Fire and explosion characteristics of vent gas from lithium-ion batteries after thermal runaway: A comparative study

The combustion and explosion of the vent gas from battery failure cause catastrophe for electrochemical energy storage systems. Fire extinguishing and explosion proof countermeasures therefore require rational dispose of the flammable and explosive vent gas emitted from battery thermal runaway. However, the fire and explosion nature of the multiphase vent gas remains unclear. This paper comparatively investigates the fire and explosion hazards of the vent gas emitted by different kinds of lithium-ion batteries after thermal runaway. Hazard data are collected for batteries with cathode LiNi_xCo_yMn_zO₂ (x from 0.33 to 0.8) and LiFePO₄, which are prevailingly used or to be used in energy storage scenarios. The composition and content of the vent gas were analyzed using a pressurized container and gas chromatography. A 1-liter explosion sphere was used to determine the explosion limits, explosion pressure, and maximum rise rate of explosion pressure for five cell chemistries at 298 K and 101 kPa absolute pressure. The laminar burning velocities of the five vent gases were measured by Bunsen burner. The minimum concentration of fire extinguishing agent was tested using a cup burner. The results show that the fire and explosion hazards posed by the vent gas from LiFePO₄ battery are greater than those from Li(Ni_xCo_yMn_1-x-y)O₂ battery, which counters common sense and sets reminders for designing electric energy storage stations. We may need reconsider the choice of cell chemistries for electrical energy storage systems, and care more about the safety design against the fire and explosion disaster that may occur at system level. The explosion characteristics of the vent gases from five cell chemistries and the minimum fire extinguishing concentration can enlighten future risk assessments of electrochemical energy storage systems.