Branched, Side-Chain Grafted Polyarylpiperidine Anion Exchange Membranes for Fuel Cell Application

Anion exchange membrane (AEM) is the heart of alkali electrolyte membrane fuel cells (AEMFCs). To achieve high performance of AEMFC, high conductivity and alkaline stability of AEMs are highly desired. In the present work, we report the synthesis of ether-free polymers with different degrees of Y-shaped branching as AEM materials. Our investigations reveal that incorporating bulky, rigid, and Y-branching units into the polymer backbone can increase the free volume of the AEM and thus help build ion channels with lower hydroxide ion transport resistance. The resultant AEM showed a markedly improved ionic conductivity (116.92 mS/cm at 80 °C), while the simple linear type of the AEM only showed an ion conductivity of 63.63 mS/cm at a similar ion exchange capacity. With such an AEM, the peak power density of the H2/O2 single cell at 60 °C reaches 275 mW/cm2.