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Prof. Dr.-Ing. Julia Kowal

Julia Kowal

Room: EMH 163


Einsteinufer 11

Sec. EMH 2

10587 Berlin

Phone: +49 (0)30 314-25394

Fax:     +49 (0)30 314-21133


Consultation hours: On Mondays 9 - 10 h and on appointment 

Please note: Until further notice, there is no consultation hour with personal contact. Please phone me or write me an email.

The consultation hours on December 21 and 28 are cancelled.


since 03/2014
Chair of Electrical Energy Storage Technology at the TU Berlin
01/10 - 02/14
Senior engineer at the department of Electrochemical Energy Conversion and Storage Systems, ISEA, RWTH Aachen
PhD at RWTH Aachen, Topic: "Spatially-resolved impedance of nonlinear inhomogeneous devices - using the example of the lead-acid battery"
Visiting researcher at the company Exide in Azuqueca de Hénares, Spain
Visiting Researcher at the research centre RISØ in Roskilde, Denmark
Research assistant at the department of Electrochemical Energy Storage Conversion and Systems at the Institute For Power Electronics and Electrical Drives (ISEA), RWTH Aachen
Studies of electrical engineering at RWTH Aachen Diploma thesis: "Investigation of the thermal behaviour of electrochemical energy storage systems in vehicle on-board power supplies"



Awards and Scholarships
Herbert-Kind-Price of ETG in the VDE
Brigitte-Berkenhoff-Price for the best graduate in the field of electrical engineering at RWTH Aachen
Aachen's VDE price
Sponsorship through the Prof. Dr. Koepchen Merit Foundation (RWE)


On-line state-of-health estimation of Lithium-ion battery cells using frequency excitation
Citation key KIM2020101841
Author Jonghyeon Kim and Lars Krüger and Julia Kowal
Pages 101841
Year 2020
ISSN 2352-152X
DOI https://doi.org/10.1016/j.est.2020.101841
Journal Journal of Energy Storage
Volume 32
Abstract With the rapid growth of the battery market, improved cell state estimation techniques are required as well. The cell state-of-health (SoH) estimation can be applied to battery management systems (BMS) to extend the usable cycle life and to prevent critical safety issues caused by ignition or explosion. Electrochemical impedance spectroscopy (EIS) is one of the non-destructive battery cell analysis methods that allows estimation of electrochemical parameters. However, in order to use the EIS, it is not only time-consuming to measure the impedance in a wide frequency range, but also the cells must be separated from the circuit for measurement. The purpose of this paper is to estimate the SoH of the Lithium-ion battery cell in operation. For this purpose, cell impedances at different cell SoC, cell SoH and cell temperature are compared. The experimental results are shown using a measurement system designed to measure the cell impedance during cell charging and discharging. Through this, it is shown that SoH estimation is possible even when the cell SoC and the cell temperature are unknown.
Link to publication Download Bibtex entry

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Auxiliary Functions


Technische Universität Berlin
Electrical Energy Storage Technology
Institute of Energy and Automation Technology
Faculty IV
sec. EMH 2
Einsteinufer 11
D-10587 Berlin


Sec. EMH2
Room EMH 162
+49 (0)30 314-21633
+49 (0)30 314-21133