Enhancing the electrochemical and cyclic performance of IRFBs through electrode modification using novel MnO2@CeO2 composite

Abstract

In this work, we have coated MnO2@CeO2 composites onto graphite felts (GF) by electrostatic spraying leading to substantially improved electrochemical performance characteristics of iron redox flow batteries. GF are extensively used as electrodes but they do not have the desired electrochemical properties. MnO2@CeO2 composites have novel electrocatalyst features. Hence, MnO2@CeO2 composites were developed and applied to GF. Chemical and structural features of the bare graphite felt electrode and MnO2@CeO2 composite-modified graphite felt electrode (MGF) were characterized using scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller surface area analysis. Similarly, the electrochemical performance was investigated using cyclic voltammetry, electrochemical impedance spectroscopy, Tafel, and charge–discharge performance experiments. The charge−discharge experiments were performed at 1 to 3 mg cm− 2 weight of MGFs and varying the current densities from 40 to 70 mA cm− 2. The coulombic efficiency (ηC) and peak power density (PPD) of the cell (132 cm2) determined at 50 mA cm− 2 for 2 mg cm− 2-MGF electrode was found to be 99.10% and 55.56 W cm− 2, respectively. Among the three different types of electrodes, the MGF electrode showed better electrocatalytic performance mainly due to the excellent conducting network of the oxygen moieties of MnO2@CeO2 composites. After 25 cycles, the average ηC and PPD of the cell using 2 mg cm− 2-MGF was found to be 96.06% and 55.16 mW cm− 2, respectively, indicating the good stability of the electrode.