Biomass-based vegetable-/fruit-derived solvents for green recovery of LiFePO4 cathodes from spent lithium-ion batteries: alternatives to ionic liquids, deep eutectic solvents and low-melting mixture solvents†

Abstract

Lithium iron phosphate (LFP)-based lithium-ion batteries (LIBs) are widely used in various fields due to their advantages such as low cost, long service life, and high energy density. The widespread use of LFP-based LIBs leads to the generation of large quantities of spent LFP cathode materials, which contribute to environmental pollution and resource waste. Therefore, it is necessary to develop a new strategy to recycle spent LFP cathode materials from LIBs. Here, we use non-toxic, low-cost and naturally available vegetable-/fruit-derived solvents (VFSs) to efficiently and mildly recover LFP cathodes from LIBs. The highest leaching efficiency of Li and Fe from LFP using VFSs is 98.8% and 99.8%, respectively. The superhigh leaching efficiency of Li and Fe achieved by VFSs is comparable to that obtained using other green solvents, including ionic liquids, deep eutectic solvents, and low-melting mixture solvents; however, VFSs in this work are greener, cheaper and even could be edible. In addition, a high precipitation efficiency of Li (83.4%) and Fe (98.5%) could be achieved at room temperature after screening 69 kinds of antisolvents.