Cross-Linked Sulfonated Poly(arylene ether sulfone) Membrane Using Polymeric Cross-Linkers for Polymer Electrolyte...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Polymer electrolyte membrane fuel cells (PEMFCs) require stable membranes capable of operating under harsh conditions.
• Highly sulfonated polymers offer high proton conductivity but often suffer from poor mechanical stability.
• Developing cross-linked membranes is crucial for enhancing the durability and performance of PEMFCs.

Purpose of the Study:

• To prepare and characterize cross-linked membranes using highly sulfonated poly(arylene ether sulfone) (SPAES) and various polymeric cross-linkers.
• To investigate the effect of cross-linker hydrophilicity on the physicochemical properties and proton conductivity of the membranes.
• To evaluate the performance of membrane electrode assemblies (MEAs) fabricated with these novel membranes under high-temperature and low-humidity conditions.

Main Methods:

• In-situ casting and heating processes were employed to create cross-linked membranes.
• SPAES with a high degree of sulfonation was used as the polymer matrix.
• Polymeric cross-linkers with varying hydrophilicities were utilized to form cross-linked structures.
• Physicochemical properties, proton conductivity, and MEA performance were systematically evaluated.

Main Results:

• Cross-linked structures effectively stabilized the highly sulfonated SPAES membranes.
• Hydrophilic cross-linkers significantly improved membrane properties and maintained reasonable proton conductivity.
• An MEA utilizing a membrane with a hydrophilic polymeric cross-linker achieved a maximum power density of 176.4 mW cm⁻² at 120 °C and 40% RH.
• The developed membranes demonstrated outstanding cell performance under challenging operating conditions.

Conclusions:

• Facile in-situ cross-linking provides a viable route to enhance the stability of highly sulfonated SPAES membranes.
• The judicious selection of hydrophilic polymeric cross-linkers is key to optimizing membrane properties for high-performance PEMFCs.
• These cross-linked membranes show great promise for enabling efficient fuel cell operation at elevated temperatures and reduced humidity levels.