Efficient Lithium Extraction from a Spent Ternary Lithium-Ion Battery by Redox-Mediated Selective Leaching

The selective extraction of lithium from spent lithium-ion batteries coupled with cathode material regeneration presents significant technical challenges. This study introduces a novel methodology for the selective extraction of lithium under pH-neutral conditions. Under optimized parameters, exceptional performance metrics were achieved, with lithium leaching efficiency reaching 91.87% and leaching selectivity attaining 100%. Comprehensive kinetics analyses demonstrate that the lithium extraction process is predominantly governed by surface chemical reaction mechanisms. Furthermore, advanced spectroscopic and diffraction characterization of the leached residues reveals that Mn2+ generates MnO2 through a redox-mediated mechanism, whereby electrons are transferred to cathode material, facilitating valence reduction of transition metal elements and consequent Li+ release from the crystal lattice. The recovered Li2CO3 from the leachate and the resulting residues were subsequently utilized in a streamlined regeneration protocol to synthesize new cathode materials. Comparative investigations involving the regeneration of residues from Ni2+, Co2+, and Mn2+ leaching systems were conducted. Notably, the Mn2+ leaching system, which demonstrated the highest lithium extraction efficiency, yielded excellent regenerated cathode materials, attributed to the optimally porous microstructure of the precursor residues. This research establishes an innovative strategy for efficient lithium recovery with subsequent regeneration of cathode materials through an environmentally benign process.