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

Abstract

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.