Carbothermic reduction of spent Lithium-Ion batteries using CO₂ as reaction medium

It is of great importance to seek a sustainable/eco-friendly recycling strategy for spent lithium-ion batteries (LIBs) considering a rapid growth of electric vehicle (EV) market. As such, this study laid a great emphasis on a carbothermic reduction (CTR) process to recover metal(oxide)s from spent LIBs. The CTR process was particularly done from the CO₂ environment to offer a more sustainable/favorable valorization platform for spent LIBs. CO₂ was used as reaction medium in the CTR process, and such effort led to the enhanced generation of CO by means of CO₂ reduction (the Boudouard reaction: CO₂ + C ⇌ 2CO). In reference to the CTR process from an inert gas condition, this study confirmed that CO₂ changes reduction behaviors of the cathode materials (metals) in LIBs. To scrutinize the reduction mechanisms (of metals in LIBs) induced by CO₂, metal recovery of Li, Ni, Co, and Mn from the two atmospheric conditions were determined. Thermodynamic calculations were done to theoretically support all claims given in this study. Enhanced carbon removal and Li₂CO₃ formation were indeed realized from the CTR process under the CO₂ condition, which were beneficial in metal recovery from spent LIBs. As such, this study demonstrates that the CO₂-assisted CTR process could offer an environmentally favorable platform for metal recovery from spent LIBs.