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Phoenix666 writes:

Have you ever taken the back off your phone and seen that your battery has swollen up like an inflatable pillow? For the first time, scientists have been able to peer deep inside to see what is happening.

Lithium-ion batteries have become ubiquitous in phones, laptops and hoverboards because they are lightweight and hold a lot of charge. However, a  recent spate of explosions has raised safety concerns.

One reason these batteries are damage-prone is because of their structure, says Toby Bond at Canadian Light Source, a synchrotron facility in Saskatoon, Canada. They usually contain electrode sheets wrapped in a spiralling "Swiss roll", or "jelly roll", configuration to fit in as many energy-producing layers as possible, but this causes problems if gas forms inside.

Gas can build up if a battery becomes overheated or overcharged, or is left drained of charge for too long. Under these conditions, the liquid components in the battery can vaporise and produce gas. This causes the external casing to swell up, resulting in the characteristic pillow appearance.

Original Submission