Vacuum Pyrolysis of Pine Sawdust to Recover Spent Lithium Ion Batteries: The Synergistic Effect of Carbothermic Reduction and Pyrolysis Gas Reduction

Abstract

Minimizing the energy consumption and expanding the usage of renewable material in the recovery of spent lithium ion batteries (LIBs) are significant for exploring more sustainable recycling approaches. Herein, we report a biomass carbothermic reduction approach to selectively recycle Li and Co from spent LIBs at a low temperature of 673 K. Pine sawdust (PS) was selected as the sample to provide reducing gas and carbon during the pyrolysis. During the reduction process, the PS-derived reducing gas and charcoal codrove the conversion of LiCoO2 to Co/CoO and Li2CO3, and over 94% of Li and 97% of Co were recovered. The synergistic effect of carbon and reducing gas is key to achieving the transformation process at a lower temperature than the common carbothermic reduction. Economic and environmental analysis based on the EverBatt model shows that this strategy reduces energy consumption and greenhouse gas (GHG) emissions, thereby increasing potential profit. Overall, this paper provides a green method to recycle spent LIBs via waste biomass with minimized secondary wastes.