Precise and controlled carbothermal reduction for selective lithium extraction from spent cathodes via double-enhancement process

Carbothermal reduction is considered to be an efficient and cost-effective method for the recovery of cathodes in spent lithium-ion batteries (S-LIBs). However, the conventional direct mixed roasting with high reaction temperature, slow solid phase reaction kinetics and uncontrollable reduction process greatly hinders the lithium recovery efficiency and carbon emission reduction. Here, we propose a dual super-liquid film reactors (SLFR) enhancement strategy to achieve nanoscale mixing of spent anode and cathode materials to improve the kinetics of the roasting and water leaching processes. This strategy reduces the reaction temperature and time to 550°C and 1 h, improves the mass transfer efficiency of the solid phase reaction and aqueous leaching, precisely reduces LCO to CoO instead of Co metal, increases the lithium leaching rate from 85.6 % to 98.6 %, shortens the leaching time from 60 min to 40 s, and reduces the carbon dosage from 5 % to the theoretical value of 3 %, achieving zero carbon emission from the reduction process. This work provides a new general strategy for efficient, clean and precise carbothermal reduction of spent cathode materials for selective lithium extraction, and demonstrates the scalability in industrial applications.