Integration of porous graphitic carbon and carbon fiber framework for ultrahigh sulfur-loading lithium–sulfur battery

Abstract

A lithium–sulfur battery, a potential next-generation secondary battery, is affected by poor conductivity of sulfur and the dissolution of intermediate polysulfides. Here we report a lithium–sulfur battery with ultrahigh sulfur loading and excellent cycling stability using porous graphitic carbon (PGC) as a high-conductivity carrier of sulfur and carbon fiber with crisscross conductive framework as an electric attachment site of sulfur. PGC is fabricated through a simple and environmentally friendly synthesis process involving high-temperature graphitization in a N₂ atmosphere followed by an annealing process in air. Due to the presence of porous graphitic structure, with C–O termination groups, PGC endows the lithium–sulfur battery system with excellent cycling performance. The lithium–sulfur battery cathode constructed by PGC with a sulfur loading of 2.5 mg cm⁻² still retains a high specific capacity of 734.4 mA h g⁻¹ after 200 cycles. Meanwhile, an ultrahigh sulfur loading of 12.8 mg cm⁻² for a CR2025 coin cell is achieved, which is the highest sulfur loading reported in the literature for the coin cell. The ultrahigh sulfur loading cell also shows good electrochemical properties, profiting from the mesopores terminated with C–O groups, high specific surface area of 1129.9 m² g⁻¹ and high-conductivity graphitic structure.