Hydrogen storage is essential to enable the transition of our fossil-fuel-based economy towards a ‘green economy’. Battery storage alone cannot fully compensate for the enormous fluctuations in feed-in from renewable energy sources caused by environmental and weather conditions (calm winds, the day-night cycle, seasonal variations). Similarly, the chemical industry requires large quantities of hydrogen to replace coal as a reducing agent in many processes, particularly those involving pyrometallurgy. This problem can be partially solved through the chemical storage of hydrogen in hydrides.

The aim of our research is to investigate reactive mixtures of various (complex) hydrides by a combination of experimental and modeling approaches. Of particular interest is the coupling of calorimetric with volumetric measurements (high-pressure Sievert apparatus and high-pressure DSC), as this approach allows further conclusions to be drawn about the system’s behaviour (cycle stability, kinetic effects).

Further information on H₂ storage at the IPC can be found here.

 

 

Thermodynamics of Alkaline Earth Metal Borohydrides

The thermodynamics of alkaline earth metal borohydrides is of interest because they are relatively stable (with the exception of Be(BH4)2 and Ra(BH4)2) and can therefore be synthesised and characterised. Their high thermal stability poses a problem, making their use as components in reactive mixtures an interesting application.

 

Selected publications

Konrad Burkmann, Klaus Bohmhammel, Jürgen Seidel, Florian Mertens, Thermodynamics of Alkaline Earth Boranates: On the Application of Neumann-Kopp’s Rule for the Estimation of Heat Capacities and Absolute Entropies, J. Phase Equilib. Diffus. 2026, 47, 17–25, doi: 10.1007/s11669-026-01229-3

Konrad Burkmann, Franziska Habermann, Alexander Walnsch, Bianca Störr, Jürgen Seidel, Klaus Bohmhammel, Roman Gumeniuk, Florian Mertens, Heat Capacity and Absolute Standard Entropy of the High-Temperature Polymorph of Calcium Boranate and Thermodynamic Calculations Regarding its Decomposition and Rehydrogenation, ChemPhysChem 2025, 26, e202500108, doi: 10.1002/cphc.202500108

Konrad Burkmann, Markus Mehlhorn, Angus Demmer, Jakob Kraus, Franziska Habermann, Jürgen Seidel, Klaus Bohmhammel, Jens Kortus, Florian Mertens, A thermodynamic assessment of the decomposition and rehydrogenation of o1-Ba(BH4)2 based on DFT calculations and correlation functions, Phys. Chem. Chem. Phys. 2025, 27, 17063–17072, doi: 10.1039/d5cp00744e

Konrad Burkmann, Angus Demmer, Franziska Habermann, Bastian Hansel, Bianca Störr, Jürgen Seidel, Roman Gumeniuk, Martin Bertau, Klaus Bohmhammel, Florian Mertens, Heat capacity and absolute standard entropy of Sr(BH4)2, J. Therm. Anal. Calorim. 2025, 150, 5409–5417, doi: 10.1007/s10973-025-14085-z

 

Thermodynamics of Transition Metal Borohydrides

Transition metal hydrides often exhibit fast reaction rates for hydrogen absorption and release and also possess the thermal stability required for practical applications. An overview of our research to date in this field can be found in the following publications.

Selected publications

Konrad Burkmann, Franziska Habermann, Bianca Störr, Jürgen Seidel, Roman Gumeniuk, Klaus Bohmhammel, Florian Mertens, ‘Calorimetric determination of the heat capacity function and absolute entropy of yttrium borohydride (Y(BH4)3) prepared mechanochemically’, RSC Mechanochem. 2025, 2(4), 563–572, doi: 10.1039/d4mr00124a

Konrad Burkmann, Franziska Habermann, Erik Schumann, Jakob Kraus, Bianca Störr, Horst Schmidt, Erica Brendler, Jürgen Seidel, Klaus Bohmhammel, Jens Kortus, Florian Mertens, Structural and thermodynamic investigations of Zr(BH4)4 and Hf(BH4)4 between 280 K and their decomposition temperatures, New J. Chem. 2024, 48(6), 2743–2754, doi: 10.1039/d3nj05601e