Upcycling strategy of spent LiCoO2: Toward enhanced high-voltage stability based on Al doping

Abstract

Direct regeneration of spent LiCoO₂ in recycling field is regarded as a promising strategy to reduce production costs and alleviate the burden of metal pollution. Targeting the extensively studied high-voltage LiCoO₂ electrode, the simultaneous achievement of restoring the spent LiCoO₂ and upgrading the high-voltage stability of regenerated LiCoO₂ poses a considerable challenge. Herein, based on a first-principles-informed thermodynamic study, a modulation strategy has been proposed by introducing Al doping during direct regeneration to enhance the high-voltage performance of regenerated LiCoO₂. The calculated results reveal that, due to the sufficient Li vacancies in the spent LiCoO₂, Al atoms can preferentially occupy the Li vacancies (denoted as Al_V(Li)) rather than Co sites (denoted as Al_Co) by synergistically regulating Co chemical potential and temperature. Inspiringly, the surface stability of regenerated LiCoO₂ with Al_V(Li) doping is significantly enhanced at high voltages. Furthermore, although both Al_V(Li) and Al_Co doping improve the electronic conductivity of regenerated LiCoO₂, only the Al_V(Li) doping exhibits an improvement of the Li⁺ diffusion kinetics. This innovative strategy provides a novel perspective for the efficient and high-quality recycling of the spent LiCoO₂ in industrial applications.