The Le Chatelier's principle enables closed loop regenerating ternary cathode materials for spent lithium-ion batteries

The surging number of spent lithium-ion batteries (LIBs) has created great challenges to the ecological environment and lithium resources, and how to achieve high-value recycling of spent LIBs is an effective route to address the current challenges. In this paper, based on Le Chatelier's principle, we propose a strategy for efficient and green closed-loop recycling and utilization of spent NCM523 without alkali solution using Le Chatelier's principle. Citric acid as leaching agent, and oxalic acid with larger pKa as precipitant is susceptible to release H+ in the carboxylic acid group and combine with citrate ion after adding to the leaching solution. The compound decomposition reaction occurs in the system to obtain oxalic acid precursor and citric acid simultaneously, realising the closed-loop utilisation of leaching solution recycling. The regeneration of LiNi0.5Mn0.3Co0.2O2 (NCM523) was successfully achieved by combining the salt solution precipitation and roasting processes, resulting in a leaching rate of more than 99 % for Li, Ni, Co and Mn. The restored NCM523 exhibits uniform particle size distribution and intact laminar structure, as well as good cycling stability and rate performance as cathode materials for LIBs. The strategy is more atom economy efficiency and enviro-friendly than traditional pyrometallurgical and hydrometallurgical recycling technologies, which enables green and efficient closed-loop recycling of spent LIBs. This work provides an efficient and economic solution for the recovery and regeneration of spent lithium-ion battery cathode materials.