Combustion Characteristics of Electrolyte Pool Fires for Lithium Ion Batteries

Combustion characteristics of electrolyte pool fires are investigated both theoretically and experimentally under various pan diameters and external heat fluxes using a cone calorimeter. The heat release rate (HRR), mass loss rate (MLR), flame height and gas release rate are measured. Experimental results show that the peak HRR and MLR per unit area are proportional to external heat fluxes and inversely proportional to pan diameters. Dimensionless flame height is observed to decrease under a bigger pan diameter. Peak CO and CO2 production rates increase with a bigger pan diameter or external heat flux, but these two factors show limited influence on the mole ratio of CO/CO2. Comparing to hydrocarbons, the electrolyte has relatively low effective heat of combustion and high heat of gasification which results in lower HRR or MLR, and a higher flame height. An empirical model is developed to predict the peak HRR of the electrolyte pool fire based on pan diameter and external heat flux. Besides, Heskestad's correlation has been improved to predict the average flame height of the electrolyte pool fire by considering the effective heat of combustion, pan diameter and mass stoichiometric ratio of air to fuel.