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 (1567 mAh g⁻¹ at 0.1 C). 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 (400 mAh g⁻¹) over 500 cycles at higher current of 2 C. [Figure not available: see fulltext.].