A simplified method for the recycling of spent lithium-ion batteries via manganese selective recovery by anoxic ammonia leaching and spontaneous precipitation

Due to the high cost of the manganese solvent extraction process in the conventional recycling of spent NCM-ternary lithium-ion batteries (LIBs), we employed an anoxic complexation ammonia leaching-spontaneous precipitation process to selectively recover manganese from the black mass of spent ternary LIBs. This innovation serves as a substitution for the conventional acid leaching-manganese solvent extraction, aiming to reduce costs and enhance the efficiency of the recycling process. Specifically, the controlled reduction roasting was performed to achieve the dissociation of LiNixCoyMnzO2 and the phase transition to MnO and metallic Ni and Co. Exploiting this difference, ammonia-ammonium carbonate were employed as leaching agents, which enabled the selective leaching of over 96 % of manganese, while those of nickel and cobalt were only 1.2 % and 2.6 %. After filtration, the MnCO3 product with high purity was precipitated by allowing the leachate to stand for 12 h without adding any reagent. The ammonia solution could be circulated to leaching the subsequent batch of spent LIBs. Thermodynamic calculations were used to elucidate the leaching and crystallization mechanisms. Comparative process analysis and economic assessments confirmed that the proposed new method is extremely appealing due to its high selectivity, considerable economic advantages, and environmental benefits.