Membranes with precise control of selective layer are designed and prepared by adjusting diffusion of solvents. Combining experiments and theoretical calculations, the formation mechanism of ion conductive membranes prepared by a non‐solvent induced phase separation (NIPS) method is found to be related to internal diffusion flux of solvent to the non‐solvent bath and external diffusion flux of non‐solvent to the casting solution. By regulating the internal and external diffusion rates via a two‐step NIPS method, a series of polybenzimidazole (PBI) porous membranes with independently controlled thin selective skin layers and highly porous support layers are fabricated, which achieve a simultaneous improvement in ion selectivity and proton conductivity. A vanadium flow battery assembled with a PBI membrane demonstrates an energy efficiency of 80% at a current density of 220 mA cm⁻², which is the highest value among the reported PBI membranes. This provides a simple and effective way to fabricate membranes with well‐defined morphologies.

中文翻译：

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高功率密度液流电池具有由溶剂扩散控制的选择性层定义明确的膜

通过调节溶剂的扩散来设计和制备具有精确控制选择层的膜。结合实验和理论计算，发现通过非溶剂诱导相分离（NIPS）方法制备的离子导电膜的形成机理与溶剂向非溶剂浴的内部扩散通量和非溶剂溶液的外部扩散通量有关。浇铸溶液的溶剂。通过两步NIPS方法调节内部和外部扩散速率，制造了一系列具有独立控制的薄选择性表皮层和高度多孔支撑层的聚苯并咪唑（PBI）多孔膜，可同时提高离子选择性和质子电导率。^－2，是所报道的PBI膜中的最高值。这提供了一种简单有效的方法来制造具有明确形态的膜。