High performance membranes based on pyridine containing poly (aryl ether ketone ketone) for vanadium redox flow battery applications

Abstract This reported study describes an effort to produce durable membranes for high performance vanadium redox flow batteries (VRFB). The reported novel, positively-charged membranes are derived from pyridine-containing poly(aryl ether ketone ketone) (PyPEKK) and are prepared using an environmentally-friendly method. Basic pyridine groups on the polymer backbone serve as proton acceptor sites and these electron-rich, polar sites establish proton transport channels, which provide PyPEKK membranes with an area resistance as low as 0.15 Ω cm2, which is comparable to Nafion 212 (0.13 Ω cm2). The novel PyPEKK membranes have low vanadium permeability due to the Donnan repulsion between the positively charged protonated pyridine groups and the vanadium ions. Consequently, the resulting dense structure of these PyPEKK membranes produce an impressive energy efficiency in VRFB (89.0% at 80 mA cm−2, and 80.1% at 180 mA cm−2). The PyPEKK membrane exhibit stable performance of 1000 cycles and low oxidation. These PyPEKK membranes are highly promising candidates for VRFB application.