Cooling water injection for EV battery fires: A targeted method to suppress thermal runaway

The increasing incidence of fires caused by thermal runaway (TR) in electric vehicles (EVs) with lithium-ion batteries is a growing public concern. Such fires are difficult to suppress due to high heat release rates, thermal insulation of battery cases, and oxygen generation within cells. This study proposes the Cooling Water Injection Case (CWIC), which delivers cooling water directly into the battery case through a hose pre-installed on the EV. Model-scale experiments with lithium-ion batteries were conducted, and results were analyzed using a simplified heat transfer model. The findings show that CWIC can suppress a passenger EV battery fire within minutes using about 100 kg of water. Based on these results, fire response plans tailored to severity are proposed, specifying necessary tools and operational guidelines. Compared with conventional firefighting tools, CWIC offers faster response, reduced water use, improved containment of harmful gases, compatibility with various vehicle designs, and enhanced firefighter safety. These advantages make CWIC a promising and practical solution for mitigating TR-induced fires in EVs, with potential implications for fire safety policy and EV design standards.