Ultra-fine Co nanoparticles in-situ anchored on porous conductive nanosheets as efficient electrocatalysts for promoting sulfur redox reaction kinetics

Abstract

Lithium-sulfur (Li-S) batteries are considered as one of the most promising energy storage devices due to their high theoretical energy density. However, the sluggish conversion kinetics and the polysulfides shuttling cause terrible capacity attenuation, impeding the practical developments. Herein, the Co/N co-doped mesoporous carbon nanosheet is developed after the pyrolysis of metal organic framework on graphene oxide layer, which is further explored as kinetics promotor towards advanced Li-S batteries. In this structure, the mesoporous carbon nanosheets with large specific surface area serve as the polysulfide trappers by physical constraint and the ultra-fine Co nanoparticles provide chemical adsorption and electrocatalytic capability for polysulfides, thus effectively suppressing the shuttle effect and accelerating the reaction kinetics. As a result, the Li-S batteries with modified kinetic modulation separators exhibit a high capacity of 585.3 mAh g−1 after 500 cycles at 1.0 C and excellent rate capability (511.2 mAh g−1 at 3 C).