Document Type

Journal Article

Publication Date

2023

Abstract

With the increasing consumption of lithium-ion batteries (LIBs), it is highly desirable to develop efficient and energy saving strategies for battery material recovery and regeneration. In this study, a synergetic pyrolysis strategy was developed to recover valuable metals by thermal treatment of LiNi1/3Co1/3Mn1/3O2 (NCM) cathode materials with the addition of polyethylene terephthalate (PET) plastics. It is the first time that PET plastics served as reaction additives to accelerate the lattice decay and thermal decomposition of NCM materials. With the assistance of PET synergetic pyrolysis, NCM started to decompose at only 400°C, and was completely converted to Li2CO3, MnO and Ni-Co alloy after thermal reaction at 550°C for 30 min with the NCM:PET mass ratio of 1.0:0.3. The thermal degradation of PET was retarded with various free radicals and reductive gases released. Furthermore, a density functional theory (DFT) calculation verified the combination preference of O-Li bonding between horizontal PET and the Li terminated NCM (001) surface. The surface adsorption caused atom capture and the free radical/gaseous reduction reactions explained the synergetic effect of PET on promoting the lattice destruction of NCM cathode materials. Moreover, the complete decomposition of NCM well benefited the post treatment, and the subsequent 2 separation of Li and transition metals (TM: Ni, Co and Mn) could be efficiently achieved by water washing method. Regenerated NCM was also synthesized by using the recovered Li- and TM- containing products as feedstocks. As a result, this study provided a novel NCM recovery strategy with significant privileges of chemical free, energy saving, highly efficient and scalable. Meanwhile, this strategy proposed an ideal solution for the minimization and utilization of PET plastics. In addition, the mechanism study provided a theoretical guidance on the industrialization and broaden application of PET plastic for effective metal recovery from spent LIBs by this synergetic pyrolysis strategy.

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