The high demand for electrical energy induced by the rapid population growth has arisen the necessity
to develop sustainable and environmentally friendly energy sources. In this context, fuel cells are one of the most
promising technologies to obtain electrical energy from a wide variety of fuels with good efficiencies and lower
emission of pollutants. In particular, Solid Oxide Fuel Cells (SOFCs) have attracted great attention in recent years
due to their fuel flexibility, good tolerance to impurities in the fuel and higher efficiencies.
However, the high operating temperatures of SOFCs (600-800 ºC) needed to achieve a good electrode performance
and a sufficient ionic conductivity for the electrolyte, negatively affect the long-term stability of these devices. For
this reason, decreasing the operating temperature is one of the main goals for the wide implementation of SOFCs. It
is well known that the crystal structure and composition of the electrodes play a key role in the electrochemical
performance; nevertheless, the microstructural optimization of the electrodes has demonstrated to be crucial to
boost the electrochemical properties at low operating temperatures in both oxidizing and reducing conditions.
In this PhD thesis, different nanostructured and nanocomposite electrode layers based on the combination of
perovskite-type electrodes, i.e. LaCrO3, SrTiO3 or LaFeO3 and the ionic conductor Ce0.9Gd0.1O1.95 (CGO) with
fluorite-type structure have been prepared and tested for their implementation in SSOFCs. The electrode layers
were prepared directly onto Zr0.84Y0.16O1.92 (YSZ) or La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM) electrolytes by
spray-pyrolysis. Additionally, pulsed laser deposition (PLD) was employed for the preparation of active layers. For
comparison purposes, the same electrode compositions were prepared as powders from freeze-dried precursors
and then deposited onto the electrolyte by screen-printing method.