Over the last decade or so, there have been a number of recalls of Li-ion powered products. In the mid 2000s, Dell notebooks suffered a number of issues and HP has recently warned those who bought some of its products during the last three years of ‘the potential to overheat, posing a fire and burn hazard to customers’.
Li-ion was also an issue with Boeing’s 787 Dreamliner aircraft, with fires reported on a couple of planes, notably an Ethiopian Airlines 787 at Heathrow and a Japan Airlines plane at Boston. Understandably, all 787s were grounded.
Now, the latest Li-ion battery issue sees Samsung recalling its Galaxy Note7 phone following a spate of phone fires, mainly centred around charging.
Why should Li-ion batteries catch fire? There are a number of reasons, but two stand out: overcharging; and manufacturing issues.
Li-ion batteries need to be charged carefully and a number of companies have battery charging ICs which do the job perfectly. But if there’s a problem with one chip out of millions, that could have unpleasant consequences.
The other problem is that Li-ion battery manufacturers are being pushed to make their products as small as possible. This means the separators used to keep various parts of the battery apart are thinner than ever and manufacturing issues could expose the battery to damage.
One solution is to use a different battery chemistry. Lithium sulphur, for example, could provide up to five times the energy density of Li-ion, as well as a higher operating voltage. But the way in which the sulphur cathode in such batteries expands creates significant issues and the technology remains in the early stages of development.
Battery chemistry hasn’t evolved at anything like the rate of electronics technology, partly because manufacturers haven’t been pushed to create new chemistries. It’s only in the last couple of years that the pressure has mounted. Because of this, it’ll still be sometime before Li-ion is replaced with a safer means of powering devices.
