Nitrogen-doped biomass carbon microtubules as sulfur carriers for iron-sulfur batteries

Aqueous iron-sulfur (Fe–S) batteries are considered to be promising energy storage devices owing to their low cost and environmental friendliness. However, the poor electrical conductivity of its sulfur monomers and intermediate polysulphides leads to poor electrochemical performance. Hence, the carrier material of sulfur assumes a crucial role in its performance. In this study, a method using sycamore tree fruit fluffs through hydrothermal activation is introduced, which successfully synthesizes nitrogen-doped carbon microtubes (NDCM) as a carrier for sulfur cathode material. Among them, nitrogen doping can enhance the electrical conductivity characteristics of carbon materials. The nitrogen-doped carbon microtubes prepared have a large specific surface area of 279.49 m 2 /g and high electrical conductivity. This significantly alleviates the issue of low conductivity in elemental sulfur and intermediate polysulfide compounds, thus enhancing electrochemical performance. The electrochemical results show that it provides a capacity of 232.74 mAh g −1 at a current 0.1 A g −1 , exhibiting good cycling life (79 % capacity retention rate after 50 cycles at a current 0.3 A g −1 ). This study provides a new methodology for utilizing waste biomass as a carrier for sulfur electrodes.