Researchers analyze material with 'colossal ionic conductivity'

Jul 31, 2008
Researchers analyze material with 'colossal ionic conductivity'
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. Image: Oak Ridge National Laboratory

A new material characterized at the Department of Energy's Oak Ridge National Laboratory could open a pathway toward more efficient fuel cells.

The material, a super-lattice developed by researchers in Spain, improves ionic conductivity near room temperature by a factor of almost 100 million, representing "a colossal increase in ionic conduction properties," said Maria Varela of ORNL's Materials Science and Technology Division, who characterized the material's structure with senior researcher Stephen Pennycook.

The paper, a collaboration between researchers at the Universities of Madrid and at ORNL, was published today in Science.

The analysis was done with ORNL's 300 kilovolt Z-contrast scanning transmission electron microscope, which can achieve aberration-corrected resolutions near 0.6 angstrom, until recently a world record. The direct images show the crystal structure that accounts for the material's conductivity.

"It is amazing," Varela said. "We can see the strained, yet still ordered, interface structure that opens up a wide pathway for ions to be conducted."

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," Varela said.

Other fuel cell materials force ions to travel through tight pathways with few spaces for the ions to occupy, slowing their progress. Rather than forcing the ions to jump from hole to hole, the new material has "lots of vacant spaces to be occupied," said Varela, so the ions can travel much more quickly.

Unlike previous fuel cell materials, which have to achieve high temperatures to conduct ions, the new material maintains ionic conductivity near room temperatures. High temperatures have been a major roadblock for developers of fuel cell technology.

The research team with Spain's Universidad Complutense de Madrid and Universidad Politécnica de Madrid produced the material and observed its outstanding conductivity properties, but the structural characteristics that enable the material to conduct ions so well were not known until the material was put under the ultra-high resolution microscopes at ORNL.

Source: Oak Ridge National Laboratory

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User comments : 5

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irjsi
3 / 5 (2) Jul 31, 2008
Bravo! Bravisimo ! ! !
Get the lattices into pilot
production facilities for cost/scale
evaluations and into fuel cells.
The World is Hungry for energy and motive
power.
Saludes Ustedes
Rogelio Stewart,
Phoenix AZ
Bruggeling
not rated yet Aug 01, 2008
Why isn't the title of this article : "Spanish scientists develop material with 'colossal ionic conductivity'" ?

I am a long time reader of this site and now and then I am a bit annoyed with the Anglo-American bias. There, I said it :)
earls
not rated yet Aug 01, 2008
There are two different parties. The Spanish that developed the material and the US (ORNL) that analyzed it. This article is geared towards the latter.

On the ORNL page there's an image of the superlattice: http://www.ornl.g...80731-02
Bruggeling
not rated yet Aug 01, 2008
With two thirds of the article describing the properties of the material we can safely say this is chauvinistic bias. But I suppose that is to be expected in view of the readership ?
Eco_R1
not rated yet Aug 04, 2008
whats the use, we will only get to see it in like a 100 years!!!