Potential Safety Hazards Associated With Li-Ion Battery Thermal Runaway Vent Gas Heat Transfer in Energy Storage Systems

Abstract This study focuses on assessing the safety hazards associated with Lithium-ion battery vent gas in energy storage systems by convective heating due to direct impingement. Heat fluxes and convection heat transfer coefficients of vent gas at the module top surface were estimated. This analysis was carried out by CFD and thermal runaway model simulations. Four cases of two gap heights between the cells and walls of their module (H) and two vent gas jet velocities (vJet) were investigated. vJet values used in the simulations were based on venting predictions for failing 5 Ah and 10 Ah cells, and the two gap heights were selected based on estimates from a deployed system. The simulations results show that the vent gas could play a vital role in module-to-module thermal runaway propagation by pre-heating the cells in adjacent modules. Multiple sequential failures are needed to initiate a thermal runaway in the cell directly exposed to the vent gas jet. The analysis shows that vent gas jet temperature has a significant effect on the number of failures needed to raise the exposed cell surface temperature to a dangerous level.