Structure/performance relations for Ni/yttria-stabilized zirconia anodes for solid oxide fuel cells
The relations between morphology and electrochemical performance of Ni/yttria-stabilized zirconia (YSZ) anodes are investigated. Four types of anodes are prepared on YSZ electrolyte three-electrode pellets. A fine cermet of 0.5--1 {micro}m particles, a coarse cermet of 2--3 {micro}m particles, a porous Ni-paste anode, and a Ni-felt anode. The anodes are characterized by impedance spectroscopy at open-circuit potential, and the electrode relevant part (polarization resistance, R{sub p}) of the spectra is identified and investigated. The active thickness of the fine cermet anode is demonstrated to be about 10 {micro}m and is believed to relate to the conductivity of the YSZ network. In the temperature range 850--1,000 C, R{sub p} exhibits an apparent activation energy which increases with coarseness of the anode. No significant dependence on {rho}{sub H{sub 2}} (0.01--0.97 atm) at 1,000 C is observed. A dependence on {rho}{sub H{sub 2}O} of about R{sub p} {proportional_to} {rho}{sub H{sub 2}O}{minus}1/2 is found. Physical transport limitations are suggested as possible causes for the observed anode polarization.
- Research Organization:
- Univ. of Waikato, Hamilton (NZ)
- OSTI ID:
- 20023336
- Journal Information:
- Journal of the Electrochemical Society, Vol. 147, Issue 2; Other Information: PBD: Feb 2000; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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