Electrochemical Performance of Ni-CGO Nano-Grained Thin Film Anodes for Micro SOFCs

NiO-Ce0.8Gd0.2O1.9-x (CGO) thin film anodes with thicknesses around 400 nm were prepared by air blast spray pyrolysis. The film composition was 60/40 vol% Ni/CGO in the reduced state. The films were deposited on tape-cast YSZ electrolytes. The material was amorphous after deposition and was crystallized by sintering in air between 650 and 1200 degrees C. The temperature treatment resulted in films with average grain sizes of the NiO and CGO grains between 5 and 250 nm. The area specific resistance of the thin film anodes was measured in a humidified 1:4 H-2:N-2 atmosphere as a function of grain size within the temperature interval of 400-600 degrees C. The area specific resistance (ASR) was predominantly depending on the grain size of the films. At 550 degrees C, an ASR of 0.5 Omega cm(2) was found for the 5 nm grain size anode. The value increased to 30 Omega cm(2) for the 250 nm grain size anode.