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 mgLi2S 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. Facile and scalable fabrication of high-performing sulfur cathodes is challenging in the commercialization of Li–S batteries. The authors report a strategy of simply burning Li foils in a CS2 vapour for the cathode design, which shows promising battery performance.