A comparative study of Nafion series membranes for vanadium redox flow batteries

In this study, a series of the commercial Nafion membranes (equivalent weight of 1100gmol−1) with thickness of 50μm (Nafion 112), 88μm (Nafion 1135), 125μm (Nafion 115), and 175μm (Nafion 117) are selected to investigate the thickness impact of Nafion on the performance of vanadium redox flow battery (VRFB). VRFBs are evaluated at a broad current density range from 40 to 320mAcm−2. The self-discharge process, cell efficiencies, electrolyte utilization, and long-term cycling stability of VRFBs based on various Nafion membranes are compared comprehensively. Owing to the good balance between vanadium ions permeability and membrane resistance, Nafion 115 membrane presents the highest energy efficiency and electrolytes utilization at current density from 120 to 240mAcm−2. A simple and powerful online monitoring system is developed to monitor the electrolyte imbalance process during the cycle-life test of VRFB. The capacity fading mechanism of VRFBs with different Nafion membranes is also discussed. [Display omitted] •Nafion 112, 1135, 115 and 117 membranes are evaluated for VRFB application.•VRFBs with various Nafion membranes are tested at current density of 40–320mAcm−2.•Nafion 115 presents the highest EE and electrolyte utilization at 120–240mAcm−2.•An online monitoring system is developed to record the electrolyte imbalance process.