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초록

Vanadium redox flow batteries (VRFBs) have attracted considerable attention due to their outstanding safety, design flexibility, and high performance. However, the severe polarization and the limited activity of carbonbased electrodes confine VRFB applications to large-scale energy storage systems. This study introduces a facile method for preparing mesoporous graphite felt (mp-GF) via thermal decomposition, employing a manganese oxide coating derived from alkylammonium permanganate. The resulting mp-GF offers mesopores, abundant oxygen-containing functional groups, and Mn3O4 catalysts, enhancing electrochemical activity and electrolyte utilization. VRFBs assembled with mp-GF electrodes achieved a voltage efficiency of 83.1 % and an energy efficiency of 80 % at a high current density of 200 mA cm(-2), outperforming the 78.3 % and 75.3 % efficiency of thermally treated graphite felt (TGF), the conventional electrode in VRFBs. We further investigate the dynamics of VRFBs using an electrochemical model that incorporates parameter identification based on the measured charge-discharge curves. The identified specific surface area of mp-GF is approximately 30 times greater than that of thermal-treated graphite felt. Consequently, the cell with mp-GF operates within a broader state of charge (SOC) range and at lower overpotentials.