Characterisation of heat and gas emissions in thermally induced battery failure on commercially available 18650 Li-ion cells

A method of holistic characterisation of thermally induced cell
failure has been established. Single cylindrical cells are subjected
to a defined heating ramp. Critical heat influx triggers gas
generation from chemical degradation reactions. The onset of fast
exothermic reactions then drives the total breakdown of cell
components towards the thermal runaway. The large quantities (up
to 6000 cm³) of vent gas are investigated quantitatively. H2, CO
and CO2 as well as short-chain hydrocarbons are detected in this
process. Thermal characterisation of endothermic and exothermic
effects is performed, indicating up to 30 kJ of heat being released
from a single 18650 cell during full-scale exothermic breakdown
and cell deflagration.