Hydrothermal assisted RGO wrapped fumed silica-sulfur composite for an advanced room-temperature sodium-sulfur battery

Abstract

A promising cathode material RGO/SiO2/S composite for an advanced room-temperature sodium‑sulfur (RT Na[sbnd]S) batteries is synthesized via incorporating nanosulfur into amorphous fumed silica wrapped with reduced graphene oxide (RGO) through the hydrothermal method. Fumed silica (SiO2) offers a high surface area beneficial for sulfur loading. In the presence of ethylenediamine (EDA), nanosulfur is incorporated into SiO2. Additionally, hydrothermal treatment of the prepared solution that contained EDA facilitates the optimal reduction of graphene oxide (GO) into nitrogen–doped interlinked, conducting, and porous RGO. EDA played a multifunctional role as nanosulfur precursor, a nitrogen source, as well as a reducing agent. The synthesized RGO/SiO2/S composite delivers a high initial discharge capacity of 923 mAh/g at 0.1 C-rate with excellent coulombic efficiency (∼99 %). During cycling, fumed silica in the composite buffers volume expansion that happens throughout the cycling process, while RGO in the composite enhances the conductivity of the sulfur. Additionally, the presence of nitrogen also improves the conductivity of the cathode material. © 2024 Elsevier Ltd