Electrochemical selective lithium extraction and regeneration of spent lithium iron phosphate

In this paper, a green, efficient and low-cost process for the selective recovery of lithium from spent LiFePO₄ by anodic electrolysis is proposed. The leaching rates of Li, Fe and P under different conditions were explored and the optimal conditions are obtained. In the optimal conditions, Li, Fe and P leaching rates were 96.31%, 0.06% and 0.62% respectively. The Li/Fe selectivity was over 99.9%. The product obtained is isostructural FePO₄ and retains the original particle morphology. The FePO₄ obtained can be synthesised into LiFePO₄/C by direct regeneration process or impurity removal regeneration process. The material synthesized by the latter process has a better electrochemical performance, with a discharge specific capacity of 144.5 mAh/g at 1.0C and a capacity retention of 92.0% over 500cycles. The superior performance can be attributed to an impurity removal process that reduced agglomeration and improved particle morphology.