Selective recovery of valuable materials from retired ternary lithium-ion batteries based on carbon monoxide reduction

Abstract

Recycling valuable materials from retired Li-ion batteries (LIBs) can help alleviate the shortage of critical materials, thereby promoting both environmental and economic development. The oxygen-free roasting pre-treatment has emerged as a promising and reliable method for the selective recovery of valuable materials from retired LIBs. In this study, a retired LiNi_0.65Co_0.15Mn_0.2O₂ cell, without disassembling and crushing, is subjected to roasting under a carbon monoxide (CO) atmosphere. The composition of roasted products is analyzed, and results indicate that NCM is completely converted into Li₂CO₃, Ni, Co, and MnO at 500 °C, which is lower than the conventional carbothermal reaction temperature. The gaseous products generated during the process consist primarily of CO₂, CO, and H₂. Li, transition metals, and graphite are recovered through water and acid leaching processes. 97.48% of Li is recovered from the water-leaching solution after reduction roasting under a CO atmosphere. Subsequently, 99.99% Ni, 99.98% Co, and 99.94% Mn are obtained via acid leaching of the water-extraction residue. The reactions between decomposed products of NCM and Al (Cu) foil will be inhibited under a CO atmosphere. Based on the above results, the retired LIBs can be directly treated without dismantling and crushing by using pyrosis gases as reductants. Consequently, this method demonstrates significant potential for large-scale industrial applications.