Real-time monitoring of thermal runaway gases in lithium-ion batteries

Owing to their high energy density, long cycle life, and environmentally friendly properties, lithium-ion batteries (LIBs) are essential to electric vehicles, energy storage systems (ESSs), and portable electronics. However, as LIB use expands, safety concerns—especially thermal runaway (TR), which can cause fires and explosions—are drawing increasing attention. TR is typically triggered by internal short circuits, overcharging, or high-temperature exposure, leading to irreversible chemical reactions, excessive heat generation, and flammable gas emission, ultimately posing critical safety hazards. This review focuses on advanced techniques for real-time monitoring of gases released during TR in LIBs. Cutting-edge analytical methods—including real-time techniques such as Raman spectroscopy and microelectromechanical systems (MEMS)-based sensors, as well as time-resolved gas chromatography (GC)—have demonstrated enhanced sensitivity and accuracy in gas detection. These methods enable early detection and warning of TR, significantly improving battery safety and allowing end users and system operators to take timely, effective countermeasures. In conclusion, real-time gas monitoring technologies are essential for addressing LIB safety issues and enhancing the overall reliability and safety of LIBs in electric mobility and grid-scale energy storage. Future research is expected to advance these technologies, facilitating their integration into large-scale systems and establishing new standards for the safe, sustainable use of LIBs.