Lithium-ion batteries are, by their very nature, dangerous. 

And a great article in online technical magazine Wired explains fully why. 

It reveals: “Inside the battery the main line of defence against short circuiting is a thin and porous slip of polypropylene that keeps the electrodes from touching. If that separator is breached, the electrodes come in contact and things get very hot very quickly.

“The batteries are also filled with a flammable electrolyte, one that can combust when it heats up, then really get going once oxygen hits it. Not scary enough? That liquid is mixed with a compound that can burn your skin.” 

So why even use them?

Wired states: “Lithium-ion batteries are incredibly efficient. They stuff freakish amounts of energy in a tiny package, one that can keep a phone or laptop running all day. Li-ion power cells are also a very mature technology. The first rechargeable lithium-ion batteries were used in Sony’s Handycams more than 25 years ago, and now there are dozens of battery suppliers around the world.

“If you're making a camera, car, plane, or fitness tracker, including a Li-ion cell is generally a plug-and-play step in the manufacturing process.

“But unlike most mature tech, they seem to get more volatile as time goes on. That's because we demand higher-capacity batteries in slimmer packages at cheaper prices.

“Most modern gadgets are designed to be as slim, light, and sleek as possible. That can wreak havoc on an otherwise well-built battery, especially a high-capacity cell packed into a small body. 

“Pressure from the hardware surrounding the battery can cause damage to the electrodes or the separator and lead to short circuiting. Inadequate venting or thermal management can cause the flammable electrolyte inside the battery to heat up. 

“Once it's too hot, chemical reactions can cause it to heat up even more and spiral out of control. It's a situation called thermal runaway that often ends in an explosion or fire—and then a bigger one once oxygen comes into contact with the chaos.” 

And thermal runaway can cause major problems when it happens on aircraft. 

A pioneering invention called AvSax are now on board several major US carriers.

The AvSax is a special fire-retardant bag used when lithium-ion batteries in mobile phones or other electronic devices catch fire and has been deployed on planes several times already this year.

Simply pour at least two litres of water into an AvSax and then drop the burning device into the bag. The water activates the polymer gel inside the bag causing it to expand around the device. Should the device keep on venting then the AvSax is tough enough to absorb the force.

In short, the AvSax cools the batteries in the device, reducing the likelihood of the battery catching fire but if it does go into thermal runaway it is all contained within the bag.

There are hundreds of potential fire risks among the electronic gadgets people take on board aircraft.

Planes carrying 100 passengers could have around 500 lithium batteries on board when you tot up all the laptops, cameras, e-readers, tablet computers and mobile phones .. and they pose a potential fire danger.

To read the full Wired article go to https://www.wired.com/2017/03/dont-blame-batteries-every-lithium-ion-explosion/