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Light-based battery makes its own power

Sure, you can make solar-powered devices that store their excess energy in a battery, but what about the battery itself? Unfortunately, it's still behind the times -- the lithium-ion cells you see today have to be connected to another device to charge, and they're occasionally very dangerous thanks to their chemical makeup. A team of Indian researchers may have just licked those problems, though. They've developed a battery whose titanium nitrate anode (where current flows into the device) is driven by light, both natural and artificial. In a well-lit area, a prototype can recharge itself without using either an external source or unstable chemicals.

The existing technology isn't ready for prime time yet. While it tops up in 30 seconds, it's barely powerful enough to run an LED light or a small fan, let alone your phone. If the technology improves, however, you could see more gadgets that not only don't have to be plugged in, but won't ignite if you drop them a certain way.