Insights into Thermal Runaway of Cylindrical Lithium-ion Batteries by Internal Temperature Sensors

This study presents a novel method for implementing internal temperature sensors in cylindrical lithium-ion batteries by laser ablation to enhance the understanding of thermal runaway (TR) behavior. Using commercial 21700 cells, Accelerating Rate Calorimetry (ARC) experiments were conducted at various states of charge. The results showed that internal temperature changes during safety-critical events, such as venting and TR, were significantly higher compared to externally measured cell surface temperatures.