Many electric cars run on rechargeable lithium-ion batteries, an expensive, inefficient technology that accounts for more than half of the vehicle's total cost and a whole lot of weight. One promising alternative is the lithium-sulfur battery, which can theoretically store five times more energy at a much lower cost - sure, it may cause acid rain but that is technology issue to be solved, not a science one.
Lithium-sulfur technology has a major science drawback: After a few dozen cycles of charging and discharging, the battery stops working.