Effect of amination agent on the properties of quaternized poly(phthalazinone ether sulfone) anion exchange membrane for vanadium redox flow battery application

Two kinds of anion exchange membranes with different amine functional groups are prepared from chloromethylated poly(phthalazinone ether sulfone) with different amine agents. Effects of amination process such as amination time, amination temperature and species of amination medium on the membranes ion exchange capacity (IEC), water content (Wc), VO2+ ions permeability (Ks) and area resistance (R) are investigated. With the increasing of amination time, temperature and concentration, IEC and Wc of membranes increase, R decreases. And anion exchange membrane functionalized by trimethylamine has better comprehensive properties (IEC = 1.69 mmol g−1, Wc = 28%, Ks = 2.79 × 10−5 cm min−1 and R = 0.53 Ω cm2). Applying to all-vanadium redox flow battery, energy efficiency (EE) of the membrane reaches 87.9%. Using ethylenediamine/trimethylamine as the amination reagent, the membrane performs good water stability and vanadium ions selectivity (Wc = 22%, Ks = 4.3 × 10−6 cm min−1, IEC = 1.40 mmol g−1, R = 1.00 Ω cm2 and EE = 83.4%). Compared with Nafion-112, Nafion-117 membrane, quaternized poly(phthalazinone ether sulfone) anion exchange membranes exhibit higher energy efficiency and better vanadium selectivity.