Durability and thermal cycling of Ni/YSZ cermet anodes for solid oxide fuel cells

ISSN： 0021-891X

Source： Journal of Applied Electrochemistry, Vol.30, Iss.2, 2000-02, pp. : 247-257

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Abstract

The long-term properties of Ni/yttria stabilized zirconia (YSZ) cermet anodes for solid oxide fuel cells were evaluated experimentally. A total of 13 anodes of three types based on two commercial NiO powders were examined. The durability was evaluated at temperatures of 850 ^∘C, 1000 ^∘C and 1050 ^∘C over 1300 to 2000 h at an anodic d.c. load of 300 mA cm^−2 in hydrogen with 1 to 3% water. The anode-related polarization resistance, R_P, was measured by impedance spectroscopy and found to be in the range of 0.05 to 0.7 Ω cm^2. After an initial stabilization period of up to 300 h, R_P varied linearly with time within the experimental uncertainty. At 1050 ^∘C no degradation was observed. At 1000 ^∘C a degradation rate of 10 mΩ cm^2 per 1000 h was found. The degradation rate was possibly higher at 850 ^∘C. A single anode was exposed to nine thermal cycles from 1000 to below 100 ^∘C at 100 ^∘C h^−1. An increase in R_P of about 30 mΩ cm^2 was observed over the first two cycles. For the following thermal cycles R_P was stable within the experimental uncertainty.