A Recyclable Cooperative Approach for Selective Lithium Recovery from Industrial‐Grade Spent Lithium‐Ion Battery Black Mass via Oxidative Delithiation and Complexation Mechanism

Extracting lithium selectively from an industrial-grade lithium-ion battery (LIB) black mass having multiple metal ions is challenging but crucial from an industrial standpoint. However, most of the methods involve harsh conditions and sacrificial reagents, are energy-intensive and time-consuming, and generate secondary pollution. This study presents a lithium selective, ligand-assisted cooperative approach for the selective leaching of lithium under mild conditions. It is revealed that the synergistic actions of anthraquinone salt (Na₂AQAc) and H₂O₂ generate highly reactive oxygen species (ROS) such as ^•OH, ^•O₂ ^-, and ¹O₂ that facilitate oxidative delithiation supported by spin trapping EPR and quenching experiments. As a result, a phase transition of cathode material and concurrent lithium abstraction by the ligand, forming an octanuclear lithium complex ([Li₈(AQAc^2-)₂(μ-OH₂)₂(H₂O)₁₂]⁴⁺) in the leachate was observed. Consequently, a leaching efficiency of 97% with over 99% selectivity was achieved under the optimized conditions of 3.5% H₂O₂ (v/v), 30 °C, 72 mM Na₂AQAc, 40 g L^-1 pulp density, and a reaction time of 1 h. A recycling strategy was demonstrated to recover anthraquinone acid, and lithium was separated as high-purity Li₂CO₃. This method offers the advantages of room-temperature operation, neutral pH conditions, shorter time duration, minimal reagent usage, and the ability to recycle the reagents.