Impact of side-chains in poly(dibenzyl-co-terphenyl piperidinium) copolymers for anion exchange membrane fuel cells

Anion exchange membrane fuel cells (AEMFCs) have experienced rapid advancement in the past few years due to the discovery of high-performance AEMs and ionomers. Here, we report a series of side-chain-type poly(dibenzbeyl-co-terphenyl piperidinium) (s-PDTP) copolymers as ionomers and membranes for AEMFC applications. The features of aryl ether-free PDTP polymer backbone and pendent ammonium groups endow both high alkaline stability and excellent micromorphology to s-PDTP copolymers. These ion-exchange-capacity (IEC)-controlled s-PDTP membranes possess high OH− conductivity >120 mS cm−1 at 80 °C, reasonable molecular weight (Mw = 150–290 kDa), and excellent ex-situ durability in 1 M NaOH at 80 °C for 1000 h (∼90% conductivity remaining). For ionomer research, s-PDTP ionomers with moderate IEC (∼3.0 mmol g−1) and rational water uptake (∼200%) exhibit optimal AEMFC performance based on a PDTP membrane compared to high-IEC or low-IEC s-PDTP ionomers (>3.4 mmol g−1 or <2.4 mmol g−1). Based on Pt/C, s-PDTP-based AEMFCs reach a peak power density (PPD) of 1.47 W cm−2 in H2–O2 and 1.04 W cm−2 in H2-air (CO2-free) at 80 °C.