Thermal runaway-induced current interrupt device and vent activation behaviour in an 18650 lithium-ion battery cap using the Johnson-Cook criterion

Lithium-ion batteries (LIBs) thermal safety issues such as thermal runaway (TR) triggered by thermal or mechanical abuse have been one of the most important factors hindering its development at present. In order to effectively release the excessive pressure caused by TR, a safety vent is used as a reliable safety device in commercial LIBs. However, the current interrupt device (CID) and vent activation behaviour and mechanism are still unclear in the mesoscale. Herein, finite element simulations of metallic material deformation and failure during CID and vent activation at preset dynamic incremental pressure loads and various constant temperatures for a commercial 18650 LIB were carried out by introducing the Johnson-Cook (J-C) damage model in this study. The three-dimensional evolution, dynamical and mechanical analysis of the deformation to damage behaviour are quantitatively characterized. The CID- and vent-activation pressure based on the J-C damage criterion is significantly higher than the pressure value corresponding to the maximum von Mises stress. The results show fracture strain of the burst disk notch and plate will not exceed 0.93 % and 0.048 % respectively when the TR reaches the onset temperature. The temperature-dependent activation time reduction rate was developed to quantify the effect of temperature on the CID-and vent-activation times, indicating that TR temperature's effect on vent activation is significantly stronger than that of CID. These results may provide a reliable guide to LIB safety design.