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

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.