Investigation of thermal runaway characteristics of lithium-ion battery in confined space under the influence of ventilation and humidity

The thermal runaway (TR) characteristics of batteries in tunnels with ventilation and humidity have not been well-understood. This paper employed experimentally investigated battery TR under the influence of ventilation and humidity, examining the TR process and hazard evolution. The results show that the characteristic time of thermal runaway increased exponentially with increasing wind speed, while the characteristic temperature decreased exponentially. At 3 m/s wind speed, TR onset time exceeded 20 min, and TR onset temperature decreased by 39.8 %. The influence range of the smoke threat initially increased and then decreased with increasing wind speed. The threat was greatest at 1 m/s, with dimensionless peak temperature rise (Delta Tpeak/T0) Delta T peak /T 0 ) and CO concentrations of 6.1 and 1383 ppm, respectively, on the downwind side. Increased humidity in the tunnel further delayed TR and reduced its threat. A wind speed of 1 m/s corresponding to a humidity of 85-90 % was found to be the optimal condition for mitigating thermal runaway in humidified tunnel. The input heat and self-generated heat are the main causes of triggering thermal runaway and increasing battery temperature, both of which are influenced by wind speed and humidity. This paper provides a deep insight on the TR hazards in complex confined space.