A wise man once said:<\/p>\n\n\n\n
\nDon\u2019t put Li-Ion batteries in an oven or smash a nail into them.<\/p>\nby a wise man<\/cite><\/blockquote>\n\n\n\n
Ok it wasn\u2019t a wise man, it was me. But still, I would say this is general life-advice one should adhere to. Unless<\/em> of course you are working in a lab investigating the thermal runaway behavior of batteries. These are essential tests to understand how batteries respond to overheating (i.e. \u201cstick it in an oven and see what happens\u201d) or impact damage (i.e. a \u201clet\u2019s hammer a nail into this thing\u201d). Before we talk about such tests in more detail, let\u2019s take a quick step back and recap on what Thermal Runaway is and why it\u2019s important.<\/p>\n\n\n\n
Thermal Runaway: a recap<\/h2>\n\n\n\n
Thermal runaway of batteries is a dangerous phenomenon where the battery cell overheats uncontrollably. A self-sustaining feedback loop occurs where the battery receives a certain amount of heating, and if left unaddressed, this in turn triggers a series of chemical reactions inside the battery cell.<\/p>\n\n\n\n
These reactions release even more heat and gases, which can result in huge pressure build up inside the battery. Extremely hot (over 1000o<\/sup>C!) and combustible venting gases are then emitted from the battery cell. When these gases ignite, fire spreads to other battery cells and catastrophic damage can occur to an electric vehicle, property and of course presents a high risk to life.<\/p>\n\n\n\n
Look at this short video which shows the violent nature of a thermal runaway event:<\/p>\n\n\n\n