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CN-116750740-B - Method for recycling waste lithium iron phosphate battery

CN116750740BCN 116750740 BCN116750740 BCN 116750740BCN-116750740-B

Abstract

The invention relates to the technical field of battery recovery and discloses a method for recovering and treating waste lithium iron phosphate batteries, which comprises the following steps of discharging, disassembling, crushing and sorting the waste lithium iron phosphate batteries to obtain lithium iron phosphate powder; roasting lithium iron phosphate powder to obtain roasting powder, mixing the roasting powder, adding mixed acid to leach, filtering to obtain leaching solution and leaching slag, adding iron powder into the leaching solution to perform precipitation reaction, filtering to obtain copper-removing liquid, adjusting pH value of the copper-removing liquid to perform precipitation reaction, filtering to obtain aluminum-removing liquid, adding complexing agent and reducing agent into the aluminum-removing liquid, adjusting pH value to perform precipitation reaction to obtain lithium iron phosphate precursor slurry, drying the lithium iron phosphate precursor slurry, adding a carbon source to perform roasting to obtain the lithium iron phosphate anode material. The method has the characteristics of short flow, environmental protection and economy, and the prepared lithium iron phosphate anode material has good product consistency, uniform particles and excellent electrical property, and can realize industrial mass production.

Inventors

  • LI YUNXIA
  • OUYANG HONGYONG
  • XIE FUBING
  • FANG PAN
  • ZHANG DANNI
  • ZHUO RUI
  • LV ZHENGZHONG

Assignees

  • 湖北金泉新材料有限公司

Dates

Publication Date
20260505
Application Date
20230524

Claims (8)

  1. 1. The method for recycling the waste lithium iron phosphate battery is characterized by comprising the following steps of: (1) Discharging, disassembling, crushing and sorting the waste lithium iron phosphate batteries to obtain a shell, a diaphragm, a current collector and lithium iron phosphate powder containing active substances; (2) Roasting the lithium iron phosphate powder in a non-oxidizing atmosphere to obtain roasted powder; (3) Adding mixed acid into the roasted powder to adjust the pH value for leaching, and filtering to obtain leaching liquid and leaching slag; (4) Adding iron powder into the leaching solution to perform precipitation reaction, and filtering to obtain copper-removing liquid; (5) Adding a pH regulator into the copper removal liquid to regulate pH for precipitation reaction, and filtering to obtain aluminum removal liquid; (6) Adding a complexing agent and a reducing agent into the aluminum removal liquid, adding a pH regulator to regulate the pH value, and carrying out precipitation reaction in a non-oxidizing atmosphere to obtain lithium iron phosphate precursor slurry; (7) Drying the lithium iron phosphate precursor slurry to obtain lithium iron phosphate precursor powder, adding a carbon source, and calcining in a non-oxidizing atmosphere to obtain a lithium iron phosphate anode material; In the step (3), the pH value is adjusted to 2-5, the mixed acid comprises inorganic acid and organic acid with the mass ratio of (1-5) to 1, the inorganic acid is phosphoric acid, the organic acid is at least one of tartaric acid, oxalic acid, malic acid, citric acid and ascorbic acid, the leaching operation temperature is 70-90 ℃ and the leaching operation time is 3-6 hours; in the step (5), the pH value is adjusted to 5-7; in the step (6), the pH value is adjusted to 8-10, the complexing agent is at least one of sodium nitrilotriacetate, ethylenediamine tetraacetate and diethylenetriamine pentacarboxylate, the addition amount of the complexing agent is 5-15% of the molar amount of Fe 2+ in the aluminum removal liquid, the reducing agent is at least one of ascorbic acid, oxalic acid and hydrazine hydrate, the addition amount of the reducing agent is 0.5-5.0% of the theoretical total mass of the lithium iron phosphate precursor, the temperature of the precipitation reaction is 70-95 ℃, and the time is 2-6 hours.
  2. 2. The method for recycling waste lithium iron phosphate batteries according to claim 1, wherein the roasting operation in the step (2) is performed at a temperature of 450-650 ℃ for 2-6 hours.
  3. 3. The method for recycling waste lithium iron phosphate batteries according to claim 1, wherein in the step (3), before adding the mixed acid, pure water is further added into the calcined powder for size mixing, and the liquid-solid ratio obtained by size mixing operation is (3-6): 1.
  4. 4. The method for recycling waste lithium iron phosphate batteries according to claim 1, wherein the adding amount of the iron powder in the step (4) is 1.0-1.5 times of the molar amount of Cu 2+ in the leaching solution, the temperature of the precipitation reaction is 30-85 ℃, and the time is 0.5-6 hours.
  5. 5. The method for recycling waste lithium iron phosphate batteries according to claim 1, wherein in the step (5), the pH regulator is at least one of lithium hydroxide, ammonia water, sodium hydroxide, sodium carbonate and active calcium oxide, the temperature of the precipitation reaction is 30-90 ℃ and the time is 0.5-3 h.
  6. 6. The method for recycling waste lithium iron phosphate batteries according to claim 1, wherein in the step (7), the carbon source is at least one of citric acid, oxalic acid, sucrose, glucose and polyethylene glycol, the addition amount of the carbon source is 0.1% -0.5% of the mass of the lithium iron phosphate precursor powder, the temperature of the calcination operation is 350-500 ℃, and the time is 2-6 hours.
  7. 7. The method for recycling waste lithium iron phosphate batteries according to claim 1 or 6, wherein the temperature of the drying operation in the step (7) is 200-400 ℃.
  8. 8. The method for recycling waste lithium iron phosphate batteries according to claim 1, further comprising the step of (8) crushing the lithium iron phosphate positive electrode material to a D50 particle size of 1-16 μm.

Description

Method for recycling waste lithium iron phosphate battery Technical Field The invention relates to the technical field of battery recovery, in particular to a method for recovering and treating waste lithium iron phosphate batteries. Background In recent years, with the development of lithium ion battery technology and the increasing importance of people on safety, the commercial application scale of lithium iron phosphate batteries exceeds that of ternary batteries, and domestic lithium ion battery tap lead enterprises such as CATL, yi-tui lithium energy, bidi and the like continuously produce lithium iron phosphate power batteries in large quantities, and are widely applied to the field of new energy automobiles. The service cycle of the lithium ion power battery is 6-8 years, so that the recycling problem of the lithium iron phosphate battery is increasingly caused. The most widely used field of battery recovery in China is wet recovery technology. Chinese patent 202110978962.4 discloses a full recovery method of lithium iron phosphorus of a waste lithium iron phosphate positive electrode material, which comprises the steps of mixing the waste lithium iron phosphate material with a phosphorus compound, performing heat treatment, leaching with water or dilute acid, filtering and washing to obtain filtrate, adding an iron-containing compound into the filtrate to regulate the iron-phosphorus ratio of the solution, adding an oxidant, adjusting the pH value of the solution to 1-4, precipitating iron phosphate, and adjusting the pH value of the obtained filtrate to 6-12, thereby preparing lithium carbonate. The process flow is long, the cost is high, and secondary pollution can be caused. Chinese patent 202111233873.3 discloses a short-process recovery method of waste lithium iron phosphate anode materials, which comprises the steps of repeatedly and alternately soaking the waste lithium iron phosphate battery anode materials in deionized water at 25 ℃ and 90 ℃ for three times to obtain a piece of waste lithium iron phosphate materials, drying, grinding in a ball mill to obtain a powdery active material, then placing in an NMP solvent, magnetically stirring, filtering, centrifuging, washing and drying to obtain the regenerated anode materials. The NMP solvent is used in large quantity to easily cause environmental pollution, and the obtained anode material has high impurity content and obviously low electrochemical performance. Chinese patent 202111493938.8 discloses a recovery method of a lithium iron phosphate battery anode material, which adopts an organic solvent to dissolve a binder in lithium iron phosphate anode waste, reserves a conductive agent and a carbon coating layer on the surface of lithium iron phosphate to obtain a lithium iron phosphate intermediate material, and carries out lithium supplementing operation on the lithium iron phosphate intermediate material to obtain a lithium iron phosphate repair material. The technology is still immature, is still in laboratory research stage at present, and is difficult to realize industrialized application. Chinese patent 202111593472.9 discloses a comprehensive wet recycling method of waste lithium iron phosphate positive plates, which is characterized in that positive electrode powder is subjected to acid leaching, copper and aluminum removal, an oxidant is added, ammonia water is adopted to adjust the pH of a solution to precipitate ferric phosphate, and the obtained filtrate is subjected to impurity removal to prepare lithium carbonate. The wet treatment process has long and complex flow, consumes a large amount of acid and alkali, reducing agent, oxidant and other chemical reagents, has large pollution, generates a large amount of wastewater, has low resource recovery rate and poor technical economy and environmental protection, and influences the industrialized application and popularization of the wet treatment process. Disclosure of Invention The invention aims to overcome the defects in the prior art and provide a short-flow, environment-friendly and economic method for recycling waste lithium iron phosphate batteries, and the obtained lithium iron phosphate anode material has higher purity, excellent performance and better product consistency and can realize industrial application. The aim of the invention is realized by the following technical scheme: a method for recycling waste lithium iron phosphate batteries comprises the following steps: (1) And discharging, disassembling, crushing and sorting the waste lithium iron phosphate batteries to obtain the shell, the diaphragm, the current collector and the lithium iron phosphate powder containing the active substances. The discharging operation in the step (1) is a resistor discharging or a carbon powder conductor physical discharging. (2) And roasting the lithium iron phosphate powder in a non-oxidizing atmosphere to obtain roasting powder. The temperature of the roasting operation in the step