Characterisation of thin films of ceria-based electrolytes for IntermediateTemperature - Solid oxide fuel cells (IT-SOFC)

At the present, a major technological challenge for the development of solid oxide fuel cells (SOFC) is the reduction of their operation temperature in order to reduce the costs and increase the fuel cell lifetime. Nevertheless, decrease in the operating temperature leads to losses in cell performance mainly due to the ohmic drop through the electrolyte. Therefore, several approaches are currently under investigation to overcome the electrolyte problem and the use of oxygen ion conductor thin films seems to be the most promising solution. In this respect, the well-known electrolyte CeO2-Gd2O3 (CGO) was investigated. Thin layers of less than 5 mum of CGO were deposited using two different techniques: RF magnetron sputtering and Atomic Layer Deposition (ALD). Physicochemical properties of the thin films obtained were characterised by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Furthermore, impedance measurements were carried out in order to determine the electrical properties of the CGO films, in particular their ionic conductivity.