A Study on a Method for Controlling Thermal Runaway Propagation in ESS Using Cooling Water

A method for injecting water into a module to suppress lithium-ion battery fires in an Energy Storage System (ESS) at an early stage was investigated. Fire suppression experiments were performed on a module consisting of 28 pouch-type cells (145 Ah), each charged to more than 90% capacity. To induce thermal runaway, the surface of a single cell inside the module was heated at a rate of 7 ℃/min, after which water was injected into the module at a flow rate of 20 L/min for 20 min. When the injected water effectively absorbed and removed the heat generated by the battery, fire was suppressed and thermal runaway propagation was prevented. However, under identical injection conditions, if the battery heat was not adequately absorbed, all cells were completely consumed by heat energy. This difference was attributed to the location of the water inlet. These results confirm that, in order to suppress ESS fires, it is critical to analyze the module’s internal structure and optimize the placement of both the inlet and outlet so that the injected water maintains maximum contact with the battery cells.