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Amphoteric Ion‐Exchange Membranes with Significantly Improved Vanadium Barrier Properties for All‐Vanadium Redox Flow Batteries
Author(s) -
Nibel Olga,
Rojek Tomasz,
Schmidt Thomas J.,
Gubler Lorenz
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201700610
Subject(s) - vanadium , membrane , redox , electrolyte , chemical engineering , ion exchange , chemistry , nafion , permeation , inorganic chemistry , materials science , ion , electrode , electrochemistry , organic chemistry , biochemistry , engineering
All‐vanadium redox flow batteries (VRBs) have attracted considerable interest as promising energy‐storage devices that can allow the efficient utilization of renewable energy sources. The membrane, which separates the porous electrodes in a redox flow cell, is one of the key components in VRBs. High rates of crossover of vanadium ions and water through the membrane impair the efficiency and capacity of a VRB. Thus, membranes with low permeation rate of vanadium species and water are required, also characterized by low resistance and stability in the VRB environment. Here, we present a new design concept for amphoteric ion‐exchange membranes, based on radiation‐induced grafting of vinylpyridine into an ethylene tetrafluoroethylene base film and a two‐step functionalization to introduce cationic and anionic exchange sites, respectively. During long‐term cycling, redox flow cells containing these membranes showed higher efficiency, less pronounced electrolyte imbalance, and significantly reduced capacity decay compared to the cells with the benchmark material Nafion 117.