Four-arm star-shaped high-performance poly(aryl piperidine) anion exchange membranes for fuel cells

Abstract

Anion exchange membrane fuel cells (AEMFCs) are a new generation of energy conversion technology that excels proton exchange membrane fuel cells in terms of oxygen reduction kinetics. The development of high-performance and durable anion exchange membranes (AEMs) has been a top priority for AEMFCs. In this work, we design and fabricate a novel series of AEMs by co-polymerizing tetraphenylmethane with 1-methyl-4-piperidone and p-terphenyl and subsequent quaternization of the resulting polymer. This strategy creates four-arm star shaped polymer components in the fabricated AEMs so that the polymer chain packing density is lowered, creating a high fraction of free volume in the membrane, which can help build ion channels with lower OH⁻ transport resistance. The resulting qPTTP-7 AEM shows a markedly improved ion conductivity (142.71 mS cm⁻¹ at 80 °C). After 1000, 2000 and 3000 h treatments in 1 M NaOH at 80 °C, the membrane showed an ion conductivity retention rate of 98%, 93% and 86%, respectively. With such an AEM, the H₂–O₂ single cell yields a peak power density of 1.37 W cm⁻² at 80 °C, and the fuel cell can operate at a constant current over 150 h without much voltage decay.