Facile electrochemical fabrication of PEDOT/hydrated tungsten oxides/W self-supporting electrodes with high performance for supercapacitors

Abstract

Tungsten oxide hydrates, as an emerging type of electrode materials, have excellent pseudocapacitive activity but low conductivity. Making composites with conductive polymers is a promising way to overcome this disadvantage and thus improves their capacitive performance. However, little research on this topic has been reported so far. Herein, a series of PEDOT/WO₃⋅xH₂O/W (denoted as PWHW, x = 1 or 2) self-supporting electrodes have been facilely prepared via a two-step electrochemical method, i.e., anodic oxidation of W followed by electropolymerization of 3, 4-ethylenedioxythiophene (EDOT). Importantly, the electropolymerization of EDOT brought about highly porous network structure and enhanced cycling stability to the PWHW electrodes. The porous network structure together with the high conductivity of PEDOT made the interfacial charge transfer resistance of the PWHW electrodes drastically decrease compared to that of the WO₃⋅xH₂O/W electrode (denoted as WHW). As a result, the as-prepared PWHW-200 showed a high areal capacitance (251.4 mF cm⁻²), high volumetric capacitance (723.8 F cm⁻³) and long cycling life (a capacity retention of 107 % after 10,000 cycles). What is more, an asymmetrical supercapacitor with PWHW-200 as the negative electrode could deliver a high energy density of 7.09 mW h cm⁻² at a power density of 20.41 mW cm⁻². These findings can promote the development of fabricating new inorganic-organic composites as self-supporting electrodes with high performance for energy storage devices.