Continuous and Flexible Graphene-Based Fibrous Cathode for Lithium Sulfur Batteries

The development of wearable technology is one of the major growth areas for flexible batteries which require high energy densities and shape amenabilities. Previous studies of flexible batteries may meet the energy requirements but with a trade-off between the low areal capacity, poor mechanical stability and large thickness of inactive components. A wet-spinning assembly strategy is developed to produce continuous graphene-based composite fibrous cathode consisting of reduced graphene oxide/carbon nanotubes filled with a large amount of sulfur (rGO/CNT/S) for rechargeable lithium sulfur batteries. The incorporation of GO liquid crystal renders a unidirectional alignment of rGO/CNT/S composite, enabling the rational assembly of flexible and conductive fibres as electrodes. The highly conductive fibres are mechanically robust with a tensile strength of 20 MPa and the electrical conduction is unaffected even after 100 bending cycles. The one dimensional fibrous electrodes with scalable linear densities ranging 0.028-0.13 mg cm^-1 deliver a high initial capacity of 1255 mAh g^-1 and an areal capacity of 2.49 mAh cm^-2 at C/20. The high stability of the electrochemical performance under cyclic bending and excellent mechanical flexibility of the fibrous LSBs highlight great potential of graphene-based fiber assemblies in search for shape-compliant electrode materials.