Composition-induced solvent effect regulation toward ultrafast and selective recovery of LCO cathodes from spent lithium-ion batteries

Abstract

Spent lithium-ion batteries (LIBs) have triggered an urgent demand for efficient and rapid recycling technologies to mitigate resource scarcity and environmental pollution. However, conventional LIB recycling approaches suffer from drawbacks such as harsh operating conditions, low metal selectivity, slow leaching kinetics, and secondary environmental pollution, severely restricting their large-scale sustainable application. Herein, we propose a composition-induced solvent effect regulation (CSER) strategy for recycling the LCO cathodes of LIBs. This strategy enables ultrafast and highly selective recovery of Li from the lithium cobalt oxide cathode under mild conditions. Specifically, at 80 °C for 24 h, the Li leaching efficiency reaches up to 98.3% with a negligible Co leaching efficiency of only 3.5%, corresponding to a high Li/Co selectivity of 28.1. Even within 1 h, the Li leaching efficiency still achieves 83.9% while maintaining a low Co leaching efficiency of 5.5% with a metal selectivity of 15.3. Mechanism investigations demonstrate that the modulation of the solvent composition in polyethylene glycol 200 and phosphorous acid-based DESs induces a variation in the solvent effect, which, in turn, governs the metal selectivity of Li/Co. A two-stage shrinking core model (TS-SCM) is introduced, which outperforms the traditional shrinking core model (SCM) in fitting the kinetic behavior of the leaching process for LIB recovery.