Abstract
Without suitable design, lithium ion cells within electronic devices can be exposed to localised heating causing a thermal runaway event. This study focussed on determining the localised temperatures that would lead to venting and thermal runaway of a cell as well as to monitor the gases exhumed by these events. Commercially available 18650 cylindrical cells were monitored while being exposed to localised temperatures up to 250 °C. These temperatures were then applied while the cell was charged to simulate a heating scenario by the device electronics. The resulting damage to the cell was evaluated using x-ray tomography, mechanical testing and microscopy. Gases were analysed using a mass spectrometer. This work elucidates a particular failure mode of lithium ion cells allowing for a better understanding of battery safety and associated system design improvements. Additionally we anticipate this approach to facilitate further regulatory approvals for consumer electronics.