A nail is enough to cause a mobile phone to erupt in smoke and flames. 

A lecture on BBC TV has shown just how easy it is to send a lithium ion battery into dangerous thermal runaway with a dramatic experiment on TV. 

It was given by chemist Saiful Islam who told the audience it was far too dangerous for the experiment to be done in the studio and instead it had to be carried out on the building's roof. 

The audience watched as a nail was forced into a mobile phone which instantly caught fire with a loud pop, filling the large see-through container it was in with smoke. 

Saiful, a professor of materials chemistry at Bath University, explained: “That is an intense reaction. What's happening there is that the nail connects two electrodes and short circuits the battery which makes in overheat and this mimics the shortcomings caused by bad battery design.

“It's not the lithium that explodes, it's the liquid electrolyte that sits between the two electrodes and that electrolyte is made up of a lithium salt in a solvent and that solvent is highly flammabnle. If it gets too hot it simply erupts out of the casing.” 

Several mobile phones have caught fire on planes – some after they have become trapped in seats and being crushed sparked the same chemical reaction, causing them to catch fire. 

To see the video go to http://www.bbc.co.uk/programmes/b086yr10

* A pioneering invention called an AvSax (www.avsax.com) can minimise the fire danger on board aircraft in seconds with its unique use of water.

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