Recovery of valuable metals from spent lithium-ion batteries through biomass pyrolysis gas-induced reduction

The development of spent lithium-ion batteries (LIBs) recycling technologies can effectively alleviate environmental pressure and conserve metal resources. We propose a win-win strategy for pyrolysis gas reduction by lignocellulosic biomass, ensuring gas-induced reduction by spatial isolation of biomass and lithium transition metal oxides (LiTMOX (TM = Ni, Co, Mn)), and avoiding the separation of solid carbon and TMOX (TM = Ni, Co, Mn). In the spent LiCoO2 batteries, the lithium recovery efficiency reaches 99.99% and purity reaches 98.3% at 500 °C. In addition, biomass pyrolysis gas reduction is also applicable to treat spent LiMn2O4 and LiNi0.6Co0.2Mn0.2O2 batteries. Thermodynamic analysis verifies that CO dominates the gas reduction recovery process. DFT calculation indicates that the gas reduction induces the collapse of the oxygen framework of LiTMOX (TM = Ni, Co, Mn). Everbatt-based economic and environmental analysis illustrates that this is an environment-friendly and energy-saving method.