In this work a simulation model was presented to predict lifetime of a lithium-ion battery under realistic operation condition. The model approach couples an impedance based electric-thermal model to a semi-empirical aging model, to account for the impact of aging on the dynamical behavior of the battery. The aging model is based on results obtained from extended accelerated aging tests, which were used to parameterize the model. From the aging test results simplifications for the model approach could be derived. It was observed that calendar aging test results can be used for a first approximation of lifetime, as cycle life of the batteries exceeds by far the requirements of application. Test results showed, that a square root of time dependency can be applied to the data, as well as an exponential behavior of aging on voltage and temperature. The aging behavior of the OCV curve was accounted for, using the actual instead of the nominal capacity for the definition of DOD. The sensitivity of the Impedance parameters L, R2, C2, Φ1 and Φ2 on aging is small and was therefore neglected. Mathematical functions, based on physical aging effects, were obtained from the test results to describe the aging behavior and to ensure the ability of the model to make extrapolations. The functions were implemented in a semi-empirical aging model. Based on the model different drive cycles, use patterns and management strategies can be analyzed with regard to their impact on lifetime. Exemplarily the impact of a realistic HEV profile on the aging of a high power cell was simulated for different operation ranges. More detailed accounts on the results as well as a verification of the model are presented in a paper submitted to the Journal of Power Sources.
Analyzing calendar aging data towards a lifetime prediction model for lithium-ion batteries
2012
11 Seiten, 10 Bilder, 2 Tabellen, 19 Quellen
Conference paper
English
Alterungsverhalten , dynamisches Verhalten , Simulationsmodellbildung , Extrapolation , Vorhersagemodell , Zeitabhängigkeit , Nennleistung , Betriebsbedingung , Lithiumbatterie , Spannung (elektrisch) , Lebensdauervorhersage , Fahrzyklus , Betriebsbereich , Betriebskennzahlen , Alterung , Lithiumionenbatterie , Hybridfahrzeug