Doctoral Dissertations
Date of Award
5-2024
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Mechanical Engineering
Major Professor
Peng Zhao
Committee Members
Feng-Yuan Zhang, Hsin Wang, Xia Wang
Abstract
In the contemporary landscape, lithium-ion batteries (LIBs) are key components powering a wide array of electronic devices and electric vehicles (EVs). As society increasingly relies on these batteries for their efficiency and functionality, understanding and mitigating potential risks, such as thermal runaway (TR) events, become imperative. The objective of this dissertation is to comprehensively understand TR characteristics of LIBs through a combination of experiments and numerical simulation, thereby enhancing battery safety, refining design standards, and providing insights and guidelines for the prevention and management of TR events.
Firstly, this dissertation explores the safety regime of LIBs TR through a computational approach, identifying critical heat source intensity and duration time that determine the boundaries between TR and safe operational zones. Additionally, it studies heat release during an internal short circuit (ISC) event, combining thermal-electrochemical and thermal runaway models.
Secondly, this dissertation presents an in-depth investigation into the effects of radiative heat transfer on TR propagation. It employs a theoretical model to assess the nonlinear and non-monotonic nature of radiative effects between cylindrical Li-ion cells and examines the blocking effect in various cell arrangements.
Thirdly, this dissertation investigates cell-to-cell variability in TR characteristics among LIBs with lithium cobalt oxide (LCO), highlighting the challenges in accurately predicting TR events. It also explores the utility of statistical analysis and uncertainty quantification in TR kinetic models.
Fourthly, this dissertation analyzes the impact of aging on the TR behavior of lithium nickel cobalt manganese oxide (NCM) and lithium iron phosphate (LFP) batteries. It reveals significant effects of aging on battery safety, including variations in onset temperatures for exothermic reactions, TR delay time, and cell voltage drops.
Lastly, this dissertation introduces a novel approach to suspend TR, focusing on preserving the electrochemical performance retention of LFP cells. It emphasizes the importance of a temperature threshold for preventing further damage. Furthermore, size and time dependence of particle emission from TR has been investigated for its environmental and health concerns.
This dissertation adopts a comprehensive approach involving experimental research, statistical analysis, and modeling. It provides valuable insights for enhancing battery safety and mitigating potential hazards.
Recommended Citation
Zhang, Liwen, "Thermal Runaway of Li-ion Batteries: Triggering, Emission, and Mitigation. " PhD diss., University of Tennessee, 2024.
https://trace.tennessee.edu/utk_graddiss/10193