Electrical and Thermal modeling of a Lithium Titanate Oxide-based cell for Railway Application

Abstract

The electrical and thermal behaviour of a prismatic LTO cell is analyzed and modelled for different operation ranges. Afterwards the validated models are used to simulate a complete traction battery compromising of over 1000 interconnected cells for a high-power railway application. Under consideration of side cooling pipes and cell-to cell variations the whole traction battery was simulated and validated using the open source available ISEA Framework.
The electrical behavior of the cell is analyzed, with the help of electrochemical impedance spectroscopy (EIS) measurements, that were performed under variation of temperature and SOC. Afterwards these measurements were used to fit the parameters of a 2RC electrical equivalent circuit (EEC). Besides the electrical model of a cell, the thermal model also plays a significant role. Due to the strong temperature dependency of battery systems, an exact representation of the thermal behavior can help to estimate the thermal stability of the whole system. Within a cell, the amount of heat radiation from the individual components is insignificantly low. Additionally, the influence of convection between the electrolyte and the electrode can be neglected due to the limited flow velocity of the electrolyte. Accordingly, the most dominant effect of heat transfer within a cell is heat conduction, which shows anisotropic behaviour and is calculated by considering individual material parameters.
The electrical and thermal model are both validated, using prior conducted measurements at cell level. Afterwards the combined electrical and thermal models are used to model and simulate a high-power traction battery for railway application.

Full text

Chair for Electrochemical Energy Conversion
and Storage Systems
Battery Ageing • Battery Models • Battery Diagnostics • Battery Pack Design • Electromobility • Stationary Energy Storage • Energy System Analysis
Electrical and Thermal Modeling of a Lithium Titanate
Oxide based Battery for Railway Application
Advanced Battery Power: P-115
Ahmed Chahbaza,b, Fabian Meishnera,b, Cem Ünlübayira,b, Dirk Uwe Sauera,b,c
a Chair for Electrochemical Energy Conversion and Storage Systems, Institute for Power Electronics and Electrical Drives (ISEA), RWTH Aachen University, Jägerstrasse 17/19, 52066 Aachen, Germany
b Jülich Aachen Research Alliance, JARA-Energy, Templergraben 55, 52056 Aachen, Germany
CHelmholtz Institute Münster (HI MS), IEK-12, Forschungszentrum Jülich, 52425 Jülich, Germany

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Chair for Electrochemical Energy Conversion and Storage Systems
01.05.2021 Ahmed Chahbaz
Electrical and Thermal Modeling of a Lithium Titanate
Oxide-based Cell for Railway Application
Thermal Model
Electrical Model Battery Pack Modelling
■EIS measurements used to analyze
electrical behaviour
■Impedance model based simulation
■2-RC electrical equivalent circuit
■Anisotropic thermal behaviour due to
winding of cell
■Finite Volume Method used for
simulation
Validation
Ø-Deviation: 19.6 mV
Ø-Deviation: 0.65 K
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