Poly (phthalazinone ether ketone) anion exchange membranes with pyridinium groups as ion exchange groups for vanadium redox flow battery

Poly(phthalazinone ether ketone) anion exchange membranes with pyridinium groups (PyBPPEK) as ion exchange groups for vanadium redox flow battery were prepared from poly(phthalazinone ether ketone) containing bromomethyl groups and pyridine. FTIR were used to confirm the chemical structure of PyBPPEK. The thermal stability of PyBPPEK membranes were tested by using TGA analysis. PyBPPEK membranes exhibited tensile strength higher than 50 MPa and elongation at break higher than 25%. Columbic efficiencies of VRB with PyBPPEK membrane were higher than that of VRB with Nafion117 membrane. The energy efficiency of VRB with PyBPPEK membrane reached 89.7% at a charge-discharge current density of 40 mA·cm^-2 while the energy efficiency of VRB with Nafion117 membrane was 86.0% at the same current density. When the ion exchange capacity of PyBPPEK membrane was 1.50 mmol·g^-1, columbic efficiencies and energy efficiencies of VRB with the PyBPPEK membrane were higher than those of VRB with Nafion117 membrane at charge-discharge current densities ranging from 20 mA·cm^-2 to 60 mA·cm^-2. The results suggested that PyBPPEK membranes could be potential membranes for VRB applications.