Monitoring thermal runaway of lithium-ion batteries by means of gas sensors

Thermal runaway in lithium-ion batteries (LIBs) cannot be completely avoided and poses a risk of fire and explosion incidents. Existing battery management systems (BMSs) lack the timeliness and accuracy in warning of the thermal runaway, thus it is difficult to prevent such accidents. This paper presents a review of the research progress in LIB thermal runaway, focusing on the evaluation of different indicative signals and detection methods including temperature, electrical signal, and gas monitoring. The limitations of temperature and electrical signal monitoring, such as lacking timeliness and insufficient sensitivity, contribute to the inadequate reliability of current BMSs. To overcome these limitations, a gas monitoring solution is proposed for the ultra-early warning of the thermal runaway. By analysing the release of gases during the thermal runaway process, certain gases like CO2, volatile organic compounds (VOCs), particularly hydrocarbons (CxHy), and CO are identified as suitable indicators for the ultra-early detection of the thermal runaway. The introduction of gas sensors capable of detecting these gases is discussed. Given the low power consumption and high safety requirements, low/room temperature gas sensors, such as Non-Dispersive Infra-Red (NDIR) and light-excited/assisted gas sensors, have great potential for the ultra-early warning of the thermal runaway of LIBs.