
352 Electrochemically Enabled Sustainability
membranes need to complete the current circuit by transferring ions. A high
ion conductivity is required to minimise the ohmic losses and increase/
maintain the voltage efciency (VE); (b) High ion selectivity: these mem-
branes should possess low permeation rates of active species to minimise
self-discharge induced by side reactions; and (c) Good chemical stability or
sustainability to ensure the cycle life of a battery.
The membranes traditionally used in VFBs are peruorinated sulphonic acid
polymers such as Dupont’s Naon
®
, which consists of a exible hydrophobic
peruorinated backbone and a side ...