Term of Award

Fall 2024

Degree Name

Master of Science, Mechanical Engineering

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Mechanical Engineering

Committee Chair

Hayri Sezer

Committee Member 1

Hossain Ahmed

Committee Member 2

David Calamas

Abstract

Considering the high increase of lithium-ion batteries (LIBs) through the years, it is important to analyze the impact of the operational conditions, such as charging and discharging on the transient thermal behavior of LIBs for thermal management of Li-Ion batteries. A pseudo two-dimensional mathematical model based on the finite volume method (Doyle-Fuller Newman) available in an open-source environment such as Python, was utilized for the electrochemical evaluation of the Li-Ion battery. For simplicity, a lumped thermal model was integrated with the electrochemistry model to evaluate the transient behavior of Li-Ion cells under varying conditions. Both the electrochemistry and lumped thermal models utilize Euler’s method for time integration to assure the numerical stability of a system of coupled non-linear PDEs. A cylindrical li-ion battery, LGM50, with Nickel Manganese Cobalt Oxide (NMC) cathode chemistry is used in the simulations. The utilized models are first validated and verified against experiments and available numerical simulations in the literature. In the present study, a real-life case, city driving conditions of an electric vehicle by using the Urban Dynamometer Driving Schedule (UDDS) is simulated to investigate the thermal transient behavior of the Li-Ion battery.

The numerical results showed that the cell operating at low temperatures has higher total average volume heating than the high-temperature operating conditions. At lower temperatures, the electrochemical reaction rate is lower than the high-temperature conditions. Additionally, the ionic conductivity of Li-ion is reduced at low temperatures, increasing the ohmic resistance. The heating rate inside the battery is directly proportional to the ohmic resistance, causing a high heating rate at low operating conditions.

High temperatures showed an opposite behavior, meaning that the transportation of ions becomes easier to transport, decreasing the cell’s total heating. Power is affected by the change in temperature, which showed that at high temperatures power increases and at low temperatures it has an opposite behavior. The analysis of the model outputs is a way to improve battery thermal management systems and prevent performance degradation or thermal runaway.

Research Data and Supplementary Material

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