Ternary composite solid-state flexible supercapacitor based on nanocarbons/manganese dioxide/PEDOT:PSS fibres

Highlights: • Carbon-MnO₂-PEDOT:PSS composite fibres have been prepared by all aqueous solution based depositions. • Ternary composite fibres show fexibility and excellent energy storage capacity. • Ternary fibres are assembled in solid-state supercapacitors with good capacitive performance for wearable electronics. Flexible fibre supercapacitors were fabricated by wet-spinning from carbon nanotube/carbon black dispersions, followed by straightforward surface treatments to sequentially deposit MnO₂ and PEDOT:PSS to make ternary composite fibres. Dip coating the fibres after the initial wet-spinning coagulation creates a simple solution-based continuous process to produce fibre-based energy storage. Well-controlled depositions were achieved and have been optimised at each stage to yield the highest specific capacitance. A single ternary composite fibre exhibited a specific capacitance of 351 F g⁻¹. Two ternary composite fibre electrodes were assembled together in a parallel solid-state device, with polyvinyl alcohol/H₃PO₄ gel used as both an electrolyte and a separator. The assembled flexible device exhibited a high specific capacitance of 51.3 F g⁻¹ with excellent both charge-discharge cycling (84.2% capacitance retention after 1000 cycles) and deformation cycling stability (82.1% capacitance retention after 1000 bending cycles).