Preparation of an Anion Exchange Membrane by Pyridine-Functionalized Polyether Ether Ketone To Improve Alkali Resistance Stability for an Alkali Fuel Cell

A highly stable anion exchange membrane (AEM) is constructed by linking bipyridine to a polyetheretherketone (PEEK) polymer. First, PEEK is prepared by the polycondensation reaction; N-bromosuccinimide and benzoyl peroxide are used for the bromination reaction; and then pyridine or 4,4'-bipyridine is connected to PEEK by the Friedel-Crafts alkylation reaction. The successful preparation of the target product was confirmed by the collaborative analysis of the Fourier transform infrared spectrum and H-1 nuclear magnetic resonance spectrum. The ionic conductivity test showed that the highest hydroxide conductivity of PyBPEEK-50% and BiPyBPEEK-50% at 80 degrees C reached 36.99 and 32.05 mS cm(-1), respectively, which proved that they can meet the basic requirements. The alkali stability test showed that the ionic conductivity of the membrane could still reach 88.46% after 750 h of immersion in 1 M NaOH at room temperature, which proved that the cross-linking structure composed of 4,4'-bipyridine effectively weakened the attack of OH- on AEMs. In addition, the cross-linked structure effectively balances the loss of mechanical properties as a result of water absorption and membrane swelling. The swelling rate of BiPyBPEEK-50% at 80 degrees C is only 4.4%, and the tensile strength can reach 66 MPa. Therefore, to avoid the introduction of too many uncontrollable factors in the complicated synthesis process, this work used a simple method to synthesize AEMs based on the bipyridine cross-linked structure and compared its performance gains and losses through non-cross-linked membranes. The potential application value of this method in the field of fuel cells is verified.

Automated summary

A highly stable anion exchange membrane (AEM) was constructed by linking bipyridine to a polyetheretherketone (PEEK) polymer, showing excellent ion conductivity and alkali stability. The cross-linking structure composed of 4,4'-bipyridine effectively weakened the attack of OH- on AEMs. Using a simple method to synthesize AEMs effectively balanced the loss of mechanical properties caused by water absorption and membrane swelling.