The Electric Energy Storage Systems Group was founded in September of 2014 with the appointment of Richard Hanke-Rauschenbach as a full professor at Leibniz Universität Hannover. The group is part of the Institute for Electric Power Systems (IfES) at the Faculty of Electrical Engineering and Computer Science at the Leibniz Universität Hannover. We focus on the design and operation of interconnected energy and material conversion systems as well as the development of selected components and processes. Such systems play an important role in the context of the transformation of the energy system towards higher shares of renewables as well as in the area of future drive systems of automobiles and aircrafts. Our group acts as a bridge between a variety of concentration areas within the engineering discipline, such as, electrical engineering, mechanical engineering, energy technology and computer science as well as selected branches from the natural science and economics Institutes.