Tailoring the microphase separation structure of poly(crown ether) anion exchange membranes by introducing aliphatic chains.

Energy conversion devices such as alkaline fuel cells (AFCs) rely critically on anion exchange membranes (AEMs) with high hydroxide conductivity as well as good chemical stability. Poly (crown ether) (PCE) based AEMs with different aliphatic chain lengths in polymer backbone are successfully designed and prepared in this study. The longer hydrophobic aliphatic chain segments can promote the formation of nanophase separation and ionic clusters. As examined by morphology observation such as atomic force microscopy (AFM), small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), the QAPCE-16C AEMs which the carbon number of aliphatic chains is sixteen show a well-connected ion cluster region and a distinct micromorphology separation. QAPCE-16C with an IEC of 1.43 meq g−1 shows a hydroxide conductivity of 125 mS cm−1 at 80 °C. After immersing in a 1 M sodium hydroxide solution at 80 °C for 960 h, QAPCE-16C presents good alkaline resistance with the ionic conductivity retention of 95.77%. Besides this, the peak power density of QAPCE-16C can reach to 653.8 mW cm−2 in H 2 /O 2 as well as 458.8 mW cm−2 in H 2 /Air (CO 2 -free) at 80 °C. [Display omitted] • Effect of aliphatic chain lengths on the performance of AEMs is investigated. • Introduction of aliphatic chain promotes the microphase structure of AEMs. • The QAPCE-16C AEMs show the maximum OH− conductivity of 125 mS cm−1 at 80 °C. • Power density of 653.8 mW cm−2 in a H 2 /O 2 single cell based on QAPCE-16C is obtained. [ABSTRACT FROM AUTHOR]