Development of nitrogen-doped carbons using the hydrothermal method as electrode materials for vanadium redox flow batteries

Nitrogen-doped carbons are suggested as elec-trochemically active materials for V(IV)/V(V) redox couples for a vanadium redox flow battery (VRB). These materials were synthesized using a hydrothermal reaction of aqueous glucose solution in the presence of ethylenediamine as a nitrogen source. The physical and electrochemical properties of the nitrogen-doped carbons are characterized by cyclic voltammetry, high-resolution transmission electron microscopy and X-ray photoelectron spectrometry. These results reveal that the hydrothermal method is an effective way to synthesize high-content nitrogen-doped carbons. Nitrogen doping significantly improves catalytic activity and reversibility. Therefore, use of nitrogen-doped carbon is expected to increase the energy storage efficiency of VRBs.