The preparation of a novel anion-exchange membrane and its application in all-vanadium redox batteries

An anion-exchange membrane was prepared using a homogeneous blend mixture of poly(ether sulfone) (PES) and poly(vinylpyrrolidone) (PVP). Advantageous properties of each component were retained in this PES–PVP membrane, such as good mechanical strength, ion selectivity, and excellent hydrophilicity. This membrane can potentially be an alternative candidate for the separator in all-vanadium redox battery systems, given its good ionic conductivity, low permeability of positively charged vanadium ions, resistive property against oxidants, and low cost. Because cross-mixing of the positive and negative electrolytes can be effectively prevented, the coulombic efficiencies were higher than 99% when using these anion-exchange membranes in all-vanadium redox batteries, which is significantly higher than those obtained using expensive Nafion cation-exchange membranes.