Leaching Li from mixed cathode materials of spent lithium-ion batteries via carbon thermal reduction

Abstract

The use of a carbon thermal reduction roasting method to recover lithium resources from spent lithium-ion batteries (S-LIBs) provides an important opportunity for recycling S-LIBs. The preferential extraction of Li via reduction roasting has been widely studied; however, the extraction of Li from mixed cathode materials has been rarely reported. Herein, we propose a method based on carbon thermal reduction to preferentially extract Li from mixed cathode materials. It was confirmed that there are differences in carbon thermal reduction products at 700 °C–850 °C by the thermodynamic analysis of the carbon thermal reduction process. At the same time, the effects of factors such as roasting temperature, roasting time, and material ratio on Li leaching efficiency were investigated. The Li recovery rate reached 98.86% under the optimal conditions of holding at 750 °C for 4 h with a molar ratio of mixed cathode materials to graphite of 1 : 0.25. Recovered Li₂CO₃ can be directly used as a lithium source for the regeneration of cathode materials. This study will provide new opportunities for the efficient recycling of spent lithium-ion batteries (S-LIB) mixtures.