Highly ion selective sulfonated poly(ether ether ketone)/polyzwitterion functionalized graphene oxides hybrid membrane for vanadium redox flow battery

High-density zwitterionic groups functionalized graphene oxides (PSBMA@GO) were incorporated into sulfonated poly(ether ether ketone) (SPEEK) membranes to create continuous channels for efficient proton/vanadium ion selective conduction. The incorporation of zwitterionic polymers, specifically poly(sulfobetaine methacrylate) (PSBMA) combined with graphene oxide (GO) sheets, enhanced the compatibility of additives with the SPEEK matrix. Furthermore, the impact of PSBMA@GO content on the properties of S/PSBMA@GO hybrid membranes for vanadium redox flow battery (VRFB) application was investigated. S/PSBMA@GO-1 hybrid membrane exhibits ultrahigh ion selectivity 55.3×103 S min cm-3, and the cell with this membrane shows excellent coulombic efficiencies (98.2-99.1%), energy efficiencies (83.6-74.5%) at 100-180 mA cm-2, long cycle life and high capacity retention (35.8% after 100 cycles at 100 mA cm-2). This study demonstrates that PSBMA@GO have great application potential to solve the trade-off effect between proton conductivity and vanadium ion permeability of PEM.