The influence of electrodeposited PPy film morphology on the electrochemical characteristics of Nafion-based energy storage devices

All solid-state Nafion-based energy storage devices were fabricated by electropolymerization of polypyrrole (PPy) films on both sides of carbon black (CB)/multiwall carbon nanotubes (MWCNT) – coated Nafion membrane. The influences of LiCl and LiClO4 electrolytes on the physicochemical characteristics of the deposited PPy film and subsequently on the electrochemical properties of Nafion-based energy storage devices were investigated. The synthesized electrode regions were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), Fourier transform infra-red (FTIR) and Ultraviolet visible (UV–Vis) spectroscopy. The electrochemical characteristics of the prepared samples were compared using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. SEM analysis revealed that applying LiCl as electrolyte in electropolymerization of PPy results in formation of more porous PPy films. These samples showed higher specific capacitance (~86mF·cm−2 or 245.2F·g−1) and water uptake potential (77%), which were about 73% and 42% higher than that considered for the sample prepared in LiClO4 electrolyte, respectively. The specific capacitance of both samples was also much higher than that achieved for the CB/MWCNT– coated Nafion as a standard. The galvanostatic charge/discharge measurements revealed that the samples prepared using LiCl exhibit good cycling stability even at high current densities and can retain 87% of their specific capacitance after 500cycles. It was also found these samples are able to deliver their stored energy two times faster than the sample prepared using LiClO4. •Electrodeposition of PPy film as electrode layer on both surfaces of Nafion membrane•Self-assembly of PPy electrode based energy storage devices through electrodeposition•The influences of electrolyte type on the morphology of PPy electrode layer•Determining the electrochemical characteristic of devices as a function of electrolyte type