The greatest challenge of future electrical energy systems is the fluctuating feed-in of regenerative energy and the associated guarantee of continuous availability and sufficient grid stability. The research and further development of energy conversion and energy storage technologies on a wide range of time scales from milliseconds to weeks, months and years is therefore of great importance for maintaining today's security of supply. In addition to further technological developments, fundamental innovations are expected in particular through research into new materials as well as customized material functionalizations. Exactly this competence is available at Clausthal University of Technology and flows into the processing of scientific questions in the three research clusters "Energy Conversion and Storage", "Material Functionalization" and "System Integration" of the EST. The current medium-term research topics are derived from two overarching guiding themes.