Simulation and Evaluation of Battery Aging in Electric Hybrid Storage Systems

The extension of traction batteries from electric vehicles with supercapacitors is regularly discussed as a possibility to increase the lifetime of lithium-ion batteries as well as the performance of the vehicle drive. The objective of this work was to validate these assumptions by developing a simulation model. In addition, an economic analysis is performed to qualitatively classify the simulation results. Initially, a hybrid energy storage system consisting of battery and supercapacitor was developed. A semi-active hybrid energy storage topology was selected. Subsequently, the selection of use cases as well as the application-specific definition of load cycles took place. In addition, the control strategy was further developed so that a simulation on lifetime was made possible. The end-of-life of the battery cells was defined, according to the USABC guideline values. Based on the data of the respective use case, the control strategy parameter optimization was carried out according to an empirical approach. In the final step, the developed hybrid energy storage system and the conventional battery system were compared, and the results evaluated both technically and economically. A slowdown of the aging effects and thus an improvement of the battery lifetime in the hybrid energy storage system could be clearly demonstrated. Despite proof of the technical advantage, the use of electric hybrid systems consisting of a battery and supercapacitor in electric vehicles is currently questionable due to the high additional costs. Through further technical development, subsidies or the construction of new, highly automated production facilities, supercapacitors will experience a price reduction in the future, which is why electric hybrid energy storage systems can play an important role in the mobility of tomorrow.