Efficient and high-selective lithium extraction from waste LiMn2O4 batteries by synergetic pyrolysis with polyvinyl chloride

Abstract

Recycling Li from spent lithium ion batteries (SLIBs) in an efficient and highly selective manner could protect the environment and introduce the circular economy principle to society. Simultaneously, the urgent need to address plastic waste, particularly polyvinyl chloride (PVC), has become a global concern. In this work, a strategy for Li extraction through synergetic pyrolysis of LiMn₂O₄ cathode materials (LMO) and PVC is proposed. Under optimal conditions, the recovery rates of lithium and manganese reached 99.89 % and 0.02 %, respectively, demonstrating efficient separation of these elements. Temperature was found to play a critical role in the leaching rates of lithium and manganese by promoting the decomposition and reduction of LMO. Additionally, kinetic analysis shows that the activation energy (E_a) of the synergetic pyrolysis is 139.60 KJ/mol, and the pyrolysis mechanism satisfies third-order reaction process. Eventually, the proposed mechanism involves the synergistic effects of chlorination and reduction reactions. First, HCl is generated by PVC pyrolysis under the catalytic effect of LMO. Then, the chlorination of HCl with LMO occurs by capturing structural oxygen and generating LiCl and MnCl₂. Simultaneously, the reduction reaction between the reducing species generated by PVC pyrolysis and LMO occurs to form Li₂O and MnO, ultimately enabling the separation of lithium and manganese. Overall, this paper presents a novel approach for future applications by providing a theoretical basis for selective Li extraction.