Investigation into the effects of emergency spray on thermal runaway propagation within lithium-ion batteries

Inhibition a battery's thermal runaway propagation can avoid serious accidents in electric vehicles. Emergency spray has been proven to be effective in suppressing thermal runaway of a single cell, but the effect of inhibiting thermal runaway propagation between multiple batteries still needs further investigation. In this study, the characteristics of thermal runaway propagation was experimentally investigated, and the emergency spray technology, with different cooling durations, was applied in various stages of thermal runaway propagation. The results indicated that the continuous spray could not only reduce the average maximum temperature, but also delay the diffusion among multiple batteries and provide further response time. However, after-combustion was a frequent occurrence when the spray shut down. A correlation model was proposed to evaluate the maximum heat production of lithium-ion batteries by calculating the enthalpy and mass of the reactants and short circuit energy. The required cooling quantity is determined by experiment and verified by experiment. These results could help the development of a cooling strategy for suppressing the thermal runaway propagation effectively with minimum cooling capacity.