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.