An increasing number of fires on board planes are caused by faulty batteries going into what’s known as ‘thermal runaway.’
But what is this and how can it be stopped?
Paul Shearing from battery research company UCL has written a specialist paper on the subject called Identifying The Cause Of Rupture Of Li-ion Batteries During Thermal Runaway and recently told Advanced Science News the many ways it can be triggered.
In short, he said it is caused when the battery becomes faulty which generates heat at a faster rate than the battery can deal with, leading to “cell failures which are characteristically catastrophic.”
He added: “With the increasingly widespread adoption of Li-ion batteries across a range of applications, alongside increasing energy density, it is important to understand and mitigate these problems. There are a range of issues that can trigger thermal runaway processes: unexpected chemical reactions, lithium plating inside the cell, short circuit as a result of contamination during the production process or poor ‘balance’ between the positive and negative electrode.
“Typically, during a thermal runaway process, one exothermic process will generate sufficient heat to trigger a second and so on until the cell undergoes significant ‘self heating’, leading to failure.”
When this happens the batteries can catch fire which happened on a China Southern Airlines Airbus on December 23 last year when a powerbank caught fire in a passenger’s luggage in an overhead locker.
The emergency forced the plane to land back at Penang airport in Malaysia where it had just taken off.
Paul said scientists are working hard to try to prevent these problems by testing new safety mechanisms within battery cells that would effectively shut the cell down if it overheats and lessen the impact of such a failure.
Paul revealed that the range of innovations includes “the production of new separators that are more resistant to short circuiting.”
Scientists are also looking at entirely new ways to change the chemistry in cells by moving away from lithium-ion.
But Paul stressed: “It is paramount that work on battery safety continues.”
* One way to tackle such incidents is to use an AvSax fire containment bag which can deal with fires in personal electronic devices and are now carried on planes operated by 65 airline companies across the world – including some of the biggest and best-known.
AvSax – which won the Queen’s Award for Enterprise this year - has been used 28 times to deal with emergencies since the start of 2017.
More than 13,000 are now carried on planes worldwide. If they are deployed they can be so effective the aircraft do not need to divert to another airports to make emergency landings which can cost airlines a fortune.