Hydrogen, which does not emit CO2 into the atmosphere when it is used, is of huge significance as an energy source. It can be used for a variety of different purposes and can also be used as an energy store. As a doctoral researcher at the Institute of Material Science at the University of Stuttgart, Efi Hadjixenophontos worked together with other doctoral students on the Ecostore project run by the Marie Skłodowska-Curie Actions (MSCA) research fellowship program to carry out research into how hydrogen can be used as an energy store and in solid-state batteries. The group published its findings in MDPI Open Access Journals in March 2020. The paper has been one of the University of Stuttgart’s most-cited publications this year.