Flexible-wire shaped all-solid-state supercapacitors based on facile electropolymerization of polythiophene with ultra-high energy density

The new generation of miniaturized energy storage devices offers high energy and power densities and is compatible with flexible, portable, or wearable textile electronics which are currently in great demand. Here, we demonstrate the successful development of flexible, wire shaped (f-WS) all-solid-state symmetric supercapacitors (SCs) based on a facile electropolymerization of polythiophene (e-PTh) on titania (Ti) wire. The f-WS all-solid-state symmetric SCs, exhibiting high electrochemical performance, are fabricated by slightly intertwining two similar e-PTh electrodes to form both the cathode and anode which are then individually coated with a thin layer of H₂SO₄-PVA gel, acting both as electrolyte and as separator. The optimized devices (∼1.5 cm long), based on e-PTh/Ti wire show a high capacitive performance (1357.31 mF g^-1 or 71.84 mF cm^-2) and an extremely high energy density (23.11 μW h cm^-2) at a power density of 90.44 μW cm^-2 using an operational potential window of 1.8 V, which is beneficial for applications requiring high energy and power. The robust f-WS all-solid-state symmetric SCs also exhibit excellent mechanical flexibility with minimal change in capacitance upon bending at 360°. Furthermore, the SCs were implemented in the textile of a wearable/portable electronic device using a conventional weaving method, thus demonstrating a high potential for next-generation wearable textile electronic applications.