Electrochemical\nSynergistic Recycling: Coupling Lithium\nExtraction with Regeneration of Spent LiFePO₄ Cathode Materials

Abstract

With the widespread application of lithium-ion batteries,\n a large\namount of spent lithium-ion batteries will be produced every year,\nand their recycling and reuse pose an imminent issue. The conventional\nrecycling methods, such as pyrometallurgy and hydrometallurgy, usually\ninvolve various processes like calcining, leaching, enriching, purifying,\nprecipitating, and filtering. They are associated with high energy\nconsumption, large amounts of acid and alkali reagent utilization,\nand therefore high recycling costs. Currently, recycling waste electrode\nmaterials containing high value metals, such as Li, Co, Ni and Mn,\nhas been commercially successful. However, it faces an economical\ndilemma for recycling spent LiFePO₄ cathode material which\ncomprises cheap Fe and P elements except for high value lithium element,\nespecially when the lithium price goes down. Here, this work demonstrates\nan electrochemical recycling strategy that directly combines lithium\nextraction from waste cathode materials with the regeneration of spent\nlithium iron phosphate cathode materials. Experimental results demonstrate\nthe feasibility of effective lithium extraction of waste cathode materials,\nand adequate lithium replenishment of spent LiFePO₄ electrodes\ndriven by positive bias of 0.3 V (vs SHE). The leaching rate of the\nwaste electrode materials reaches 95%, and the regenerated LiFePO₄ electrode exhibits a high specific discharge capacity of\n125.40 mAh g^–1 at 5 C. This synergistic recycling\nmethod avoids the various processes in traditional recycling methods\nand their related high energy consumption, large amount of wastewater\ndisposal, and carbon dioxide emission, thus exhibiting high economic\nbenefit and environmentally benign significance.