Controlling thermal runaway propagation in lithium-ion battery module by two-phase flow of nitrogen and water mist

Thermal runaway (TR) and its propagation in lithium-ion battery (LIB) module have been the most serious potential risk that hinders its use and development. Although carbon dioxide (CO2), liquid nitrogen, halon and other extinguishing agents have a certain effect of suppressing LIB TR propagation, these agents are not effective in preventing the LIB from re-igniting, and there are certain health hazards for people in relatively confined spaces. Considering the strong cooling effect of water mist and the oxygen asphyxiation effect of nitrogen (N-2), the controlling effect on TR propagation in LIB module and the inhibition mechanism using two-phase flow of N-2 and water mist (NWM) deserves in-depth research. Using pouch ternary NCM LIB cells, a series of experiments were conducted to study the controlling effect on TR propagation of LIB module by the low-pressure NWM of 0.3-0.7 MPa. Results show that the NWM has good cooling effect and oxygen isolation effect, which can restrain the TR of cell and prolong the TR propagation in LIB module. The heat dissipation of the LIB module by NWM (Q(NWM)) is related to the mass of water mist and the pressure of the NWM. The ratio of volume flow of water mist to N-2 under different low-pressure can be fitted with a Gaussian curve, and the Q(NWM) presents a Gaussian curve trend with different low-pressures of the NWM. When the NWM of 0.5 MPa is applied, the NWM has the best inhibition effect on the TR of the LIB module. The Q(NWM) is 1421.97 W, and the average cooling rate of a single cell can reach 3.23 celcius/s. At the same time, there is a positive correlation between the Q(NWM) and the ratio of volume flow of water mist to N-2. This study can contribute significant references for effectively controlling thermal risks caused by TR and its propagation in LIB modules in new energy application fields, as well as the formulation of safety laws and regulations.