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

Abstract

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 (M w = 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 H 2 –O 2 and 1.04 W cm −2 in H 2 -air (CO 2 -free) at 80 °C. • IEC-controlled side-chain-type poly(aryl-co-aryl piperidinium)s is developed. • The effect of IECs on the performance of s-PDTP- x ionomers and AEMs is elucidated. • s-PDTP- x copolymers display excellent durability >1000 h in 1 M NaOH at 80 °C. • s-PDTP-based AEMFCs reach power densities of 1.04 W cm −2 in H 2 -air.