Investigation of the loading and unloading process in a hydrogen storage material based on the complementary use of simulations and neutron scattering measurements

To fight against global climate change, the hydrogen economy has emerged as a possible solution. However, the realization of the hydrogen economy faces several challenges. One of these challenges is hydrogen storage. In this work, the use of complex metal hydride will be investigated as a possible solution for storing hydrogen. The investigation is aimed to have a proper understanding of the system at different length scales. In this work nanoscopic length scale is chosen and an investigation based on the complementary use of simulations and in situ SANS measurements was carried out. Several methodical challenges were encountered during the journey. These challenges were mostly related to the calculation of scattering patterns from simulations. One of these challenges was an inherent finite size effect in the calculated scattering pattern due to the finite size of the simulation box. To remove this effect, a novel method was developed that has advantages over existing methods. Another challenge was the analytical calculation of scattering patterns from continuum simulation, which was overcome by proposing a novel numerical method for calculating scattering patterns from continuum simulations. The fast computation of scattering patterns from simulations was also a challenge. The fast computation was ensured by implementing the developed methods in the software solution Sassena. The existing version of Sassena was improved to optimize the computational performance. One challenge specific to this work was calculating the neutron count rate because it was the chosen measurement parameter for the in situ SANS measurement used in this work. To accomplish this, another novel method was developed that takes the instrument specifications into account and calculates the neutron count rate per unit neutron flux. The calculated parameter was multiplied by an empirical factor and compared with measured data to validate the simulations. In the final stage of this thesis, the developed methods were used to investigate the hydrogen storage process at the nanoscopic length scale, which revealed gas entrapment at the nanoscopic level. The dynamics at the nanoscopic length scale were also investigated, and the phenomenological reasons behind different features appearing in the measured data were explained. The effect of nanoscopic phenomena on engineering length scale measurements was also investigated for the chosen system. Based on the outcome of this thesis a multiscale simulation of the hydrogen storage process of the hydrogen storage process can be created in the future. In addition, the methods developed in this work will provide a framework for evaluating neutron scattering data using simulations in future.

Recommended citation: Majumdar, A. "Investigation of the loading and unloading process in a hydrogen storage material based on the complementary use of simulations and neutron scattering measurements." CAU Kiel. https://nbn-resolving.org/urn:nbn:​de:gbv:8:3-2026-00229-3

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