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CN-122012945-A - Selective lithium extraction and green regeneration method for waste lithium titanate battery

CN122012945ACN 122012945 ACN122012945 ACN 122012945ACN-122012945-A

Abstract

The invention discloses a selective lithium extraction and green regeneration method for a waste lithium titanate battery. The method comprises the steps of firstly pretreating waste lithium titanate batteries to obtain lithium titanate-containing black powder, then selectively leaching lithium by adopting a quaternary ammonium salt/gluconic acid/glycol-based eutectic solvent to obtain a lithium-rich leaching solution and leaching residues containing titanium compounds, circularly using the leaching solution to leach lithium in the black powder until the leaching solution is saturated, adding a saturated sodium carbonate solution for reaction, performing solid-liquid separation, washing and drying to obtain battery-grade lithium carbonate, removing impurities, washing and drying the leaching residues to obtain titanium compounds, and finally preparing the lithium titanate anode material by taking the lithium titanate-rich leaching solution and the battery-grade lithium carbonate as precursors. The invention replaces the traditional strong acid leaching process with the environment-friendly green solvent, has the remarkable advantages of simple process, cyclic utilization of the solvent, no secondary pollution and the like, realizes the efficient and selective extraction of lithium in the waste lithium titanate battery and the green short-process regeneration of the lithium titanate negative electrode material, and has excellent industrialized application prospect.

Inventors

  • ZHANG XIHUA
  • ZHANG JINWEN
  • Rong Xingzhong
  • HOU WEI
  • CHENG ZHIPENG
  • LI GAOXIANG
  • WANG JINGWEI

Assignees

  • 上海第二工业大学

Dates

Publication Date
20260512
Application Date
20260109

Claims (9)

  1. 1. The method for selectively extracting lithium from the waste lithium titanate battery and regenerating the waste lithium titanate battery is characterized by comprising the following steps of: (1) Discharging, crushing and sorting the waste lithium titanate battery to obtain black powder rich in lithium titanate negative electrode active materials; (2) Mixing quaternary ammonium salt, gluconic acid, ethylene glycol and water, heating at constant temperature, and stirring to obtain eutectic solvent solution; (3) Adding the black powder obtained in the step (1) into the eutectic solvent solution obtained in the step (2) for heating and stirring reaction, and carrying out solid-liquid separation after the reaction is completed so as to realize selective leaching of lithium, thereby obtaining filtrate rich in lithium ions and filter residues taking titanium compounds and graphite as main components; (4) Adding saturated sodium carbonate solution into the filtrate obtained in the step (3), and washing and drying for multiple times to obtain battery grade lithium carbonate with purity higher than 99.5%; (5) Removing graphite from the filter residue obtained in the step (3) by a flotation method, removing impurities, washing and drying to obtain a titanium-containing compound; (6) And (3) taking the battery grade lithium carbonate obtained in the step (4) and the titanium-containing compound obtained in the step (5) as lithium titanate negative electrode material precursors, fully mixing, and preparing the lithium titanate negative electrode material through high-temperature roasting, thereby realizing the green short-process regeneration of the lithium titanate negative electrode material in the waste lithium titanate battery.
  2. 2. The method for selectively extracting lithium from the waste lithium titanate battery and regenerating the waste lithium titanate battery according to claim 1 is characterized in that in the step (1), the waste lithium titanate battery is disassembled after being discharged to obtain a positive electrode material, a negative electrode material, an organic diaphragm and a shell, the negative electrode material is cut into pieces, the pieces are placed into an N-methylpyrrolidone (NMP) solution to be stirred, then solid-liquid separation, washing and drying are carried out, and aluminum foil is removed to obtain the negative electrode active material powder of the waste lithium titanate battery.
  3. 3. The method for selectively extracting lithium and regenerating green from a waste lithium titanate battery according to claim 1, wherein in the step (2), the content of quaternary ammonium salt in the eutectic solvent solution is 5-25 wt%, the molar ratio of gluconic acid to ethylene glycol is 1:3-3:1, and the water content is 10-60 wt%.
  4. 4. The method for selectively extracting lithium and regenerating green from waste lithium titanate battery as claimed in claim 1, wherein in the step (2), the quaternary ammonium salt is any one or more of betaine, betaine hydrochloride, choline chloride or choline acetate.
  5. 5. The method for selectively extracting lithium and regenerating the waste lithium titanate battery according to claim 1, wherein in the step (2), the reaction temperature is 50-100 ℃, the reaction time is 30-150 min, and the stirring rotation speed is 300-800 rpm.
  6. 6. The method for selectively extracting lithium and regenerating the waste lithium titanate battery according to claim 1, wherein in the step (3), the liquid-solid ratio of the eutectic solvent solution to the black powder is 10-30 mL/g, the leaching temperature is 60-110 ℃, the leaching time is 60-120 min, and the stirring rotation speed is 300-800 rpm.
  7. 7. The selective lithium extraction and green regeneration method of the waste lithium titanate battery of claim 1, wherein in the step (3), the filtrate is recycled, and the number of times of leaching the lithium in the black powder obtained in the step (1) is 3-10 until the black powder is saturated.
  8. 8. The method for selectively extracting lithium and regenerating the waste lithium titanate battery according to claim 1, wherein in the step (4), a saturated sodium carbonate solution is added at a temperature of 80-100 ℃, the reaction is continued for 30-180 min after the addition, the filtration is performed after the reaction is finished, the filter residue is washed for a plurality of times by hot water at 55-65 ℃, and then the filter residue is dried at a temperature of 100-110 ℃.
  9. 9. The method for selectively extracting lithium and regenerating the waste lithium titanate battery according to claim 1 is characterized in that in the step (6), the high-temperature roasting temperature is 700-950 ℃, the roasting time is 6-24 hours, and the molar ratio of lithium atoms in the battery-grade lithium carbonate to titanium atoms in the titanium-containing compound obtained in the step (5) is controlled to be 0.84:1-0.88:1.

Description

Selective lithium extraction and green regeneration method for waste lithium titanate battery Technical Field The invention relates to the technical field of recycling of retired power batteries, in particular to a method for selectively extracting lithium from a negative electrode material of a waste lithium titanate battery and regenerating the negative electrode material. Background With the rapid development of new energy automobiles, large-scale energy storage systems and high-end portable electronic devices, the global demand of lithium ion batteries as core energy storage units is continuously rising. Among the numerous negative electrode materials, lithium titanate, with its unique "zero strain" crystal structure, excellent safety characteristics and ultra-long cycle life, has established an irreplaceable position in fields with stringent requirements for power output, durability and safety, such as electric buses, frequency modulation energy storage of the power grid and start-stop systems of automobiles. However, as early commercialized lithium titanate batteries gradually enter the scrapping stage, how to realize efficient, economical and environmentally friendly recovery and regeneration of the key components thereof, particularly the lithium titanate material itself, has become a key technical proposition for pushing sustainable recycling of resources and coping with environmental challenges. Currently, research and industrial application of lithium ion battery recycling technology mainly focuses on high-value cathode materials (such as ternary materials and lithium iron phosphate) and negative graphite. In contrast, for lithium titanate cathodes that are extremely chemically stable, there are significant limitations to the current mainstream recovery technology route. Although the traditional pyrometallurgical technology can treat complex materials, the traditional pyrometallurgical technology needs to be carried out at an extremely high temperature exceeding 1400 ℃, so that not only is the energy consumption huge, but also the framework structure of lithium titanate can be thoroughly destroyed in a strong reducing atmosphere, so that the volatilization loss of lithium element is caused, titanium element enters metallurgical slag, and finally, only low-value degradation recovery can be realized, the high-end electrochemical performance of the materials cannot be reserved, and harmful gas and high waste gas treatment cost are generated. The widely applied hydrometallurgical technology, namely the strong acid leaching method, generally depends on high-concentration sulfuric acid, hydrochloric acid and even hydrofluoric acid, and can dissolve metal ions in lithium titanate under the severe conditions of high temperature and high pressure by means of a strong oxidant such as hydrogen peroxide and the like. The process has the advantages of serious equipment corrosion, large amount of acid heavy metal-containing wastewater which is difficult to treat, and more importantly, lithium and titanium ions are indiscriminately leached out, so that a single component can be obtained only by adopting complex separation and purification steps in the follow-up process, the process is tedious, the consumption of chemical reagents is large, the environmental footprint is outstanding, and the core concept of green circulation is contrary. On the other hand, in the simpler direct physical repair method, the lithium titanate powder is recovered after the organic matters are removed through disassembly and heat treatment, and although the flow is short, electrolyte decomposition products accumulated in the long-term cycle process of the battery, metal impurity ions from the anode and residual carbon materials cannot be effectively removed. These impurities seriously impair the electrode interface stability of the regenerated material, resulting in electrochemical properties, especially first coulombic efficiency, rate capability and long-cycle stability, which are far from reaching the application standard of the power battery, and greatly limit the regeneration value thereof. In summary, the prior art systems, in the face of the particular material lithium titanate, have revealed a fundamental contradiction in that lithium titanate itself presents excellent stability to the battery, just as an obstacle to be overcome during its recycling. Neither the strong fire method with strong destructiveness, the strong acid wet method with serious pollution nor the physical method with insufficient purity can meet the triple requirements of high-efficiency recovery, environment friendliness and high-performance regeneration. Therefore, development of a new process capable of selectively extracting valuable components under mild conditions and directly regenerating them into high-performance electrode materials has been a clear and urgent technological development in this field. Disclosure of Invention The invention aims to ov