Closed-loop regeneration of LiFePO4 from spent lithium-ion batteries: A "feed three birds with one scone" strategy toward advanced cathode materials

The treatment of spent lithium-ion batteries has become an urgent issue along with the explosive growth of consumption. Traditional metallurgical technologies can recover lithium and other valuable elements in LiFePO4, yet existing various disadvantages to be solved, such as long acid leaching process and harsh reaction conditions. Herein, a delicate method of recycling waste LiFePO4 via a "feed three birds with one scone" strategy is developed and regenerated as the advanced cathode material. Particularly, it effectively separates the three materials, aluminum foil, lithium-contain compound and high-purity FePO4, via one-step oxidation leaching reaction at room temperature. The leaching rate of Li exceeds 98% by adding ammonium persulfate, which is facilitated to obtain transformed lithium carbonate and high-purity precursor FePO4. The reaction mechanism of oxidation leaching process is analyzed through kinetic and thermodynamic analyses, which believe that the leaching reaction of oxidation is controlled by an ion diffusion. Meanwhile, the recycled Li2CO3 and FePO4 are utilized as raw materials to synthesize LiFePO4 cathode, making the utmost advantages of waste LiFePO4 elec-trode. As anticipated, the regenerated LiFePO4 displays excellent rate capability (discharge capacity of 135.5 mAh g(-1) at 1C) and cyclic properties (capacity retention of 98.0% after 400 cycles). This green and effective method can efficiently recycle waste LiFePO4 electrodes and inspire the regeneration of electrode materials from spent lithium-ion batteries.