Spent-graphite anode from failed batteries: Regeneration and chemical prelithiation for sustainable fresh Li-ion batteries

Recycling of spent lithium-ion batteries require substantial attention for a sustainable future. Increasing deployment of batteries leads to large volume of failed batteries few years later depending on life time of the batteries. Recycling of graphite from the failed batteries has been mostly ignored. Graphite requirement of 1800 kt by 2030 is projected, which is approximately 260 % increase compared to present consumption. Present work unveils a solution to the increasing demand of battery-grade graphite anodes by a sustainable process. The combined practice of regeneration and prelithiation of spent-graphite (SG) is a viable solution for industrial scale processing. Regeneration process includes two steps, washing with N-Methyl-2-pyrrolidone and thermal processing. Regenerated SG has been tested for half-cell that delivered a poor initial Coulombic efficiency (ICE) of about 65 % only, which could affect the full-cell performance. To improve ICE, a chemical prelithiation strategy leading to higher ICE with a mean value of 103.5 % has been achieved. Also, reversible capacity of about 410 mAh/g at a specific current of 100 mA/g, good cycling stability and rate capability has been demonstrated. Further, the prelithiated SG anode coupled with LiMn2O4 cathode delivered an initial energy density of 370 Wh/kg in a lab-scale cell demonstrating its potential.