Constructing a Homogeneous Medium Layer To Promote the Direct Regeneration of Spent Lithium Iron Phosphate

With the massive application of lithium-ion batteries in electric vehicles, spent lithium iron phosphate (LFP) batteries have accumulated in recent years, inducing an urgent requirement in recycling technology. Direct repair technology has been considered as a promising approach for recycling spent LFP. However, the traditional solid-phase repair technology is limited by the heterogeneous contact between the lithium source and spent LFP. Herein, polyacrylonitrile (PAN) was selected as the additive to facilitate the intimate contact between the lithium source and spent LFP. PAN displays a strong interaction with defective LFP, leading to the effective contact between spent LFP and the lithium replenishment agent. Moreover, PAN is favorable for the diffusion of lithium ions in the spent LFP lattice during the regeneration process. Therefore, the unevenly distributed FeLi defects in spent LFP are well-repaired. As a result, the regenerated LFP exhibits a high capacity of 155 mA h g–1 at 0.1 C and improved cycling stability with a capacity retention of ∼87% after 400 cycles at 1 C.