Anode Characterization and SOFC Performance using Ni-YSZ Anodes Formed by Ni Impregnation Methods

Abstract

Impregnation technique has been used to load Ni on to a preformed porous anode matrix. Button cells with YSZ electrolyte and porous anode matrix (YSZ) have been fabricated by tape casting technique. Performance curves for a cell with 4.25 volume % Ni-YSZ anode, showed that power density increased with temperature and attained a maximum of 30.87mW/cm2 at 900oC, which is low when compared to conventional cells, which have more than 30 volume % Ni incorporated in them. Electrical conductivities of 155 S/cm and 14.7 S/cm were observed at 10.48 and 4.85 volume % Ni loadings respectively which are comparable to values obtained in literature on 30 Vol% NiO-YSZ prepared by ceramic mixing process. One of the reasons for low cell performance is that Ni film formed at such low loadings undergoes sintering and loses connectivity at the operational temperatures. This was revealed by temperature programmed conductivity studies. At loadings above 5%, the Ni film is stable and as such may be considered as anodes for SOFC's.