Triple Layer Tungsten Trioxide, Graphene, and Polyaniline Composite Films for Combined Energy Storage and Electrochromic Applications.

Hailong Lyu

doi:10.3390/polym12010049

Abstract

Different polyaniline (PANI)-based hybrid films were successfully prepared by electro-polymerizing aniline monomers onto pre-spin-coated indium tin oxide (ITO) glass slides with WO3, graphene, or WO3/graphene films. Comparing with pristine PANI, the shifts of the characteristic peaks of PANI-based nanocomposites in UV-visible absorption spectra (UV-vis) and Fourier transform infrared spectroscopy (FT-IR) indicate the chemical interaction between the PANI matrix and the nanofillers, which is also confirmed by the scanning electron microscope (SEM) images. Corresponding coloration efficiencies were obtained for the WO3/PANI (40.42 cm2 C−1), graphene/PANI (78.64 cm2 C−1), and WO3/graphene/PANI (67.47 cm2 C−1) films, higher than that of the pristine PANI film (29.4 cm2 C−1), suggesting positive effects of the introduced nanofillers on the electrochromic performance. The areal capacitances of the films were observed to increase following the order as bare WO3 < WO3/graphene < pristine PANI < WO3/PANI < graphene/PANI < WO3/graphene/PANI films from both the cyclic voltammogram (CV) and galvanostatic charge-discharge (GCD) results. The enhanced energy storage and electrochromic performances of the PANI-based nanocomposite films can be attributed to the capacitance contributions of the introduced nanofillers, increased PANI amount, and the rougher morphology due to the embedment of the nanofillers into the PANI matrix. This extraordinary energy storage and electrochromic performances of the WO3/graphene/PANI film make it a promising candidate for combined electrochromic and energy storage applications.

Highlights

Energy shortage and environmental pollution have been two major subjects of modern society, which urgently requires developing clean, efficient, and renewable sources of energy, as well as advanced technologies associated with energy storage and conversion [1,2,3]
Corresponding coloration efficiencies were obtained for the WO3 /PANI (40.42 cm2 C−1 ), graphene/PANI (78.64 cm2 C−1 ), and WO3 /graphene/PANI (67.47 cm2 C−1 ) films, higher than that of the pristine PANI film (29.4 cm2 C−1 ), suggesting positive effects of the introduced nanofillers on the electrochromic performance
Similar cyclic voltammogram (CV) curves except different anodic current peaks are obtained for these PANI-based nanocomposites films

Summary

Introduction

Energy shortage and environmental pollution have been two major subjects of modern society, which urgently requires developing clean, efficient, and renewable sources of energy, as well as advanced technologies associated with energy storage and conversion [1,2,3]. As a promising novel energy storage device with fast charging-discharging rate and extremely long cycling life, electrochemical supercapacitor possesses higher energy density than conventional dielectric capacitors and higher power density than common batteries [4,5]. Electrochemical supercapacitors include two typical categories based on different charge storage mechanisms, that is, electric double-layer capacitors (EDLCs) with a non-Faradic process through the ion adsorption between the interfaces of electrodes and electrolyte, and pseudo-capacitors with a Faradic process via fast surface redox reaction [6]. Carbon materials usually employed as EDLCs exhibit excellent cycling life (>105 cycles) but limited capacitance. Metal oxides and conducting polymers as main materials for pseudo-capacitors always possess much larger capacitances but the shrinkage and swelling lead to much shorter cycling life. In order to overcome their corresponding deficiencies, it is proposed that

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Conclusion