Early Warning of Thermal Runaway for Lithium-Ion Battery Enabled by Embedded Optical Sensing

Early warning of Thermal Runaway (TR) is crucial for enhancing the safety and reliability of lithium-ion batteries. In this work, Fiber Bragg Grating (FBG) sensors, embedded in pouch cells and isolated from the influences of strain using a quartz tube, are demonstrated to monitor the internal strain and temperature of the battery without affecting its electrochemical performance. This sensing approach is applied to real-time monitoring of side reactions during the TR, and the internal sensing demonstrated significantly enhanced sensitivity and faster response characteristics compared to external sensing. Furthermore, the internal strain and temperature can be monitored to provide an early indication of TR, offering a predictive advantage over conventional methods that rely on electrical signals. Collectively, these findings provide solutions for advanced battery management systems to ensure the safety of lithium-ion battery.