Poly(fluorene)‐Based Anion Exchange Membrane Demonstrating Excellent Durability at 1.5 A cm‒2 for 2400 h in Water Electrolyzers

The study reports that the poly(fluorene)-based PFAA-QA AEM with excellent mechanical properties, high alkaline and dimensional stability, and satisfactory OH⁻ conductivity. The PFAA-QA-based AEMWE demonstrated remarkable long-term durability at 1.5 A cm⁻² and 70 °C for 2400 h, surpassing the durability of most AEMWEs with a low voltage degradation rate (>29 mV kh⁻¹).

Abstract

Anion exchange membrane water electrolyzer (AEMWE) is a cost-effective alternative to proton exchange membrane water electrolyzer for green hydrogen production. However, AEMWE commercialization is hindered primarily by the lack of a reliable anion exchange membrane (AEM) for long-term cell durability. In this study, a poly(fluorene)-based PFAA-QA AEM is developed with a simple structure, exhibiting satisfactory OH⁻ conductivity (>174.6 mS cm⁻¹ at 80 °C), good mechanical properties (tensile strength >35 MPa and elongation at break >51%), and excellent alkaline stability (>2000 h in 3 m KOH at 80 °C). These characteristics allow PFAA-QA-based AEMWEs to demonstrate a high cell performance (3.95 A cm⁻² at 70 °C and 1.95 V) and long-term durability at high current densities (1.5 A cm⁻² for 2400 h at 70 °C). Therefore, the durability of these AEMWEs surpasses that of most AEMWEs with a low voltage decay rate (>29 mV kh⁻¹).