Efficient direct regeneration of spent LiFePO4 by low-temperature sintering

The morphology, crystal structure, and electrochemical performance of spent LiFePO 4 (S-LFP) are recovered by one-step low-temperature solid phase sintering. After sintering at 550 °C for 3 h, the secondary particle size distribution of regenerated LiFePO 4 (R-LFP) becomes narrower, and the D 50 is reduced from 5.6 to 2.3 μm. In addition, the content of Li−Fe antisite defect is reduced from 5.73% to 1.20%, and the F is doped to O(2) site in the structure of R-LFP. Moreover, a coating layer comprising carbon and LiF is formed on the surface of R-LFP because of the decomposition of PVDF. Therefore, the R-LFP demonstrates exceptional Li + diffusion dynamics and conductivity, which delivers a high discharge capacity of 157.3 mA·h/g at 0.1 C . And it maintains 92% of its initial capacity after 500 cycles at 1 C .