Lithium-ion battery thermal runaway propagation prevention — predicting critical parameters considering uncertainty

Li-ion batteries (LIBs) are integral to modern society, driving the electrification of transport and supporting renewable energy generation to meet Net Zero. However, LIBs suffer from the potential to undergo thermal runaway (TR) which can lead to fire and explosions. Computational modelling of TR is essential to understanding its hazards, and to accurately quantify risks there is a need to account for the uncertainty in TR behaviour. To adequately predict the safe limits of battery operation we incorporate the stochasticity of thermo-physical and kinetic reaction parameters in module thermal runaway propagation (TRP) analysis. A 0-dimension heat transfer model for TRP predictions is validated against experimental findings. From this, Monte Carlo simulations are undertaken to determine the uncertainty in the predicted cell temperatures, times to cell TR and times to TRP. The critical heat dissipation coefficient to prevent TRP considering cell uncertainty was found to be 2.5 and 4.6 times larger for LFP and NMC stacks, respectively, compared to the scenario where cell uncertainty was not considered. For the LFP stack, the less severe TR events mean, in theory, that TRP can be prevented by heat pipe or submersion cooling thermal management systems. Without considering cell stochasticity there is a significant overestimate of TRP time and an underestimate of critical heat dissipation coefficient to prevent TRP. Hence, the predicted safe time for evacuation and appropriate thermal management methods are inaccurate. This work highlights the need to incorporate uncertainty in predictions of risk.