Journal of Power Sources, Vol.375, 404-411, 2018
Recyclable cross-linked anion exchange membrane for alkaline fuel cell application
Cross-linking can effectively solve the conductivity-swelling dilemma in anion exchange membranes (AEMs) but will generate solid wastes. To address this, we developed an AEM cross-linked via disulfide bonds, bearing quaternary ammonium groups, which can be easily recycled. The membrane (RC-QPPO) with IEC of 1.78 mmol g(-1), when cross-linked, showed enhanced mechanical properties and good hydroxide conductivity (24.6 mS cm(-1) at 30 degrees C). Even at higher IEC value (2.13 mmol g(-1)), it still has low water uptake, low swelling ratio and delivers a peak power density of 150 mW cm(-2) at 65 degrees C. Exploiting the formation of disulfide bonds from -SH groups, the membrane can be readily cross-linked in alkaline condition and recycled by reversibly breaking disulfide bonds with dithiothreitol (DTT). The recycled membrane solution can be directly utilized to cast a brand-new AEM. By washing away the residual DTT with water and exposure to air, it can be cross-linked again and this process is repeatable. During the recycling and cross-linking processes, the membrane showed a slight IEC decrease of 5% due to functional group degradation. The strategy presented here is promising in enhancing AEM properties and reducing the impact of artificial polymers on the environment. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:Membrane recycling;Anion exchange membrane;Reversible cross-linking;Disulfide linkage;Fuel cell