DOI: https://doi.org/10.55373/mjchem.v27i4.182

Keywords: Polyaniline; oxalic acid; graphite felt,VRFBs; EIS; CV

Abstract

The increasing global demand for sustainable energy storage solutions has driven advancements in vanadium redox flow batteries (VRFBs). However, the low power density of VRFBs remains a critical challenge due to the limited electrochemical performance of conventional graphite felt (GF) electrodes. In this study, polyaniline (PANI) doped with oxalic acid was synthesized via oxidative polymerization and used to modify GF electrodes to enhance their conductivity and electrochemical activity. Structural and morphological characterizations, including FTIR and FESEM-EDX, suggested the successful incorporation of PANI onto the GF surface, significantly improving the electrode's porosity and active surface area. The modified electrode demonstrated a fivefold reduction in charge transfer resistance (Rct) and a substantial increase in electrical conductivity (from 0.0043 S/cm to 0.0214 S/cm), when analysed by electrochemical impedance spectroscopy (EIS). Cyclic voltammetry (CV) results revealed enhanced redox kinetics and pseudocapacitive behavior, enabling superior charge storage capability and improved ion transport, with a specific capacitance of 125 F g^-1 at 10 mV s^-1. Additionally, the modified electrode delivered a power density of 178.5 W g^-1, indicating excellent energy transfer capability. These findings highlight that oxalic acid-doped PANI is a cost-effective and scalable electrode modification approach, paving the way for high-performance VRFBs and other energy storage applications.