Retrieving lost Li in LIBs for co-regeneration of spent anode and cathode materials

Abstract

Direct regeneration of spent Li-ion battery electrode materials has garnered considerable attention due to its streamlined procedure, low energy consumption, and high economic viability. Typically, an Li source is required to address the vacant Li defects in spent cathodes for regeneration, while the removal of residual Li is crucial for regenerating spent anodes. Here, given our discovery that approximately 65 % of the residual Li in spent graphite demonstrates reactivity with water, we propose a straightforward water extraction method for purifying and regenerating spent graphite anode. By carefully controlling the concentrations of OH^- and Li⁺ ions in the obtained Li-rich solution, it can be directly used to relithiate spent NCM cathodes. In this method, Li⁺ ions lost from the cathode during electrochemical cycling were reintroduced back into the cathode via aqueous relithiation, eliminating the need for additional Li sources to repair the Li deficiencies in spent cathode, effectively reducing recycling costs and minimizing the environmental impact associated with raw materials. The regenerated NCM cathode and graphite anode demonstrated specific capacities of 163 mAh/g and 386 mAh/g at a rate of 0.1C, respectively, both reaching the performance levels of pristine materials. Importantly, compared to traditional direct recycling methods, the Li-retrieving regeneration method reduced greenhouse gas emissions by 16 %, energy consumption by 17 %, water consumption by 17 %, and overall recycling costs by 12 %.