Advanced scalable zeolite “ions-sieving” composite membranes with high selectivity

A zeolite composite membrane (ZCM) was designed and fabricated via a simple versatile and scalable method. A thin layer of ZSM-35 flakes with pore size between hydrated protons and vanadium ions was fixed on the poly(ether-sulfone)/sulfonated poly(ether-ether-ketone) (PES/SPEEK) porous substrate by in-situ interfacial polymerization. The ZSM flake layer can perfectly separate hydrated vanadium ions and protons, therefore, show very impressive performance for vanadium flow batteries (VFBs). As a result, a VFB assembled with an optimized ZCM exhibited a columbic efficiency more than 99% and energy efficiency of over 91% at a current density of 80 mA cm -2 , which is among the highest performance ever reported. Furthermore, the energy efficiency can reach 81.6% at a very high current density of 200 mA cm -2 and keep stable for 1000 cycles at a current density of 180 mA cm -2 . This method opened a door toward the large-scale production of highly selective composite membranes for flow batteries.