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DOE OSTI · 1569264

Self-regulating surface chemistry for more robust highly durable solid oxide fuel cell cathodes

Nicollet, Clement·Tuller, Harry
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Abstract

In this project we explored the possibility of mitigating silicon poisoning of Pr doped ceria (PCO) electrodes for oxygen reduction in SOFC. The approach was to dope PCO with various amount of lanthanum and study the new compositions in terms of their mixed conduction properties, their oxygen surface exchange kinetics, as well as their resistance to silicon poisoning. The effects of lanthanum doping on the transport properties and oxygen exchange kinetics of La x (Ce 0.9 Pr 0.1 ) 1-x O 2-δ (x=0, 0.1 and 0.2) have been investigated by electrical conductivity on bulk samples and optical relaxation on thin films respectively. Lanthanum substitution was observed to increase the magnitude of ionic conductivity to values comparable to that of single substituted La x Ce 1-x O 2-δ , with a maximum for a La content of x = 0.1, reaching σ = 9.5×10 -3 S·cm -1 at 600 °C and a decrease in activation energy from ≈ 1 eV for Ce 0.9 Pr 0.1 O 2-δ down to ≈ 0.75 eV for the lanthanum substituted compositions. At the same time, a significant electronic contribution to the total conductivity, estimated to be on the order of 10%, supports significant mixed ionic-electronic conductivity.

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Nicollet, Clement, Tuller, Harry. 2019-10-04. Self-regulating surface chemistry for more robust highly durable solid oxide fuel cell cathodes. https://doi.org/10.2172/1569264

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