CalPhaD Coffee Lecture – Development and Application of CalPhaD Databases for Energy Conversion and Storage

For more than two decades, the Thermochemistry Group at IMD-1 of Forschungszentrum Jülich has been developing, in close collaboration with GTT, a CalPhaD database containing oxide and salt systems relevant to energy conversion and storage.

A unique combination of experimental methods (DTA/TG, DSC, Dilatometry, KEMS, MBMS, (HT)XRD, SEM, etc.) enables measurements in a wide temperature range allowing us to gain a comprehensive understanding of the systems. Challenges such as the decomposition and vaporisation of samples or potential interactions with crucible materials have driven the development of customised crucibles and the refinement of experimental methods.

The experimental findings, combined with data from existing literature, are incorporated into the CalPhaD database GTOx. The liquid phase is modelled using the modified non-ideal associate species model. Stoichiometric solids are treated with a simple G(T) function, whereas the compound energy formalism (CEF) is used for solid solutions. In addition, an Arrhenius-type model for the calculation of the viscosity of molten oxides and salts has been developed. The model is based on the same structural units, i.e. the associates, as the one for the Gibbs-energy of the melt.

In the lecture, we will discusses experimental possibilities and challenges, examples of systems investigated, the development of the models and databases, and their application in energy conversion and storage applications.