Thermally reduced graphite oxide as positive electrode in vanadium redox flow batteries

Two graphene-like materials, obtained by thermal exfoliation and reduction of a graphite oxide at 700 and 1000oC, were studied as active electrodes in the positive half-cell of a Vanadium Redox Flow Battery (VRFB). In particular, that obtained at 1000oC exhibited an outstanding electrochemical performance in terms of peak current densities (30.54 and 30.05 mAcm for the anodic and cathodic peaks at 1 mVs, respectively) and reversibility (ΔEp = 0.07 V). This excellent bahaviour is attributed to the restoration of sp domains after thermal treatment, which implies the production of a graphene-like material with a high electrical conductivity and accessible surface area. Moreover, the residual functional groups, -OH, act as active sites towards the vanadium redox reactions. This represents a significant step forward in the development of highly effective VRFB electrode materials. ∗ Corresponding author: Fax: +34 985 29 76 62. E-mail address: [email protected] (C. Blanco)