Micro-Nano Conductive Network Structured Aramid Paper-Based Self-Supporting Cathode Enhances Cycling Stability in Lithium–Sulfur Battery

Abstract

Lithium–sulfur batteries (LSBs) continue to encounter significant challenges in practical applications, primarily attributed to the low electrical conductivity of the cathode active material sulfur, volume expansion during cycling and the uncontrolled shuttle effect of lithium polysulfides (LiPSs). In this work, flexible meta-aramid fibrids (AFs) were innovatively introduced, and polydopamine (PDA) was employed to effectively adhere highly conductive multiwalled carbon nanotubes (MWCNTs) to the AFs surface, thereby forming nanoscale conductive pathways. A wet-laid process analogous to aramid paper-making was utilized to enhance interfacial bonding between AFs and rigid carbon fibers (CFs), resulting in a self-supporting paper-based cathode material with a uniform, dense three-dimensional micronano-scale conductive network and stable structure. The porous structure between the fibers effectively alleviates sulfur’s volume expansion. The polar PDA coating layer offers numerous chemical adsorption sites, which chemically anchor LiPSs and thereby more effectively suppresses the shuttle effect. The research results demonstrate that the AF@PDA-MWCNT/CF/S cathode delivers an impressive initial discharge specific capacity of 1140 mAh g^–1 at a sulfur loading of 2.3 mg cm^–2 and a current density of 0.2 C. After 400 cycles at a higher current density of 1 C, the single-cycle capacity fade rate is as low as 0.005%. Even at a high sulfur loading of 3.1 mg cm^–2, the material still exhibits an initial discharge specific capacity of 890 mAh g^–1. The AF@PDA-MWCNT/CF/S composite cathode developed in this study exhibits significant application potential and offers an approach for constructing self-supporting, paper-based cathode materials.