuum dried at 80° C. for 12 hours to obtain the positive electrode sheet of the battery.
在氩气气氛的手套箱中，组装锂离子CR2032扣式电池，对电极为金属锂片，六氟磷酸锂电解液为所述锂离子CR2032扣式电池的电解液，电池隔膜为Celgard 2400。In a glove box with an argon atmosphere, a lithium-ion CR2032 button cell was assembled. The counter electrode was a metallic lithium sheet, the lithium hexafluorophosphate electrolyte was the electrolyte of the lithium-ion CR2032 button cell, and the battery separator was Celgard 2400.
将组装完成后的锂离子CR2032扣式电池在蓝点测试系统上进行充放电测试，在0.1C的电流密度下，所述锂离子CR2032扣式电池的授权充放电比容量分别为160.8mAh·g-1和156mAh·g-1；循环稳定性好。The assembled lithium-ion CR2032 button battery was subjected to charge and discharge tests on a blue dot test system. At a current density of 0.1C, the authorized charge and discharge specific capacities of the lithium-ion CR2032 button battery were 160.8mAh·g -1 and 156mAh·g -1 , respectively; and the cycle stability was good.
实施例2Example 2
将1.4kg磷酸铁、0.349kg碳酸锂、122g葡萄糖、157g液态聚丙烯腈和4.1L去离子水混合，转移到砂磨机中砂磨3h，在220℃喷雾干燥2h后，再在氩气气氛下800℃进行烧结10h，得到磷酸铁锂正极材料(含碳量约为2.05wt％，磷化铁的含量约为0.7wt％，粒径为350nm左右)。1.4 kg of iron phosphate, 0.349 kg of lithium carbonate, 122 g of glucose, 157 g of liquid polyacrylonitrile and 4.1 L of deionized water were mixed, transferred to a sand mill and sand ground for 3 hours, spray dried at 220°C for 2 hours, and then sintered at 800°C under an argon atmosphere for 10 hours to obtain a lithium iron phosphate positive electrode material (carbon content of about 2.05 wt%, iron phosphide content of about 0.7 wt%, particle size of about 350 nm).
按照100:3.5:3的质量比，将所述磷酸铁锂正极材料、导电炭黑和聚偏氟乙烯混合，以N-甲基吡咯烷酮为分散剂，磁力搅拌8h后，将得到的浆料涂布在铝箔上，70℃干燥12h，80℃真空干燥12h，得到电池的正极极片。The lithium iron phosphate positive electrode material, conductive carbon black and polyvinylidene fluoride were mixed in a mass ratio of 100:3.5:3, and N-methylpyrrolidone was used as a dispersant. After magnetic stirring for 8 hours, the obtained slurry was coated on aluminum foil, dried at 70° C. for 12 hours, and vacuum dried at 80° C. for 12 hours to obtain the positive electrode sheet of the battery.
在氩气气氛的手套箱中，组装锂离子CR2032扣式电池，对电极为金属锂片，六氟磷酸锂电解液为所述锂离子CR2032扣式电池的电解液，电池隔膜为Celgard 2400。In a glove box with an argon atmosphere, a lithium-ion CR2032 button cell was assembled. The counter electrode was a metallic lithium sheet, the lithium hexafluorophosphate electrolyte was the electrolyte of the lithium-ion CR2032 button cell, and the battery separator was Celgard 2400.
将组装完成后的锂离子CR2032扣式电池在蓝点测试系统上进行充放电测试，在0.1C的电流密度下，所述锂离子CR2032扣式电池的授权充放电比容量分别为154.7mAh·g-1和150.1mAh·g-1；循环稳定性好。The assembled lithium-ion CR2032 button battery was subjected to charge and discharge tests on a blue dot test system. At a current density of 0.1C, the authorized charge and discharge specific capacities of the lithium-ion CR2032 button battery were 154.7mAh·g -1 and 150.1mAh·g -1 , respectively; and the cycle stability was good.
实施例3Example 3
将1.4kg磷酸铁、0.349kg碳酸锂、72g葡萄糖、105g液态聚丙烯腈和4.1L去离子水混合，转移到砂磨机中砂磨3h，220℃喷雾干燥2h后，在氩气气氛下800℃烧结10h，得到磷酸铁锂正极材料(含碳量约为1.1wt％，磷 化铁的含量约为0.4wt％，粒径为350nm左右)。1.4 kg of iron phosphate, 0.349 kg of lithium carbonate, 72 g of glucose, 105 g of liquid polyacrylonitrile and 4.1 L of deionized water were mixed, transferred to a sand mill and sand ground for 3 h, spray dried at 220 ° C for 2 h, and sintered at 800 ° C for 10 h in an argon atmosphere to obtain a lithium iron phosphate positive electrode material (carbon content of about 1.1 wt%, phosphorus The content of iron oxide is about 0.4wt% and the particle size is about 350nm).
图1为所述磷酸铁锂正极材料的XRD图，由图1可知，按照实施例1的条件制备出的磷酸铁锂正极材料，其中含碳量约为1.34wt％，含有磷化铁约0.5wt％。FIG1 is an XRD diagram of the lithium iron phosphate positive electrode material. As can be seen from FIG1 , the lithium iron phosphate positive electrode material prepared according to the conditions of Example 1 has a carbon content of about 1.34 wt % and contains about 0.5 wt % of iron phosphide.
图4为所述磷酸铁锂正极材料的SEM图，由图4可知，按照实施例1的条件制备出的磷酸铁锂正极材料，颗粒较为均匀，粒径均在500nm以下。按照100:3.5:3的质量比，将所述磷酸铁锂正极材料、导电炭黑和聚偏氟乙烯混合，以N-甲基吡咯烷酮为分散剂，磁力搅拌8h后，将得到的浆料涂布在铝箔上，70℃干燥12h，80℃真空干燥12h，得到电池的正极极片。FIG4 is a SEM image of the lithium iron phosphate positive electrode material. It can be seen from FIG4 that the lithium iron phosphate positive electrode material prepared according to the conditions of Example 1 has relatively uniform particles, and the particle size is all below 500 nm. The lithium iron phosphate positive electrode material, conductive carbon black and polyvinylidene fluoride are mixed in a mass ratio of 100:3.5:3, and N-methylpyrrolidone is used as a dispersant. After magnetic stirring for 8 hours, the obtained slurry is coated on aluminum foil, dried at 70°C for 12 hours, and vacuum dried at 80°C for 12 hours to obtain the positive electrode sheet of the battery.
在氩气气氛的手套箱中，组装锂离子CR2032扣式电池，对电极为金属锂片，六氟磷酸锂电解液为所述锂离子CR2032扣式电池的电解液，电池隔膜为Celgard 2400。In a glove box with an argon atmosphere, a lithium-ion CR2032 button cell was assembled. The counter electrode was a metallic lithium sheet, the lithium hexafluorophosphate electrolyte was the electrolyte of the lithium-ion CR2032 button cell, and the battery separator was Celgard 2400.
将组装完成后的锂离子CR2032扣式电池在蓝点测试系统上进行充放电测试，在0.1C的电流密度下，所述锂离子CR2032扣式电池的首圈充放电比容量分别为159.8mAh·g-1和153.9mAh·g-1；循环稳定性好，1C电流密度100圈循环后容量保持率为93.4％，如图5所示。The assembled lithium-ion CR2032 button cell was subjected to charge and discharge tests on a Blue Dot test system. At a current density of 0.1C, the first cycle charge and discharge specific capacities of the lithium-ion CR2032 button cell were 159.8mAh·g -1 and 153.9mAh·g -1 , respectively; the cycle stability was good, and the capacity retention rate after 100 cycles at a current density of 1C was 93.4%, as shown in FIG5 .
图6为所述锂离子CR2032扣式电池首圈充放电电压图，由该图可知，按照实施例1制备出的磷酸铁锂正极在首圈充放电循环中有较高的克容量以及很小的极化电压。表明优化碳含量和磷化铁的含量对提高磷酸铁锂正极的电化学性能起到很关键的作用。FIG6 is a graph of the first charge and discharge voltage of the lithium-ion CR2032 button cell, from which it can be seen that the lithium iron phosphate positive electrode prepared according to Example 1 has a higher gram capacity and a smaller polarization voltage in the first charge and discharge cycle, indicating that optimizing the carbon content and the iron phosphide content plays a key role in improving the electrochemical performance of the lithium iron phosphate positive electrode.
对比例1Comparative Example 1
将1.4g磷酸铁、0.349kg碳酸锂、209g葡萄糖和4.1L去离子水混合，转移到砂磨机中砂磨3h，220℃喷雾干燥2h后，在氩气气氛下800℃烧结10h，得到磷酸铁锂正极材料(含碳量约为1.31wt％，磷化铁的含量为0，粒径为350nm左右)。说明，不加液态聚丙烯腈无法制备出含有磷化铁的磷酸铁锂正极材料。1.4g of iron phosphate, 0.349kg of lithium carbonate, 209g of glucose and 4.1L of deionized water were mixed, transferred to a sand mill and sanded for 3h, spray dried at 220℃ for 2h, and sintered at 800℃ for 10h in an argon atmosphere to obtain a lithium iron phosphate positive electrode material (carbon content of about 1.31wt%, iron phosphide content of 0, and particle size of about 350nm). It shows that lithium iron phosphate positive electrode material containing iron phosphide cannot be prepared without adding liquid polyacrylonitrile.
图2为所述磷酸铁锂正极材料的XRD图，由图2可知，按照对比例1的条件(不加液态丙烯腈)制备出的磷酸铁锂正极材料，其中不含有磷化铁成分。 FIG2 is an XRD diagram of the lithium iron phosphate positive electrode material. As can be seen from FIG2 , the lithium iron phosphate positive electrode material prepared according to the conditions of Comparative Example 1 (without adding liquid acrylonitrile) does not contain iron phosphide components.
对比例2Comparative Example 2
参考实施例1，区别在于，烧结的温度为750℃，得到磷酸铁锂正极材料(含碳量约为1.5wt％，磷化铁的含量为0，粒径为360nm左右)。说明，烧结温度过低同样无法得到含有磷化铁的磷酸铁锂正极材料。Referring to Example 1, the difference is that the sintering temperature is 750°C, and a lithium iron phosphate positive electrode material (carbon content is about 1.5wt%, iron phosphide content is 0, and particle size is about 360nm) is obtained. It shows that if the sintering temperature is too low, a lithium iron phosphate positive electrode material containing iron phosphide cannot be obtained.
图3为所述磷酸铁锂正极材料的XRD图，由图3可知，按照对比例2的条件(750℃烧结)制备出的磷酸铁锂正极材料，其中不含有磷化铁成分。FIG3 is an XRD diagram of the lithium iron phosphate positive electrode material. As can be seen from FIG3 , the lithium iron phosphate positive electrode material prepared according to the conditions of Comparative Example 2 (sintering at 750° C.) does not contain iron phosphide.
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。 The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
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