Enhanced conversion kinetics by constructing boron and nitrogen co-doped porous carbon with sulfurophilic and sodiophilic sites in room-temperature sodium-sulfur batteries

The fabricated boron and nitrogen co-doped porous carbon host, with sulfurophilic and sodiophilic sites, enhances electrochemical energy storage by facilitating the adsorption and conversion of sodium polysulfides. [Display omitted] •A simple solid-state reaction method is reported to synthesize BN-C as S host.•The BN-C host has synergistic effect of sulfurophilic and sodiophilic properties.•The S@BN-C cathode demonstrates excellent electrochemical performance.•The mechanism of SRR is investigated using ex situ XPS and Raman techniques. Room temperature sodium-sulfur (RT Na-S) batteries are significantly impeded by multiple unfavorable features, such as polysulfide shuttling, inadequate electronic conductivity of sulfur (S), and sluggish sulfur reduction reaction (SRR) kinetics. Herein, a simple solid-state reaction method is reported to synthesize boron and nitrogen co-doped porous carbon (BN-C) as S host, which prevents polysulfide migration effectively and improves redox kinetics. The remarkable synergistic effect of B and N dual-adsorption sites in BN-C host, endowing them with sulfurophilic and sodiophilic properties that enhance the reactivity of S while promoting reaction reversibility of S and Na. The well-designed cross-linked porous structures effectively reduce the ion-transport distance and suppress the volume change of S@BN-C during cycling. As a result, the S@BN-C cathode affords outstanding cycling performance (528 mA h g−1 after 1300 cycles at 1 A g−1) and rate capability (340 mA h g−1 at 3.0 A g−1). This work presents a multifunctional S host exhibiting electrocatalytic activity, which is expected to bring a new strategy for high-performance RT Na-S batteries.