Efficient interaction of indeno carbazole and alkoxy side chains with enormous differences in polarity achieve highly conductive and longevous anion exchange membranes

Anion-exchange membranes (AEMs) have gained widespread attention as another rising star among the core components of fuel cells. However, the disadvantages of low electrical conductivity and poor chemical stability greatly limit its development. Here, indeno carbazole monomers were introduced into the ether-free backbone and hydrophilic alkoxy side chains were suspended from the side chains to prepare a series of poly (indeno carbazolyl-aryl) piperidine membranes. Indeno carbazole is a nitrogen-containing heterocyclic compound with a large conjugation system, which provides a large volume of space to avoid close stacking of polymer molecules, and provides a place for the aggregation of water molecules without excessive swelling. The hydrophilic alkoxy side chain, as a hydrophilic group, absorbs a large amount of water and at the same time the oxygen atom will form cation-dipole interactions with the cation to induce cation aggregation. In addition, the polarity difference between the hydrophobic main chain and the hydrophilic side chain creates an obvious microphase separation structure, and the high-water absorption generated by the two can also reduce the attack of alkali on the cations, thus further improving the chemical stability of the membrane. At 80 °C, the relatively low IEC qPTP-IC-O-9% membrane instead achieved the highest ionic conductivity (137.5 mS cm-1) and peak power density (406 mW cm-2), and the conductivity retention was at 97.9% after 1300 h of immersion in 3 M NaOH at 80 °C. In addition, the qPTP-IC-O-9% membrane maintained 71.7% of the initial voltage after 30 h durability test at 80 °C, 0.05 A cm-2. To sum up, the qPTP-IC-O-9% membrane has a very bright future in promoting the further rapid development of hydroxide fuel cells.