Microphase water control utilizing highly hydrophilic anion-exchange ionomers

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Anion-exchange membrane water electrolysis (AEMWE) is crucial for green hydrogen production.
• Dry-cathode operation in AEMWE simplifies systems but risks cathode drying and performance loss.
• Optimizing ionomer hydrophilicity is key to enhancing catalyst layer water management.

Purpose of the Study:

• To develop a novel three-dimensional (3D) ionomer for AEMWE.
• To improve water/gas management in the cathode catalyst layer.
• To enhance ion transport, device durability, and overall AEMWE performance.

Main Methods:

• Synthesis of a 3D ionomer integrating triptycene and bisphenol fluorene units with phenolic hydroxy groups.
• Characterization of ionomer properties: water uptake, hydroxide conductivity, and alkaline stability.
• Performance evaluation of the developed ionomer in an AEMWE device under operating conditions.

Main Results:

• The novel ionomer exhibits significantly enhanced water uptake (53.6% higher) and excellent hydroxide conductivity (188 mS cm⁻¹ at 80 °C).
• The ionomer demonstrates superior stability with <8% cation degradation after 1440 hours in alkaline conditions.
• AEMWE devices utilizing this ionomer achieved high performance (6.1 A cm⁻² at 2.0 V, 80 °C), outperforming commercial benchmarks.

Conclusions:

• The developed 3D ionomer effectively addresses cathode drying issues in AEMWE through enhanced hydrophilicity and water mobility.
• Molecular design integrating 3D architecture and hydrophilic modification is a viable strategy for advancing AEMWE technology.
• This research provides valuable insights for developing next-generation ionomers for efficient and durable green hydrogen production.