Recycling of spent lithium-ion batteries: Selective ammonia leaching of valuable metals and simultaneous synthesis of high-purity manganese carbonate

Recycling of spent lithium-ion batteries (LIBs) has drawn considerable attention in recent years, as an economic solution to the resource shortage. Selective ammonia leaching is recognized as an economical and environment-friendly method, yet it is difficult to separate and reuse the valuable metals from the leachate. In this study, we proposed an NH3-(NH4)(2)CO3-Na2SO3 leaching system to selectively recover the valuable metals from commercial LiNixCoyMn1-x-yO2 (NCM) and spent NCM. For single-stage leaching, 79.1% of the lithium, 86.4% of the cobalt, and 85.3% of the nickel were selectively leached under optimal conditions, and a mere 1.45% of the manganese was dissolved in the solution. The leaching process in the NH3-(NH4)(2)CO3-Na2SO3 system was consistent with the surface chemical reaction control model. For multistage leaching, almost all metals (98.4% of the lithium, 99.4% of the cobalt, 97.3% of the nickel) could be leached and a high-purity (>99%) MnCO3 product was simultaneously obtained. The introduction of CO32 not only led to the production of MnCO3 with wide application prospects, but also greatly reduced the consumption of the reducing agent. This study is thus beneficial for recycling of the valuable metals and synthesis of the MnCO3 product from the spent LIBs. (C) 2020 Elsevier Ltd. All rights reserved.