Recycle of spent LiFePO4 batteries: An eco-friendly closed-loop technique based on less solvent solid state reaction

Lithium iron phosphate (LFP) batteries have become one of the most popular batteries due to their high safety and low cost. However, the lifespan of LFP batteries is limited, making effective recycling processes crucial for environmental protection, resource conservation, and economic benefits. Less solvent solid state reaction (LSR) is reactions of solids with the help of a little solvent, which has advantage of almost 100% conversion of reactants and no waste generation. Herein, LFP (S-LFP) from spent batteries was first entirely decomposed to produce FePO4 4 and LiH2PO4 2 PO 4 in H3PO4-H2O2 3 PO 4-H 2 O 2 leaching systems using the LSR method. Then, battery-grade Li2CO3 2 CO 3 was prepared by adding CaCl2 2 and Na2CO3 2 CO 3 to LiH2PO4. 2 PO 4 . As a result, the battery of regenerated LiFePO4 4 (R-LFP) using recycled FePO4 4 and Li2CO3 2 CO 3 exhibits superior electrochemical performance compared to those with unused LiFePO4, 4 , including a higher discharge specific capacity (140.7 mAhg-1- 1 at 0.1C) and excellent cycle life, with a capacity retention of 98.6% over 500cycles at 1.0C. The LSR method provides a green and sustainable closed- loop recovery strategy for S-LFP cathode materials, which reduces the number of processing steps and chemical consumption, promotes resource conservation and environmental protection, and facilitates the sustainable industrial development of S-LFP batteries.