Selective recovery of lithium from spent lithium-ion batteries via mild hydrothermal driven Lewis acid-base reaction in aqua solution

Selective metal recovery from spent lithium-ion batteries has attracted wide attention since a high recovery rate and minimized environmental impact can be expected. However, either high temperature or high chemical consumption in order to realize effective lithium recovery is required, as the cathode inherent with high physiochemical stability, especially when the cobalt content is high (e.g. LiCoO2). Herein, we discover that Lewis acids in cathode scraps induce phase transition from LiCoO2 to Co(CoO2)2 and Li+, thus realizing fully selective recovery of lithium in a mild environment. Since Lewis acids are produced from scraps, the chemical consumption is reduced. Meanwhile, relying on the mild phase transition caused by Lewis acids, the morphology of the waste are maintained in the Co(CoO2)2 products, resulting in a comparable electrochemical performance with commercial Co3O4 anode materials. Consequently, a closed-loop route for recycling cathode scrap is established at mild conditions with low cost and environmental impact.