High performance transition metal oxide composite cathode for low temperature solid oxide fuel cells

Low temperature solid oxide fuel cells (SOFCs) with metal oxide composite cathode on the ceria-carbonate composite electrolyte have shown promising performance. However, the role of individual elements or compound is seldom investigated. We report here the effect of the ZnO on the physico-chemical and electrochemical properties of lithiated NiO cathode. The materials and single cells are characterized by X-ray diffraction, scanning electron microscopy, DC polarization electrical conductivity, electrochemical impedance spectroscopy and fuel cell performance. The ZnO modified lithiated NiO composite materials exhibit smaller particle size and lower electrical conductivity than lithiated NiO. However, improved electro-catalytic oxygen reduction activity and power output are achieved after the ZnO modification. A maximum power density of 808 mW cm(-2) and the corresponding interfacial polarization resistance of 0.22 Omega cm(2) are obtained at 550 degrees C using ZnO modified cathode and 300 pm thick composite electrolyte. The single cell keeps reasonable stability over 300 min at 500 degrees C. Thus, ZnO modified lithiated NiO is a promising cathode candidate for low temperature SOFCs. (C) 2011 Elsevier B.V. All rights reserved.