Reducing the environmental impact of lithium-ion battery recycling through co-processing of NCM and LFP

Abstract

Due to its potential environmental hazards and the importance of valuable metal supply, the recycling of spent lithium-ion batteries (LIBs) has attracted widespread attention. The hydrometallurgical process for recycling spent lithium-ion batteries faces the problem of excessive acid consumption and the need for different redox additives to improve the leaching rate of major metals which will result in issues such as resource waste and secondary pollution. In this study, using LFP and NCM as raw materials, the inherent oxidation/reduction characteristics between them were utilized to achieve leaching rates of over 99 % for Ni, Mn, Li, and over 95 % for Co, without the addition of any redox additives under near stoichiometric sulfuric acid. The leaching kinetics and reaction mechanism of different metals indicate that LFP rapidly dissolves in the sulfuric acid solution, with the released Fe2+ acting as a reducing agent. The subsequent slower reaction between Fe2+ and NCM becomes the rate-controlling step. Afterwards, the leachate regulated by solution control can be further used to prepare Ni-Co-Mn hydroxide precursors and lithium carbonate after the formation of FePO4. This method effectively reduces chemical consumption, mitigates environmental footprint, and achieves highly economical recovery of metals from spent lithium-ion batteries.