Current induced degradation of the La0.85Sr0.15MnO3+/YSZ8 and Pt/YSZ8 interfaces

Electrochemical reduction of oxygen by the use of both a cone shaped La0.85Sr0.15MnO3+δ electrode and Platinum electrodes together with the solid electrolyte YSZ8, induced significant changes in the materials. The cone was after use no longer homogenous (EDX analysis in figure), and the cone top hat lost material – a crater was formed(figur). The concentration of manganese were higher and the concentration of the strontium lower than the starting composition. The variation in the relative elements contents penetrated 0.5mm into the cone. The structure of the electrolyte was also changed (figur). On the surface of the YSZ material was accumulated in a brown/red ring. EDX analysis showed that the outer and inner parts of the ring contained significant amounts of manganese (figure). The current induces changes in the surface structure of platinum electrodes where studied in at typical 3 electrode set-up with three identical Pt-electrodes. The cathode was polarized –0.1V at 1000oC in air in 85 days. The current through the anode and cathode was measured and is displayed in figure (). The current increased the first 50 days, where after is became approximately constant. Inspection showed that the contact area of the cathode with the electrolyte had developed into a depression in the cathode. The area of the surface was increased by the formation of a “sponge structure”. The contact area of the anode was not changed much but electrolyte was bound to the middle of the area. The bounded electrolyte had a porous structure. The contact area of the reference electrode were plane, and showed very little changes. The findings indicates that bonding between the electrode and electrolytes is enhanced by the current and a cationionic transport takes place.