Designing high electrochemical surface area between polyaniline and hydrogel polymer electrolyte for flexible supercapacitors.

• Polyaniline morphology can be tuned by changing polymerization current density. • Polyaniline nanowire arrays increase ECSA with hydrogel polymer electrolyte (HPE). • Polyaniline nanowire arrays show a specific capacitance of 373.6 F g−1. • Performance of PANI-0.3 with HPE is comparable to that with aqueous electrolyte. • Flexible supercapacitor can light a LED under flat, folded and twisted conditions. High electrochemical surface area (ECSA) is the precondition for high performance of flexible supercapacitors, but remains a considerable obstacle. Because of the lower fluidity of hydrogel polymer electrolyte (HPE, generally utilized to fabricate flexible supercapacitors) than aqueous electrolyte (AE, used in traditional supercapacitors), it is difficult to infill a porous electrode with HPE completely, leading to a low ECSA between electrode materials and HPE. In this work, the structures of the polyaniline nanowires are designed to increase the ECSA. In comparison with nanowire network structure, the patulous structure of the polyaniline nanowire arrays is beneficial to increase the ECSA. The polyaniline nanowire arrays show a specific capacitance of 373.6 F g−1 at 0.1 A g−1 with the HPE, which is comparable to that with the AE at 0.1 A g−1 (376.6 F g−1). Flexible supercapacitors based on the polyaniline nanowire arrays exhibit similar performances under flat, folded, and twisted conditions, demonstrating their high potential application in flexible electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]