These days, the gadgets we carry are improving with frightening speed – each year bringing a cavalcade of new features, capabilities, and improved hardware. But the power sources that run those gadgets seem to be stuck in about 2007. We know that the world is going device-crazy, with mobile internet use expected to surpass PC use by next year, and a whole new category of wearable devices (led by smart watches) on the way. So why are batteries still so terrible?