Oxygen Ion Distribution in SOFC Cells, Successfully Visualized

Technology Brief Description:
A new technology developed this time uses the stable isotopes of oxygen (18O) as labeling elements, and further uses the SIMS (secondary ion mass spectrometry) for measuring a distribution of concentrations of oxygen stable isotopes (18O) at high resolution of the order of micrometers or smaller.

Reference is made to Figs. A to D (the uppermost drawings of HERE). A medium-temperature planar tubular cell stack (Figs. A and B) of a practical SOFC machine, which is operating at high temperature, was used. The stable isotopes of oxygen (18O) were introduced into the SOFC machine. And the fuel cell reaction took place. The cell stack was rapidly cooled down to normal temperature. In this state, a measurement was made of a concentration distribution of the oxygen stable isotopes in the solid electrolyte. As a result, active sites of oxygen ionizing reaction in the cell were visualized and specified (Figs. C and D).

The technology is capable of specifying portions in the electrodes and the electrolyte where oxygen ionization reaction activity is high, and further visualizing a concentration distribution associated with the oxygen ions (diffusion). Therefore, the technology will provide helpful instructions to designers of high performance electrode/electrolyte interfaces and contribute to elucidation of the deterioration mechanism.

Background Description:
As known, SOFC (solid oxide fuel cell) has advantageous features of high power generation efficiency, substantially eliminating the need of catalyst, and the like. And it has been known as the next generation fuel cell. In Japan, residential SOFC micro-CHP systems have been under demonstration test from 2007. Osaka gas, Toyota, Kyocera, etc. has substantially completed development of the same type of fuel cell system, and entered the demonstration test. "BlueGen" of Ceramic Fuel Cells Limited in Australia is well known for the SOFC micro-CHP system. The output power of BlueGen is 2 kW.
SOFC has the electrolyte consisting mainly of solid ceramics. In the SOFC, oxygen molecules (O2) are ionized into oxygen ions (O2-). The oxygen ions diffuse into the solid electrolyte, and then react with hydrogen to produce electricity. To enhance the performances of the SOFC, it is necessary to reduce reaction resistance associated with the oxygen ionization and the oxygen ion diffusion.

Motions of oxygen and oxygen ions have been estimated indirectly. A model of the electrode reaction mechanism was established. The model was placed in various conditions. Electrical signals produced from the model were measured. There are almost no technologies being capable of directly visualizing portions of the practical SOFC machine where oxygen ionization reaction activity is high and concentration distributions of oxygen ions associated with the diffusion of the oxygen ions.
For somewhat more detail, visit HERE.
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Ikuo Kawai & UNHCR
News: Sept. 23, 2010 -
1) Koydo says: Japanese prime minister Naoto Kan stated at the Millennium Development Goals summit, New York, that Japan pledges to contribute a total of 8.5 billion dollars to the U.N. for five years from now on: 5 billion dollars for anti-infectious disease measures, and 3.5 billion dollars for the spread of universal primary education.
2) Time says: U.N.: More Funds Pledged to Fight Poverty
(UNITED NATIONS) — A three-day summit to push global leaders to meet U.N. goals to significantly reduce poverty by 2015 wraps up Wednesday with new financial pledges from countries but no certainty there will be enough money and political commitment to meet the targets.
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