Recycling of Li(Ni,Co,Mn)O₂ via a chlorination technique

Abstract

A new approach to recycle Li(Ni,Co,Mn)O₂ (NCM, Ni : Co : Mn=1 : 1 : 1) is introduced and experimentally demonstrated. Chlorine gas was employed as a reaction agent to selectively extract Li from NCM. Through a reaction at 550 °C for 4 h under a 180 mL/min Ar+20 mL/min Cl₂ flow, Li was converted into water-soluble LiCl, while the initial transition metals (Ni, Co, and Mn) were converted into a spinel-type oxide phase. Minor amount of transition metals, which reacted with Cl₂ to produce transition-metal chlorides, were recovered in the subsequent precipitation step. An amount of 94.9 wt% of transition-metal recovery ratio was achieved through the recovery processes. The amount of Li recovered as Li₂CO₃ was 35.8 wt% of the initial amount. A new NCM was successfully re-synthesized using the recovered materials as well as additional Li₂CO₃, resulting in a layered NCM structure. The re-synthesized NCM was electrochemically evaluated by fabricating a CR2032 coin cell which exhibited a capacity of 105 mAh/g.