Charged issue: how phone batteries work – and why some explode

Batteries fuel modern life, from smartphones to electric cars. But how do they store electricity and why don't they last long enough? And, as Samsung might be asking itself, why do they blow up?

Battery life is an explosive issue. Literally, as Samsung is discovering to its dismay. The company's Galaxy Note 7 smartphone was praised upon release for best-in-class battery life, far outpacing its key competitor, the iPhones 6S and 7 Plus. Then it started blowing up. Samsung issued a recall and replace programme, and the replacements also started blowing up, forcing the company to suspend production entirely.

The affair marks the latest road block on the long fight to improve the batteries that power our electronics. While processing speed doubles around every 18 months, battery capacity takes almost a decade to improve to the same degree. That gap is starting to cause problems, but as Samsung has found to its cost, it's not easy to fix.