Enhanced performance of a flexible supercapacitor due to a combination of the pseudocapacitances of both a PANI/MWCNT composite electrode and a gel polymer redox electrolyte

Abstract

In this paper, a combination of the pseudocapacitances of both an enzymatically synthesized polyaniline/multi-walled carbon nanotube (PANI/MWCNT) composite with a core shell structure and a gel polymer redox electrolyte was used to improve the specific characteristics of a supercapacitor (SC). The gel of polyvinyl alcohol in sulfuric acid containing sodium 1,2-naphthoquinone-4-sulfonate (PVA/H₂SO₄/NQS) was used as a gel polymer redox electrolyte. Electrochemical studies have shown that the redox behavior of NQS is a diffusion-controlled and quasi-reversible process. The PANI/MWCNT composite in 13 mM NQS solution had a high specific capacitance of ca. 1100 F g⁻¹ at a scan rate of 5 mV s⁻¹ (three electrode cell configuration). The symmetrical flexible SC device based on the PANI/MWCNT composite and the PVA/NQS gel redox electrolyte had a power density of 1.8 kW kg⁻¹ and an energy density of 23.3 W h kg⁻¹. After 3000 cycles of potential scanning, the specific capacitance of the SC device decreased by less than 7%.