6. A Graphene Foam Electrode with High Sulfur Loading for Flexible and High-Energy Li–S Batteries

Flexible energy storage devices are becoming increasingly important for future applications but are limited by the lack of suitable lightweight electrode materials with robust electrochemical performance under cyclic mechanical strain. Here, we proposed an effective strategy to obtain flexible Li–S battery electrodes with high energy density, high power density and long cyclic life by adopting graphene foam-based electrodes. Graphene foam can provide a highly electrically conductive network, robust mechanical support and sufficient space for a high sulfur loading. The sulfur loading in graphene foam-based electrodes can be tuned from 3.3 to 10.1 mg cm⁻². The electrode with 10.1 mg cm⁻² sulfur loading could deliver an extremely high areal capacity of 13.4 mAh cm⁻², much higher than the commonly reported Li–S electrodes and commercially used lithium cobalt oxide cathode with a value of ~3–4 mAh cm⁻². Meanwhile, the high sulfur-loaded electrodes retain a high rate performance with reversible capacities higher than 450 mAh g⁻² under a large current density of 6 A g⁻² and preserve stable cycling performance with ~0.07% capacity decay per cycle over 1000 cycles. These impressive results indicate that such electrodes could enable high performance, fast-charging and flexible Li–S batteries that show stable performance over extended charge/discharge cycling.