Experimental Research on the Ignition Characteristics and Inhibition Strategy for Venting Emissions Mixture of Failure LiFePO4 Battery

When the concentration of a gas is below its lower flammable limit and the content of a liquid is below its minimum explosible concentration, their combined fuel mixture can be ignitable. The flammability characteristics and inhibition strategies for battery emission mixtures deserve further in-depth research attention. This article presents experimental research on the ignition characteristics and inhibition strategy for a venting emission mixture of a failure LiFePO4 battery. By identifying the components of venting emissions, ignition experiments for gases, electrolyte mist, their combination fuels, and mixtures with additives are performed to determine the flammable parameters, including ignition sensitivity and severity. The hybrid combination of non-flammable venting gases and electrolyte mist has the potential to induce ignition. However, there still exists a non-ignition region, where the gas concentration ratio (mg) is below 0.15 and the liquid concentration ratio (ml) is below 0.1. A safety design principle can be proposed: increasing ignition temperature, prolonging ignition time, and reducing maximum pressure. Adhering to this principle, a non-flammable electrolyte consisting of 1 mol LiPF6 in EC:DEC = 1:1 vol%, with FEC at 10% and VC at 1%, can be considered as an optimization strategy. In comparison to the original gas–liquid mixtures, the region where no ignition occurs becomes wider when both the mg is below 0.45 and the ml is below 0.3. The new two-phase mixture has an ignition temperature of 835 °C, which is, respectively, 50% higher than that of the original mixture. Overall, this experimental research demonstrates an innovative methodology for assessing the battery venting emission mixture safety while proposing a design principle for modifying non-flammable electrolyte functional materials. Consequently, these findings can contribute to formulating more suitable preventive and protective measures for commercial electric vehicles and battery energy storage systems’ thermal safety designs.