Publication date: 15th December 2025
The increasing use of lithium-ion batteries (LIBs) in portable devices and electric vehicles will result in a growth of spent LIBs. Disposing of these batteries wastes valuable critical mineral resources and has a significant environmental impact. Given that the materials of greatest economic value are found in the cathode, the development of efficient recycling strategies for the recovery of cathode materials from spent LIBs is essential[1]. Direct recycling methods, which restore the structure of degraded cathode particles without compromising the bulk phase, have emerged as an energy-efficient alternative to conventional metallurgical processes, whose multi-step nature requires substantial quantities of chemical agents[2]. Although direct recycling of cathode material has clear environmental and energy efficiency advantages, scaling limitations of reported methods have restricted large-scale implementation.
In this work, we describe a novel and scalable method for the direct electrochemical recycling of lithium iron phosphate (LFP) from discarded LiBs, using a flow cell and the redox mediation process. Electrochemical recycling using redox mediators effectively restores the oxidation state of iron and facilitates the reinsertion of Li ions, effectively addressing the main degradation mechanism of cathode LFP. In this procedure, pellets of degraded LFP powder (S-LFP) are placed in a tank, where they are directly reduced and relithiated by a redox mediator (RMred) dissolved in an aqueous electrolyte containing lithium (relithiation anolyte), pumped from an electrochemical cell into the relithiation tank. Redox mediators transport charge from the electrochemical cell, where Li₄Fe(CN)₆ is oxidized, to the S-LFP pellets, while Li ions are supplied from a counter compartment containing Li₄Fe(CN)₆ through an ion-selective membrane. Consumption of the redox mediator regeneration solution is minimal thanks to a closed-loop electrochemical regeneration process. The concept is validated using two different redox mediators, each associated with different energy demands in the recycling process. The total regeneration of the S-LFP is confirmed by structural and electrochemical characterization, showing that the regenerated material has a crystalline structure comparable to that of the LFP in a new cathode.
The authors acknowledge financial support by the Spanish Ministry of Science and Innovation (Grant PID2023-148703OA-I00 funded by MICIU/AEI/ 10.13039/501100011033 and by ERDF/EU). The authors also acknowledge the financial support from the Convert2Green project. This project has received funding from the European Union’s Horizon Europe Research and Innovation Programme under grant agreement No. 101092347. This work was supported by the Regional Government of Castilla y Leon (Junta de Castilla y Leon), the Ministry of Science and Innovation MICIN, and the European Union NextGeneration EU/PRTR (C17. I1). The authors would like to thank the Diamond Light Source for providing the beamtime (SP38116). G.M.T. acknowledges a fellowship from the Regional Government of Castilla y Leon (Junta de Castilla y León), which is partially supported by the European Social Fund.
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