Advanced ultrasonic detection of lithium-ion battery thermal runaway under various heating powers

Lithium-ion batteries (LIBs) are essential in modern technologies, including energy storage systems and electric vehicles, owing to their high efficiency and compact design. However, their vulnerability to thermal runaway (TR) triggered by overheating, particularly without effective early safety warnings, significantly limits their broader adoption. In this study, we systematically examine TR progression in LIBs under various heating powers by integrating ultrasonic diagnostics with conventional parameters, such as the force, voltage, and temperature. Using Floquet-Bloch analysis regarding internal periodic multi-layers, we employ a wide frequency range of ultrasonic waves covering a highly dispersive region near 2 MHz. This, in turn, enhances sensitivity to microstructural changes within the LIB during the early stages of TR. In particular, this method demonstrates superior performance compared to conventional indicators, such as the expansion force, providing early warnings of venting by 282 s–953.8 s and TR by 377 s–851 s under various heating powers ranging from 600 W to 1200 W. Furthermore, we present a comprehensive safety metric that incorporates early warning ultrasonic features along with multidimensional parameters. These findings establish a robust framework for using ultrasonic diagnostics to enhance the safety and reliability of LIBs for critical applications.