Selective lithium recovery from spent LiFePO4 battery cathode materials using a green oxidizing reagent

The green and efficient recovery of Li + from spent LiFePO 4 (S-LFP) batteries and subsequent preparation of high-purity lithium products hold significant industrial importance. It can be applied in various fields such as electronic products, energy storage, and healthcare. A green and non-toxic potassium monopersulfate triple salt (PMTS) was used for the first time as a dual-functional reagent serving as both leaching reagent and oxidant, enabling highly in-situ selective leaching of Li + from S-LFP. Furthermore, a novel extraction system employing dibenzoylmethane (DBM) and triisobutyl phosphate (TIBP) was innovatively applied to selectively recover Li + from the leachate, ultimately yielding battery-grade lithium carbonate. Under optimized conditions, the leaching efficiency of Li + reached up to 99.40 % with nearly negligible iron dissolution (0.01 %). The DBM-TIBP system achieved selective extraction of Li + from the leachate with a single-stage extraction efficiency exceeding 94 %. A comprehensive purification process involving washing with NH 4 Cl/LiCl solution, three-stage cross-flow stripping with NH 4 HCO 3 solution, and high-temperature crystallization was implemented. This protocol achieved remarkable impurity removal efficiencies of 99.05 % for K + and 98.10 % for Na + while maintaining complete Li + retention. The stripping efficiency of Li + reached up to 99.36 %, leading to producing battery-grade lithium carbonate with 99.9 % purity. Additionally, potassium sulfate with 98.30 % purity was recovered from the residual leachate via fractional crystallization. This cost-effective and environmentally benign strategy provided a new perspective for industrial-scale green recycling of S-LFP battery cathode materials.