High ion selectivity Aquivion-based hybrid membranes for all vanadium redox flow battery

Polymer based on norbornene was synthesized via ring-opening metathesis polymerization with norbornene possessed the advantages of easily modified molecular architectures, simple and controllable polymerization method, and great chemical stability. Novel Aquivion-based hybrid membranes were prepared by introducing polymer based on norbornene to Aquivion ionomers with short side chain. The resistance of Aquivion/PAN-10% hybrid membrane was the lowest among them due to the formation of hydrogen bonds between “acid-base” pairs. At the same time, all Aquivion-based hybrid membranes in this work possess excellent VO 2+ permeability owing to the ionic crosslinking and Donnan effect. The Aquivion/PAN-2.5% hybrid membranes can still last for 31 h above 0.8 V because of the low VO 2+ permeability. And Aquivion/PAN-2.5% hybrid membranes also exhibited more excellent Coulombic efficiency than Aquivion/PAN-5% hybrid membranes and Aquivion/PAN-10% hybrid membranes. The voltage efficiency of Aquivion/PAN-10% hybrid membranes was higher than that of Aquivion/PAN-2.5%. Aquivion/PAN-2.5% possesses an energy efficiency of 73.02% at the current density of 160 mA·cm −2 . Graphical abstract The Aquivion-based hybrid membranes possess excellent ion conductivity due to the formation of hydrogen bonds between “acid-base” pairs and low VO 2+ permeability owing to the ionic crosslinking and Donnan effect.