Highly stable aromatic poly (ether sulfone) composite ion exchange membrane for vanadium flow battery

Enhancing the chemical stability of ion exchange membranes is essential for improving cycle life and enabling the widespread utilization of flow batteries. Although numerous studies have been devoted to generate ion exchange membranes with high efficiency and stability, the progress is heavy going, especially for the non-fluorinated ion exchange membranes. Here we describe the preparation and utilization of an aromatic poly (ether sulfone) composite ion exchange membrane for vanadium flow battery application. The ion exchange groups are constructed by fixing the phosphotungstic acid into the alkaline poly (vinyl pyrrolidone) through the acid-base reaction, while the aromatic poly (ether sulfone) is used as the matrix. The stability and performance of the prepared membrane are verified by utilizing it in a vanadium flow battery. Both in situ and ex situ oxidation stability tests demonstrate that the aromatic poly (ether sulfone) composite ion exchange membrane has excellent stability in vanadium flow battery medium. In addition, a battery with a prepared membrane exhibits a coulombic efficiency of 99.36% and an energy efficiency of 81.61% at the current density of 140 mA cm−2. The aromatic poly (ether sulfone) composite ion exchange membrane represents a close step towards the design and construction of alternative types of membranes for battery application.