Biomass pomelo peel modified graphite felt electrode for iron-chromium redox flow battery

Iron-chromium redox flow battery (ICRFB) is an energy storage battery with commercial application prospects. Compared to the most mature vanadium redox flow battery (VRFB) at present, ICRFB is more low-cost and environmentally friendly, which makes it more suitable for large-scale energy storage. However, the traditional electrode material carbon felt (CF) has poor electrochemical activity and hydrogen evolution side reactions, which hinders the application of ICRFB. In this paper, the surface of graphite felt (GF) was modified with pomelo peel powder to prepare biomass-modified graphite felt (Bio-GF). The optimal mass of pomelo peel powder and concentration of sucrose solution and pyrolysis temperature were determined. The surface morphology, elemental composition, hydrophilicity and electrochemical performance of the optimal biomass-modified GF(Bio-GF-O) were characterized. In addition, high performance can be achieved by employing ICRFB assembled with the Bio-GF-O electrode. At a low current density of 40 mA cm-2, the Coulombic efficiency(CE) was 92.34%, the voltage efficiency (VE) was 91.81%, and the energy efficiency (EE) was 84.78%. At the high current density of 120 mA cm-2, the CE increased and up to 96.87%, the VE and EE still have excellent cycle stability. It can be concluded that the use of waste biomass materials to modify GF to improve its electrochemical performance is conducive to the application of ICRFB.