High-temperature polymer electrolyte fuel cells at their full potential

Bauhaus Luftfahrt analyzed the key technology advances and improvement potentials of HT-PEFCs. Their higher operating temperature, ranging from 120 °C to 200 °C, enables efficient heat dissipation and enhanced energy recovery, allowing a more effective and lighter thermal management system. Furthermore, operating at higher temperatures enhances reaction kinetics and improves tolerance toward contaminants (e. g. CO, H₂S).

Proton conduction is typically achieved via polybenzimidazole (PBI) polymer membrane doped with phosphoric acid (PA). This allows the use of dry gases, eliminating the need for a humidification system and thereby reducing the overall system weight and complexity. Although PBI-PA membranes offer great benefits, they encounter challenges such as acid leaching in the presence of liquid water and reduced mechanical strength caused by the excessive doping, which reduces the durability and the electrode power density.

Despite these drawbacks, significant advancements over the past decade have addressed these issues (e.g. membrane electrode assembly (MEA)), allowing operation over a wide range of conditions. This progress positions HT-PEFC as a promising candidate for powering next-generation aircraft.