Mesoporous graphene-silica composite for Li-S battery

Abstract

Despite the promising theoretical capacity (1675 mAh/g) of elemental sulfur, Li-S battery systems suffer from the insulating nature of elemental sulfur and Li2S, the low retention of sulfur in cathode due to the lithium polysulfide dissolution and thus the passivation of the Li anode. In order to circumvent these problems, we synthesized mesoporous graphene-SiO2 (m-GS) composite with the aim of designing a cathode structure with high sulfur retention and consequently high charge/discharge rate capability. A SBA-15-like ordered mesoporous silica structure was introduced onto the surface of functionalized graphene via ternary cooperative assembly among triblock copolymer, silica precursor, and graphene. We expect that a) the well-defined mesoporous silica structure exhibits high polysulfide retention and allows for fast reaction kinetics of sulfur, b) the graphene alleviates the insulating nature of silica and sulfur and c) the synthesis of m-GS is conducted under mild conditions.