Insights Into the Fuel Oxidation Mechanism of La[sub 0.75]Sr[sub 0.25]Cr[sub 0.5]Mn[sub 0.5]O[sub 3−δ] SOFC Anodes

Solid oxide fuel cells (SOFCs) were fabricated by applying reproducible thin, dense (LSCM) anode and (LSM) cathode films to yttria-stabilized zirconia (YSZ) electrolytes by ultrasonic spray pyrolysis. A gold grid was applied to the anode film by lithography and plating, enabling adequate electrical contact while maintaining an open surface area for reaction. Alignment of the two electrode films and correct placement of the reference electrode enabled the separation of the anode and cathode impedance responses. Although the open-circuit voltage (OCV) of the fuel cell at with humidified fuel was close to that predicted by the Nernst equation, the anode polarization resistance was large . The addition of Pd to the anode film led only to a small decrease in polarization resistance, indicating that oxygen ion conductivity was the limiting factor for fuel. The OCV for was close to that when an inert gas (He) was supplied to the anode. This OCV increased to 0.87 V upon addition of Pd to the LSCM film surface. This indicates that the bare LSCM film is limited by a low activation activity.