CN116443840A - Lithium iron phosphate positive electrode material and preparation method thereof - Google Patents
Lithium iron phosphate positive electrode material and preparation method thereof Download PDFInfo
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- CN116443840A CN116443840A CN202310312564.8A CN202310312564A CN116443840A CN 116443840 A CN116443840 A CN 116443840A CN 202310312564 A CN202310312564 A CN 202310312564A CN 116443840 A CN116443840 A CN 116443840A
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- iron phosphate
- lithium iron
- positive electrode
- sintering
- electrode material
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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 159
- 239000007774 positive electrode material Substances 0.000 title claims abstract description 34
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 239000000463 material Substances 0.000 claims abstract description 94
- 238000005245 sintering Methods 0.000 claims abstract description 59
- 239000002245 particle Substances 0.000 claims abstract description 32
- 239000000843 powder Substances 0.000 claims abstract description 29
- 239000000047 product Substances 0.000 claims abstract description 25
- 238000002156 mixing Methods 0.000 claims abstract description 11
- 239000011265 semifinished product Substances 0.000 claims abstract description 10
- 238000000498 ball milling Methods 0.000 claims description 39
- 238000000034 method Methods 0.000 claims description 24
- 239000002002 slurry Substances 0.000 claims description 20
- 239000002994 raw material Substances 0.000 claims description 19
- 238000001035 drying Methods 0.000 claims description 16
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 15
- 229910052799 carbon Inorganic materials 0.000 claims description 15
- 239000003979 granulating agent Substances 0.000 claims description 14
- 239000005955 Ferric phosphate Substances 0.000 claims description 10
- 229940032958 ferric phosphate Drugs 0.000 claims description 10
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims description 10
- 229910000399 iron(III) phosphate Inorganic materials 0.000 claims description 10
- 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 9
- 239000008103 glucose Substances 0.000 claims description 9
- 238000000227 grinding Methods 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
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 7
- XVAMCHGMPYWHNL-UHFFFAOYSA-N bemotrizinol Chemical compound OC1=CC(OCC(CC)CCCC)=CC=C1C1=NC(C=2C=CC(OC)=CC=2)=NC(C=2C(=CC(OCC(CC)CCCC)=CC=2)O)=N1 XVAMCHGMPYWHNL-UHFFFAOYSA-N 0.000 claims description 7
- 229910052744 lithium Inorganic materials 0.000 claims description 7
- CWIPUXNYOJYESQ-UHFFFAOYSA-N oxaldehyde;1,3,5-triazine-2,4,6-triamine Chemical compound O=CC=O.NC1=NC(N)=NC(N)=N1 CWIPUXNYOJYESQ-UHFFFAOYSA-N 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 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 6
- 229930006000 Sucrose Natural products 0.000 claims description 6
- 239000005720 sucrose Substances 0.000 claims description 6
- 229920005989 resin Polymers 0.000 claims description 5
- 239000011347 resin Substances 0.000 claims description 5
- 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 4
- 239000006229 carbon black Substances 0.000 claims description 4
- FDATWRLUYRHCJE-UHFFFAOYSA-N diethylamino hydroxybenzoyl hexyl benzoate Chemical compound CCCCCCOC(=O)C1=CC=CC=C1C(=O)C1=CC=C(N(CC)CC)C=C1O FDATWRLUYRHCJE-UHFFFAOYSA-N 0.000 claims description 4
- 229960001630 diethylamino hydroxybenzoyl hexyl benzoate Drugs 0.000 claims description 4
- 239000002202 Polyethylene glycol Substances 0.000 claims description 3
- 239000010406 cathode material Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229920001223 polyethylene glycol Polymers 0.000 claims description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 2
- 238000005056 compaction Methods 0.000 abstract description 9
- 239000010405 anode material Substances 0.000 abstract description 7
- 230000000694 effects Effects 0.000 abstract description 4
- 239000011149 active material Substances 0.000 abstract description 3
- 238000009826 distribution Methods 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 12
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 12
- 239000013078 crystal Substances 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 6
- 229910021641 deionized water Inorganic materials 0.000 description 6
- 238000011049 filling Methods 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- 238000007789 sealing Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000008187 granular material Substances 0.000 description 5
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000010532 solid phase synthesis reaction Methods 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000003763 carbonization Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000012792 core layer Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000005281 excited state Effects 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 1
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 239000010450 olivine Substances 0.000 description 1
- 229910052609 olivine Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- 239000011164 primary particle Substances 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000003786 synthesis reaction 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
- 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
- C01P2006/90—Other properties not specified above
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention belongs to the technical field of active material electrode preparation, and relates to a lithium iron phosphate anode material and a preparation method thereof. Aiming at the technical problem of poor energy density caused by nonuniform particle size, low compactness and limited battery capacity in the preparation process of the lithium iron phosphate positive electrode material in the prior art, the application provides a preparation method of the lithium iron phosphate positive electrode material, which is used for classifying a semi-finished product of the lithium iron phosphate material to obtain a fine powder lithium iron phosphate material and a crude lithium iron phosphate material; sintering the fine powder lithium iron phosphate material for the third time to obtain a preformed product of the lithium iron phosphate material; mixing a preformed product of the lithium iron phosphate material with a crude lithium iron phosphate material to obtain the lithium iron phosphate positive electrode material, manufacturing mixing effects of particles with different sizes, optimizing particle distribution of the lithium iron phosphate material, and forming a compact lithium iron phosphate structure, so that fine powder of the lithium iron phosphate particles is less, and the prepared lithium iron phosphate positive electrode material has higher compaction density.
Description
Technical Field
The invention belongs to the technical field of active material electrode preparation, and particularly relates to a lithium iron phosphate anode material and a preparation method thereof.
Background
The lithium battery mainly comprises four parts of an anode, a cathode, electrolyte and a diaphragm. The proportion of the cost of the positive electrode material battery can be up to about 30%, and the positive electrode material battery mainly comprises lithium iron phosphate, ternary materials, lithium manganate and lithium cobaltate at present. The lithium cobaltate has the advantages of high voltage, high tap density, stable structure, good safety, high cost and low gram capacity, and has the defect of very limited global reserve of cobalt serving as a core raw material, and is unfavorable for controlling the cost. The ternary material has an overall energy density higher than that of lithium iron phosphate and lithium cobalt oxide. The lithium iron phosphate has the capacity between the two, and has the advantages of high energy density, long cycle life, stable voltage platform, good safety and environmental friendliness, and is widely applied to the fields of new energy automobiles and energy storage. In the aspect of safety, the safety of the lithium iron phosphate is better than that of ternary, and the lithium iron phosphate crystal is of an olivine structure, so that the structural framework can be kept stable even under the high-temperature or overcharge condition. Under high temperature or pressure conditions, the ternary material may decompose to produce a large amount of oxygen and emit a large amount of heat, causing the electrolyte to ignite. The cost of the lithium iron phosphate is lower than that of ternary, and compared with ternary, the cost of the lithium iron phosphate can be reduced by about 2/3 at the positive electrode level; the use cost of the lithium iron phosphate is obviously better than that of ternary, the lithium iron phosphate has the cost reduction advantages of more than 50% and more than 20% on the positive electrode and the battery core layer, and the price fluctuation of the lithium iron phosphate is far less than that of ternary because of no noble metals such as cobalt, nickel and the like, thereby being beneficial to cost management and control.
The essence of lithium ion batteries is to utilize the redox reaction of lithium ions to realize the interconversion of electric energy and chemical energy. In a battery, the active materials that participate in the reaction are a positive electrode, a negative electrode, and an electrolyte or electrolyte. The positive electrode material is the core of the lithium battery, and the performance of the positive electrode material has a great influence on the battery, so that the naming of the lithium battery is mainly determined by the property of the positive electrode material. The positive electrode material is critical to the performance of the lithium ion battery, and the evaluation indexes of the lithium ion battery comprise energy density, cycle life, rate capability, safety performance and the like. Wherein the energy density depends on the relative voltage and gram capacity of the positive and negative electrodes, and the theoretical voltage and theoretical capacity are both constant for a specific material system.
The large-scale production process of lithium iron phosphate can be divided into a solid-phase method and a liquid-phase method, and the solid-phase method and the liquid-phase method have advantages and disadvantages respectively. The method adopts low-cost sintering of an oxide raw material of burning-resistant iron to form primary seed crystals, the primary seed crystals have high compaction characteristics, then the primary seed crystals are mixed with ferric phosphate, lithium carbonate, additives and a carbon source for grinding, spray granulation, sintering and crushing, the primary seed crystals promote the synthesis of lithium iron phosphate crystals, the part of lithium iron phosphate has high capacity characteristics, and after secondary heat treatment, primary particles are increased, the compaction density is increased, but the scheme only can improve the particle size uniformity of the product to a certain extent, and in practical production, the uniformity and uniformity of the final particles are influenced due to the variety of the raw materials, the proportion of the components of the raw materials, the process temperature, the time and the like. The compaction density has a larger influence on the performance of the battery, the larger the compaction density is, the higher the capacity of the battery can be, the compaction density is also regarded as one of the reference indexes of the energy density of the material, under certain process conditions, the larger the compaction density is, the higher the capacity of the battery is, and the lithium iron phosphate on the market is compacted at about 2.3g/cc at present.
Disclosure of Invention
1. Technical problem to be solved by the invention
Aiming at the technical problems of poor energy density caused by nonuniform particle size, low compactness, limited battery capacity and poor energy density of the lithium iron phosphate anode material in the preparation process of the lithium iron phosphate anode material in the prior art, the application provides a preparation method of the lithium iron phosphate anode material, which is used for preparing the mixing effect of particles with different sizes, optimizing the particle distribution of the lithium iron phosphate material, forming a compact lithium iron phosphate structure, reducing the fine powder of the lithium iron phosphate particles and obtaining the lithium iron phosphate anode material with higher compaction density.
2. Technical proposal
In order to achieve the above purpose, the technical scheme provided is as follows:
the preparation method of the lithium iron phosphate cathode material comprises the steps of preparing lithium iron phosphate slurry, sequentially carrying out first sintering and second sintering on the lithium iron phosphate slurry to obtain a semi-finished product of the lithium iron phosphate material, and grading the semi-finished product of the lithium iron phosphate material to obtain a fine powder lithium iron phosphate material and a crude lithium iron phosphate material; sintering the fine powder lithium iron phosphate material for the third time to obtain a preformed product of the lithium iron phosphate material; and mixing the lithium iron phosphate material preform with the crude lithium iron phosphate material to obtain the lithium iron phosphate positive electrode material.
Further, the fine powder lithium iron phosphate material has a particle size D50 of 0.5 μm or less and the crude lithium iron phosphate material has a particle size D50 of greater than 0.5 μm.
Further, the process parameters of the third sintering are as follows: the temperature is 600-800 ℃ and the time is 5-10 h.
Further, before classifying the semi-finished product of the lithium iron phosphate material, the method further comprises the following steps:
ball milling, drying, grinding and sintering the raw materials for preparing the lithium iron phosphate slurry for the first time to obtain a ball milling product; the particle size D50 of the ball milling product is 0.2-0.8 mu m.
Preferably, the ball milling step uses a ball milling tank, and the ball milling tank is made of agate; the rotation speed of the ball milling tank is 100-400 rpm, and the time is 8-16 h.
Further, the raw materials for preparing the lithium iron phosphate slurry comprise a carbon source, ferric phosphate and lithium carbonate; the mass of the carbon source accounts for 5-15 wt% of the total mass of the raw materials; the molar ratio of lithium to iron is 1.05-1:1.
Further, the carbon source is one or more of glucose, sucrose, polyvinyl alcohol, polyethylene glycol and carbon black.
According to the scheme of the mixed carbon source, glucose is used as a representative small molecular sugar to form a uniform coating layer after melting in the presintering process, the fluidity of the large molecular sugar is slightly poor, the large molecular sugar is bonded to form large and small particle agglomerated particles, and the presintering temperature is adjusted to enable multiple carbon sources to respectively play different roles, so that the mixing effect of the particles with different sizes is manufactured.
Further, the technological parameters of the first sintering are as follows: the temperature is 350-800 ℃ and the time is 4-8 h; the technological parameters of the second sintering are as follows: the temperature is 600-800 ℃ and the time is 4-8 h.
Further, adding a particle granulating agent into the ball-milling product, performing secondary ball milling, drying and secondary sintering to obtain a semi-finished product of the lithium iron phosphate material.
Through a secondary ball milling means, edges and corners of the lithium iron phosphate are further eliminated, and simultaneously, a granulating agent is added to further crosslink the lithium iron phosphate particles together, long chains firmly grasp the lithium iron phosphate particles after carbonization to form a pomegranate-shaped compact secondary aggregate, so that the compactness of the lithium iron phosphate is increased; in the heating process of the granulating agent, the interior of the molecule is reconstructed, an electron excited state is tightly combined with oxygen atoms on the surface of the ferric phosphate, and the heated molecule is further shrunk to form a compact lithium iron phosphate structure.
Further, the granular granulating agent is one or more of bis-ethylhexyloxyphenol methoxyphenyl triazine, melamine Glyoxal (MG) resin and diethylamino hydroxybenzoyl hexyl benzoate, and the mass of the granular granulating agent accounts for 1-8wt% of the total mass of the raw materials.
The lithium iron phosphate anode material is prepared by using the preparation method.
3. Advantageous effects
Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects:
(1) According to the preparation method of the lithium iron phosphate positive electrode material, the semi-finished product of the lithium iron phosphate material is classified to obtain a fine powder lithium iron phosphate material and a crude lithium iron phosphate material, the fine powder lithium iron phosphate material is sintered for the third time to obtain a lithium iron phosphate material prefabricated product, and the lithium iron phosphate material prefabricated product and the crude lithium iron phosphate material are mixed to obtain the lithium iron phosphate positive electrode material. After secondary sintering growth, the fine powder lithium iron phosphate material is mixed and added, so that the particle distribution of the lithium iron phosphate material is optimized, the fine powder of the lithium iron phosphate particles is less, the particles are compact, and the secondary agglomeration is compact, so that the lithium iron phosphate material has higher compaction density.
(2) The lithium iron phosphate positive electrode material is prepared by the preparation method, and the compactness can reach 2.61g/cc, so that the lithium iron phosphate positive electrode material can obtain larger battery capacity in the fields of new energy automobiles and energy storage.
Detailed Description
The invention is further described below in connection with specific embodiments.
The following description of the embodiments of the present invention will be made clearly and completely, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments; all other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The preparation method of the lithium iron phosphate positive electrode material comprises the following specific steps:
(1) Adding a proper amount of deionized water into a ball milling tank, sequentially adding a carbon source, ferric phosphate and lithium carbonate into the ball milling tank, sealing the tank body, filling nitrogen for protection, controlling the molar ratio of LL to be 1.05 to 1, and adding glucose accounting for 5% of the total mass of the raw materials.
(2) The ball mill was started at 200rpm for 10 hours to a slurry particle size D of 50.5. Mu.m.
(3) And (5) quickly transferring the ball-milled slurry to an oven for drying.
(4) Grinding the dried sample, and transferring the ground sample into a sintering furnace for presintering at 350 ℃ for 5 hours.
(5) After pre-sintering, the sample is transferred to a ball milling tank again, ethanol and 1% of the granule granulating agent bis-ethylhexyloxyphenol methoxyphenyl triazine are added, and the speed is 300rpm for 4 hours.
(6) And (3) rapidly drying the products after the secondary ball milling, and placing the dried samples in a sintering furnace for sintering at 800 ℃ for 3 hours.
(7) And grading the products after secondary sintering to obtain fine powder lithium iron phosphate materials and crude lithium iron phosphate materials respectively, wherein the granularity D50 of the fine powder lithium iron phosphate materials is smaller than or equal to 0.5 mu m, and the granularity D50 of the crude lithium iron phosphate materials is larger than 0.5 mu m.
(8) And placing the fine powder lithium iron phosphate material into a sintering furnace, and sintering at 600 ℃ for 8 hours to obtain a lithium iron phosphate material preform.
(9) Mixing the crude lithium iron phosphate material with the preformed lithium iron phosphate material to obtain a highly compacted lithium iron phosphate material.
The performance parameters of the lithium iron phosphate positive electrode material prepared in the embodiment are shown in table 1.
Example 2
(1) Adding proper deionized water into a ball milling tank, sequentially adding a carbon source, ferric phosphate and lithium carbonate into the ball milling tank, sealing the tank body, filling nitrogen for protection, controlling the molar ratio of LL to be 1:1, and adding sucrose and glucose accounting for 5% of the total mass of the raw materials.
(2) The ball mill was started at 400rpm for 8 hours to a slurry particle size D of 50.4. Mu.m.
(3) And (5) quickly transferring the ball-milled slurry to an oven for drying.
(4) Grinding the dried sample, and transferring the ground sample into a sintering furnace for presintering at 500 ℃ for 3 hours.
(5) After pre-firing, the sample was again transferred to a ball milling tank, ethanol was added, 5% of the granular granulating agent melamine glyoxal resin, 400rpm for 16h.
(6) And (3) rapidly drying the products after the secondary ball milling, and placing the dried samples in a sintering furnace for sintering at 600 ℃ for 4 hours.
(7) And grading the products after secondary sintering to obtain fine powder lithium iron phosphate materials and crude lithium iron phosphate materials respectively, wherein the granularity D50 of the fine powder lithium iron phosphate materials is smaller than or equal to 0.5 mu m, and the granularity D50 of the crude lithium iron phosphate materials is larger than 0.5 mu m.
(8) And placing the fine powder lithium iron phosphate material into a sintering furnace, and sintering at 600 ℃ for 4 hours to obtain a lithium iron phosphate material preform.
(9) Mixing the crude lithium iron phosphate material with the preformed lithium iron phosphate material to obtain a highly compacted lithium iron phosphate material.
The performance parameters of the lithium iron phosphate positive electrode material prepared in the embodiment are shown in table 1.
Example 3
(1) Adding a proper amount of deionized water into a ball milling tank, sequentially adding a carbon source, ferric phosphate and lithium carbonate into the ball milling tank, sealing the tank body, filling nitrogen for protection, controlling the molar ratio of LL to be 1.03:1, and adding glucose, polyethylene glycol, sucrose and carbon black in an amount of 3% by mass of the total raw materials.
(2) The ball mill was started at 300rpm for 12 hours to a slurry particle size D of 50.3. Mu.m.
(3) And (5) quickly transferring the ball-milled slurry to an oven for drying.
(4) Grinding the dried sample, and transferring the ground sample into a sintering furnace for presintering at 700 ℃ for 4 hours.
(5) After pre-sintering, the sample is transferred to a ball milling tank again, and ethanol, 1% of granule granulating agent bis-ethylhexyloxyphenol methoxyphenyl triazine, 2% of melamine glyoxal resin and 2% of diethylamino hydroxybenzoyl hexyl benzoate are added for 4 hours at 300 rpm.
(6) And (3) rapidly drying the products after the secondary ball milling, and placing the dried samples in a sintering furnace for sintering at 700 ℃ for 5 hours.
(7) And grading the products after secondary sintering to obtain fine powder lithium iron phosphate materials and crude lithium iron phosphate materials respectively, wherein the granularity D50 of the fine powder lithium iron phosphate materials is smaller than or equal to 0.5 mu m, and the granularity D50 of the crude lithium iron phosphate materials is larger than 0.5 mu m.
(8) And placing the fine powder lithium iron phosphate material into a sintering furnace, and sintering at 800 ℃ for 4 hours to obtain a lithium iron phosphate material preform.
(9) Mixing the crude lithium iron phosphate material with the preformed lithium iron phosphate material to obtain a highly compacted lithium iron phosphate material.
The performance parameters of the lithium iron phosphate positive electrode material prepared in the embodiment are shown in table 1.
Example 4
(1) Adding proper deionized water into a ball milling tank, sequentially adding a carbon source, ferric phosphate and lithium carbonate into the ball milling tank, sealing the tank body, filling nitrogen for protection, controlling the molar ratio of LL to be 1.02:1, and adding glucose, sucrose and carbon black in an amount of 5% by weight of the total raw materials.
(2) The ball mill was started at 200rpm for 10 hours to a slurry particle size D of 50.5. Mu.m.
(3) And (5) quickly transferring the ball-milled slurry to an oven for drying.
(4) Grinding the dried sample, and transferring the ground sample into a sintering furnace for presintering at 800 ℃ for 5 hours.
(5) After pre-sintering, the sample was transferred again to a ball milling tank, ethanol was added, 1% of the granule granulating agent bis-ethylhexyloxyphenol methoxyphenyl triazine, 2% of Melamine Glyoxal (MG) resin, and 200rpm for 4 hours.
(6) And (3) rapidly drying the products after the secondary ball milling, and placing the dried samples in a sintering furnace for sintering at 600 ℃ for 8 hours.
(7) And grading the products after secondary sintering to obtain fine powder lithium iron phosphate materials and crude lithium iron phosphate materials respectively, wherein the granularity D50 of the fine powder lithium iron phosphate materials is smaller than or equal to 0.5 mu m, and the granularity D50 of the crude lithium iron phosphate materials is larger than 0.5 mu m.
(8) And placing the fine powder lithium iron phosphate material into a sintering furnace, and sintering at 700 ℃ for 8 hours to obtain a lithium iron phosphate material preform.
(9) Mixing the crude lithium iron phosphate material with the preformed lithium iron phosphate material to obtain a highly compacted lithium iron phosphate material.
The performance parameters of the lithium iron phosphate positive electrode material prepared in the embodiment are shown in table 1.
Example 5
(1) Adding proper deionized water into a ball milling tank, sequentially adding a carbon source, ferric phosphate and lithium carbonate into the ball milling tank, sealing the tank body, filling nitrogen for protection, controlling the molar ratio of LL to be 1.01:1, and adding glucose accounting for 3% of the total mass of the raw materials and sucrose accounting for 7% of the total mass of the raw materials.
(2) The ball mill was started at 300rpm for 15 hours to a slurry particle size D of 50.8. Mu.m.
(3) And (5) quickly transferring the ball-milled slurry to an oven for drying.
(4) Grinding the dried sample, and transferring the ground sample into a sintering furnace for presintering at 600 ℃ for 5 hours.
(5) After pre-sintering, the sample is transferred to a ball milling tank again, ethanol, 3% of granule granulating agent bis-ethylhexyloxyphenol methoxyphenyl triazine and 2% of diethylamino hydroxybenzoyl hexyl benzoate are added, and 350rpm is used for 8 hours.
(6) And (3) rapidly drying the products after the secondary ball milling, and placing the dried samples in a sintering furnace for sintering at 800 ℃ for 5 hours.
(7) And grading the products after secondary sintering to obtain fine powder lithium iron phosphate materials and crude lithium iron phosphate materials respectively, wherein the granularity D50 of the fine powder lithium iron phosphate materials is smaller than or equal to 0.5 mu m, and the granularity D50 of the crude lithium iron phosphate materials is larger than 0.5 mu m.
(8) And placing the fine powder lithium iron phosphate material into a sintering furnace, and sintering at 780 ℃ for 8 hours to obtain a lithium iron phosphate material preform.
(9) Mixing the crude lithium iron phosphate material with the preformed lithium iron phosphate material to obtain a highly compacted lithium iron phosphate material.
The performance parameters of the lithium iron phosphate positive electrode material prepared in the embodiment are shown in table 1.
Comparative example 1
(1) Adding a proper amount of deionized water into a ball milling tank, sequentially adding a carbon source, ferric phosphate and lithium carbonate into the ball milling tank, sealing the tank body, filling nitrogen for protection, controlling the molar ratio of LL to be 1.05 to 1, and adding glucose accounting for 5% of the total mass of the raw materials.
(2) The ball mill was started at 200rpm for 10 hours to a slurry particle size D of 50.5. Mu.m.
(3) And (5) quickly transferring the ball-milled slurry to an oven for drying.
(4) Grinding the dried sample, and transferring the ground sample into a sintering furnace for presintering at 350 ℃ for 5 hours.
(5) After pre-sintering, the sample is transferred to a ball milling tank again, ethanol and 1% of the granule granulating agent bis-ethylhexyloxyphenol methoxyphenyl triazine are added, and the speed is 300rpm for 4 hours.
(6) And (3) rapidly drying the products after the secondary ball milling, and placing the dried samples in a sintering furnace for sintering at 800 ℃ for 3 hours.
(7) And grading the product after secondary sintering to obtain the lithium iron phosphate material.
The performance parameters of the lithium iron phosphate positive electrode material prepared in the embodiment are shown in table 1.
Table 1 summary of the properties of lithium iron phosphate cathode materials prepared in examples and comparative examples
Claims (10)
1. The preparation method of the lithium iron phosphate cathode material comprises the steps of preparing lithium iron phosphate slurry, and sequentially carrying out first sintering and second sintering on the lithium iron phosphate slurry to obtain a semi-finished product of the lithium iron phosphate material, and is characterized in that:
classifying the semi-finished product of the lithium iron phosphate material to obtain a fine powder lithium iron phosphate material and a crude lithium iron phosphate material;
sintering the fine powder lithium iron phosphate material for the third time to obtain a preformed product of the lithium iron phosphate material;
and mixing the lithium iron phosphate material preform with the crude lithium iron phosphate material to obtain the lithium iron phosphate positive electrode material.
2. The method for preparing the lithium iron phosphate positive electrode material according to claim 1, wherein the method comprises the following steps: the fine powder lithium iron phosphate material has a particle size D50 of 0.5 μm or less and the crude lithium iron phosphate material has a particle size D50 of greater than 0.5 μm.
3. The method for preparing a lithium iron phosphate positive electrode material according to claim 2, characterized in that: the technological parameters of the third sintering are as follows: the temperature is 600-800 ℃ and the time is 5-10 h.
4. A method for preparing a lithium iron phosphate positive electrode material according to any one of claims 1 to 3, characterized in that: the method further comprises the following steps before classifying the semi-finished product of the lithium iron phosphate material:
ball milling, drying, grinding and sintering the raw materials for preparing the lithium iron phosphate slurry for the first time to obtain a ball milling product; the particle size D50 of the ball milling product is 0.2-0.8 mu m.
5. The method for preparing a lithium iron phosphate positive electrode material according to claim 4, wherein the method comprises the following steps: the raw materials for preparing the lithium iron phosphate slurry comprise a carbon source, ferric phosphate and lithium carbonate; the mass of the carbon source accounts for 5-15 wt% of the total mass of the raw materials; the molar ratio of lithium to iron is 1.05-1:1.
6. The method for preparing a lithium iron phosphate positive electrode material according to claim 5, wherein the method comprises the following steps: the carbon source is one or more of glucose, sucrose, polyvinyl alcohol, polyethylene glycol and carbon black.
7. The method for preparing a lithium iron phosphate positive electrode material according to claim 4, wherein the method comprises the following steps: the technological parameters of the first sintering are as follows: the temperature is 350-800 ℃ and the time is 4-8 h; the technological parameters of the second sintering are as follows: the temperature is 600-800 ℃ and the time is 4-8 h.
8. The method for preparing a lithium iron phosphate positive electrode material according to claim 4, wherein the method comprises the following steps: and adding a particle granulating agent into the ball-milling product, performing secondary ball milling, drying and secondary sintering to obtain a semi-finished product of the lithium iron phosphate material.
9. The method for preparing the lithium iron phosphate positive electrode material according to claim 8, wherein the method comprises the following steps: the granular granulating agent is one or more of bis-ethylhexyloxyphenol methoxyphenyl triazine, melamine glyoxal resin and diethylamino hydroxybenzoyl hexyl benzoate, and the mass of the granular granulating agent accounts for 1-8wt% of the total mass of the raw materials.
10. A lithium iron phosphate positive electrode material is characterized in that: prepared using the preparation method of any one of claims 1-9.
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