Like many people, I've been surprised to hear reports of fires involving mobile phone batteries. Lithium-ion batteries are used in lots of devices, but sometimes they can go wrong in a way that causes them to catch fire. So now scientists have created batteries with fire extinguishers built in.
A fire-retardant chemical sits inside a shell within the battery. When the battery gets very hot the shell melts, releasing the chemical and stopping the fire within seconds. I wonder when we'll start to see this in our own phones?