Enhanced Polysulfide conversion in Room-Temperature Sodium-Sulfur batteries via nanoscale TiO2 modified porous carbon structures.

Room-temperature sodium-sulfur (RT Na-S) batteries, known for their high-energy density, low cost and environmental friendliness, have attracted much attention. However, the development of RT Na-S batteries has encountered a number of challenges, including low conductivity and large volume changes of sulfur during the charge-discharge cycles. In this study, TiO2 nanoparticles modified porous carbon hosts for sulfur in RT Na-S batteries were prepared by a simple and efficient spray drying method combined with solution immersion. This approach significantly improved the electrochemical performance of RT Na-S batteries, especially under high current density (200 mAh/g capacity after 200 cycles at 5.0 A/g) and under high load (250 mAh/g capacity after 80 cycles at 0.5 A/g, the mass load is 3.7 mg cm-2). TiO2 modified porous carbon cathode not only had effective adsorption effect on polysulfides, but also showed strong catalytic ability of sulfur to Na2Sx and Na2Sx to Na2S in sulfur conversion reaction.