High-performance poly(fluorenyl aryl piperidinium)-based anion exchange membrane fuel cells with realistic hydrogen supply

Anion exchange membrane fuel cells (AEMFCs) have advanced rapidly in the past four years, while the majority of the state-of-the-art AEMFCs relies on unrealistic and uneconomical operating conditions, particularly a high hydrogen flow rate (>1000 mL min−1). Here, we report a poly(fluorenyl aryl piperidinium) (PFAP) ionomer that enables high power of AEMFC with low hydrogen flow rate (≤100 mL min−1 for 5 cm2 cell). The high water permeability of the ionomer is beneficial to prevent anode flooding under moderate relative humidity. The relationship between hydrogen flow rate and limiting current density is revealed based on PFAP copolymers. Specifically, the peak power density of AEMFC is 1.77 W cm−2 with a H2 flow rate of 75 mL min−1, retaining >70% power density from the H2 flow rate of 1000 mL min−1 (2.42 W cm−2). Importantly, the present AEMFCs display much higher hydrogen utilization efficiency above 90% and hydrogen fuel power (∼30 W cm−2 L−1) than previously reported AEMFCs (<30% and 0.4–3.5 W cm−2 L−1). Moreover, the present AEMFCs show stable cell performance with a low hydrogen flow rate at 70 °C for >110 h.