Flame propagation characteristics and reaction kinetics of electrolyte solvent vapor (ethylene carbonate) released from lithium-ion batteries

The accidental release of electrolyte solvent (ethylene carbonate, EC) vapor is a critical factor exacerbating fire incidents in lithium-ion batteries. This study investigated the combustion behavior of premixed EC gases under various initial conditions. An increase in both the initial pressure and the equivalence ratio increases intrinsic instability, which enables EC flames to reach the self-acceleration phase sooner and thereby increases the risk of accidents. To gain deeper insights into these phenomena, we analyzed the effects of the equivalence ratio and initial pressure on the controlling parameters for thermodiffusion (T-D) and hydrodynamic instability (D-L), flame morphology, critical conditions for instability onset, and self-acceleration of premixed EC flames through linear stability theory. Furthermore, we updated the chemical kinetics model for EC, improving the prediction accuracy of the laminar burning velocity by 54.2%. Finally, a strong linear correlation between the experimental critical Peclet number normalized by the effective Lewis number and the experimental Markstein length was identified. The findings of this study will contribute to understanding the flame propagation characteristics and complex chemical processes of electrolyte solvent vapors, which are crucial for preventing fires in lithium-ion battery energy storage systems.