Lithium-ion batteries have been widely used as secondary batteries for electric vehicles due to their high energy density. However, due to various mechanical and electrical abuses, lithium-ion batteries are subjected to thermal runaway leading to explosion and various side reactions with gas generation. Although many studies have been conducted on these side reactions, there are many limitations, such as the lack of research on side reactions at the cathode with a nickel content of more than 80%, and the fact that the phenomena occurring at each electrode are considered separately without testing the combination of materials. 

The research team used pyrolysis experiments with combinations of battery components to identify the mechanisms of side reactions in lithium-ion batteries using high-nickel cathode materials, and developed a highly reliable reaction model based on this. A total of 15 reactions were conducted to simulate performance degradation during thermal runaway, generated gases, and pressure increase through temperature and volume changes, reflecting the decrease of active materials and electrolyte as the reaction progresses.

The thermal runaway reaction mechanism and reaction model proposed in this study can be applied to predict cell performance degradation and thermal runaway in various abnormal situations. Furthermore, it will be possible to overcome various experimental limitations and promote technological advancements to increase battery safety, and contribute to improving the safety of electric vehicles and promoting the market penetration of electric vehicles by solving the thermal runaway problem.

The research team plans to apply and validate the developed reaction mechanism and reaction model to predict cell performance degradation and thermal runaway due to separator melting in various abnormal situations, and furthermore, they plan to identify detailed reaction mechanisms for individual reactions.

Core methodology and key findings for elucidating thermal runaway mechanisms in high nickel anode-based lithium-ion batteries

[Reference] Kim, Minuk, Jaeyoung Jeon, and Jongsup Hong. "Reaction mechanism study and modeling of thermal runaway inside a high nickel-based lithium-ion battery through component combination analysis." Chemical Engineering Journal (2023): 144434.

[Main Author] Minuk Kim (Yonsei University), Jaeyoung Jeon (Yonsei University), Jongsup Hong (Yonsei University)

* Contact email : Professor Jongsup Hong (jongsup.hong@yonsei.ac.kr)