Fabrication, electrochemical characterization and thermal cycling of anode supported microtubular solid oxide fuel cells

This work describes the manufacture and electrochemical characterization of anode supported microtubular SOFC's (solid oxide fuel cells). The cells consist of a Ni-YSZ anode tube of 400 mu m wall-thickness and 2.4 mm inner diameter, a YSZ electrolyte of 15-20 mu m thickness and a LSM-YSZ cathode. The microtubular anode supporting tubes were prepared by cold isostatic pressing. The deposition of thin layers of electrolyte and cathode are made by spray coating and dip coating respectively. The cells were electrochemically characterized with polarization curves and complex impedance measurements using 5% H-2/95% Ar and 100% of H-2, humidified at 3% as reactant gas in the anodic compartment and air in the cathodic one at temperatures between 750 and 900 degrees C. The complex impedance measurements show an overall resistance from 1 to 0.42 Omega cm(2) at temperatures between 750 and 900 degrees C with polarization of 200 mA cm(-2). The I-V measurements show maximum power densities of 0.3-0.7 W cm(-2) in the same temperature interval, using pure H-2 humidified at 3%. Deterioration in the cathode performance for thin cathodes and high sintering temperatures was observed. They were associated to manganese losses. The cell performance did not present considerable degradation at least after 20 fast shut-down and heating thermal cycles. (C) 2008 Elsevier B.V. All rights reserved.