A Green and Efficient Recycling Strategy for Spent Lithium-Ion Batteries in Neutral Solution Environment.

Traditional acid or/and ammonia leaching techniques are usually applied to extract valuable metals during hydrometallurgical recovery of spent lithium-ion batteries. However, the excessive and repeated use of acids and bases inevitably increases the environmental burden and safety threats. Herein, considering the advantages of neutral pH solution system in terms of safety and environmental protection, neutral leaching has been pioneeringly proposed to achieve a low-cost and harmless hydrometallurgical process. Specifically, benefited from the ligand complexation reaction of glycine, the valuable metals can be efficiently leached within neutral environment. More importantly, a strategy of solid-solid reduction with primary batteries effect is employed to achieve an efficient neutral leaching within rapid time, breaking through the reaction limitation of shrinking core model. As anticipated, an efficient leaching of 99.99 % Li, 96.86 % Ni, 92.35 % Co, and 90.59 % Mn can be achieved within 15 minutes, which has extended applications for various kinds of layered cathodes. Therefore, it is sturdily confirmed that the intractable problem, the effective extraction is available only under the aggressive acid/alkali-ion conditions, is well-solved within a mild leaching atmosphere. This green and efficient strategy in neutral solution environment opens a new pathway to realize the large-scale pollution-free recycling of spent batteries.