A Multifunctional Amino Acid Enables The Direct Recycling of Spent LiFePO 4 Cathode Material.

Lithium iron phosphate (LiFePO 4 , LFP) batteries have been extensively used in electric vehicles and energy storage due to their good cycling stability and safety. However, the finite service life of lithium-ion batteries has led to significant amounts of retired LFP batteries, urgently required to be recycled by environmentally friendly and effective methods. Here, we propose a direct regeneration strategy using natural and low-cost L-threonine as a multifunctional reductant. The hydroxyl groups and amino groups in L-threonine act as electron donors and nitrogen sources, respectively. The reductive environment created by L-threonine not only aids in converting the degraded FePO 4 phase back to a single LFP phase, but also facilitates the elimination of detrimental Li-Fe anti-site defects, thus reconstructing fast Li + diffusion channels. Meanwhile, N atoms derived from amino groups are able to dope into carbon layers, generating more active sites and enhancing the conductive properties of LFP particles. The regenerated LFP shows great electrochemical performance with a discharge capacity of 147.9 mAh g -1 at 1 C rate and a capacity retention of 86% after 500 cycles at 5 C rate. Furthermore, this approach is also feasible for LFP black mass sourced from practical industrial dismantling lines, providing considerable prospects for the large-scale practical application of LFP recycling. This article is protected by copyright. All rights reserved.