Regulated Electronic and Ionic Conductive Framework for High Energy Density Lithium–Sulfur Batteries

Abstract

Achieving high energy density in lithium–sulfur (Li–S) batteries necessitates thick cathodes with high sulfur loadings and a lean electrolyte. However, these configurations introduce critical challenges, including low conductivity, polysulfide shuttling, volume expansion, and mechanical instability, which significantly impede battery performance. In this study, we present a regulated electronic and ionic conductive framework that integrates carbon nanotubes (CNTs) and sulfur onto the surface of air plasma-treated aramid fibers (APAF) in a layer-by-layer fashion (denoted as CNT/S/APAF). This composite framework is then incorporated into a CNT network to form free-standing sulfur cathodes for high energy density Li–S batteries. The resulting structure promotes efficient electron transport, improves electrolyte wettability, suppresses polysulfide diffusion, and mitigates volume expansion. These synergistic effects lead to superior sulfur utilization and cycling stability. The Li–S cells with CNT/S/APAF cathodes exhibit an impressive initial specific capacity of 1437.6 mAh g^–1 and areal capacity of 11.3 mAh cm^–2, with a sulfur loading of 7.83 mg cm^–2 and an electrolyte-to-sulfur (E/S) ratio of 5 μL mg^–1. Furthermore, they achieve a high energy density of 468.6 Wh kg^–1 and maintain excellent cycling stability, retaining a capacity of 6.5 mAh cm^–2 after 100 cycles. This scalable approach provides a practical, high-performance solution for next-generation batteries.