Tremendous efforts have been dedicated to developing sustainable and affordable ion exchange membranes for flow batteries. Challenges remain in terms of high cost, low coulombic efficiency caused by the crossover of active species, and stability. Inspired by the highly hydrophilic and interconnected 3D networks of nanofibers of bacterial cellulose (BC), an unprecedented ion exchange membrane possessing high ionic selectivity is created by impregnating a hydrophobic copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) into BC aerogel scaffolds. The high proton conductivity of the membrane stems from the intrinsically high hydrophilic network of the BC fibrils, which offers a percolated pathway for the proton conduction. At the same time, the selectivity arises from the hydrophobic lamination on the BC scaffold that acts as a barrier for the migration of vanadium ions and reduces its crossover. Therefore, the hydrophilic ion transport paths of BC inside of a stable PVDF-HFP matrix result in a high proton conductivity of 0.0095 S cm⁻¹ at 25 °C and a significantly less vanadium permeation rate. Besides, the membrane yields a high tensile strength of 114 MPa and excellent thermal stability. Moreover, vanadium redox flow battery assembled using the BC/PVDF-HFP membrane demonstrated cyclings for 300 continuous cycles at a constant current density of 100 mA cm⁻² and achieved an average coulombic efficiency of 97.56%, voltage efficiency of 81.56%, and energy efficiency of 79.49%. The higher CE, and, therefore, energy efficiency of the BC/PVDF-HFP membrane than those of the Nafion 115 can be attributed to the natural percolated 3D networks of BC.

致力于开发可持续且价格合理的液流电池离子交换膜。挑战仍然在于高成本，因活性物种交叉而导致的库仑效率低以及稳定性。受到细菌纤维素（BC）纳米纤维的高度亲水性和相互连接的3D网络的启发，通过将疏水性共聚物聚偏二氟乙烯-共六氟丙烯（PVDF-HFP）浸渍到BC中，创造了一种具有高离子选择性的前所未有的离子交换膜。气凝胶支架。膜的高质子传导性源于BC原纤维的固有的高亲水性网络，该网络为质子传导提供了渗透的途径。同时，选择性来自BC支架上的疏水性层压，该疏水性层压充当了钒离子迁移的屏障，并减少了其交叉。因此，在稳定的PVDF-HFP基质内部，BC的亲水离子传输路径导致质子电导率为0.0095 S cm在25°C时为^-1，钒的渗透速率明显更低。此外，该膜还具有114 MPa的高拉伸强度和出色的热稳定性。此外，使用BC / PVDF-HFP膜组装的钒氧化还原液流电池在100 mA cm ^-2的恒定电流密度下显示了300个连续循环，并实现了97.56％的平均库仑效率，81.56％的电压效率和能量。效率为79.49％。与Nafion 115相比，BC / PVDF-HFP膜具有更高的CE，从而具有更高的能效，这可归因于BC的自然渗透3D网络。