Functional thin films as cathode/electrolyte interlayers: a strategy to enhance the performance and durability of solid oxide fuel cells†
Electrochemical devices such as solid oxide fuel cells (SOFC) may greatly benefit from the implementation of nanoengineered thin-film multifunctional layers providing, alongside enhanced electrochemical activity, improved mechanical and long-term stability. In this study, an ultrathin (400 nm) bilayer of samarium-doped ceria and a self-assembled nanocomposite made of Sm0.2Ce0.8O1.9-La0.8Sr0.2MnO3-δ was fabricated by pulsed laser deposition and is employed as a functional oxygen electrode in an anode-supported solid oxide fuel cell. Introducing the functional bilayer in the cell's architecture results in a simple processing technique for the fabrication of high-performance fuel cells (power density 1.0 W cm−2 at 0.7 V and 750 °C). Durability tests were carried out for up to 1500 h, showing a small degradation under extreme operating conditions of 1 A cm−2, while a stable behaviour at 0.5 A cm−2 (2.8% Vin kh−1). Post-test analyses, including scanning and transmission electron microscopy and electrochemical impedance spectroscopy, demonstrate that the nanoengineered thin film layers remain mostly morphologically stable after the operation.