Strukturelle Eigenschaften und der Zusammenhang zwischen Struktur und Dynamik spielen in verschiedenen Bereichen der Energieforschung eine große Rolle, z.B. bei der Wasserstoff-Speicherung oder in verschiedenen Arten von Brennstoffzellen.
Fuel cells convert chemical (e.g. in the form of hydrogen gas) into electrical energy. Many different components play together in order to conduct the protons through the electrolyte in the cell, while electrons have to go the long way as electrical current via an energy consumer from the anode side of the fuel cell to the cathode side. The structure of the multi layer system “fuel cell” plays a crucial role, from microscopic length scales (nanometers) up to macroscopic distances (mm).
High temperature polymer electrolyte fuel cells (HT-PEFCs) are studied in this respect under different points of view. In close collaboration to the institute IEK-3 the link between macroscopic process design and microscopic understanding is established. Neutron scattering helps in this respect to study the structural aspects of the materials and to correlate them with diffusion processes, which determine e.g. the proton conductivity of the membrane.
Proton conducting membranes
The proton conducting membrane in HT-PEFCs is typically a polymer swollen with phosphoric acid. The structure of this component is studied with neutron diffraction and small angle scattering over a large range of length scales. The proton diffusion in such a complex system is studied with quasielastic neutronscattering, which offers unique possibilities due to the large incoherent neutron scattering cross section of the proton and the possibility to use deuterium instead, which has largely different scattering properties. The diffusion of the proton can be determined with quasielastic neutronscattering on length scales in the nanometer range also correlation of polymer segmental mobilities with transport properties may be considered.