Gas Sensing Technology for the Detection and Early Warning of Battery Thermal Runaway: A Review

With the increasing popularity of battery technology, the safety problems caused by the thermal runaway of batteries have been paid more attention. Detecting the gases released from battery thermal runaway by gas sensors is one of the effective strategies to realize the early safety warning of batteries. The inducing factors of battery thermal runaway as well as the types and mechanisms of the gases generated at each reaction stage are first reviewed. According to the amount and starting time of gas release, five gases suitable for early detection of battery thermal runaway are mainly introduced, including hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), ethylene (C2H4), and methane (CH4). The application prospects of various gas-sensing technologies in the detection and early warning of battery thermal runaway are further evaluated. Benefiting from the superiorities of small size, high sensitivity, and stable performance, the resistive gas sensors are considered as promising candidates in this field, and their sensing mechanisms are also described in this review. In addition, the applicability and optimization strategies of gas sensors for the detection and early warning of battery thermal runaway are further reviewed systematically, on the basis of various aspects including sensing material, material design, sensing performance, etc. Finally, the potential directions and key points for the future development of gas sensors in the detection and early warning of battery thermal runaway are proposed.