Nanofiltration (NF) membranes: the next generation separators for all vanadium redox flow batteries (VRBs)?

NF membranes, as an alternative to traditional ion exchange membranes, were first proposed and successfully prepared for VRBs based on a totally new concept of tuning the vanadium/proton selectivity via pore size exclusion. The results showed that membranes show increasing vanadium ion/proton (V/H) selectivity with decreasing pore size distribution. VRBs assembled with prepared NF membranes exhibited comparable performance to that of commercialized Nafion. The concept could potentially overcome the traditional restriction from ion exchange membranes and provide much more material options for VRB membranes.