Performance of room-temperature activated tubular polypyrrole modified graphite felt composite electrode in vanadium redox flow battery

Abstract

In this paper, the graphite felt (GF) composite electrode modified with the conducting polymer of tubular polypyrrole (PPy) was prepared at room temperature with the advantages of low-energy and acid free synthetic process. The material characteristics and electrochemical properties of PPy power and PPy modified GF composite electrodes (PPy-GF) were studied by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) tests, electrochemical impedance spectroscopy (EIS) analysis, and charge-discharge tests. The vanadium redox flow battery (VRFB) assembled with room-temperature activated PPy-GF electrode exhibits improved performance with the energy efficiency (EE) up to 82.20% at the current density of 80 mA•cm−2, which is 6.10% and 4.02% higher than that with Pristine GF and Air heated GF, respectively. Moreover, the cell equipped with the composite electrode treated in 2 mg/mL PPy solution shows the highest discharge capacity of 724.4 mA•h and superior cycling stability after 100 cycles.