A Closed-Loop Process for Selective Metal Recovery from Spent Lithium Iron Phosphate Batteries through Mechanochemical Activation

Abstract

With the increasing consumption of lithium ion batteries (LIBs) in electric and electronic products, the recycling of spent LIBs has drawn significant attention due to their high potential of environmental impacts and waste of valuable resources. Among different types of spent LIBs, the difficulties for recycling spent LiFePO4 batteries rest on their relatively low extraction efficiency and recycling selectivity in which secondary waste is frequently generated. In this research, mechanochemical activation was developed to selectively recycle Fe and Li from cathode scrap of spent LiFePO4 batteries. By mechanochemical activation pretreatment and the diluted H3PO4 leaching solution, the leaching efficiency of Fe and Li can be significantly improved to be 97.67% and 94.29%, respectively. To understand the Fe and Li extraction process and the mechanochemical activation mechanisms, the effects of various parameters during Fe and Li recovery were comprehensively investigated, including activation time, cathode powder to additive mass ratio, acid concentration, the liquid-to-solid ratio, and leaching time. Subsequently, the metal ions after leaching can be recovered by selective precipitation. In the whole process, about 93.05% Fe and 82.55% Li could be recovered as FePO4·2H2O and Li3PO4, achieving selective recycling of metals for efficient use of resources from spent lithium ion batteries.

Progress and Status of Hydrometallurgical and Direct Recycling of Li-Ion Batteries and Beyond

“…However, phosphoric acid is also efficient to dissolve spent LFP even at low acid concentrations (0.5-0.6 M) and room temperature, as demonstrated by Bian et al and Yang et al [76,183]. Both authors recovered Fe(III)PO 4 •2H 2 O through reflux evaporation after leaching.…”

“…After leaching, hydrated FePO4 is precipitated through reflux evaporation while lithium is extracted as Li3PO4 with NaOH. [76] In both processes, although leaching conditions appear promising for larger scales, the…”

“…After leaching, hydrated FePO 4 is precipitated through reflux evaporation while lithium is extracted as Li 3 PO 4 with NaOH. [76] In both processes, although leaching conditions appear promising for larger scales, the evaporation step represents a major challenge for their commercial application because it consumes significant amounts of energy.…”

“…H3PO4 leaching process suggested by Yang et al (according to[76]); here, LFP and EDTA-2Na are for LiFePO4 and ethylenediamine tetraacetic acid disodium salt, respectively.…”

Sustainable development of mining processes based on mechanochemical leaching of ore

“…At the same time, the degree of efficiency of utilized wastes is extremely low [25][26]. Only 15% of large ore deposits consider mining and treatment wastes as part of their technological cycle.…”