Electrochemical energy storage systems have been extensively studied because they provide stable and reliable electricity for power systems. Among them, Vanadium Redox Flow Batteries (VRFBs) have attracted a great attention because of their high stability, wide application range, technological maturation, low maintenance cost and long lifetime compared to lithium batteries. In the VRFB systems, the ion exchange membrane (IEM) is a core component that transports protons while preventing both anolyte and catholyte from cross-mixing.
In general, Nafion membranes, which are widely used in fuel cells and redox flow cells, have high proton conductivity and chemical stability but their commercialization is limited by their high cost and low ion selectivity. At present, some cheaper ion exchange membrane materials are being used: sulfonated aryl-based polymers such as sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly (ether sulfone) (SPES) and sulfonated poly(phthalazinone ether ketone) (SPPEK). Of them, the SPEEK ionomer is considered as the most promising alternative to Nafion for VRFBs due to its ease of preparation, low cost, relatively good ionic conductivity, and chemical and mechanical stabilities.
Han Song Il, a post-graduate student at the Faculty of Chemical Engineering, has prepared composite membranes incorporating SPEEK as a proton conductive medium into TiO2 nanopapers to improve the mechanical and chemical stabilities of SPEEK membranes for VRFBs.
The SPEEK/TiO2 nanopaper composite membranes exhibited almost twice the tensile strength and only one-third the vanadium ion permeability compared to pristine SPEEK (DS=60%).
For more information, please refer to his paper “High durable SPEEK/TiO2 nanopapercomposite membrane for vanadium redoxflow battery” in “Journal of Saudi Chemical Society” (SCI).
© 2021 Kim Chaek University of Technology