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[Display omitted] • Effect of crown ether cavity size on the performance of AEMs is investigated. • The QAPCE-18-6 AEM exhibits a highest ionic conductivity of 122.5 mS cm−1 at 80 °C. • The peak power density of QAPCE-18-6 in a H 2 /O 2 single cell is 562 mW cm−2. Anion exchange membrane fuel cells (AEMFCs) have emerged as a promising alternative to proton exchange membrane fuel cells (PEMFCs) due to their adaptability to low-cost stack components and non-noble-metals catalysts. However, the poor alkaline resistance and low OH− conductivity of anion exchange membranes (AEMs) have impeded the large-scale implementation of AEMFCs. Herein, the preparation of a new type of AEMs with crown ether macrocycles in their main chains via a one-pot superacid catalyzed reaction was reported. The study aimed to examine the influence of crown ether cavity size on the phase separation structure, ionic conductivity and alkali resistance of anion exchange membranes. Attributed to the self-assembly of crown ethers, the poly (crown ether) (PCE) AEMs with dibenzo-18-crown-6-ether (QAPCE-18-6) exhibit an obvious phase separated structure and a maximum OH− conductivity of 122.5 mS cm−1 at 80 °C (ionic exchange capacity is 1.51 meq g−1). QAPCE-18-6 shows a good alkali resistance with the OH− conductivity retention of 94.5% albeit being treated in a harsh alkali condition. Moreover, the hydrogen/oxygen single cell equipped with QAPCE-18-6 can achieve a peak power density (PPD) of 574 mW cm−2 at a current density of 1.39 A cm−2. [ABSTRACT FROM AUTHOR]

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]

To investigate the influence of main chain structure on the performance of anion exchange membranes (AEMs), crosslinked naphthalene-based block polymer AEMs are synthesized via nucleophilic polycondensation, Williamson reaction, atom transfer radical polymerization (ATRP) reaction, bromination, and quaternization. With a helical structure, the naphthalene-based triblock backbone can provide the ion channels inside AEMs, further enhance the ionic conductivity and dimensional stability. The crosslinked network of long alkyl chains ensures desirable mechanical properties of AEMs. The prepared NAPEK-PVP-X AEMs have a high alkaline stability, a low swelling ratio and a high ionic conductivity. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used to confirm the hydrophilic/hydrophobic microphase separated structure of the AEMs. More developed ion transport channels of naphthalene-based AEMs are shown by molecular dynamics (MD) simulations. A power density peak of 160.73 mW cm−2 is obtained by assembling the NAPEK-PVP-10-Q4 AEM into a single cell operating at 60 °C. The study provides a resource for future work on AEMs. [Display omitted] • Naphthalene-based triblock and bisphenol A-based triblock main chain are fabricated. • The long flexible crosslinked chain further enhanced the mechanical property of AEMs. • The naphthalene-based triblock polymer AEMs show efficient ion transport. [ABSTRACT FROM AUTHOR]