Acid-free mechanochemical process to enhance the selective recycling of spent LiFePO4 batteries.

Abstract

With the large-scale application of LiFePO4 (LFP) in energy storage and electric vehicles, the recycling of spent lithium LFP batteries has gained more attention. However, recycling spent LFP is less economically feasible owing to the poor economic value of Fe products, which causes a problem for both the efficiency and economy. This work proposes a highly economical acid-free mechanochemical approach for the efficient and selective extraction of lithium (Li) from spent LFP battery cathode materials. The selective release of 98.9 % of Li from the LFP crystal structure is achieved at a reaction time of 5h, a rotational speed of 500rpm, and sodium citrate (Na3Cit) to LFP mass ratio of 10. Meanwhile, Fe is reserved in the form of FePO4 in the olivine structure. The use of Na3Cit as a co-milling agent ensures a pollution-free recovery process and efficient extraction of Li+. The chelation of Li+ with organic ligands (Cit3-) is the key to the efficient selective recovery of Li+ from the olivine LFP structure via the mechanochemical process. The economic analysis indicates that the method is feasible and ensures industrial viability. The acid-free mechanochemical (MC) process reported in this work provides a novel route to selectively recover Li from spent LFP efficiently and highly economically.