Targeted metals extraction from spent LiNiCoMnO batteries via thermochemical-induced sulfation roasting: Thermodynamics & kinetics.

To alleviate the energy crisis and control environmental pollution raised by spent lithium-ion batteries (LIBs), the development of efficient and economic methods for their recycling is crucial for sustainable development of new energy industry. Herein, a combined pyro - hydrometallurgical process was adopted for recovery of valuable metal elements for spent LiNiCoMnO (NCM523). Different from conventional pyrometallurgical methods with high temperature and energy consumption, the NHHSO roasting strategy works at 400 °C and achieves remarkable leaching efficiencies of Li, Co, Mn, and Ni achieved 97.5 %, 91.4 %, 91.3 %, and 95.50 %, respectively. Under the ideal conditions, abundant water-soluble metal-ammine-sulfates and metal-sulfates were revolved from NCM523. The process factors, including sulfation-roasting temperature, reagent mass ratio, roasting time, are intensively studied. Furthermore, a plausible reaction mechanism was deeply investigated with assistance of macro-micro scale, thermodynamic and kinetic analysis. Wherein, the Li of the NCM523 first react sufficiently with NHHSO owing to higher thermodynamic/kinetic motivation at the primary stage during the sulfation-roasting procedure. Subsequently, the transition metal (Ni, Co, and Mn) from the lithium-depleted NCM523 would revolve to corresponding metal-ammine-sulfates or metal sulfates, and their sulfation-roasting kinetics conformed to the unreacted nuclear model. This study proposed an alternative green route of low energy consumption and acid-free procedure for recovering spent NCM batteries, which is conducive to industrial-scale recycling of waste LIBs in the future.