Regeneration and reuse of anode graphite from spent lithium-ion batteries with low greenhouse gas (GHG) emissions

Abstract

Regenerating spent graphite (SG) from retired lithium-ion batteries (LIBs) can effectively avoid resource waste. However, the technology is challenged by the impurity content and energy consumption. In this study, micro-expanded graphite (MEG) was synthesized by one-step oxidation method using waste LIBs anode graphite as material and perchloric acid as intercalation and oxidant agent. Then, its performance as a LIBs anode material were investigated as well as the greenhouse gas (GHG) emissions of the whole process were calculated. Perchloric acid was successfully embedded in the SG during the reaction, which effectively removed the impurities in the graphite. Defects introduced during intercalation and delamination, such as nanopores and intercrystalline cracks. Both provide additional space for Li ions during charging and discharging, thereby promoting capacity enhancement. The prepared MEG expresses a rate capability as high as 340.32 mAh/g at a current density of 0.1 C and still retains 81.73% of the capacity after 100 cycles at a current density of 1 C. Additionally, the GHG emissions of the synthesis process of this article and other literatures are compared. The results demonstrated that perchloric acid treatment process provides a low-carbon, time- and energy-saving approach for regenerated SG as battery grade material.