Burning lithium in CS₂ for high-performing compact Li₂S–graphene nanocapsules for Li–S batteries

Tremendous efforts have been made to design the cathode of Li–S batteries to improve their energy density and cycling life. However, challenges remain in achieving fast electronic and ionic transport while accommodating the significant cathode volumetric change, especially for the cathode with a high practical mass loading. Here we report a cathode architecture, which is constructed by burning lithium foils in a CS₂ vapour. The obtained structure features crystalline Li₂S nanoparticles wrapped by few-layer graphene (Li₂S@graphene nanocapsules). Because of the improvement on the volumetric efficiency for accommodating sulfur active species and electrical properties, the cathode design enables promising electrochemical performance. More notably, at a loading of 10 mg_Li2S cm⁻², the electrode exhibits a high reversible capacity of 1,160 mAh g⁻¹s, namely, an area capacity of 8.1 mAh cm⁻². Li₂S@graphene cathode demonstrates a great potential for Li-ion batteries, where the Li₂S@graphene-cathode//graphite-anode cell displays a high capacity of 730 mAh g⁻¹s as well as stable cycle performance.