Direct regeneration of spent graphite anode material via a simple thermal treatment method

Abstract

The demand for recovering lithium-ion battery components is increasing due to the surging volume of spent lithium-ion batteries. Graphite is commonly used as the anode material in lithium-ion batteries, and recovering graphite from spent anodes has attracted significant attention. Currently, acid leaching is used to simultaneously recover metal impurities and graphite from anodes, but the subsequent disposal of acidic waste pollutes the environment, contradicting green chemistry principles. This work reports a CO₂ roasting process that repairs the graphite structure by annealing spent graphite in CO₂. This converts metal impurities into water-soluble carbonates that can be removed via aqueous washing. CO₂ roasting more effectively removes impurities from graphite compared to N₂ roasting, and also enhances the rate performance of recycled graphite. At high current densities of 1C and 2C, the regenerated graphite achieved discharge capacities of 366 and 332 mA h g⁻¹, respectively, comparable to commercial graphite. This environmentally friendly process recovers graphite anodes without requiring acid leaching, providing a new approach for designing high-rate recycled graphite anodes.