Highly conductive fluorine-based anion exchange membranes with robust alkaline durability†
Anion exchange membranes (AEMs) with robust alkaline stability and high ionic conductivity are imminently required for the promising electrochemical energy conversion devices – fuel cells. Herein, a series of novel crosslinked AEMs with hydrophobic fluorine-based polymer backbones bearing special functional sites and hydrophilic long flexible multi-cation side chains are prepared. Morphology observation and ion transport analysis confirm the existence of distinct microphase separation and efficient ion-conducting channels within the membranes resulting from the inherent chemical structure. A highest ionic conductivity of 136.27 mS cm−1 can be achieved by TQ-PDBA-70% (IEC = 2.16 meq. g−1) at 80 °C. Meanwhile, the prepared TQ-PDBA-X AEMs exhibit a desirable swelling ratio (<10%) and excellent mechanical properties (tensile stress > 22.8 MPa). It is worth noting that the retained ionic conductivity of the TQ-PDBA-70% AEM is 98.14%, 95.50%, 77.90%, 72.02% and 58.15% after being immersed in 1, 2, 4, 8 and 10 M KOH at 80 °C for 1000 h, respectively. Chemical structure change of the TQ-PDBA-70% AEM before and after the alkaline stability test is negligible, as revealed by FT-IR. Moreover, TQ-PDBA-70% has high ionic exchange capacity (IEC) retention and maintains good mechanical properties. A single cell assembled with TQ-PDBA-70% has a maximum power density of 158.8 mW cm−2 under a current density of 360 mA cm−2. These results suggest that this type of structure opens a new strategy for developing high performance AEMs.
- This article is part of the themed collection: Journal of Materials Chemistry A HOT Papers