Nonaqueous redox flow batteries (RFBs) have received significant research interest, but the lack of promising separators with advanced performance seriously hinders the development of nonaqueous RFBs. Here, a robust yet flexible membrane with enhanced selectivity for nonaqueous RFBs is designed via in situ synthesis of metal–organic frameworks (MOFs) in a porous polymeric membrane (Celgard) with a gradient density. The crossover of active species is mitigated by the reduced effective pore size while high ionic conductivity is maintained, which is attributed to the 3D channel structure of MOFs and their gradient distribution in the membrane. A Li/ferrocene RFB with the MOF‐imbedded membrane delivers an excellent high‐rate capability and enhanced cycling stability. The discharge capacity reaches as high as ≈94% of theoretical value at a current density of 4 mA cm⁻², and maintains 76% even at 12 mA cm⁻². Moreover, a much slower capacity decay rate is achieved (0.09% per cycle over 300 cycles) by using the composite membrane compared with the pristine Celgard membrane (0.24% per cycle). The demonstrated strategy provides new insight into rational design and fabrication of size‐sieving separators for RFBs and can promote further research of MOFs' capability in energy storage.

中文翻译：

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用于非水氧化还原液流电池的基于梯度分布的金属-有机骨架的多孔膜

非水氧化还原液流电池（RFB）受到了广泛的研究兴趣，但是缺乏有前途的隔板和先进的性能严重阻碍了非水RFB的发展。在这里，通过在具有梯度密度的多孔聚合物膜（Celgard）中原位合成金属有机骨架（MOF），设计了一种对非水RFB具有增强选择性的坚固而灵活的膜。活性物种的交叉由于减小的有效孔径而得以缓解，同时保持了较高的离子电导率，这归因于MOF的3D通道结构及其在膜中的梯度分布。具有MOF嵌入膜的Li /二茂铁RFB具有出色的高倍率性能和增强的循环稳定性。^-2，甚至在12 mA cm ^-2时也保持76％。此外，与原始的Celgard膜相比（每周期0.24％），通过使用复合膜可实现更低得多的容量衰减率（在300次循环中每循环0.09％）。演示的策略为合理设计和制造RFB筛分分离器提供了新的见识，并可以促进对MOF储能能力的进一步研究。