Nafion/TiO2 hybrid membrane fabricated via hydrothermal method for vanadium redox battery

To improve the performance of Nafion membrane as a separator in vanadium redox battery (VRB) system, a Nafion/TiO2 hybrid membrane was fabricated by a hydrothermal method. The primary properties of this hybrid membrane were measured and compared with the Nafion membrane. The Nafion/TiO2 hybrid membrane has a dramatic reduction in crossover of vanadium ions compared with the Nafion membrane. The results of scanning electron microscope, energy dispersive X-ray spectroscopy, and X-ray diffraction of the hybrid membrane revealed that the TiO2 phase was formed in the bulk of the prepared membrane. Cell tests identified that the VRB with the Nafion/TiO2 hybrid membrane presented a higher coulombic efficiency (CE) and energy efficiency (EE), and a lower self-discharge rate compared with that of the Nafion system. The CE and EE of the VRB with the hybrid membrane were 88.8% and 71.5% at 60 mA cm(-2), respectively, while those of the VRB with Nafion membrane were 86.3% and 69.7% at the same current density. Furthermore, cycling tests indicated that the Nafion/TiO2 hybrid membrane can be applied in VRB system.