Closed-loop extraction–stripping process for lithium–iron separation from FeCl3 leachate of spent LiFePO4 cathode power

The use of Fe 3+ salts for leaching spent LiFePO 4 (LFP) batteries is gaining attention due to its mild, eco-friendly conditions. However, efficient Fe/Li separation remains challenging, as precipitation causes Li loss or impurity introduction, and conventional solvent extraction offers low Li efficiency (∼80 %) and complex processes. This study employed data mining and theoretical analysis to rapidly identify a synergistic P204/N235 extraction system. A closed-loop process coupling H 3 PO 4 stripping and FePO 4 precipitation was developed, achieving 99.45 % Fe removal and only 1.25 % Li loss in a single extraction stage. The Fe/Li separation factor reached 14,243. During stripping, Fe recovery reached 95 % in one stage. The aqueous phase over 10 stripping cycles was reused for FePO 4 preparation, and the raffinate was retained for Li recovery. This integrated approach enables efficient Fe/Li separation and high-value resource utilization from LFP leachates.