Modelling Li-ion cell thermal runaway triggered by an internal short circuit device using an efficiency factor and Arrhenius formulations

This paper presents a novel model for analyzing the thermal runaway in Li-ion battery cells with an internal short circuit device implanted in the cell. The model is constructed using Arrhenius formulations for representing the self-heating chemical reactions and the State of Charge. The model accounts for a local short-circuit, which is triggered by the device embedded in the cell windings (jelly roll). The short circuit is modeled by calculating the total available electrical energy and adding an efficiency factor for the conversion of electric energy into thermal energy. The efficiency factor also accounts for the energy vented from the cell. The results show good agreement with the experimental data for two cases – a 0D model and a 3D model of a single cell. Introducing the efficiency factor and simplifying the short-circuit modeling by using an Arrhenius formulation reduces the calculation time and the computational complexity, while providing relevant results about the temperature dynamics. It was found that for an 18650 NCA/graphite cell with a 2.4 Ah capacity, 28% of the electrical energy leaves with the effluent.