How electric vehicle battery explodes? Fully explained

So till now, we understood about the batteries, but our main focus is how do they explode or why do batteries catch fire. Let deep dive into it.

   Now first we need to understand that an explosion doesn’t necessarily require an exorbitant amount of energy. Yes, you read it right, the explosion doesn’t necessarily require a great amount of energy but what it takes is the least time frame to release every small amount of energy stored inside. For example, a ‘Li-ion battery stores 1kWh of storage capacity, it will be self-sufficient for combustion if all of that 1kWh is made to release in few seconds.

Now as of before let’s discourse about the battery explosion at a smaller frame. Let’s take a smartphone battery and before talking about its explosion let’s see its components. So every battery has an anode, cathode, and a separator in common and if an explosion takes place it happens due to these three components only. 
So, what happens is the separator which separates both the anode and cathode but let their ions transfer only, breaks or damage and finally, the shortcircuit takes place which further leads to an explosion.

When we specifically talk about EV batteries the major cause of the explosion of batteries is their “Separator”. The main application of the separator is to keep the material of both anode and cathode away but continue the transfer of ions feasibly. But as market demand and technological advancements happening it happened to make the separator thinner and more thinner. However, a separator lasts very-very long but in such conditions, even a single mishandling with the battery can lead to permanent damage to the battery. 
Let’s elaborate more, the separator is delicate and sensitive to any external pressure or internal chemical misbalance. While charging the battery expands (a very little) and when discharged it compresses (a very little) and it creates pressure on the separator and the separator may fail and the moment the separator fails the anode and cathode come into contact which leads to shortcircuit. As shortcircuit happen it creates permanent damage inside the battery and slowly-slowly it releases all its electrical energy into heat and chemical energy and due to this, the explosion takes place.

Now as we came to a conclusion that the failure of the separator is the reason behind the failure of a battery, we will figure out the potential reason behind the damage of the separator.
Mainly there are two reasons that impact the separator i.e. electrical instability and external shocks which can give potential damage to a thin separator. We will understand both phrases separately, electrical instability occurs when the battery is being charged or discharged more than the rated capacity. Whenever you buy any rechargeable battery you will surely see rated Undervoltage and overvoltage but if the battery exceeds these ratings while charging, the separator will surely damage.
External shock including accident, battery falling from a certain height, stretch and buries, etc. external shocks may not damage the battery immediately but after a certain period is will explode or cause heavy damage.