Reduced graphene oxide-encapsulated mesoporous silica as sulfur host for lithium-sulfur battery

With up to fivefold higher in energy density vs. lithium-ion battery, lithium-sulfur (Li-S) battery is a compelling energy storage system, complemented by a very low cost of sulfur. However, current Li-S cells face the capacity decay caused by the dissolution of lithium polysulfides. In this work, a new material concept, namely the layer @ adsorbent is introduced to address the capacity fading problem. This architecture utilizes mesoporous SiO2 holding sulfur and polysulfides and the whole S fused SiO2 was intimately encapsulated by reduced graphene oxide (RGO). Benefiting from the enhanced capillary force from SiO2, as well as the improved conductivity from RGO chamber, this layer @ adsorbent architecture could easily spread and adsorb polysulfides. The initial discharge capacity is approaching its theoretical capacity (1567mAhg(-1) at 0.1C). A stable cycle performance over 500 cycles is demonstrated with the capacity loss of merely about 0.05% per cycle. Additionally, the cathode with higher sulfur content (67%) delivers a stable reversible capacity (400mAhg(-1)) over 500 cycles at higher current of 2C.