Humans emit about 30 billion tonnes of CO2 each year through their energy requirements, which has important negative consequences for climate change. The move towards a different “greener” society is inevitable. In this sense, highly efficient renewable energy systems such as fuel cells are extremely necessary for achieving the goal of increasing the number of green cities around the world. Solid oxide fuel cells (SOFC) are a competitive candidate for stationary high power applications in this effort to reduce global pollution levels.
A solid oxide fuel cell is a conversion system based on a cell consisting of an anode, cathode, and electrolyte, which directly produces electricity and heat from the chemical reaction between a fuel (e. g., natural gas, biodiesel, H2 and ethanol) and oxidising agent (O2).
The objective of the work plan is to study the structural and transport properties in triple-conducting (electronic, ionic, and protonic) perovskite materials for use as cathodes in proton conducting SOFCs. The final goal is the fabrication of a complete fuel cell (anode/electrolyte/cathode) employing the developed cathode materials.
The project will consist of the following phases:
The impact of particle size on the physical properties; synthesis of oxides with general formula Ba2-xAxFe2-xMxO5+x (A = rare-earth; M = Mn and Ni) for use as cathode in proton-conducting SOFC. The synthesis of these materials will be carried out using ceramic method and sol-gel methods, focusing on the impact on physical properties of modifying the particle size.
The structural and morphological characterisation of the materials will be carried out using a combination of techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Selected Area Electron Diffraction (SAED) and Transmission Electron Microscopy (TEM).
Surface vs bulk. The role of the surface; the surface and bulk composition of these materials exhibit important differences, with a significant impact on the catalytic and oxygen-exchange performance. In addition, under operation conditions, the electrode surface can degrade due to cation segregation, leading to a deterioration of performance. XPS and SEM will, therefore, be performed to study the surface composition before and after the electrochemical characterization to rule out any cation segregation.
Electrical and Electrochemical behaviour; the evaluation of the transport properties will be carried out through the following methods:
• Total conductivity will be determined by a four-probe direct current (d.c.) current-voltage measurement.
• Electrochemical behaviour will be investigated by AC impedance spectroscopy.
• Proton partial conductivity will be study through the effect of oxygen partial pressure and water-vapour partial pressure on the electrical properties (defect-chemistry method).
• Fabrication and testing of single cell (anode/electrolyte/cathode).
For further information, please contact with Dr. Daniel Muñoz Gil (email: [email protected])