Template-free electrochemically polymerized polypyrrole nanowires and their application in flexible solid-state supercapacitors

Treated carbon cloths combined with polypyrrole (PPy) nanowires (TCC@PPyW) were fabricated by template-free electrochemical deposition of pyrrole in the presence of sodium citrate dihydrate and sodium perchlorate. The morphologies and electrochemical performances of the samples were studied using scanning electron microscopy, cyclic voltammetry, galvanostatic charge-discharge measurements and electrochemical impedance spectroscopy. The morphologies of PPy nanostructure were controlled by regulating interfacial pH, deposition time and concentration of sodium perchlorate. PPy nanorods were generated with the aid of water oxidation when the pH of pyrrole solution was 7.9, and PPy nanowires could be obtained by increasing the deposition time or the concentration of sodium perchlorate. The resulting PPy nanowires were about 100 nm in diameter and up to 600 nm in length. TCC@PPyW electrodes provided a large contact area for electrolyte, which facilitated the rapid delivery of electric charge. As a result, the TCC@PPyW electrodes exhibited a high areal specific capacitance of 841.2 mF cm(-2) at 0.4 mA cm(-2) and a high energy density of 420.6 mu Wh cm(-2) at a power density of 0.2 mW cm(-2). An all-solid-state flexible symmetric supercapacitor without any binder, incorporated with TCC@PPyW as electrodes and poly(vinyl alcohol)-LiCl gel as gel electrolyte, is also reported. The TCC@PPyW supercapacitor displayed excellent flexibility and rate capability. (c) 2021 Society of Chemical Industry