With the increasing use of renewable energy sources, efficient short- and long-time storage technologies have become essential for balancing supply and demand. There is no single energy storage solution that is ideal for every time-scale application. Electrochemical energy storage systems, typically tailored for either high-power or high-energy applications, encounter operational limitations when deployed outside their optimal usage parameters, leading to diminished longevity, performance, and cost-effectiveness. Combining storage components into a complex system allows to benefit on the advantage and to mitigate inherent weaknesses.

The ResHy project (Ressourcenschonende Hybridbatterie; engl.: Sustainable hybrid battery) realized in cooperation of EnBW AG and Fraunhofer ISE, aims for the development of a novel electrochemical hybrid storage system. The system synergizes a high-capacity sodium-based component (SIB) with a second-life lithium-ion battery (LIB) and will be implemented and operated at a 60 MWp solar park in Gundelsheim, planned by EnBW AG. To ensure the harmonious integration and aging of these two battery types, it is crucial to understand their individual and collective aging behaviors.

To address this, the research involves the construction of a generic model to discern aging parameters within such hybrid storage systems, employing intuitive equations for ease of comprehension and accessibility. The model assimilates empirical data derived from battery aging measurements to pinpoint the aging parameters. A key element of this research involves the comparative analysis of different aging studies via the proposed model, with the aim of fostering a framework for aging factor comparability, thereby facilitating the quantification of stress factor effects on the aging trajectory.

The overall objective is to identify the degradation factors impacting battery longevity and to formulate a comprehensive aging model. By predicting the system performance and elucidating the effects of the interplay of technologies, this project seeks to enhance the operational efficiency and economic viability of the hybrid storage system, thereby contributing to the optimization of energy storage strategies in the renewable energy sector.