Highly stable microtubular cells for portable solid oxide fuel cell applications

Abstract

In this work, extruded support tubes based on Nickel Oxide-YSZ (yttria stabilized-zirconia) were manufactured by Powder Extrusion Moulding (PEM). An YSZ layer is then deposited by dip coating as the electrolyte and subsequently, standard La0.8Sr0.2MnO3-δ (LSM)/YSZ composites were deposited by dip coating as oxygen electrodes. Microstructure of the anode support was optimized in order to achieve the maximum fuel utilization and as a consequence, a high performance of the cells. Experiments as a function of the fuel composition showed power densities above 500 mWcm−2 at 800°C at 0.7V, with high fuel utilization (∼75%). Long-term durability studies were also performed for a period above 1000hours. The experiment was conducted at 800°C using pure humidified hydrogen at a fixed voltage of 0.8V. It was observed that the current density of the cell is significantly evolving during the initial period of about 100hours, as a consequence of reconditioning of nickel particles at the anode support. Once the system is stabilized, no degradation was observed up to 1000hours under operating conditions, obtaining current densities in the range of 400 mAcm−2 at 0.8V and 800°C.