Synthesis of NAFION precursor monomer (blue box with vinyl ether on one end, -SO2F precursor functional group on the other). Copolymerization with 6 moles of CF2=CF2 (TFE).
Electric current is carried through the NAFION* membrane by Na+ ions. At the cathode, water is split into OH- ions (they combine with Na+ -> NaOH) and hydrogen by the addition of electrons. At the anode, Cl- ions are discharged -> chlorine.
Exploded view of a PEM fuel cell using a NAFION membrane as the electrolyte (same function as the sulfuric acid in a car battery : Allows flow of H+ ions, but not electrons). Electrons travel through the external circuit providing power.