Abstract: The voltammetric behaviors of graphite (GP) and its composites with acetylene black (AB) were studied in 5mol/L H₂ SO₄+1mol/L VOSO₄ solution with cyclic voltammetry (CV), and surface morphologies of the composites were observed with scan electron icroscope (SEM). The results obtained with voltammetry show that the redox couples of V(Ⅳ)/V(Ⅴ) and V(Ⅱ)/V(Ⅲ), as positive and negative electrodes of all vanadium flow liquid battery, respectively, have good reversibility but low current on the GP electrode, and the current can be improved by AB. The SEM observation shows that the granulars of AB are dispersed evenly on the surface of sheet GP when they are mixed together. The best compositions for the positive and the negative of all vanadium flow liquid battery determined by comparing voltammetric behavior of the composite electrodes with different content of AB, are (wAB:wGP) 15:85 for the positive and 4:96 for the negative.

Key words: all vanadium redox flow battery, graphite, acetylene black, composite electrodes