Collaboratively adjusting the electron structure of N/Cr dual-doping CoSe2 for boosting catalytic effect of coated separators in Li-S batteries

Abstract

Transition metal compounds are a kind of catalysts to coat separators for solving the slow reaction kinetics and alleviating the shuttle effect of lithium sulfur (Li-S) batteries. Up to now, doping modification for transition metal compounds have been extensively studied to enhance their catalytic properties. Nevertheless, dual-doping is rarely studied despite of largely study of single-doping. Herein, CoSe₂ is doped with N/Cr with different electronegativity to enhance intrinsic catalytic activity and enrich active sites. After dual doping, the electron structure of N/Cr-CoSe₂ is regulated with charge redistribution and adjusted d band center. This enables N/Cr-CoSe₂ to achieve the best adsorption effect and catalytic capacity, benefitting from multiple interactions with enriched adsorption sites and elongated S-S bonds of adsorbed Li₂S₄. As a consequence, the Li-S batteries equipped with N/Cr-CoSe₂ coated separators deliver the highest discharge capacity for the best reaction kinetics, in comparison to that of Cr doped CoSe₂ and undoped one. This work could provide some reference for improving their catalytic effect of transition metal compounds by dual-doping modification.