Highly efficient recovery of waste LiNixCoyMnzO2 cathode materials using a process involving pyrometallurgy and hydrometallurgy

Substantial environmental and economic benefits can be achieved by recycling used lithium-ion batteries. Hydrometallurgy is often employed to recover waste LiNixCoyMnzO2 cathode materials. As Ni, Co and Mn are transition metals, they exhibit similar properties; therefore, separating them is difficult. Thus, most researchers have focused on leaching processes, while minimal attention has been devoted to the separation of valuable metals from waste LiNixCoyMnzO2 cathode materials. Herein, we propose an environment-friendly, gentle process involving the usage of pyrometallurgy and hydrometallurgy to gradually leach valuable metals and effectively separate them. Interestingly, Li is recovered through a reduction roasting and water leaching process using natural graphite powder, Ni and Co are recovered through ammonia leaching and extraction processes and Mn is recovered through acid leaching and evaporation-crystallization processes. Results show that similar to 87% Li, 97.01% Co, 97.08% Ni and 99% Mn can be leached using water, ammonia and acid leaching processes. The result obtained using the response surface methodology shows that the concentration of (NH4)(2)SO3 is a notable factor affecting the leaching of transition metals. Under optimal conditions, similar to 97.01% Co, 97.08% Ni and 0.64% Mn can be leached out. The decomposition of LiNixCoyMnzO2 is a two-step process. This study provides valuable insights to develop an environment-friendly, gentle leaching process for efficiently recycling valuable metals, which is vital for the lithium-ion battery recycling industry.