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

Abstract

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 Na₂S_x and Na₂S_x to Na₂S in sulfur conversion reaction.