N, O Co-Doped Carbon Nanoflakes Decorated Carbon Cloth as Flexible Self-Supported Sulfur Host for Lithium-Sulfur Batteries

Abstract

The commercial exploitation of Lithium-sulfur batteries (LSBs) faces several obstacles, especially the shuttle effect caused by lithium polysulfides (LiPSs) and their sluggish electrochemical reaction dynamic. With the goal of overcoming these obstacles, a novel polyimide-derived Nitrogen and oxygen co-doped nanoflakes decorated carbon cloth (NOCC) has been developed via an in-situ imidization and carbonization strategy to fabricate flexible, self-supported cathodes for high-performance LSBs. The interlinked carbon fiber framework of the NOCC endows the sulfur host with excellent electronic conductivity. Simultaneously, the N, O co-doped nanoflakes embedded on the carbon fiber skeleton possess strong chemical adsorption of LiPSs and excellent electrocatalytic efficiency for LiPSs redox owing to the abundant polar nitrogen and oxygen groups. Additionally, the porous structured NOCC promotes rapid lithium-ion transport and physically restricts LiPSs. Consequently, the NOCC as a sulfur host (NOCC@S), with sulfur content of 1.5 mg cm-2, exhibits an initial discharge capacity as high as 1661 mA h g-1 (approaching the theoretical value) at 0.2 C. Furthermore, it demonstrates superb rate capabilities, maintaining a discharge capacity of approximately 538 mA h g-1 at 5 C. This new material aims to fabricate flexible, self-supported cathodes for high-performance LSBs, providing a potential breakthrough in commercialization of these batteries.

Keywords: Polyimide-derived N, O co-doped carbon nanoflakes, Carbon cloth, Flexible self-supported sulfur cathodes, Lithium-sulfur batteries