Mechanochemical enhanced lithium selective extraction from spent cathode material via two-step molten salt treatments

The rapid development and widespread use of lithium-ion batteries (LIBs) in electric vehicles and stationary energy storage systems has been stimulated by the global push toward carbon neutrality. Thus, recycling spent LIBs as an efficient way to cope with the resulting resource scarcity and environmental damage has attracted much attention. Herein, based on previous studies, a process for selective Li extraction from a recovered spent LiMn2O4 (LMO) cathode with two-step molten salt treatments is proposed in this paper. The selective extraction of Li from the spent LMO cathode by (NH4)2SO4 molten salt is significantly promoted by mechanochemical treatment. Approximately 100% of the Li in the spent LMO is selectively extracted after step two of the molten salt treatment, and the Mn-containing phases in the spent LMO cathode are converted to Mn2O3. A Li2SO4·H2O product satisfying the requirements of Standard YS/T 1241–2018 is obtained from the purified Li2SO4 water-leachate after crystallization and calcination. In addition, 93.65% Mn in the water-leaching residue of Mn2O3 achieved sulfate conversion with (NH4)2SO4 molten salt reduction, and a first-grade product of MnSO4·H2O satisfying the requirements of Standard HG/T 4823–2015 was obtained after water-leaching and crystallization.