Enhanced lithium extraction from spent LiFePO4 via high-throughput electrochemical flow cell technology

Abstract

In recent years, the strong demand for electronic products and new energy vehicles has stimulated the large-scale production of lithium-ion batteries. As these batteries reach the end of their service life, the imperative for industrial-scale recycling has garnered global attention. At present, prevailing recycling methods, predominantly rooted in hydrometallurgy and pyrometallurgy, entail intricate procedures and substantial chemical consumption. Here, we present an innovative and economical approach for the recycling of spent LiFePO₄ materials. By virtue of a novel high-throughput electrochemical flow cell, spent LiFePO₄ battery materials are continuously decomposed into valuable chemicals. FeCl₃ and its complexes with glycine, malonic acid, malic acid, and xylitol (the ratio of FeCl₃ to ligand is 1:4) were selected as redox mediators. The redox mediators involved in the reaction are instantly regenerated on the anode for subsequent rounds of reactions, while Li ⁺ ions are extracted from the LiFePO₄ and concentrated in the cathode side, conjunction with H₂ generation. Through comprehensive analysis of chemical reactions within the reaction tank and the electrochemical reaction rates on the electrode, we demonstrate the superior extraction performance of malonic acid-Fe³⁺. Furthermore, the hydrogen evolution reaction kinetics is boosted by a platinum carbon electrocatalyst. This electrolyzer can operate at a high current density of 200 mA cm⁻², significantly reducing the reaction time for recycling 1 g of LiFePO₄ material to a mere 0.17 h. This substantial enhancement in recycling efficiency not only streamlines the process but also conserves valuable chemical resources.