Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 149714

149714 - Understanding Internal Short Circuit Caused Thermal Runaway of Li-Ion Cells Through In-Situ Diagnosis 

Thermal runaway of lithium-ion (Li-ion) batteries is a critical challenge for various applications such as consumer electronics, electric vehicles, and grid-scale energy storage. What makes the challenge most concerning is that, in some cases, the batteries suddenly caught fire when the devices or vehicles were in normal use or not in use. Industrial or governmental investigations attributed most of those battery fires to thermal runaway triggered by spontaneous internal short circuit (ISC). In some reports the ISC was further attributed to battery cell manufacturing defects. However, many questions remain to be answered. For example, what is the threshold of ISC causing thermal runaway? How exactly does ISC form and slowly evolve to the threshold of thermal runaway, in some cases after years of normal operation? Is it possible to prevent ISC from reaching the threshold? These questions become increasingly intriguing and urgent as the deployment of Li-ion batteries rapidly increases in recent years. Answering these questions require a better understanding of the behaviors of ISC and thermal runaway of Li-ion battery cells. Because ISC and thermal runaway are highly localized and transient phenomena, conventional characterization methods of measuring overall cell voltage, current or surface temperature are insufficient. In comparison, in situ diagnosis could provide details of critical parameters, such as cell voltage and temperature at the ISC location, ISC current, and ISC resistance. The detailed experimental data can enhance the understanding of how an ISC forms, evolves, and triggers thermal runaway.

Our group has been developing novel in situ diagnostic methods and using the methods to reveal interesting phenomena on ISC caused thermal runaway. We first developed a small, slow and in situ sensing nail penetration method¹, which enabled observation of multiple ISC temperature peaks before thermal runaway. The observation implied that temperature is not a reliable parameter in determining the threshold of thermal runaway triggered by ISC. Then we integrated the method with a segmented cell design to enable simultaneous measurement of ISC temperature, ISC current and ISC resistance². Through this integrated characterization, we revealed that the multiple peaks of ISC temperature before thermal runaway can be attributed to the change of ISC current, which can be further attributed to the change of ISC resistance involving the change of ISC type during nail penetration. More recently, we developed a method to create different types of ISC while monitor ISC temperature, ISC current and ISC resistance³. This method enables detailed evaluation of different types of ISC in terms of their behaviors and risks of causing thermal runaway. Furthermore, by applying in situ diagnosis to large segmented cells⁴, we observed that thermal runaway triggered by nail penetration of a small segment did not propagate to the entire cell, which implies a potential strategy of mitigating thermal runaway.

References

1.           S. Huang, X. Du, M. Richter, J. Ford, G. M. Cavalheiro, Z. Du, R. T. White and G. Zhang, Journal of the Electrochemical Society, 167, 090526 (2020).

2.           S. Liu, S. Huang, Q. Zhou, K. Snyder, M. K. Long and G. Zhang, Journal of The Electrochemical Society, 170, 060515 (2023).

3.           M. K. Long, S. Liu and G. Zhang, Energy Advances, 2, 2018 (2023).

4.           S. Liu, S. Huang, Q. Zhou, K. Snyder, M. K. Long and G. Zhang, Journal of Energy Storage.

 

Presenting Author: Guangsheng Zhang The University of Alabama in Huntsville

Presenting Author Biography: Dr. Guangsheng Zhang is an Associate Professor in the Department of Mechanical & Aerospace Engineering at The University of Alabama in Huntsville (UAH). Before joining UAH in 2017, Dr. Zhang was a Research Associate at the Electrochemical Engine Center at Penn State. His research interests focus on the fundamental understanding of thermal-electrochemical coupled phenomena in batteries and fuel cells. In particular, his team uses in situ diagnosis to understand the failure mechanisms of lithium-ion batteries under extreme conditions, such as internal short circuit, thermal runaway, fast charging, and thermal degradation. His team received an NSF CAREER Award in 2023 to conduct research on short circuit caused thermal runaway of lithium-ion batteries.

Authors:

Guangsheng Zhang The University of Alabama in Huntsville