Polybenzimidazole and Polyvinylpyrrolidone Blend Membranes for Vanadium Flow Battery.

The membrane, as one of the key components in vanadium flow battery, plays an important role in battery performances and cost. In this paper, a series of new blend membranes based on polybenzimidazole and polyvinylpyrrolidone are proposed to combine the beneficial features of the two components, such as great chemical stability, low vanadium ion permeability and low area resistance. To begin with, blend membranes with different ratios of the two compositions are fabricated, followed by a microstructure characterization, demonstrating that the polybenzimidazole and polyvinylpyrrolidone can be compatible with each other and of good film-forming property. After that, the membrane performance investigation shows that the low area resistance, superior vanadium resistance and strong chemical stability can be simultaneously achieved. Furthermore, the cell testing indicates that the energy efficiencies are respectively 79% and 67% at the current densities of 100 mA cm⁻² and 200 mA cm⁻², and the cycling life could be over 120 times for the cell with the blend membrane of 30% polyvinylpyrrolidone and 70% polybenzimidazole. Accordingly, this work not only provides a kind of advanced membrane for the vanadium flow battery, but also offers an effective method to design, optimize and fabricate the membranes incorporating the features according to needs. [ABSTRACT FROM AUTHOR]