how the heck does this explode?

A Wiimote Explodes Due to Parents Putting Lithium Batteries instead of Regular Alkaline Ones Just recently, a Belleville, Michigan family came home to find their room full of smoke. However, it wasn't a fire that created the smoke, it was one of their Wii remotes. How? Well it exploded. Luckily nobody was hurt since they were out of the house...