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CN-121990547-A - Method for directly regenerating lithium iron manganese phosphate material by using waste lithium iron phosphate and application

CN121990547ACN 121990547 ACN121990547 ACN 121990547ACN-121990547-A

Abstract

The invention discloses a method for directly regenerating a lithium iron manganese phosphate material by using waste lithium iron phosphate and application thereof, which comprises the steps of discharging, disassembling and separating a waste lithium iron phosphate battery to obtain waste lithium iron phosphate anode powder, measuring the contents of iron, phosphorus and lithium elements in the waste lithium iron phosphate battery, supplementing a lithium source, a manganese source, a phosphorus source and sucrose according to a measurement result, enabling the molar ratio of Li to Mn to Fe to P in a system to be 1.05:0.3:0.7:1, enabling the adding amount of the sucrose to be 15% of the mass of a target product lithium iron manganese phosphate, preparing the phosphorus source and the sucrose into a mixed solution A, performing ball milling on the waste anode powder after independent ball milling activation, mixing the waste anode powder with the lithium source, the manganese source and the solution A, drying to obtain powder, and finally sintering the powder at 600-800 ℃ in an inert atmosphere, and cooling to obtain the lithium iron manganese phosphate anode material. According to the invention, in-situ doping of manganese is realized on the premise of keeping the waste particle skeleton, the material is directly repaired and upgraded from lithium iron phosphate to lithium manganese iron phosphate, the energy density is improved by about 20%, the excellent electrochemical performance is shown, and the method has a good industrialization prospect.

Inventors

  • TANG SHAOCHUN
  • XU ZISHUO
  • CAO XUAN

Assignees

  • 南京大学
  • 海安南京大学高新技术研究院

Dates

Publication Date
20260508
Application Date
20260305

Claims (6)

  1. 1. The method for directly regenerating the lithium iron manganese phosphate material by using the waste lithium iron phosphate is characterized by comprising the following steps of: firstly, discharging, disassembling and separating a waste lithium iron phosphate battery to obtain waste lithium iron phosphate positive electrode powder, and measuring the contents of iron element, phosphorus element and lithium element in the waste lithium iron phosphate positive electrode powder; determining the amount of lithium source, manganese source, phosphorus source and sucrose to be supplemented according to the determination result in the step one, so that the molar ratio of lithium, manganese, iron and phosphorus in a supplemented system reaches Li: mn: fe: P=1.05:0.3:0.7:1, wherein the addition amount of the sucrose accounts for 15% of the mass of the lithium iron manganese phosphate as a target product; Dispersing the weighed waste lithium iron phosphate anode powder in deionized water for ball milling to activate the surface, dispersing the weighed phosphorus source and sucrose in deionized water to prepare a mixed solution A, mixing the ball-milled waste lithium iron phosphate slurry, lithium source and manganese source with the mixed solution A, ball milling, drying and grinding to obtain precursor powder; and step four, sintering the precursor powder at 600-800 ℃ in inert atmosphere, and cooling to obtain the lithium iron manganese phosphate anode material.
  2. 2. The method for directly regenerating lithium iron manganese phosphate materials from waste lithium iron phosphate according to claim 1, wherein the ball milling in the third step is wet ball milling, the ball milling medium is water or ethanol, the ball milling time is 4-12h, and the ball milling rotating speed is 200-600rpm.
  3. 3. The method for directly regenerating lithium iron manganese phosphate materials from waste lithium iron phosphate according to claim 1, wherein the drying temperature in the third step is 60-100 ℃ and the drying time is 8-16h.
  4. 4. The method for directly regenerating lithium iron manganese phosphate materials from waste lithium iron phosphate according to claim 1, wherein in the fourth step, the sintering temperature is 700 ℃, and the heat preservation time is 8-12 hours.
  5. 5. The lithium iron manganese phosphate positive electrode material obtained by the method according to any one of claims 1 to 4.
  6. 6. The use of the lithium iron manganese phosphate positive electrode material according to claim 5 in the preparation of lithium ion batteries.

Description

Method for directly regenerating lithium iron manganese phosphate material by using waste lithium iron phosphate and application Technical Field The invention relates to the technical field of direct regeneration of waste lithium batteries, in particular to a method for directly regenerating a lithium iron phosphate material by waste lithium iron phosphate and application thereof. Background The lithium iron phosphate battery has been widely used in the fields of new energy automobiles, energy storage systems, portable electronic devices and the like by virtue of core advantages of excellent safety performance, low cost, long cycle life and the like. With the rapid development of new energy industry, the market holding quantity of lithium iron phosphate batteries continues to increase. Since the service life of lithium iron phosphate batteries is usually 5-8 years, a large number of retired waste lithium iron phosphate batteries have entered the recovery treatment stage. The waste lithium iron phosphate battery not only contains valuable metal elements such as iron, lithium, phosphorus and the like, but also contains toxic and harmful components such as electrolyte, binder and the like. If the recovery treatment is improper, on one hand, the waste of metal resources is caused, and on the other hand, the environmental problems such as soil pollution, water pollution and the like can be caused. Currently, the main stream recovery technologies of waste lithium iron phosphate batteries are mainly divided into three types: (1) And the fire recovery technology is to remove organic components in the battery through high-temperature roasting, and then separate valuable metals by utilizing the density difference of molten metals. The technology has the problems of high energy consumption, easy generation of harmful gas, low metal recovery rate and the like. (2) The wet recovery technology is to dissolve metal elements in the positive electrode material by using acid and alkali solution, separate components such as lithium, iron, phosphorus and the like step by adjusting pH value, adding precipitant and the like, and finally recover the components in the forms of lithium carbonate, ferric phosphate and the like. Although the technology has higher metal recovery rate, the process is complex, the consumption of the reagent is large, the treatment cost of the generated wastewater is high, and the recovered product needs to be synthesized into the anode material again, so that the 'repair-upgrade' integration cannot be directly realized. (3) And in the direct regeneration technology, impurities on the surface of the positive electrode material are removed through a physical or chemical means, the crystal structure defect of the material is repaired, and the positive electrode material is not required to be completely decomposed into a single metal compound. However, the existing direct regeneration technology mainly aims at the performance restoration of the lithium iron phosphate material, only can restore partial electrochemical performance of the retired battery anode material, however, the method cannot change the intrinsic low-voltage characteristic (discharge platform-3.4V) of the lithium iron phosphate material, so that the energy density of the regenerated material is still limited by the voltage platform (theoretical value about 578 Wh/kg), and the requirement of the fields of new energy automobiles, high-end energy storage and the like on the high-energy density battery material is difficult to meet. In theory, manganese element has higher oxidation-reduction potential, doping manganese element in lithium iron phosphate crystal lattice can raise the discharge voltage platform of the material from 3.4V to above 4.1V, and the energy density of the material can be raised by about 20%. However, the principle is applied to the direct regeneration of the waste lithium iron phosphate, and the technical barriers that a residual carbon layer exists on the surface of the waste particles, lattice defects exist and part of Fe 2+ is oxidized into Fe 3+ are faced, so that the uniform doping of Mn and the complete repair of the lattice are difficult to realize. Therefore, a method for directly regenerating the lithium iron manganese phosphate material by using the waste lithium iron phosphate is developed, and a direct regeneration technology of doping and upgrading of manganese element is synchronously realized, so that the recovery process can be simplified, the energy consumption and the cost can be reduced, the energy density of the material can be obviously improved, and the method has important industrialized value. Disclosure of Invention The embodiment of the application solves the technical problem that the energy density cannot be improved due to the fact that the existing direct regeneration technology can only repair lithium iron phosphate by providing a method for directly regenerating lithium iron phosphate by w