Carbon-wrapped cobalt nanoparticles on graphene aerogel for solid-state room-temperature sodium-sulfur batteries

Abstract

Room-temperature sodium-sulfur battery has attracted more and more widespread attention on account of the low cost, high capacity and reliable efficiency. Nevertheless, how to further improve sulfur reactivity and high-rate cycling performance remains challenging. Herein, carbon-wrapped nanocobalt anchored on graphene aerogel is fabricated to resolve low sulfur reactivity, conductivity and the large volumetric expansion during the charge/discharge process. The novel sulfur composite cathode shows up an initial discharge capacity of 572.8 mAh g−1 at 5C with an extremely low average capacity fading of 0.01% per cycle from 200 to 1000 cycles. Significantly, the cathode is also used for assembling solid-state Na/S batteries, with an initial discharge capacity of 484.9 mAh g−1 at 0.5C and a retainion capacity of 226 mAh g−1 after 1000 cycles. This outstanding performance is ascribed to the electrocatalytic effects of the nanocobalt and the conductive and flexible graphene aerogel, which can effectively enhance chemical reaction kinetics and accommodate the fast volume change.