RuO2-Modified Sulfurized Polyacrylonitrile Composite Cathodes for Sodium-Sulfur Batteries With Enhanced Electrochemical Performance

Abstract

Sulfurized polyacrylonitrile (SPAN) composite cathode for sodium-sulfur (Na-S) batteries has gained popularity as it addresses challenges associated with the dissolution of polysulfides in liquid electrolytes. However, SPAN cathodes suffer from sluggish kinetics, which can be addressed by catalytic enhancers. Nevertheless, the majority of research on composite sulfur cathodes with catalysts is centered around Li-S chemistries. The research gap arises from the sluggish kinetics of ${\mathrm{Na}}^{+}$ ions within the SPAN matrix. Ruthenium dioxide $\left({\mathrm{RuO}}_2\right)$, known for its exceptional catalytic activity, is employed in this work as a functional modification on SPAN, for Na-S batteries. The SPAN cathode without a catalyst exhibited a capacity of only $330{\text{mAhg}}^{-1}$ at C/2, while SPAN with ${\mathrm{RuO}}_2$ catalyst demonstrated a 97% improvement by exhibiting a specific capacity of $650{\text{mAhg}}^{-1}$ at the same C rate. Moreover, even after 300 cycles, the catalyst-modified SPAN composite retained at least 60% of its initial capacity $\left(410{\text{mAhg}}^{-1}\right)$, whereas the cathode without ${\mathrm{RuO}}_2$ completely degraded after 250 cycles. This notable improvement is accompanied by a decrease in the charge transfer resistance from 267.2 to 77.6 Ω, indicating improved electrochemical performance and stability with the incorporation of the ${\mathrm{RuO}}_2$ catalyst. This research is, to the best of our knowledge, the first to demonstrate high-performance ${\mathrm{RuO}}_2$-modified SPAN cathode material for Na-S batteries.