The aim is to develop innovative hybrid systems consisting of Li- and Na-ion batteries and supercapacitors, which can be used as energy storage systems in mobile applications and to improve the performance of stationary storage. The development of innovative liquid and gel polymer electrolytes based on novel solvents aims to improve the safety of these systems. In addition, new carbon-based electrodes will be produced and the interfacial processes between electrodes and electrolyte will be understood in order to improve performance.