Rapid Selective Recycling of Spent LiFePO₄ Cathodes via a Deep Eutectic Solvent-Assisted Carbothermal Shock Method.

Abstract

The surge in lithium-ion battery adoption has underscored the critical need for innovative recycling technologies, particularly for lithium iron phosphate (LiFePO₄, LFP) cathodes, which dominate the market due to their safety and cost advantages. However, the thermally stable olivine structure of LFP presents formidable challenges for conventional pyrometallurgical recycling, resulting in excessive energy consumption to break down the LFP structure, substantial lithium loss, and diminished economic viability. Herein, we introduce a carbothermal shock process, synergistically enhanced by deep eutectic solvents composed of choline chloride (ChCl) and urea, to address these limitations. This ultrafast approach (∼20 s) overcomes the issue of insufficient contact in solid-solid reactions through the complete encapsulation of spent LFP by ChCl, effectively preventing Li volatilization during the short reaction time. The process yields high-purity Fe₂P and Li₃PO₄, which are efficiently separated using magnetic methods, achieving high recovery efficiencies of Li (97.39%) and Fe (99.17%). Notably, the recovered Fe₂P demonstrates enhanced catalytic performance in the alcoholysis of waste polyethylene terephthalate plastics, creating a synergistic valorization pathway. This effective method not only eliminates complex separation processes but also advances the circular economy, enabling high-value resource recovery for the lithium-ion battery ecosystem.