Electrochemical Performance of Ni-CGO Nano-Grained Thin Film Anodes for Micro SOFCs U. P. Muecke a , K. Akiba a , T. Salkus b , N. Stus c and L. J. Gauckler a a ETH Zurich, Department of Materials, Nonmetallic Inorganic Materials Wolfgang-Pauli-Str. 10, 8093 Zurich, Switzerland b Faculty of Physics, Vilnius University, Saulėtekio al. 9/3, LT-10222 Vilnius, Lithuania c Department of Chemistry, Kyiv National Taras Shevchenko University 64 Volodymyrska str., 01033 Kyiv, Ukraine NiO-Ce 0.8 Gd 0.2 O 1.9-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°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°C. The area specific resistance (ASR) was predominantly depending on the grain size of the films. At 550°C, an ASR of 0.5 Ωcm 2 was found for the 5 nm grain size anode. The value increased to 30 Ωcm 2 for the 250 nm grain size anode. Introduction Miniaturized solid oxide fuel cells (µ-SOFCs) operating at temperatures of 400- 600°C are currently under investigation for battery replacement in portable electronic devices (1, 2). Thin film deposition methods such as sol-gel (3), sputtering (4), spray pyrolysis (5) or pulsed laser deposition (6) can be used for the preparation of the anode, electrolyte or cathode layers. The thicknesses of the individual layers are usually below one micrometer, reducing the ohmic resistance of the cell and compensating for the reduced conductivities at lower temperatures. Thin film electrolytes (7, 8) and cathodes (9) have already been studied for use in traditional SOFCs or as model electrodes, respectively. However, little is known about the microstructure and electrochemical performance of thin film anodes with grain sizes in the nanometer range. The aim of this paper was therefore to study the polarization resistance of nanocrystalline Ni-CGO thin film cermets as a function of grain size. Experimental NiO-CGO thin films with a thickness of 400 nm were prepared by air blast spray pyrolysis. Spray-pyrolyzed films are generally amorphous after deposition (10) and can be crystallized in a post-deposition annealing step. The average grain sizes after sintering ECS Transactions, 7 (1) 1617-1621 (2007) 10.1149/1.2729269, ©The Electrochemical Society 1617 Downloaded 16 Feb 2012 to 152.88.98.107. Redistribution subject to ECS license or copyright; see http://www.ecsdl.org/terms_use.jsp