Regeneration of anode materials from complex graphite residue in spent lithium-ion battery recycling process

Abstract

The complex graphite residue from spent lithium-ion battery processing is a typical hazardous waste, and its high-value utilization is of great significance to environmental protection. Owing to the high content of impurity elements and the collapse of the graphite structures, recovery of anode graphite materials from the residue has been considered infeasible. In this research, we find that intercalation of alien elements in the graphite structure is the main obstruction to achieving satisfactory electrochemical performance with the regenerated graphite anode material. Therefore, we focused for the first time on structural reconstruction and developed a unique perspective for the purification of complex graphite materials. The crystal structure is swollen by sequential alkaline–acidic treatment to remove impurities, reducing the impurity element content by two orders of magnitude (18.9% to 0.1%). Subsequently, it is possible to apply thermal treatment to heal the graphite structure. The regenerated graphite achieves exciting performance with a well-recovered microstructure. It achieves an initial charge capacity and retention rate of 359 mA h g⁻¹ and 97.7%, respectively, which are the same levels observed with commercial materials. This study provides a method for recovering the complex graphite residue from spent lithium-ion battery processing that reduces carbon emissions by 37.0% compared to the conventional method, offering the possibility of a green approach for large-scale applications.