Sulfonated Microporous Polyxanthene Binder for High-Temperature Hydrogen Fuel Cells.

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• High-temperature proton exchange membrane fuel cells (HT-PEMFCs) using phosphoric acid-doped polybenzimidazole (PBI) suffer from low power output and platinum (Pt) utilization.
• This is largely attributed to limitations in electrode binder materials, affecting ionomer stability and reactant transport.

Purpose of the Study:

• To develop and evaluate a novel electrode binder material for HT-PEMFCs.
• To improve Pt utilization and overall cell performance at elevated temperatures.

Main Methods:

• Synthesis of a sulfonated microporous polymer, sulfonated polyxanthene (SPX).
• Characterization of SPX for chemical stability and structural properties.
• Fabrication and testing of HT-PEMFCs utilizing SPX as an electrode binder at 180 °C.

Main Results:

• SPX exhibits excellent chemical stability and a rigid, contorted structure.
• The SPX binder effectively reduces ionomer adsorption on Pt catalysts and minimizes phosphoric acid loss.
• SPX facilitates rapid transport of reactant gases and water within the catalyst layer.
• Fuel cells with SPX binders achieved a Pt utilization of 42.51% and a peak power density of 805 mW cm⁻² at 180 °C.

Conclusions:

• Sulfonated polyxanthene (SPX) is a superior electrode binder for HT-PEMFCs compared to PBI.
• The unique properties of SPX significantly enhance catalyst utilization and power output in high-temperature fuel cell applications.
• SPX offers a promising solution for overcoming performance bottlenecks in PBI-based HT-PEMFCs.