A chemical diffusion-controlled electrode reaction at the compact La{sub 1{minus}x}Sr{sub x}MnO{sub 3}/stabilized zirconia interface in oxygen atmospheres
- Tohoku Univ., Sendai (Japan). Research Inst. for Scientific Measurements
- Yokohama National Univ. (Japan). Inst. of Environmental Science and Technology
solid oxide fuel cells (SOFCs) are now considered to be one of the most promising systems of highly efficient conversion of fossil energy resources. Most types of SOFCs under development are composed of single cells with stabilized or partially stabilized zirconia (SZ) as the electrolyte, porous nickel-SZ cermet exposed to fuel gas as the anode, and porous perovskite-type La{sub 1{minus}x}Sr(CA){sub x}MnO{sub 3{minus}d} exposed in air or oxygen as the cathode. In order to elucidate how the oxide-ion electron mixed conduction in an oxide cathode affects the kinetics of the cathode reaction in solid oxide fuel cells, a compact La{sub 0.63}Sr{sub 0.27}MnO{sub 3} layer was prepared as a working electrode on the electrolyte of 3 mole percent Y{sub 2}O{sub 3} doped ZrO{sub 2} by a laser flash evaporation method, and electrochemical measurements were made as a function of oxygen partial pressures, P(O{sub 2}), at 700 to 900 C. Contrary to the case of a porous electrode system, the electrode interface conductivity was found to increase with decreasing P(O{sub 2}). With large anodic polarization, the oxide layer was found to be peeled off by oxygen evolution at the electrode/stabilized zirconia interface. The kinetics controlled by chemical diffusion of oxygen in the oxide layer were observed under cathodic polarization with P(O{sub 2}) < 10{sup 4} Pa at 900 C. The oxide ion conductivity in La{sub 0.63}Sr{sub 0.27}MnO{sub 3} was found to be proportional to a{sub O}{sup {minus}1/2}, where a{sub O} is the oxygen activity in the oxide.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 404653
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 10 Vol. 143; ISSN 0013-4651; ISSN JESOAN
- Country of Publication:
- United States
- Language:
- English
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