Electric cars face severe limits in how far they can drive before running out of juice. Better batteries that can both store more energy and give it up quickly are essential for extending that range. Now, researchers at the Massachusetts Institute of Technology (MIT) in Cambridge have come up with a novel battery-making strategy that steers in that direction. For now, the new batteries can power only small devices. But if the strategy can be made to work on a larger scale, a task more difficult than just using more battery material, it could give electric car makers the jolt they need.