Fire Extinguishing Effect of Water Mist with Different Pressures on LFP Battery Module

The problem that fire needs to be extinguished quickly after batteries catch fire is urgently required to be solved in the large-scale application of electrochemical energy storage stations. At present, tests of extinguishing fire of lithium-ion battery with fine water mist are mostly focused on small-capacity single cells. The test platform is far from the actual environment of the energy storage cabin. Therefore, according to the extinguishing mechanism for verifying water mist fire-extinguishing effect, we designed a test plan according to the energy storage battery's actual operating conditions, and built a test platform reference to the actual energy storage cabin. A 344 Ah LFP battery module was adopted as a test object. Under the abuse of overcharge, the battery module would thermally run away and then burn. Four types of water mist with different pressures were used to extinguish and compare the fire extinguishing effects. The test proves that fine water mist with a sufficient pressure can effectively extinguish the fire of the LFP battery module. During the extinguishing process, there are cooling and heat insulation radiation mechanisms, and a fine water mist barrier phenomenon has been observed. It is found that the pressure of fine water mist below 10 MPa is inversely proportional to the fire extinguishing time. As the pressure increases, both the fire extinguishing rate and the cooling rate increase. The experimental results show that, for the fire protection design of large-capacity LFP battery modules, it is more economical and efficient to choose a fine water mist of 6 MPa or more as the fire extinguishing agent. The results of this study can provide test support for the fire protection measures of lithium iron phosphate energy storage power stations and the formulation of battery module fire-extinguishing specifications. © 2021, High Voltage Engineering Editorial Department of CEPRI. All right reserved.