Development of boosted microphase separation exploiting highly rigid poly(phenyl-alkane)s anion exchange membranes for excellent performance fuel cells

Abstract

The advancement of the ionic conductivity and dimensional stability of anion exchange membranes (AEMs) while ensuring excellent alkali stability is the critical challenge in the development of AEM fuel cells. Construction of efficient ion transport channels through well-designed microphase morphology is considered to be an effective strategy to achieve this goal. Herein, we propose an ingenious design that a novel aryl ether-free poly(phenyl-alkane)s-based AEMs to optimize the conductivity and longevity of AEMs using rigid aryl units, i.e., 1,4-dimethoxybenzene and spirobisindane, as the main chains with connecting flexible alkyl chains. The rigid and non-rotatable aromatic structure can facilitate the formation of a well-defined microphase separation structure with long chain quaternary ammonium by reducing chain segment interactions, and can also ameliorate the dimensional stability of the membrane. Consequently, the as-prepared membrane exhibits an excellent hydroxide conductivity of 130 mS cm⁻¹ at 80 °C and approaches a terrific conductivity retention rate of 90 % after immersion in 1 M NaOH solution at 80 °C for 1000 h. Furthermore, the as-prepared membrane achieves an excellent peak power density of 1.36 W cm⁻² in the H₂-O₂ fuel cell and its initial voltage shows no signs of decreasing after running for 20 h under 0.2 A cm⁻².