In-situ anchoring sulfiphilic silica nanoparticles onto macro-mesoporous carbon framework for cost-effective Li-S cathodes

Abstract

Porous carbons have been the leading conductive hosts for constructing cathodes of lithium-sulfur batteries but are currently challenged by the weak polar surface and cost-effective synthesis. Herein, a 3D hierarchical macro-mesoporous carbon with in-situ silica anchoring (SMC) is prepared via an economical and high-throughput sol-gel approach, followed by the ambient pressure drying and carbonization. The resultant carbons possess developed porosity with bi-continuous macro-mesoporous network. Moreover, the ultrathin silica nanoparticles are homogeneously anchored onto surface of macro-mesoporous carbon framework, which can greatly enhance the polar of carbon surface, thus improving the wettability and dispersion of sulfur during melt impregnation process. In addition, the polysulfides mobilization is also dramatically restrained through chemical binding between silica nanoparticles and polysulfides. Combined with the 3D conductive macro-mesoporous network, the resultant sulfur cathode could deliver a high reversible capacity of 969.7 mAh g−1 and enhanced capacity of 625.5 mAh g−1 with a capacity fading rate of only 0.088% per cycle after 400 cycles at 0.2 C. The present work may provide a direct and cost-effective approach to surface chemistry modification of carbon-based sulfur hosts to ultimately advance energy conversion and storage system.