Nitrogen-doped porous carbon hosted sulfur-rich polymer for room temperature Na-S batteries with superior cycle performances.

• Sulfur-rich polymer cathode for sodium-sulfur batteries was prepared by inverse vulcanization. • The failure mechanism of sulfur-rich polymer cathode at first charge was studied. • Nitrogen-doped carbon is combined with sulfur-rich polymer to reverse the failure. • The composite cathode exhibits unprecedented performance of similar materials. Room temperature sodium-sulfur (RT Na-S) batteries are one of the most promising energy storage systems with high energy density due to the abundant reserves of sodium and sulfur elements on Earth. As a potential cathode material, sulfur-rich polymers are rarely reported in RT Na-S batteries compared with other metal-sulfur batteries. The unusual occurrence is a result of sulfur-rich polymer cathodes failing in Na-S batteries. To reverse the process, herein, we first illuminate the failure mechanism of sulfur-rich polymer cathodes (S-DIB as an example) in Na-S batteries, which root from the chemical reaction between the polysulfide and the sodium anode. To address this issue, we incorporate nitrogen-doped carbon (NC) into composites with S-DIB to establish ion diffusion pathways and limit polysulfide diffusion. The resulting S-DIB@NC composite demonstrates exceptional cycling performance, achieving a high capacity of 457 mA h g-1 after 1300 cycles. This research constitutes a significant step towards enhancing the viability of sulfur-rich polymers in Na-S batteries and paves the way for their widespread application. [Display omitted] [ABSTRACT FROM AUTHOR]