Thermal runaway is a condition where the battery's temperature increases rapidly and sets the stage for 'Electric Arcing'. It's a dramatic process where the battery doesn't just fail; it transforms into a volatile environment. The temperature can escalate up to 900°C, igniting a chain of exothermic reactions. Remarkably, a battery can emit around 66% of its mass in the form of gas and particles during this event. This ejection is not just a byproduct; it is the precursor to electric arcing.
Arcing in batteries is like an uncontrolled electrical wildfire. It occurs when electric currents traverse through a gas-filled gap, creating intensely hot plasma channels. In the confined spaces of a battery pack, this can result in severe consequences, from burning through the casing to igniting flammable gases. The complex movement of particles and gases during thermal runaway creates the perfect storm for such arcs to form.
To study this arcing, researchers (Ledinski T et. al., 2023) have recreated thermal runaway scenarios in controlled setups. The focus has been on understanding how the mix of gas and particles emitted during this process can lead to electric breakthroughs, subsequently causing arcing. By analyzing the ejected particles and studying the composition of the emitted gas, they have started to piece together the puzzle of these dangerous electrical phenomena. Electric breakthroughs, often referred to as electrical breakdowns, occur when an insulating material becomes electrically conductive.
Contrary to initial assumptions, it's the ejected particles, more than the venting gas, that play a pivotal role in triggering electric arcs. Experiments reveal that these particles, especially "copper fragments" from within the battery, can create pathways conducive to electrical breakthroughs. This finding shifts the narrative from a generalized hazard to a more targeted understanding of arcing's root causes.
The insights gained from these studies are vital for future battery designs. They point towards the necessity of rethinking the internal architecture of battery systems, especially considering the pathways of venting jets in cases of thermal runaway. Preventive measures could include designing layouts that minimize the risk of these jets interacting with electrical components, thereby reducing the likelihood of arcing.
Studying the phenomenon of thermal runaway and formulating innovative designs and solutions through rigorous testing such as this can lay the groundwork for mitigating or even eliminating the devastating impacts of thermal runaways, as observed in various incidents. This approach not only enhances our understanding of the underlying mechanisms but also drives the development of safer and more resilient battery technologies.
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