Zr-MOF-Enabled Controllable Ion Sieving and Proton Conductivity in Flow Battery Membrane |
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Authors: | Li Xin Dezhu Zhang Kai Qu Yuqin Lu Yixing Wang Kang Huang Zhaohui Wang Wanqin Jin Zhi Xu |
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Affiliation: | 1. State Key Laboratory of Materials-Oriented Chemical Engineering, National Engineering Research Center for Special Separation Membrane, College of Chemical Engineering, Nanjing Tech University, Nanjing, 211816 China;2. State Key Laboratory of Chemical Engineering, School of Chemical Engineering, East China University of Science and Technology, Shanghai, 200237 China |
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Abstract: | Membrane with ordered channels is the key to controlling ion sieving and proton conductivity in flow batteries. However, it remains a great challenge for finely controlling the nanochannels of polymeric membranes. Herein, two types of acid-stable Zr-metal organic framework (MOF-801 and MOF-808) with variable pore structures and channel properties are introduced as fillers into a non-fluorinated sulfonated poly (ether ether ketone) (SPEEK). The membrane incorporated with MOF-801 of a smaller triangular window (≈3.5 Å) successfully translates the molecular sieving property into the flow battery membrane, resulting in enhanced coulombic efficiency (98.5–99.2%) at 40–120 mA cm−2 compared with the pristine SPEEK membrane (97.1–98.5%). In contrast, more protophilic internal interconnected channels of MOF-808 yield faster proton highway, leading to a significant increase of voltage efficiency (93.7–84.1%) at 40–120 mA cm−2 compared with the pristine SPEEK membrane (91.7–78.9%). By regulating the ion sieving and proton conductivity, MOF-801/MOF-808 binary composite membrane exhibits synchronously improved performance in the vanadium redox flow battery system. The revealed structure–property relationship in the Zr-MOFs-based membranes provides a general guideline to design new proton exchange membranes with ordered channels for flow battery application. |
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Keywords: | flow batteries ion sieving membranes proton conductivity Zr-metal organic frameworks |
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