Thermal runaway experimental analysis on 18650 Lithium-ions batteries during nail penetration test

The need to find an alternative to transport powered by fossil fuels to reduce our impact on the planet is accompanied by the constant search for energy storage technologies. The excessive use of fossil fuels has led to a serious state of air pollution and is complicit in global warming; for these reasons, it has become of fundamental importance to change, gradually, the power system of transportation. Lithium-ions batteries are the most widespread technology for this purpose, but a fundamental parameter to take into consideration is the risk in case of an accident: during a collision with another vehicle, the batteries located inside the car are stressed considerably and this can be the cause of a puncture or irreversible deformation of the cell; events of this type are considered a risk for the occupants of the vehicle and all those involved in the accident as it can result in a high-temperature fire that can be potentially lethal. The stresses to which the vehicle is subjected during driving on the road such as vibrations, shocks and temperature changes must also be considered, stresses that, in the long run, can damage the battery pack. This work will examine the effects of different forms of abuse on Lithium-ions batteries, with a focus on mechanical and thermal abuse; specifically, the experimental section will collect data about the behaviour of 18650 cylindrical cells after nail penetration: tests were performed in different temperature conditions to better understand how the environment influences the thermal runaway. Thanks to temperature and gas sensors, it was possible to characterize the 18650 thermal runaway to find analogies and differences between each cell in different ambient conditions. The collected data can be useful to better understand the behaviour of Lithium-Ion cells subjected to different forms of abuse and can help to find solutions to reduce the dangerous effects for the safety of people who use this storage technology.