Heiko Witzenhausen

RWTH Aachen University · Institute for Power Electronics and Electrical Drives

This work introduces a sophisticated impedance-based equivalent circuit model of the electrochemical processes inside a lithium-ion battery cell. The influence on the electrical voltage response is derived and merged into a mathematical calculation framework describing all fundamental phenomena inside a battery. The parameters, whose sole influence...

Modelling of batteries has become an important part in the design process of battery application. Especially for electric vehicles the design options can become very complex. To be able to make better design decisions, powerful modelling tools are necessary. However, one of the major drawbacks of complex models is the additional effort that is need...

Lithium ion batteries are key to the development of electric vehicles. While on the one hand, their energy and power density needs to be increased, on the other hand their aging behavior needs to be understood as well. Electrochemical Impedance Spectroscopy (EIS) is a mighty tool to investigate aging processes of batteries [1]. One advantage over e...

Promotion: Elektrische Batteriespeichermodelle: Modellbildung, Parameteridentifi kation und Modellreduktion Ziel dieser Arbeit ist es, allein durch das Strom- und Spannungsverhalten möglichst viel über eine Batterie herauszufinden, ohne ins Innere blicken zu können. Dafür wird zunächst eine elektrische Modellbeschreibung zu den Prozessen im Inneren...

Batteries need to pass several stress tests before deployment. These tests can range in complexity from seconds (short-time electrochemical impedance spectroscopy) to several years during life time estimation tests. Several publications have shown that at the end of life, the behavior of specimens can drastically differ, even though initial measure...

Electrochemical impedance spectroscopy (EIS) has been a reliable tool for parameterizing batteries. Using data gained from these spectra can be challenging due to the ambiguity. One possibility of interpretation is called Distribution of Relaxation Times (DRT) which approximates impedance spectra through an infinite number of RC elements. In this p...

In this work a three dimensional impedance-based electric battery model is coupled with a thermal model. Both parts are verified by comparing measurement and simulation. Subsequently the model is used to simulate a locally limited internal short-circuit inside a cell and inside a battery pack. Based on the simulations, suggestions for improvements...

Performance, safety and lifetime of Li-ion batteries are closely connected topics, which are significantly influenced by electrical and thermal inhomogeneities occurring during operation inside the system. For R&D of battery packs it is a key issue to identify these inhomogeneities and to minimize the stress inside the cells by means of adequate ce...

Lithium batteries are the most promising battery technology for use in next generation hybrid and full electric vehicles. While performance and lifetime are already satisfactorily, safety concerns and costs are important factors, which hinder the breakthrough in automobile application. The aim to reach a higher degree of intrinsic safety and lower...