CeO2 decorated graphite felt as a high-performance electrode for vanadium redox flow batteries

In this work, CeO2 nanoparticle decorated graphite felts (CeO2/GFs) were prepared by a facile precipitation method. The corresponding CeO2/GF composites containing different contents of CeO2, i.e. 0.1, 0.2, 0.3, 0.5 wt% were synthesized individually as electrodes for vanadium redox flow battery (VRFB) application. Scanning electron microscopy and X-ray diffraction analysis indicated the homogeneous dispersion of CeO2 nanoparticles on GF. The cyclic voltammetry results revealed that the CeO2/GFs exhibited higher activity and better reversibility towards the VO2+/VO2+ redox reaction compared with the pristine GF. Among all the electrodes, 0.2 wt% CeO2/GF demonstrated the best electrochemical properties, thus nominating CeO2 content of 0.2 wt% as an optimum content. The VRFB single cell tests indicated that 0.2 wt% CeO2/GF showed the highest energy efficiency of 64.7% at the current density of 200 mA cm−2, which was significantly higher than that of the pristine GF (53.9%). Furthermore, the cycle life test of a VRFB single cell demonstrated the outstanding stability of the CeO2/GFs electrode.