Synthesis of Ni-Rich Cathode from Li-Ion Battery Waste Using Environmentally Friendly Hydrometallurgy Process: Effect of Heat Treatment Atmosphere

This study investigated the recovery of nickel and other valuable metals from spent batteries, utilizing environmentally friendly hydrometallurgical techniques, i.e., organic acid leaching and oxalic acid co-precipitation, to recover the metal ions. The recovered metal ions in the form of oxalate precipitate served as a precursor for synthesizing nickel-rich cathodes, specifically nickel-cobalt-manganese (NCM) cathode with a composition of Ni:Co:Mn of 8:1:1. In this work, the effect of heat treatment atmosphere on the properties of the synthesized cathode materials was studied. The effect of heat treatment without and with oxygen flow was evaluated to determine its impact on the cathode’s structural integrity, electrochemical performance, and electrochemical stability. The results indicated that the choice of heat treatment atmosphere significantly influences the crystallinity, structure formation, particle morphology, and electrochemical properties of the cathode materials, e.g., specific capacity and cycling stability. The sample prepared by heat treating the precursors under oxygen flow demonstrated a higher initial specific discharge capacity of 181 mAh/g compared to that prepared without oxygen flow (87 mAh/g). This study demonstrated that synthesizing nickel-rich cathode materials from waste lithium-ion batteries can become a sustainable approach to ensure future battery production by reducing raw material demand and waste. Additionally, the findings on heat treatment atmosphere provided valuable insights for further study in optimizing the synthesis process of Ni-rich NCM cathode from waste battery cathode.