Experimental study of intermittent spray cooling on suppression for lithium iron phosphate battery fires

Nowadays, fires caused by thermal runaway (TR) of lithium ion battery (LIB) remains a potential risk in its application. An effective method is urgently required to suppress LIB fires. In this work, a novel cooling method combining dodecafluoro-2-methylpentan-3-one (C6F12O) agent with intermittent spray cooling (ISC) is proposed for suppression of lithium iron phosphate (LFP) battery fires. Besides, the influence of spray frequency and duty cycle (DC) on spray cooling efficiency are discussed. The results indicate that atomized C6F12O can effectively suppress LFP fires, reduce the production of toxic gases and heat release rate (HRR). However, after C6F12O runs out, the rapidly elevated temperature and the release of combustible gases mean that the TR battery requires longer and more efficient cooling. Compared with continuous spray cooling (CSC), ISC not only extends low temperature duration but also decreases the temperature rise rate of the battery. As DC increasing, C6F12O agent first exhibits an enhancement effect and then an inhibition effect on cooling performance. It is suggested that the optimum DC is 55.4% for the suppression of 14 Ah LFP fires. For the LIBs with higher capacity and higher fraction of active materials, the optimum DC is required to be higher.