Abstract Aromatic ionomers have emerged as promising alternatives to perfluorosulfonic acid polymers to be applied as proton exchange membranes in fuel cells. However, the paradox between the ion conductivity and stability is still a challenge precluding the commercialization of aromatic ionomers. In this paper, we report the design of a novel sulfonated poly(arylene ether nitrile) multi-block structure by introducing a key component, alkyl benzotriazole (Bt) side chains, into the hydrophobic segments. The modified structure could facilitate polymer phase-separation and generate self-standing films with excellent mechanical properties, and it effectively suppresses the excessive swelling of the membrane owing to strong electrostatic interactions between the Bt chains and sulfonic acid groups. Moreover, the Bt unit could act as both a proton acceptor and proton donor, causing a dramatic increase in the ion conductivity of the membrane. The most optimal membrane possesses an ion-exchange capacity of 2.15 meq g−1 and exhibits a weaker relative humidity (RH) dependence and higher proton conductivity than the commercial Nafion 212 over the entire RH range. Remarkably, the maximum power output of the fuel cell based on the most optimal membrane reaches 1090, 856, and 451 mW cm−2 at 95%, 70%, and 30% RH, respectively, which are more than 2 times higher than those of the non-Bt analogue. Further, the current densities (I0.6) ranging up to 1500 and 1000 mA cm−2 (0.6 V) at 95% and 70% RH are both much higher than those of the Nafion. Our study provides a novel methodology for the design of aromatic ionomer structures with excellent performances for practical fuel cell application.

中文翻译：

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带有低聚苯并三唑悬垂物的多嵌段磺化聚（亚芳基醚腈）聚合物具有极高的 H 2 /O 2 燃料电池性能

摘要 芳香族离聚物已成为全氟磺酸聚合物的有前途的替代品，可用作燃料电池中的质子交换膜。然而，离子电导率和稳定性之间的矛盾仍然是阻碍芳族离聚物商业化的挑战。在本文中，我们报告了通过将关键组分烷基苯并三唑 (Bt) 侧链引入疏水链段来设计新型磺化聚（亚芳基醚腈）多嵌段结构。改性后的结构可以促进聚合物的相分离并产生具有优异机械性能的自支撑膜，并且由于Bt链和磺酸基之间的强静电相互作用，它有效地抑制了膜的过度膨胀。而且，Bt 单元可以作为质子受体和质子供体，导致膜的离子电导率显着增加。最优化的膜具有 2.15 meq g-1 的离子交换容量，并且在整个 RH 范围内表现出比商业 Nafion 212 更弱的相对湿度 (RH) 依赖性和更高的质子传导率。值得注意的是，基于最佳膜的燃料电池在 95%、70% 和 30% RH 时的最大功率输出分别达到 1090、856 和 451 mW cm-2，比那些高出 2 倍以上。非 Bt 类似物。此外，在 95% 和 70% RH 下，电流密度 (I0.6) 范围高达 1500 和 1000 mA cm-2 (0.6 V)，均远高于 Nafion。