Recovery and Reuse of Anode Graphite from Spent Lithium-Ion Batteries via Citric Acid Leaching

With the rapid growth of retired lithium-ion batteries (LIBs), the recycling of electrode materials has become a hot topic in research. Considering the economic factors, the recovery of cathode electrodes has always been the focus of research. Until now, the recovery of anode electrode materials has gained much attention due to their large proportion in batteries. This research focuses on the recovery and regeneration of anode graphite. Based on the existing form of lithium in anode graphite carbon powder, environmentally friendly citric acid is selected as the extraction reagent to extract lithium and regenerate spent graphite. Through orthogonal experiments and conditional experiments, the optimal conditions for extracting the lithium element from the spent LIB anodes were a temperature of 90 °C, S/L ratio of 1:50 g mL-1, CAC of 0.2 mol L-1, and time of 50 min, and the leaching rate of lithium ions can reach 97.58%. The electrochemical performance tests showed that the regenerated graphite anode material after the extraction of lithium had a high discharge capacity of 330 mA h g-1 after 80 cycles at 0.5 C, and the Coulombic efficiency is maintained above 99%. By comparing the regenerated graphite and the pretreated spent graphite, the regenerated leached graphite has obviously excellent electrochemical performance, and its properties can be comparable to those of artificial graphite. This experimental result provides a theoretical basis for the subsequent recycling of anode electrode graphite.