NC/Co@NC catalyst with hollow structure accelerates lithium-sulfur battery reaction kinetics

Abstract

Lithium-sulfur (Li-S) batteries have gained significant interest due to their impressive energy density. Nonetheless, poor conductivity and shuttle effect hamper their further development. Here, we prepared NC/Co@NC catalyst materials by a self-templating method to improve the battery performance. The ZIF-8@ZIF-67@PDA was initially prepared by utilizing the favorable compatibility between ZIF and dopamine, and subsequently annealed to form NC/Co@NC materials. The NC/Co@NC catalyst can effectively adsorb lithium polysulfides (LiPSs), lower the reaction barrier and accelerate its conversion to lithium sulfide (Li2S). Moreover, the configuration of the hollow structure enhances the catalyst-electrolyte interface, which can maximize the catalytic ability of NC/Co@NC. The improved ion diffusion rates benefiting from the hollow structure can also be realized. With these combined effects, Li-S cells incorporating the NC/Co@NC hollow catalysts achieved a high sulfur utilization and superior rate behaviour, that is 1176 and 470 mAh g−1 at 0.2 and 4C, respectively. Furthermore, the cells achieved an ultralow capacity degradation of merely 0.08% per cycle after 300 cycles at 1C, further confirming their potential.