Electrochemical hydrogen compressors (EHC) are favored for their quiet operation, efficiency, and low energy consumption in hydrogen purification and compression. A key challenge in EHC development is developing high-performance proton exchange membranes (PEMs) that manages water effectively. Herein, we've crafted a series of comb-shaped N-alkylation sulfonated poly(oxindole biphenylene) (SPOBP-C-x) (n = 0, 6, 10, 16) PEMs with varying side chain lengths. These PEMs feature distinct designs with sulfonic acid groups and hydrophobic chains attached to different locations of the indigo groups, which not only enhance ion conductivity by inducing the formation of microphase separated morphology but also retain their water absorption behaviors. The SPOBP-C-10 membrane displayed the highest proton conductivity of 209.7 mS/cm (60 °C) and retain water uptake of 148.8 wt%. All the membranes exhibited low hydrogen back-diffusion permeability. Moreover, SPOBP-C-10 membranes outperformed Nafion 112 in EHC cells, with SPOBP-C-10 exhibiting a notably low 0.1 V operating voltage at 1 A/cm (RH = 100%). EHC device durability tests for SPOBP-C-10 at 200 mA/cm and 60 °C demonstrated a stability for over 440 h with very slight variations in voltage. These results indicate that the comb-shaped structure with alkyl side chains and sulfonic acid groups adjacent to the backbone is an effective strategy for achieving satisfactory high conductivity, water uptake and energy efficiency of PEMs for use in EHC.

中文翻译：

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用于增强电化学氢压缩性能的无醚主链梳形磺化聚（羟吲哚联苯）膜的有前途的候选者

电化学氢气压缩机（EHC）因其在氢气纯化和压缩方面运行安静、效率高、能耗低而受到青睐。 EHC 开发的一个关键挑战是开发能够有效管理水的高性能质子交换膜 (PEM)。在此，我们制作了一系列具有不同侧链长度的梳形 N-烷基化磺化聚（羟吲哚联苯）（SPOBP-Cx）（n = 0、6、10、16）PEM。这些质子交换膜具有独特的设计，磺酸基团和疏水链附着在靛蓝基团的不同位置，不仅通过诱导微相分离形态的形成来增强离子电导率，而且还保留了其吸水行为。 SPOBP-C-10 膜表现出最高的质子电导率，为 209.7 mS/cm (60 °C)，并保持吸水率为 148.8 wt%。所有膜都表现出低的氢反扩散渗透性。此外，SPOBP-C-10 膜在 EHC 电池中的性能优于 Nafion 112，SPOBP-C-10 在 1 A/cm（RH = 100%）下表现出明显低的 0.1 V 工作电压。 SPOBP-C-10 在 200 mA/cm 和 60 °C 下的 EHC 设备耐久性测试表明，其稳定性超过 440 小时，电压变化非常轻微。这些结果表明，具有烷基侧链和邻近主链的磺酸基团的梳状结构是实现 EHC 中使用的 PEM 令人满意的高电导率、吸水率和能量效率的有效策略。