Recycling of Lithium Iron Phosphate Cathode Materials from Spent Lithium-Ion Batteries: A Mini-Review

Lithium-ion batteries (LIBs), successfully commercialized energy storage systems, are now the most advanced power sources for various electronic devices and the most potential option for power storage in e-vehicle applications. The usage of Li-ion batteries is rising proportionately to the significant growth in the global demand of LIBs. Given the present circumstances, recycling of used LIBs is essential for the recovery of less abundant resources and also to conserve the environment. Although the complete recovery of metal values from the black mass is still a major constraint in the recycling process, there have been various methodologies adopted for the efficient recycling of LIBs which mostly include pyrometallurgical and/or hydrometallurgical techniques. The major focus of this work, lithium iron phosphate (LiFePO4, LFP), has grabbed massive attention with its increasing demand in e-vehicle industries owing to its safety and less use of nonabundantly available metals. Due to their high lithium content, spent LiFePO4 batteries have garnered a lot of research interest for their efficient recovery, thereby bringing higher economic gains. This review focuses exclusively on different methodologies and provides an overview on the recycling of LFPs through various pyrometallurgical, hydrometallurgical, and electrochemical processes by thoroughly analyzing the pertinent literature. With the aim of maximizing the recovery efficiencies of metals along with ambient reaction conditions, we can propose that hydrometallurgical methods were found to have a potential recycling route for LFPs compared to other methods. Thus, currently, the most promising method for LFP recycling appears to be mechanically treating the cells initially and then hydrometallurgically processing the active LFP cathode material. Thus, this review illustrates a comparative study of various methods for the effective recycling of LFPs for making it industrially applicable and environmentally friendly.