Polybenzimidazole (PBI) is considered as the one of the most promising materials for proton exchange membranes (PEMs) owing to its negligible crossover and outstanding chemical stability. However, the low proton conductivity of PBI membrane restricts its commercial application in vanadium flow battery (VFB). Herein, the PBI hybrid membranes with high proton conductivity were prepared by introducing crystalline covalent organic frameworks (TpPa and TpPa-SOH (STpPa)). Owing to the highly ordered sub-nanometer pores within TpPa and STpPa, faster proton highway was constructed in the hybrid membrane. Meanwhile, the sulfonic acid groups introduced to STpPa further provided additional proton transport sites and vanadium permeation barriers to achieve high ion selectivity. Accordingly, the cell assembled with PBI hybrid membrane with 3% STpPa achieved superior voltage efficiency (95.22%–74.84%) and energy efficiency (91.38%–74.38%) at 40–240 mA cm, and exhibited superb electrochemical stability during 800 cycles at 160 mA cm. This work offers a facile and efficient strategy to construct high-performance PBI-based PEMs by incorporating functional porous materials, which has incredible prospect for use in VFBs.

中文翻译：

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用于钒氧化还原液流电池的具有高效质子选择性传输通道的聚苯并咪唑-共价有机骨架杂化膜

聚苯并咪唑（PBI）由于其可忽略的交叉和出色的化学稳定性而被认为是最有前途的质子交换膜（PEM）材料之一。然而，PBI膜的低质子电导率限制了其在钒液流电池（VFB）中的商业应用。在此，通过引入结晶共价有机骨架（TpPa和TpPa-SOH（STpPa））制备了具有高质子电导率的PBI杂化膜。由于TpPa和STpPa内高度有序的亚纳米孔，杂化膜中构建了更快的质子高速公路。同时，STpPa中引入的磺酸基团进一步提供了额外的质子传输位点和钒渗透势垒，以实现高离子选择性。因此，用3% STpPa的PBI杂化膜组装的电池在40-240 mA cm下实现了优异的电压效率（95.22%-74.84%）和能量效率（91.38%-74.38%），并在800个循环中表现出优异的电化学稳定性。 160毫安厘米。这项工作提供了一种简单有效的策略，通过结合功能性多孔材料来构建基于 PBI 的高性能 PEM，这在 VFB 中具有令人难以置信的应用前景。