| 초록 |
Perfluorosulfonic acid (PFSA) based membranes such as Nafion, which is used in vanadium redox flow battery (VRFB), have excellent proton conductivity and outstanding chemical stability. However, due to their randomly interconnected ion channels, they have a high degree of vanadium ion crossover, resulting in reducing cell performance, so that thick membranes are inevitably used despite the high cost and membrane resistance. In this study, we fabricate a ultra-thin graphene-oxide (GO)/PFSA composite membrane of highly aligned ion channels by molecular arrangement on the air/water interface. Well-ordered ion channels dramatically suppress the vanadium ion crossover, enhancing ion selectivity compared to commercial PFSA membranes. Moreover, GO sheets have strengthening effect of film matrix, the design of GO sheets covalently bonded with PFSA ionomers and sub-100 nm ultra-thin thickness allow to fast proton transport over various current densities. The VRFB single cell with the GO/PFSA composite membrane exhibits improved performance with the energy efficiency of 77.7%, which is 4.6% higher than Nafion 211 at 200 mA/cm2 and demonstrating its practical applicability for VRFBs. |
