Molecular framework engineering of sulfur-containing polymers for enhanced ion transport efficiency in Li-S battery

Abstract

Organic sulfur-containing polymers offer promising avenues for advancing lithium-sulfur (Li-S) battery technology due to their cost-effectiveness, versatile structural design, and high theoretical capacity. However, challenges such as low conductivity, poor stability, and solubility in electrolytes hinder their practical application. This study focuses on molecularly crosslinked organic sulfur-containing polymers to mitigate these issues. A novel organic sulfur-containing polymers molecular framework was constructed using polyacrylonitrile (PAN) as the backbone and cross-linked with p-phenylenediamine (PPD), which effectively enhances ion transport kinetics and structural stability during electrochemical reactions. The prepared PAN@PPD@S cathode exhibited outstanding performance with a specific capacity of 726 mAh g⁻¹ at 5 C, significantly higher than conventional sulfur-containing polymers. It exhibited an initial discharge specific capacity of 1101 mAh g⁻¹ at 0.3 C, maintaining 956 mAh g⁻¹ after 100 cycles, to capacity decay of only 0.13 % per cycle. Moreover, the molecular framework facilitated ensures stable electrochemical performance even at high sulfur loadings, highlighting its potential for actual applications in high-energy density Li-S batteries.