Fe-functionalized mesoporous carbonaceous microsphere with high sulfur loading as cathode for lithium-sulfur batteries

For lithium‑sulfur batteries (LSBs), some barriers like low conductivity of sulfur, the large irreversible volume change and the “shuttle” issue, hinder its practical application. In this work, Fe-functionalized mesoporous carbonaceous microspheres with high conductivity and intensive chemical adsorption for polar polysulfide species (LiPSs) were successfully synthesized through economical, scalable solvothermal process and pyrolyzing method. Carbon microspheres with Fe/Fe3C components (denoted as CMS900) exhibit high conductivity and significantly enhance the electrochemical reaction kinetics despite 81 wt% sulfur loading. Furthermore, the proper amount surface oxygenic functional groups effectively immobilize sulfur via strong chemical entrapment and suppress the dissolution of LiPSs intermediates during cycling. The CMS900@S has demonstrated a high initial discharge capacity of 1269 mAh g−1 at 0.1C, over 200 cycles with the lowest average capacity fading rate of 0.06% per cycle, which can be treated as an alternative cathode material for LSBs with impressive electrochemical performance. [Display omitted] •Carbon microspheres with Fe/Fe3C components provide high conductivity for the electrode despite 81 wt% sulfur loading.•CMS900 serves as electrocatalyst to enhance conversion kinetics and provides physical shields/chemisorption for -LiPSs.•Lithium-sulfur batteries used “polar” conductive carbon matrix as cathode host display excellent electrochemical performance.