Optimizing Carbon-to-Sulfur Ratio in Polybenzoxazole-derived N-doped Carbon/Sulfur Cathodes for Lithium-Sulfur Batteries

Abstract

Lithium-sulfur batteries are promising candidates for next-generation energy storage systems due to their high theoretical energy density and cost-effectiveness. However, challenges such as poor sulfur conductivity, polysulfide shuttling, and capacity degradation remain significant barriers to commercialization. This study investigates the role of carbon-to-sulfur ratios in optimizing the electrochemical performance of nitrogen-doped carbon cathodes. By characterizing the physical and chemical properties of polybenzoxazole-derived carbon structures and their sulfur mixture, we identify the optimal carbon-to-sulfur ratio that balances electronic conductivity, sulfur utilization, and polysulfide suppression. Electrochemical analyses, including cyclic voltammetry, charge–discharge behavior, and impedance spectroscopy, reveal that a carbon-to-sulfur ratio of 10:1 achieves superior performance, with improved charge transfer, enhanced sulfur conversion efficiency, and minimized polysulfide shuttle effects. These findings provide valuable insights into material design strategies for high-performance lithium-sulfur batteries.