Environmentally friendly regeneration of graphite from spent lithium-ion batteries for sustainable anode material reuse†

Abstract

The graphite industry is currently facing significant supply and demand issues owing to the sudden rise in electric vehicle (EV) usage; however, the lithium-ion batteries (LIB) that power such vehicles will be landfilled or incinerated at the end of their lifetime, raising questions concerning their environmental impact and resource reuse. The recycling of spent LIBs using economical and environmentally sustainable technologies is therefore required. We therefore employ three different strategies to regenerate graphite from spent LIBs as an anode material in new LIBs. Acid (Gr-AcOH), alkali (Gr-KOH), and gas (Gr-N₂) treatments are used to reconstruct the structure of the spent graphite, which is then evaluated as an anode material in a half-cell configuration. The graphite regenerated by the Gr-AcOH, Gr-KOH, and Gr-N₂ techniques exhibit delithiation capacities of 328, 325, and 338 mA h g_gr⁻¹, respectively, after 150 cycles, with a coulombic efficiency of ∼99.9%. These delithiation capacities are considerably higher than that of untreated spent graphite (120 mA h g_gr⁻¹, where ‘gr’ in the subscript stands for graphite) and close to that of commercial graphite (345 mA h g_gr⁻¹). Additionally, our life cycle assessment estimates the impact of graphite regeneration ranges from 0.27 to 3.53 kg CO₂e per kg graphite, assuming a pilot-scale operation using 100 kg graphite operation. This study demonstrates the suitability of environmentally sustainable graphite recycling for LIB applications, and the implementation of circular approaches for battery anode recycling.