Toward more efficient fuel cells?
A very short report from the American Association for the Advancement of Science (AAAS), 'A cool fuel cell,' says that Spanish researchers have developed a new way to operate solid oxide fuel cells, which could potentially provide electricity on an industrial scale, at near room temperature. This new super-lattice material 'improves ionic conductivity near room temperature by a factor of almost 100 million.' Wow! As said one Oak Ridge National Laboratory (ORNL) researcher who characterized the material's structure, this represents 'a colossal increase in ionic conduction properties.' But read more...
The illustration on the left describes the behavior of this new material. "The molecular model of the ion-conducting material shows that numerous vacancies at the interface between the two layers create an open pathway through which ions can travel." (Credit for image and caption: ORNL, link to original version).
This new material has been created by Spanish researchers from the Grupo de Fisica de Materiales Complejos (Complex Materials Physics Group) at the Universidad Complutense de Madrid (UCM) and from the Escuela Técnica Superior de Ingenieros de Telecomunicaciones (ETSIT) at the Universidad Politécnica de Madrid (UPM).
The analysis of this material has been done with Oak Ridge National Laboratory (ORNL)'s 300 kilovolt Z-contrast scanning transmission electron microscope by the STEM Group of the Materials Science & Technology Division.
ORNL provided its own news release about this discovery, "ORNL researchers analyze material with 'colossal ionic conductivity'" (July 31, 2008). Here is an excerpt about what is solid oxide fuel cell (SOFC)technology. "Solid oxide fuel cell technology requires ion-conducting materials -- solid electrolytes -- that allow oxygen ions to travel from cathode to anode. However, existing materials have not provided atom-scale voids large enough to easily accommodate the path of a conducted ion, which is much bigger than, for example, an electron. 'The new layered material solves this problem by combining two materials with very different crystal structures. The mismatch triggers a distortion of the atomic arrangement at their interface and creates a pathway through which ions can easily travel,'" said Maria Varela del Arco of ORNL.
In a longer article published on August 2, 2008, Green Car Congress provides additional details. "The material could lead to more efficient and lower temperature solid oxide fuel cells (SOFCs), among other applications. SOFC technology requires ion-conducting materials -- solid electrolytes -- that allow oxygen ions to travel from cathode to anode. The conversion efficiency of chemical into electrical energy is limited by the transport of oxygen anions through the electrolyte. However, existing materials have not provided atom-scale voids large enough to easily accommodate the path of a conducted ion, which is much bigger than, for example, an electron."
This research work has been published in Science under the title "Colossal Ionic Conductivity at Interfaces of Epitaxial ZrO2:Y2O3/SrTiO3 Heterostructures" (Volume 321, Number 5889, Pages 676-680, August 1, 2008). Here is the beginning of the abstract. "The search for electrolyte materials with high oxygen conductivities is a key step toward reducing the operation temperature of fuel cells, which is currently above 700°C. We report a high lateral ionic conductivity, showing up to eight orders of magnitude enhancement near room temperature, in yttria-stabilized zirconia (YSZ)/strontium titanate epitaxial heterostructures."
I'm pretty sure that "eight orders of magnitude enhancement" for a physical process is quite unusual.
Sources: American Association for the Advancement of Science (AAAS), August 1, 2008; and various websites
You'll find related stories by following the links below.