Hierarchically Structured Cnt@Co-N-Cnf Interlayers for Enhanced Lithium Polysulfide Confinement in Lithium-Sulfur Batteries

Abstract

Lithium-sulfur batteries (LSBs) are considered promising candidates for high-energy-density storage systems. However, challenges such as the polysulfide shuttle effect and limited cycling stability hinder their commercialization. This study introduces a hierarchically structured interlayer, CNT @Co-N-CNF (CCNC), fabricated through a novel process that combines electrospinning with ZIF-67-derived carbonization. This interlayer uniquely integrates physical and chemical confinement mechanisms for lithium polysulfides (LiPSs) by leveraging a conductive carbon nanotube (CNT) network, nitrogen (N)-doping, and embedded cobalt species. Designed to enhance sulfur utilization and effectively suppress LiPS migration, the 50-CCNC interlayer demonstrates an initial discharge capacity of 1137.4 mAh g⁻1, along with excellent cycling stability in coin cell configurations. Furthermore, its practical potential is validated in a pouch stack cell configuration, achieving an initial capacity of 1059.7 mAh g⁻1 and retaining 99.54% of its capacity after 40 cycles. These findings underscore the interlayer's effectiveness in addressing key challenges for large-scale LSB applications and represent a significant step toward the commercialization of high-energy-density LSB technology.

Keywords: Polysulfide suppression, Carbon nanofiber interlayers, Lithium-sulfur batteries, Stack cell pouch