It’s a matter of chemistry
Lithium-ion batteries are in everything nowadays. Their lightweight and high capacity make them great for all kinds of mobile applications. They can be found in wireless headphones, laptops, cell phones, kids toys and portable speakers. If it needs a battery and has a large power draw, chances are the Lithium-ion battery is inside. These batteries can be safely charged over and over again without issues or developing a cell memory. Cell memory happens in older batteries when they are not charged and discharged properly. I have discussed it before in an article about keeping your batteries in top shape.
So what happens that can cause these batteries, or really any battery to explode? Let’s look at a couple of factors.
What is a Lithium-Ion Battery?
A lithium battery is a small cell that uses lithium compound that allows for the movement of electrons from one pole to the other. I am really oversimplifying it. Long story short, the Lithium is the medium used for power generation. If you want to read more, here is the Wikipedia article about it. It goes deeper into the chemistry than I can. These batteries, or more accurately, power cells, provide a lot of the characteristics of a power source that is great for small scale applications.
What goes wrong?
The simplest explanation is that the battery/cell contains a flammable material. Now, this is housed is a protective case that makes up the exterior of the battery. The problem comes from when the battery is either overcharged or allowed to drain completely. The chargers for these batteries and the batteries themselves are supposed to have circuits built in to prevent an overcharge/discharge situation. Without a charge in the cell, the lithium gets hot and the gasses expand and explode.
While most battery manufacturers follow strict quality control to ensure the cells they produce are safe, some cut corners to lower the cost of their cells, i.e. the batteries sold to Samsung for the Galaxy Note 7. These batteries were allowed to overcharge and that caused the explosion. This is also what was happening with the “hoverboards” cheap batteries in cheap toys, not the best mix.
What can you do?
First thing is to check the battery once in awhile, now this is harder with some of the newer smartphones that the battery is not removable. But for your easier to access devices, it’s a good idea to pull the battery out once in awhile and make sure it is not damaged in any way. If you see cracks or bulging stop using it right away. Don’t throw the battery away but take it to an electronics recycler.
If you are using something and it starts to smoke and get hot, the best thing to do is dump it in sand. Do not put water on it. If you do not have any sand, just throw the item far from you and allow it to explode. Then take care of the resulting fire. Once the gas escapes from the cell the fire should put itself out. If the fire catches other items on fire, that is a problem, and the fire you should fight if you can.
Also, make sure you check with the consumer safety groups in your country. They usually maintain a list of items with known issues. If there is a recall, make sure you stop using the item and return it as directed.
These batteries are safe but need to be respected, like anything else. They power our modern lives and I don’t see that changing anytime soon. Some general awareness of the explosives you are carrying in your pocket or on your head is something to be aware of, but not afraid of.