Researchers at Imperial College London, the Swedish Institute of Composites, and Volvo are looking to build auto bodies with carbon composites that can serve as capacitors (devices that hold an electrical charge)  that could store more electrical energy than batteries. The dual-function materials could also make E.V.’s and hybrid vehicles lighter.

To enable the composite materials to store electricity, the resin that binds the carbon fibers is laced with lithium ions; the fibers serve as conductive electrodes for this type of charge-holding capacitor.

If future composite structures could store energy as efficiently as lithium-ion batteries, an E.V. would require only the roof, hood, and trunk lid to be made of such materials to achieve an 80-mile range, the researchers said.