A simple and effective solvent treatment method was developed to prepare porous membranes with a tunable morphology for vanadium flow battery applications. The solvent treatment method can effectively create poly(ether sulfone) (PES) membranes with a well-controllable pore size and pore size distribution. An impressive vanadium flow battery (VFB) performance with a coulombic efficiency of over 99% and an energy efficiency of over 90% was obtained, which are the highest values ever reported for porous uncharged membranes. The concept provides an entirely novel, simple and cost-effective way to fabricate high-performance porous membranes for VFB applications.
