Low Pt loading for high-performance fuel cell electrodes enabled by hydrogen-bonding microporous polymer binders

Area of Science:

• Electrochemistry
• Materials Science
• Polymer Chemistry

Background:

• High platinum (Pt) loading is a major challenge in phosphoric acid doped polybenzimidazole fuel cells.
• Poor electrode performance stems from limited mass transport and platinum poisoning due to acid absorption.

Purpose of the Study:

• To design and synthesize effective catalyst binders to address low electrode performance and high Pt loading.
• To improve phosphoric acid management within the fuel cell electrodes.

Main Methods:

• Development of polymers of intrinsic microporosity (PIMs) with strong hydrogen-bonding functionalities.
• Synthesis of tetrazole functionalized PIM binders to enhance phosphoric acid binding energy.
• Fabrication and testing of H2-O2 fuel cells utilizing the novel binder.

Main Results:

• The tetrazole functionalized PIM binder effectively upholds phosphoric acid near Pt catalyst particles, mitigating acid adsorption.
• Improved mass transport and reduced platinum poisoning were observed.
• The fuel cell achieved a high Pt-mass specific peak power density of 3.8 W mgPt-1 at 160°C.

Conclusions:

• The developed PIM-based catalyst binder significantly enhances fuel cell performance.
• Low platinum loading (0.15 mgPt cm-2) is achievable with superior power density.
• This approach offers a promising strategy for cost-effective and efficient high-temperature fuel cells.