The Role of Oxygenic Groups and sp ³ Carbon Hybridization in Activated Graphite Electrodes for Vanadium Redox Flow Batteries

Graphite felt is a widely used electrode material for vanadium redox flow batteries. Electrode activation leads to the functionalization of graphite surface with epoxy, OH, C=O, and COOH oxygenic groups changes carbon morphology electronic structure, thereby improving electrode's electroactivity relative untreated graphite. In this study, density functional theory (DFT) calculations are conducted evaluate functionalization's contribution towards positive half-cell reaction battery. The DFT show that improve felt's affinity VO2+/VO2+ couple in following order: C=O>COOH>OH> basal plane. Projected density-of-states (PDOS) these increase sp3 hybridization same order, indicating responsible improved electroactivity, whereas groups’ presence increment. These insights can aid selection processes optimization their parameters.