Lithium-ion batteries are great and all—having heralded in a new age of portable electronics and allowed for the possibility of mass-market electric cars—but they have a few major drawbacks. For instance, they have a propensity to catch fire and explode and, although they have a much better energy storage capacity than say lead-acid or nickel metal hydride (NiMH) batteries, they still weigh too much to pack more than a couple hundred miles of range into a passenger car.