Exploring a green route for recycling spent lithium-ion batteries: Revealing and solving deep screening problem.

The conventional recycling methods of spent lithium-ion batteries (LIBs) regard Al/Cu foils as impurities, which are usually removed by deep screening or alkali leaching. Deep screening refers to the process of over-screening the electrode materials by passing the crushed materials of spent LIBs through a screen with a pore size of only 0.075 mm. However, the serious hole-blocking phenomenon of deep screening and the environmental hazards of alkali leaching restrict their practical application. Herein, a combination of mild screening, reduction leaching and selective purification is proposed to achieve green and sustainable recycling of spent LIBs. Specifically, spent LIBs are subjected to discharge, crushing and mild screening to obtain fine-mixture materials under 4-mm sieving, leaving large pieces of Cu/Al foils on the screen mesh, which can be separated as crude products by color sorting. Then, dilute H 2 SO 4 is employed to dissolve the valuable elements in underflow fractions, where residual Cu/Al foils serve as reductants to assist leaching. Eventually, through multi-step precipitates and hydrothermal treatment, a series of promising products (CuO, NaAlCO 3 (OH) 2 , precursor and Li 2 CO 3) are obtained, at high quality. This route provides a clever strategy for fine management and cascade recovery of the valuable components from spent LIBs. Image 1 • The fine management and cascade recovery of Cu/Al foils are first proposed. • Thermodynamic analysis of Cu/Al foils as reducing agent was carried out. • Multi-step precipitation and hydrothermal method were used for purification. • The deep screening problem has been solved in a green and sustainable way. [ABSTRACT FROM AUTHOR]