by Staff Writers
Vienna, Austria (SPX) Mar 30, 2017
Fuel cells use a simple chemical reaction, such as the combination of oxygen and hydrogen to form water, to generate electricity. The question of which is the best material to use when making ceramic fuel cells is not a straightforward one, however. New materials are required that act as a catalyst for the chemical reaction required with maximum efficiency, but that also last as long as possible without their properties changing.
Previous efforts to develop materials that fulfil these requirements have largely been based on trial and error. However, teams at TU Wien have now managed to find a way to make targeted alterations to the surface of fuel cells on an atomic scale and take measurements at the same time. As a result, it is now possible to explain important phenomena for the first time, including the reasons why strontium atoms are problematic and the fact that cobalt can be useful in a fuel cell.
The oxygen supply bottleneck
"The bottleneck within this whole process is the incorporation of oxygen at the cathode," explains Ghislain Rupp, from the research group led by Professor Jurgen Fleig at TU Wien's Institute of Chemical Technologies and Analytics. The team led by Professor Andreas Limbeck and based at the same institute was also involved in this research project.
Fuel cells need to be operated at extremely high temperatures, somewhere in the region of between 700 and 1000 degrees Celsius, in order to ensure that the oxygen is incorporated quickly enough. Researchers have long been trying to identify better cathode materials that will allow for the operating temperature to be reduced. "There are some well-known options that are of particular interest, including lanthanum strontium cobaltite, or LSC for short," explains Ghislain Rupp. The major problem in this case is that these materials do not remain stable in the long term. There is always a point at which the activity drops and the performance of the fuel cell dwindles. Until now, it has only been possible to guess at the precise reason for this.
Targeted surface alterations
"We use a laser pulse to vaporise various materials, which then accumulate in tiny volumes on the surface," explains Rupp. "This enables us to modify the composition of the cathode surface in small, precise doses, whilst also monitoring how this affects the resistance of the system."
The damaging effect of excessive strontium
These findings provide important information on how oxygen is fundamentally incorporated into materials such as LSC and which processes cause the performance of fuel cells to deteriorate. "This research has taken us a huge step closer to the technical use of LSC as a fuel cell material," Rupp believes. "What's more, our new method of investigation combining ultra-precise coating with electrical measurement is sure to find other important applications within the field of solid state ionics."
New Haven CT (SPX) Mar 23, 2017
Yale scientists have developed an ultra-thin coating material that has the potential to extend the life and improve the efficiency of lithium-sulfur batteries, one of the most promising areas of energy research today. In a study published online March 20 in the Proceedings of the National Academy of Sciences, researchers describe the new material - a dendrimer-graphene oxide composite film ... read more
Vienna University of Technology
Powering The World in the 21st Century at Energy-Daily.com
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