Annukka Santasalo, M.Sc., is working as a research scientist in the group of Professor Kyösti Kontturi at the Department of Chemistry. She works in the low temperature Polymer Electrolyte Fuel Cells (PEFC) team led by Dr. Tanja Kallio. The strength of the team is a broad understanding of different fuel cell components such as the catalyst materials, the fuels and the membranes used as the electrolyte. Annukka Santasalo has started her doctoral studies in 2007 and since then she has visited the University of Alicante, Spain for 6 months, working in a group led by Professor Juan Feliu, famous for their knowledge of electrocatalysis.

At the moment her scope is to apply the characterization methods she learned in Spain to analyzing new catalyst materials synthesised in Finland. Furthermore, she is working to find suitable conditions for new catalyst materials, which includes optimizing electrolyte media, temperature and alloy composition for a bimetallic catalyst for an alkaline PEFC. “The goal of our research is to develop an alkaline PEFC producing high power densities, but having low material expenses compared to already commercially available acidic PEFCs”, she explains.  There are several ways of improving the fuel cell system by changing highly expensive materials to cheaper ones without losing the efficiency and so promoting fuel cells to become a reality in the near future.

Polymer Electrolyte Fuel Cells -
Answering to the Challenge of the Energy Requirement of Portable Applications

A proton conductive membrane is used as an electrolyte in the polymer electrolyte fuel cell (PEFC). At both sides of the membrane (Figure 1) there are electrodes consisting of catalyst nanoparticles and a conductive polymer. At each end of the sandwich complex there is a metallic end plate working as an electron conductor. The liquid fuel is fed to the anode compartment and is oxidized to CO2. In addition, protons and electrons are produced. The protons are transported though the membrane to the cathode side and to maintain electrical neutrality, the electrons circulate from the anode endplate to the cathode through the outer load and this electron movement can be utilised as electric power. At the cathode protons and electrons meet in an oxygen rich atmosphere and oxygen is reduced to water. Any liquid fuel can be utilised as long as it can be oxidized at the anode and thus produce protons. Liquid organic fuels have been a focus of interest due to their high energy density and facile storability compared to standard gaseous hydrogen.  

The research focus of my thesis is finding alternative, non-noble metal catalyst materials for oxidation of alcohols in alkaline media and their integration into the working fuel cell with a hydroxyl exchange membrane. In my work, I synthesize the catalyst nanoparticles by a reducing method and characterize them physically with microscopy and X-ray techniques and electrochemically with a rotating disc method. Electrochemical study of the catalyst material already outside the fuel cell gives us a rapid way to gather information on the electrochemical activity of the catalyst for the alcohol oxidation. Subsequently, we combine the catalyst material with the membrane by spraying the catalyst polymer ink onto the membrane material and heat pressing them together. Finally, we can test our own membrane electrode assemblies in test fuel cell stations where we can control the outer conditions like temperature, humidity and pressure. This will confirm if the catalyst can be successfully used in a fuel cell.

The fuel cell team in our laboratory is specialized in the complete understanding of the fuel cell structure. We have also been studying a few experimental hydroxyl exchange membrane materials developed by both a commercial supplier and the Laboratory of Polymer Technology at Åbo Akademi. The results have been very promising and therefore we think that in six months we can have a stable and cheap polymer membrane suitable for alkaline membrane fuel cell use.