Fundamental Insights into the Effectiveness of Cathode Regeneration

Abstract

The volume of end-of-life lithium-ion batteries (LIBs) is expected to increase rapidly over the coming decade. Consequently, it is of great interest to recycle and reuse cathode materials due to their high value in LIBs. Direct cathode recycling, which aims to regenerate cathode materials without destroying their original functional structures, could potentially maximize the return value from end-of-life LIBs compared to pyrometallurgical- and hydrometallurgical-based recycling processes. Here, we fundamentally investigate the effectiveness of cathode regeneration by regenerating chemically-degraded cathodes at different levels of delithiation, which are analogous to spent cathodes at different states of health (SOH). To evaluate whether direct recycling is effective in regenerating spent cathodes at different degrees of degradation, regenerated cathodes are thoroughly compared with pristine and chemically delithiated cathodes. The use of chemically delithiated samples provides the opportunity to fundamentally examine how the disordered, lithium-deficient cathode from used LIBs is regenerated while preventing the complications associated with other cathode degradation mechanisms, including surface layer formation and particle cracking.