Fabrication of Silica/Sulfur@Polyaniline Spheres with Radial Mesochannels as Enhanced Cathode Materials for High‐Performance Lithium−Sulfur Batteries

Abstract

AbstractThe unique structure SiO2/S@polyaniline (PANI) composite with radial meso‐channels was designed and synthesized by in situ chemical oxidative polymerization of aniline on SiO2/S surface. The composite was used as the cathode for lithium−sulfur batteries. The SiO2 nanospheres with radial meso‐channels provided sufficient internal space to accommodate the volume expansion for sulfur and possessed strong adsorption capability for lithium polysulfides (LiPSs). Additionally, the thin PANI coating serving as conductive frameworks generated sufficient electrical conduction paths and effectively prevented the outward diffusion of LiPSs, leading to long‐term stability. Benefitting from the composites’ unique structural and compositional advantages, we obtained an initial specific capacity of 1008.6 mA h g−1 at 0.2 C and an outstanding cycling stability at 1 C rate over 1000 cycles with a capacity decay of 0.04% per cycle. An excellent rate performance of 630.2 mA h g−1 at 2 C was also achieved. Our work reveals the potential application of the porous SiO2@PANI‐based sulfur cathodes in future high‐performance lithium−sulfur batteries. Furthermore, first‐principle calculations and X‐ray photoelectron spectroscopy analysis prove the strong adsorption of LiPSs by the SiO2 surface. The formation of S−O bond on the SiO2 is also found to dominate the adsorption mechanism between LiPSs and SiO2.