Multifunctional hollow spheres as sulfur hosts for high-performance Li–S batteries

Abstract

For solving the problems of the poor electronic conductivity and volume change of sulfur particles, the shuttle effect of the soluble polysulfides, we design multifunctional host materials for the element sulfur by using hollow graphene and SnO2 composite spheres (HGSn). In this multifunctional host materials, graphene can significantly improve the electronic conductivity and the hollow sphere structure of HGSn proved by TEM can buffer the volume change of the discharge and charge products. Moreover, HGSn could provide physical adsorption and chemical affinity by forming C=S bond and S–Sn–O bond to greatly alleviate the polysulfide shuttle effect, which were represented by UV–Vis and FT-IR spectra, respectively. As a result, the as-prepared HGSn/S electrodes exhibit good electrochemical performance with high sulfur loading of 2.25 mg cm−2. The discharge specific capacity is 706.82 mAh g−1 after 200 cycles and 604.93 mAh g−1 after 350 cycles at 0.2C, and the capacity retention is 80.90% and 69.37% with average capacity attenuation of 0.096% and 0.088% for each cycle.