How can fuel cells be made more efficient and longer-lasting – and what role does a membrane just a few micrometers thick play? This question is addressed by a recent study* conducted by the University of Duisburg-Essen and the Center for Fuel Cell Technology (ZBT). The study was led by nanoscientists around Dr. Fatih Özcan. Using a newly developed method, the team was able to systematically analyze membrane effects for the first time. The results were published in the journal Energy Advances.
Fuel cells are considered a key technology for a climate-neutral energy supply. One particularly important type is the proton exchange membrane fuel cell (PEMFC). These devices convert hydrogen into electricity efficiently and could play a major role, especially in transportation and stationary energy systems. Inside a PEMFC, a thin polymer membrane ensures that only protons can pass through, while electrons flow externally, generating electric current. The properties of this essential membrane largely determine performance, efficiency, and durability.
Until now, it has been difficult to isolate the membrane’s specific impact, as many processes overlap in real systems. The team led by Dr. Fatih Özcan from the Chair of Particle Technology (Prof. Doris Segets) at the University of Duisburg-Essen (UDE), together with other researchers from UDE and ZBT, therefore developed a new approach: instead of analyzing the entire fuel cell, they focused specifically on the cathode in a simplified test setup. This made it possible to clearly isolate the membrane’s influence.
The researchers examined membranes of different thicknesses and chemical compositions, as well as a reference system without a membrane. Using electrochemical measurement techniques, they were able for the first time to identify and separate the causes of performance losses – including electrical resistance, reaction kinetics, and mass transport.
“Our results show that the membrane introduces additional resistances into the system and significantly affects performance,” explains doctoral researcher and first author Yawen Zhu. “What surprised us, however, is that most of this additional electrical resistance is not caused by membrane thickness, but by its mere presence – more precisely, by the contact interfaces between the membrane and the electrode.”
Membrane thickness primarily affects the speed of electrochemical reactions: the thicker the membrane, the slower the reactions proceed. “Transport losses, on the other hand, are more strongly determined by the chemical structure of the material,” says Dr. Fatih Özcan, senior author of the study. “Our research shows that membranes are far more than passive components. They also provide important insights for developing more efficient and durable fuel cells.”
* The study is part of the R2R-CCM project, funded from 2022 to 2024 by the Ministry of Economic Affairs, Industry, Climate Action and Energy of North Rhine-Westphalia. Researchers involved in the study published in Energy Advances include members of the Chair of Particle Technology at the Institute for Energy and Material Processes, the Center for Nanointegration (CENIDE), the Interdisciplinary Center for Analytics on the Nanoscale (ICAN), and the Center for Fuel Cell Technology (ZBT).