Experimental study on suppressing thermal runaway propagation of lithium-ion batteries in confined space by various fire extinguishing agents

Thermal runaway initiated in an individual cell may transfer heat to adjacent cells, and cause thermal runaway propagation. Thus, mitigation and prevention of thermal runaway propagation using extinguishing agents are significant. In this work, fire and extinguishing tests on 117 Ah LIBs with Li(Ni0.8Co0.1Mn0.1)O2 (NCM)/graphite electrodes are investigated. The suppression effects of different extinguishing agents including HFC-227ea, C6F12O and water spray on thermal runaway propagation in confined space were compared. Results show that thermal runaway propagation can occur in LIBs module even with thermal management measures. When activated immediately after the thermal runaway of the first cell, each agent can extinguish the LIBs module fire. However, the cooling capacity of extinguishing agent is the key factor to suppress thermal runaway propagation. The heat dissipation of HFC-227ea, C6F12O and water spray in fire extinguishing test is 24.8 kJ, 111 kJ and 459.8 kJ, respectively. Thus, HFC-227ea can hardly suppress the thermal runaway propagation. Although C6F12O can not prevent thermal runaway propagation, it can decrease the battery temperature, slow down the heat transfer rate and prolong the propagation time. While water spray has the best cooling effect, which can prevent thermal runaway propagation.