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CN-122025895-A - Regeneration method of lithium iron phosphate waste battery positive plate

CN122025895ACN 122025895 ACN122025895 ACN 122025895ACN-122025895-A

Abstract

The invention belongs to the technical field of secondary batteries. More particularly, to a method for regenerating a lithium iron phosphate waste battery positive plate. The method comprises the specific regeneration steps of separating a positive electrode active material layer from a current collector on the surface of a positive electrode plate, collecting the positive electrode active material layer, wherein the positive electrode active material layer comprises a lithium iron phosphate positive electrode material, a binder PVDF and a conductive agent, the lithium iron phosphate positive electrode material comprises a core and amorphous carbon coated on the surface of the core, the positive electrode active material layer is subjected to primary high-temperature heat treatment repair and cooling under the inert atmosphere condition to obtain a pretreated positive electrode material, the pretreated positive electrode material is transferred into a reactor, subjected to high-temperature decarburization treatment and then cooled to obtain a local decarburized positive electrode material, the local decarburized positive electrode material is immersed in an aluminum source solution, then dried, subjected to secondary high-temperature heat treatment repair under the inert atmosphere, and then cooled and discharged to complete regeneration.

Inventors

  • LIU HAOHAN
  • XU SITONG
  • CAO QIN

Assignees

  • 锐驰新能源(徐州)有限公司

Dates

Publication Date
20260512
Application Date
20260310

Claims (9)

  1. 1. The regeneration method of the lithium iron phosphate waste battery positive plate is characterized by comprising the following specific regeneration steps: Separating the positive electrode active material layer from the current collector on the surface of the positive electrode sheet, and collecting the positive electrode active material layer; The positive electrode active material layer comprises a lithium iron phosphate positive electrode material, a binder PVDF and a conductive agent, wherein the lithium iron phosphate positive electrode material comprises a core and amorphous carbon coated on the surface of the core; Repairing the positive electrode active material layer by one-time high-temperature heat treatment under the inert atmosphere condition, and cooling to obtain a pretreated positive electrode material; Transferring the pretreated positive electrode material into a reactor, performing high-temperature decarburization treatment, and cooling to obtain a local decarburized positive electrode material; And (3) immersing the partial decarburized positive electrode material in an aluminum source solution, drying, carrying out secondary high-temperature heat treatment restoration under an inert atmosphere, cooling, and discharging to complete regeneration.
  2. 2. The method for regenerating the lithium iron phosphate waste battery positive plate according to claim 1, wherein the primary high-temperature heat treatment repair comprises heating to 500-550 ℃ at a rate of 3-5 ℃ per minute, and performing high-temperature heat treatment for 2-3h.
  3. 3. The method for regenerating the lithium iron phosphate waste battery positive plate according to claim 1, wherein the secondary high-temperature heat treatment repair comprises heating to 700-750 ℃ at a rate of 4-6 ℃ per minute, and performing high-temperature heat treatment for 2-4h.
  4. 4. The method for regenerating a lithium iron phosphate waste battery positive plate according to claim 1, wherein the high-temperature decarbonization treatment comprises introducing carbon dioxide gas at a rate of 20-30L/min, heating to 800-900 ℃ at a rate of 2-4 ℃ and performing high-temperature decarbonization heat treatment for 2-4h.
  5. 5. The method for regenerating a lithium iron phosphate waste battery positive electrode sheet according to claim 1, wherein the positive electrode active material layer comprises the following raw materials in parts by weight: 94-96 parts of lithium iron phosphate positive electrode material, 2-5 parts of binder PVDF and 2-5 parts of conductive agent.
  6. 6. The method for regenerating a lithium iron phosphate waste battery positive plate according to claim 5, wherein the conductive agent is selected from any one or a combination of a plurality of carbon black, carbon nanotubes or graphene.
  7. 7. The method for regenerating the lithium iron phosphate waste battery positive plate according to claim 5, wherein the lithium iron phosphate positive plate material comprises an inner core and amorphous carbon coated on the surface of the inner core, and the mass of the amorphous carbon accounts for 1-5% of the total mass of the lithium iron phosphate positive plate material.
  8. 8. The method for regenerating a lithium iron phosphate waste battery positive plate according to claim 1, wherein the aluminum source solution is prepared from an aluminum nitrate solution and an ammonium dihydrogen phosphate solution, wherein the concentration of the aluminum nitrate solution and the ammonium dihydrogen phosphate solution is 0.05-0.1mol/L, and the molar ratio of Al to P in the aluminum source solution is 1:1.
  9. 9. The method for regenerating the lithium iron phosphate waste battery positive plate according to claim 8, wherein the step of immersing the partially decarburized positive electrode material in the aluminum source solution comprises the steps of adding the partially decarburized positive electrode material into the aluminum source solution according to a solid-to-liquid ratio of 1:2-5g/mL, and immersing the partially decarburized positive electrode material in the aluminum source solution for 80-120min at a temperature of 55-60 ℃ and a stirring rotation speed of 200-400 r/min.

Description

Regeneration method of lithium iron phosphate waste battery positive plate Technical Field The invention belongs to the technical field of secondary batteries. More particularly, to a method for regenerating a lithium iron phosphate waste battery positive plate. Background The regeneration process of the lithium iron phosphate positive plate aims at repairing the attenuated crystal structure in the retired material and supplementing lost lithium element so as to restore the electrochemical activity of the material. However, in the actual industrialization process, the existing regeneration technology still faces some technical bottlenecks. After the lithium iron phosphate anode material is recycled for a long time, lithium loss exists in the lithium iron phosphate material to form FePO 4 phase, and crystal structure defects and damage to a surface carbon conductive network can also occur. In particular, the heterogeneous LeFePO 4/FePO4 phase-separated structure formed inside the material results in an increase in the diffusion energy barrier of lithium ions. Therefore, how to realize the reconstruction of the structure, so that the multiplying power performance and the low-temperature performance of the regenerated material reach the standard, is one of the problems still faced by the person skilled in the art. Disclosure of Invention The invention aims at solving the technical problem of how to realize the reconstruction of the material structure in the regeneration process of the existing lithium iron phosphate anode material. Based on the problems, the invention provides a method for regenerating the lithium iron phosphate waste battery positive plate. The invention aims to provide a method for regenerating a lithium iron phosphate waste battery positive plate. The above object of the present invention is achieved by the following technical scheme: The regeneration method of the lithium iron phosphate waste battery positive plate comprises the following specific regeneration steps: Separating the positive electrode active material layer from the current collector on the surface of the positive electrode sheet, and collecting the positive electrode active material layer; The positive electrode active material layer comprises a lithium iron phosphate positive electrode material, a binder PVDF and a conductive agent, wherein the lithium iron phosphate positive electrode material comprises a core and amorphous carbon coated on the surface of the core; Repairing the positive electrode active material layer by one-time high-temperature heat treatment under the inert atmosphere condition, and cooling to obtain a pretreated positive electrode material; Transferring the pretreated positive electrode material into a reactor, performing high-temperature decarburization treatment, and cooling to obtain a local decarburized positive electrode material; And (3) immersing the partial decarburized positive electrode material in an aluminum source solution, drying, carrying out secondary high-temperature heat treatment restoration under an inert atmosphere, cooling, and discharging to complete regeneration. The beneficial effects of the technical scheme include: Firstly, carrying out primary high-temperature heat treatment repair on an anode active material layer containing a binder PVDF and a conductive agent in inert atmosphere, wherein in the process, the PVDF undergoes dehydrofluorination reaction at a temperature of more than 350 ℃ and is carbonized step by step, and simultaneously undergoes a solid phase reaction with a defect site on the surface of the conductive agent, so that the residual PVDF is converted into amorphous carbon with fluorine doping effect, and a fluorine-doped carbon three-dimensional conductive network is reconstructed together with the original conductive agent; On the basis, the material subjected to primary repair is subjected to high-temperature decarburization treatment, according to the mechanism that carbon and carbon dioxide react with Budol (C+CO 2 - & gt 2 CO) at high temperature, the reaction preferentially reacts with carbon with higher activity such as amorphous carbon, defect sites and the like, impurity carbon or excessive carbon which blocks a lithium ion diffusion channel due to cyclic damage can be selectively removed, the active surface of lithium iron phosphate is exposed, selective etching and activation of a carbon layer on the surface of the material are realized, an ion diffusion channel is opened for subsequent uniform intercalation of a lithium source and accurate deposition of a repair agent, and the problem that the carbon layer blocks lithium supplement in the traditional method is solved. Finally, the local decarburization anode material is immersed in an aluminum source solution and repaired by secondary high-temperature heat treatment, and as AlPO 4 and LiFePO 4 have strong affinity, the mechanism of reaction on the surface of the exposed lithium iron phosphate a