Regeneration of graphite from spent lithium-ion batteries as anode materials through stepwise purification and mild temperature restoration

Abstract

Graphite is one of the most widely used anode materials in lithium-ion batteries (LIBs). The recycling of spent graphite (SG) from spent LIBs has attracted less attention due to its limited value, complicated contaminations, and unrestored structure. In this study, a remediation and regeneration process with combined hydrothermal calcination was proposed to remove different impurities as value-added resources from SG. This study focuses on the application of different removal methods for different impurity metals by hydrothermal and acid leaching under different conditions for the removal of Cu, Li, Co, Mn, and Ni from SG. Then, mild-tempreture calcination of SG was performed to remove residual organic compounds. The regenerated graphite (RG) was found to have a better morphology structure and increased pore volume, which is more favorable for the embedding and desorption of lithium (Li) in graphite. In terms of electrochemical performance, the first discharge-specific capacity of RG at 0.5 C is 359.40 mAh/g, with a retention of 353.49 mAh/g after 100 cycles (retention rate of 98.36%). This study can be a green and efficient candidate for the regeneration of graphite from spent lithium-ion batteries as anode material by reduced restoration temperature, with different metal resources as by-products.