Due to various advantageous properties, lithium-ion cells are currently used in the traction battery of electric vehicles. However, over time and service life the battery cells used demonstrate effects of aging. As a result, the attainable range of the electric vehicle may be reduced and its performance also may decrease. Ultimately, it may even be necessary to replace the expensive traction battery. Against this background, the prediction of aging is of great interest to various players along the value chain of lithium-ion cells, such as suppliers and manufacturers in the automotive industry. The aim of this project is to develop an efficient and cost-effective method for the aging characterization of battery systems. The description of the relevant aging processes is to be carried out on the cell level, but also on the battery system level, in order to take into account the effects of the interconnection of the individual cells in the overall system. In order to achieve the goals of increasing efficiency, reducing costs and minimizing complexity, the results of real aging series are combined with simulation models to develop this method.