Research on the explosive characteristics and suppression mechanisms of gas generation during thermal runaway of batteries in a charged state

The gases released after the thermal runaway (TR) of batteries are important factors that trigger battery fires and explosions. This study collected gases generated by lithium iron phosphate (LFP) batteries with different remaining capacities under various charging states due to thermal abuse leading to TR. The combustion mechanisms of various gas components produced during battery thermal runaway were coupled and validated using CHEMKIN software, including vapor components of electrolytes such as dimethyl carbonate (DMC), H₂, CH₄, C₂H₆, C₂H₄, C₃H₈, CO, and CO₂. The main conclusions of this study are as follows: Batteries charged at a rate of 1.0C and heated to 100 % state of charge (SOC) exhibit the highest levels of gas hazards, with the primary components being H₂, CO₂, C₂H₄, CO, and CH₄. H₂ accounts for nearly two-thirds of the total gas composition. Simulation results show that the laminar burning velocity (LBV) reaches 73.2 cm·s⁻¹, and the flame temperature is 2261.6 K. As the proportion of DMC in the combustible gas mixture increases, both the flame temperature and net heat release decrease. At an equivalence ratio of 1.0, with 5 % dimethyl methylphosphonate (DMMP) added, the flame temperature decreases by 32.0 %, the laminar burning velocity decreases by 97.4 %, and the net heat release decreases by 99.7 %. Compared to H₂O and perfluorohexanone(Novec-1230), DMMP demonstrates superior suppression effects on LFP batteries. Among the radicals, the H radical is the most significant in promoting temperature rise, while the HO₂ radical plays the most prominent role in inhibiting the temperature increase.