Direct Electrochemical Regeneration of Lithium-Ion Battery Cathode Material through Molecular Wiring

Increasing use of lithium-ion batteries (LIBs) urges for efficient recycling strategies for their components. Direct recycling methods for cathode materials, based on repairing the structure of the degraded cathode particles without destroying the bulk phase, are promising energy-saving alternatives to traditional metallurgy processes that involve several steps and use large volumes of chemicals causing secondary pollution. Herein, we report a novel and scalable method for the direct electrochemical recycling of spent lithium iron phosphate (LFP) powder in a flow cell via redox mediation. In this method, pellets of spent LFP powder (S-LFP) placed in a tank are directly reduced and relithiated by a redox mediator dissolved in a Li-containing aqueous electrolyte, pumped from an electrochemical cell stack to the relithiation tank. Redox mediators transport charge to the S-LFP pellets from the electrochemical cell, where Li₄Fe(CN)₆ is oxidized and Li ions are supplied from a Li₄Fe(CN)₆-containing counter compartment through an ion-selective membrane. The consumption of the regenerating redox mediator solution is minimal via a closed-loop electrochemical regeneration reaction. Successful S-LFP regeneration using two redox mediators, with different energy demand processes, is confirmed by structural and electrochemical characterization.