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CN-122000321-A - Lithium iron phosphate positive electrode material, and preparation method and application thereof

CN122000321ACN 122000321 ACN122000321 ACN 122000321ACN-122000321-A

Abstract

The invention relates to the technical field of recycling of waste positive electrode materials, and discloses a lithium iron phosphate positive electrode material, a preparation method and application thereof. The lithium iron phosphate anode material is of a core-shell structure, wherein a core layer is lithium iron phosphate, and a shell layer is carbon-doped lithium fluoride. The method comprises the steps of (1) mixing lithium iron phosphate and polyvinylidene fluoride, performing primary ball milling under an inert atmosphere to obtain a primary ball milling material, (2) mixing a waste positive electrode plate stripped from a current collector with the primary ball milling material, performing secondary ball milling under the inert atmosphere to obtain a secondary ball milling material, and (3) annealing the secondary ball milling material under the inert atmosphere. The lithium iron phosphate positive electrode material has high multiplying power performance and excellent cycle performance, and meanwhile, the preparation method is used for recycling the waste positive electrode sheet without liquid injection, so that the cost is reduced, and the maximum utilization of resources is realized.

Inventors

  • LIU XIN
  • Yu Dibin
  • SUN TIANWEI
  • BAI HAO

Assignees

  • 清领华创(上海)能源科技有限公司
  • 北京清领华创科技有限公司

Dates

Publication Date
20260508
Application Date
20260121

Claims (11)

  1. 1. The lithium iron phosphate anode material is characterized by being of a core-shell structure, wherein a core layer is lithium iron phosphate, and a shell layer is carbon-doped lithium fluoride.
  2. 2. The lithium iron phosphate positive electrode material according to claim 1, wherein the core layer is contained in an amount of 97 to 99.5wt% and the shell layer is contained in an amount of 0.5 to 3wt%, based on the lithium iron phosphate positive electrode material.
  3. 3. The lithium iron phosphate positive electrode material according to claim 1 or 2, wherein the average thickness of the shell layer is 2 to 6nm, and/or The porosity of the shell layer is 3-5%, and the average pore diameter is 3-8nm.
  4. 4. A method for preparing a lithium iron phosphate positive electrode material, comprising the steps of: (1) Mixing lithium iron phosphate and polyvinylidene fluoride, and performing primary ball milling in an inert atmosphere to obtain a primary ball milling material; (2) Mixing the waste positive electrode plate stripped from the current collector with the primary ball-milling material, and performing secondary ball milling in an inert atmosphere to obtain a secondary ball-milling material; (3) And annealing the secondary ball-milling material in an inert atmosphere.
  5. 5. The method of claim 4, wherein in step (1), the weight ratio of the lithium iron phosphate to the polyvinylidene fluoride is 100:0.5-2.5.
  6. 6. The method according to claim 4 or 5, wherein in the step (1), the condition of one ball milling comprises a temperature of-40 to-30 ℃, a rotation speed of 200 to 300r/min, a time of 0.5 to 2.5 hours, and/or The particle size of the primary ball milling material is less than or equal to 30 mu m.
  7. 7. The method according to any one of claims 4 to 6, wherein in the step (2), the weight ratio of the used positive electrode sheet of the stripping current collector to the amount of the primary ball-milling material is 1:1 to 10.
  8. 8. The method according to any one of claims 4 to 7, wherein the conditions for the secondary ball milling in the step (2) include a temperature of-40 to-30 ℃, a rotational speed of 350 to 450r/min, a time of 2 to 3.5 hours, and/or The particle size of the secondary ball milling material is 3-10 mu m.
  9. 9. The method according to any one of claims 4 to 8, wherein in the step (3), the annealing conditions include a heating temperature of 150 to 400 ℃ for 0.5 to 6 hours, followed by cooling.
  10. 10. A lithium iron phosphate positive electrode material prepared by the method of any one of claims 4-9.
  11. 11. A positive electrode sheet, characterized in that the positive electrode sheet comprises the lithium iron phosphate positive electrode material according to any one of claims 1 to 3 and 10.

Description

Lithium iron phosphate positive electrode material, and preparation method and application thereof Technical Field The invention relates to the technical field of recycling of waste positive electrode materials, in particular to a lithium iron phosphate positive electrode material, a preparation method and application thereof. Background Under the drive of the rapid development of new energy industry, the demand of positive electrode materials such as lithium iron phosphate (LFP) in the market continues to increase due to the core advantages of high safety and low cost. However, in the LFP battery production process, a large amount of non-injected positive plate waste is generated, and the waste mainly comprises cut scraps, unqualified products of performance and appearance size, technical test products and the like. It is counted that about 200 tons of such waste positive plates without liquid injection are produced per 1GWh of battery. In the positive electrode coating of the waste, the LFP particle structure is kept complete, and the electrolyte is not injected, so that the waste has extremely high recycling value. For the LFP positive plate without liquid injection, most enterprises discard the LFP positive plate as solid waste or sell the LFP positive plate to a powdering enterprise for disposal at low price due to lack of a targeted high-value recovery technology, so that serious waste of raw materials is caused and environmental pressure is increased. On the other hand, in order to improve the cycle stability and rate capability of the positive electrode material, a coating modification means is often adopted, namely, a coating layer is formed on the particle surface of the positive electrode material so as to form a stable physical barrier, inhibit the interfacial side reaction of the electrolyte and the positive electrode, and reduce the migration resistance of lithium ions. However, the current coating process has obvious defects that on one hand, the cost of raw materials in the coating process is high, such as a high-purity lithium fluoride material, and on the other hand, the problem of uneven mixing and dispersion of anode particles and a coating agent in the coating process is easy to occur, so that the problem of uncontrolled thickness of the coating layer and/or local agglomeration is caused, the stability of a modification effect is difficult to ensure, and the industrial application of the modified lithium fluoride material is restricted. In summary, the current industry faces two technical problems at the same time, namely, the defect of high-valued recovery paths of additives such as positive electrode active substances, adhesives and the like in the waste positive electrode sheet without liquid injection, the prominent resource waste and environmental protection pressure, and the high cost of raw materials and unstable coating effect in the traditional coating modification process. Disclosure of Invention The invention aims to solve the problems of resource waste caused by the defect of a high-value recovery path of a waste positive plate without liquid injection in the prior art, high raw material cost and unstable coating effect of the traditional lithium battery coating modification process, and provides a lithium iron phosphate positive material and a preparation method thereof. In order to achieve the above objective, according to one aspect of the present invention, a lithium iron phosphate positive electrode material is provided, wherein the lithium iron phosphate positive electrode material has a core-shell structure, and a core layer is lithium iron phosphate, and a shell layer is carbon doped lithium fluoride. Preferably, the core layer is 97 to 99.5wt% and the shell layer is 0.5 to 3wt% based on the lithium iron phosphate cathode material. Preferably, the average thickness of the shell layer is 2-6nm. Preferably, the porosity of the shell layer is 3-5% and the average pore diameter is 3-8nm. In a second aspect, the present invention provides a method for preparing a lithium iron phosphate positive electrode material, the method comprising the steps of: (1) Mixing lithium iron phosphate and polyvinylidene fluoride, and performing primary ball milling in an inert atmosphere to obtain a primary ball milling material; (2) Mixing the waste positive electrode plate stripped from the current collector with the primary ball-milling material, and performing secondary ball milling in an inert atmosphere to obtain a secondary ball-milling material; (3) And annealing the secondary ball-milling material in an inert atmosphere. Preferably, in the step (1), the weight ratio of the lithium iron phosphate to the dosage of the polyvinylidene fluoride is 100:0.5-2.5. Preferably, in the step (1), the condition of one ball milling comprises the temperature of-40 to-30 ℃, the rotating speed of 200-300r/min and the time of 0.5-2.5h. Preferably, the particle size of the primary ball milling materia