과불화 알킬 사슬이 도입된 산화 그래핀 기반 Nafion 복합막의 바나듐 레독스 흐름 전지 응용

초록

In this study, perfluoroalkyl-grafted graphene oxide (FGO) was synthesized and incorporated into a perfluorinated polymer matrix (Nafion) to develop an ion-exchange membrane for vanadium redox flow battery (VRFB). FGO was prepared via a ring-opening esterification reaction between the carboxylic acid groups of poly(hexafluoropropylene oxide) containing carboxylic acid groups (157 FSL, DuPont) and the epoxy groups on GO in the presence of a basic catalyst. Composite membranes (N/FGO_X) with different FGO contents were fabricated and evaluated based on water uptake, dimensional stability, proton conductivity, vanadium ion permeability, and single-cell performance. The N/FGO membranes exhibited lower water uptake and less dimensional change than pristine Nafion, while maintaining similar proton conductivity. Due to the physical barrier effect of FGO, the membranes significantly reduced vanadium ion permeability, resulting in improved ion selectivity. The VRFB single-cell tests confirmed that the N/FGO membranes achieved higher discharge capacity, coulombic efficiency, and energy efficiency compared with the pristine Nafion membrane.

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