Double-oxide sulfur host for advanced lithium-sulfur batteries

Abstract

Although lithium-sulfur batteries show fascinating potential for high-capacity energy storage, their practical applications are hindered by the fast capacity decay and low sulfur utilization at high sulfur loading. Herein we report an efficient sulfur host based on two oxides, in which SiO2 hollow spheres with radial meso-channels are covered by a thin TiO2 coating. SiO2 spheres not only yield high sulfur loading as high as 80 wt% but also possess strong lithium polysulfides (LiPS) adsorption capability. The thin TiO2 coating can effectively prevent the LiPS outward diffusion, giving rise to a long-term stability. Meanwhile, the oxide-supported carbon from the carbonization of surfactants enables good electrical conductivity to facilitate electron access and improve sulfur utilization. Experimental and theoretical studies show the strong adsorption of LiPS by SiO2. Benefitting from the unique structural and compositional advantages, we achieve a high sulfur loading up to 80 wt% with ~65.5% and 33% capacity retentions over 500 and 1000 cycles when tested at 0.5 C and 1 C, respectively.