Highly Durable Ether-Free Polyfluorene-Based Anion Exchange Membranes for Fuel Cell Applications

Area of Science:

• Polymer Chemistry
• Materials Science
• Electrochemistry

Background:

• Anion exchange membranes (AEMs) are crucial for alkaline fuel cells but often face challenges in achieving high conductivity, chemical stability, and dimensional integrity.
• Existing AEMs can suffer from degradation in alkaline environments and exhibit excessive swelling, limiting their performance and lifespan.

Purpose of the Study:

• To synthesize a novel, ether-free, durable polyfluorene (PF)-based AEM.
• To enhance the solubility, flexibility, conductivity, and stability of PF-based AEMs for alkaline fuel cell applications.

Main Methods:

• Suzuki cross-coupling reaction was employed to synthesize the novel polyfluorene.
• Alkyl groups were incorporated into the polymer backbone to improve membrane properties.
• The synthesized membrane was characterized for conductivity, alkaline stability, ion exchange capacity, swelling ratio, and mechanical properties.

Main Results:

• The novel ether-free PF-based AEM exhibited high ionic conductivity (80.44 mS cm^-1) and excellent alkaline stability in 2 M KOH at 80 °C.
• The membrane demonstrated a high ion exchange capacity (2.49 mequiv g^-1) with a low swelling ratio (9.4% at 80 °C), alongside excellent mechanical and dimensional stability.
• An H₂/O₂ single cell using this AEM achieved a maximum power density of 661 mW cm^-2 at 80 °C.

Conclusions:

• The developed ether-free polyfluorene AEM offers a promising alternative for high-performance alkaline fuel cells.
• The synthesis strategy provides a simple and effective route to AEMs with superior conductivity, mechanical strength, and stability.
• This research contributes to the advancement of materials for efficient and durable energy conversion technologies.