Regenerating spent graphite from scrapped lithium-ion battery by high-temperature treatment

Regenerating spent graphite from scrapped LIBs draws a significant role in utilizing spent graphite materials and protecting ecological environment. Heat treatment is an essential step in the regeneration process of spent anode. In this study, we focused on the effect of high-temperature treatment on graphite lattice structural reconstruction and electrochemical performance. Prior to heat treatment at different temperatures (e. g. 700, 900, 1100, 1300 and 1500 °C), spent graphite could be purified in sulfuric acid solution. Then, the structural analysis was performed by using XRD tests before and after regeneration, and the results show that when temperature reaches 900 °C, recovered graphite had already formed a good crystallinity. Additionally, the analysis of size distribution, surface area and pore diameter distribution were performed to characterize physical properties. The results showed that heat-treated graphite at 900 °C (HTT-900) displayed the optimal physical properties, which was close to that of commercial graphite. Furthermore, HTT-900 retained an outstanding initial specific capacity (358.1 mAh/g at 0.1C) and a remarkable cycle stability (capacity retention of 98.8% after 100 cycles). Moreover, the reversible capacities of HTT-900 at 0.1–2.0C and another 0.1C reached up to 356.8, 340.1, 306.1, 242.6, 69.7 and 359.2 mAh/g, respectively.