Al/Ti Removal from the Sulfate Leachate of the Spent LiFePO4/C Powder through High-Temperature Co-precipitation Triggered by Fe(III)

Regenerating FePO4 from spent LiFePO4/C powder is essential in terms of comprehensive recovery and ecological protection, while the premise is the removal of Al/Ti impurities. In this work, a Fe(III)-triggered high-temperature co-precipitation approach was proposed to remove Al/Ti from the sulfate leachate of the spent LiFePO4/C powder. The effects of different parameters on Al/Ti removal were systematically evaluated. The results showed that the induction period for phase transformation from amorphous to crystalline was shortened with elevated temperature, and about 82.6% of Al and 91.0% of Ti can be effectively precipitated with the loss of Li lower than 0.2%. The introduction of Fe(III) induced the formation of crystal nucleus and triggered the precipitation of Al in the forms of Fe(1–x)AlxPO4·3H2O and Al3(PO4)2(OH)3(H2O)5, which facilitated the co-precipitation of Ti. This work provides an appealing strategy for Al/Ti removal from the spent LiFePO4/C powder, laying a foundation for the comprehensive recovery of Fe/P/Li.