Processing of 8YSZ and CGO thin film electrolyte layers for intermediate- and low-temperature SOFCs

An extensive experimental investigation has been carried out in order to prepare novel thin film electrolytes for enhanced SOFCs. Methods of producing ultra-thin 8 mol% Y2O3-doped ZrO2 (8YSZ) electrolytes (<1 mu m) and thin 10 mol% Gd2O3-doped CeO2 (10CGO) electrolytes (similar to 1 mu m) are presented. The method deposits such thin dense films onto a highly porous anode substrate. As opposed to conventional powder deposition techniques, the method involves depositing a dispersion of nanoparticles to achieve a thin-film mesoporous layer. After sintering at 1400 degrees C, the deposited mesoporous layer becomes a dense thin film with a thickness of similar to 1 mu m or even thinner. Such thicknesses are significantly below the limit currently achievable with powder deposition techniques (similar to 10 mu m). The electrolyte layer thickness is comparable to the thicknesses found in micro-SOFCs, but here conventional macroporous SOFC substrates are used. Of considerable importance is the use of a spin-coating process, due to its simplicity and the potential ease of further scaling-up. Results from SEM and leakage tests confirmed that the thin-film electrolytes are homogeneous and have a low number of defects after sintering at 1400 degrees C. The average leak rate for air was 1-2 x 10(-5) mbarl s(-1) cm(-2) for the 8YSZ electrolyte and 10(-4) mbarls(-1) cm(-2) for the 10CGO electrolyte. (C) 2014 Elsevier Ltd. All rights reserved.