Organic phosphorus-based ionic liquids for extraction of valuable metals from spent lithium-ion batteries

Traditional phosphonic acid extractants such as P507 often exhibit limited extraction efficiency. Herein, a synergistic extraction strategy is developed to enhance the recovery and separation of valuable metals from acidic leachates of spent lithium-ion batteries (LIBs) by modulating P507 with lidocaine (Lid), thereby eliminating the need for saponification pretreatment and acidification. Metal extraction proceeds via combined cation-exchange and coordination mechanisms. Quantum chemical calculations and molecular dynamics simulations reveal the metal-binding sites in the ionic liquid [LidH][P507], providing theoretical guidance for synergistic extractant design. The system achieves high recoveries of Co 2+ (98.85%), Ni 2+ (95.13%), and Mn 2+ (99.97%), with separation factors of up to 250.56 (