BMW is using carbon fiber composite unibodies for the electric i3 and i8 models to reduce their weight, thereby increasing their range. Now, Volvo is using carbon fiber in a novel way for EVs. Using carbon fiber it has developed a composite material that acts as a capacitor, storing electrical energy, so theoretically body panels and structural components could act as battery equivalents. Unlike conventional batteries, which add weight to a vehicle, the carbon fiber capacitive body panels wouldn’t just power the vehicles but also reduce weight.
To demonstrate the technology, Volvo replaced the the trunk lid, door panels, cowl, and hood of an S80 with the new composite. The panels are made of multiple layers of carbon fiber, insulated from each other with layers of fiberglass. The fiberglass acts as a dielectric with the layers of carbon fiber performing the tasks of the anode and cathode in a conventional capacitor.
Volvo estimates that replacing an EV’s entire battery pack with capacitive panels would reduce total vehicle weight by 15%. It would also help in packaging. One criticism of the Chevy Volt is that its large centrally mounted battery pack turns a five passenger platform into a four passenger car. If the car’s structure is the power source, space formerly used for batteries can be put to better use.
There are possibilities for conventional vehicles as well, with the potential to replace the heavy 12 volt starter battery with just a few capacitive carbon fiber panels.
There are possible drawbacks, including cost and safety. Carbon fiber is expensive to work with so panels would be costly to make and to replace. Also, in the event of a collision that damages the panels’ electrical safety could be a concern.
As usual, there was no world on when, or if, this technology will ever see its way to a production vehicle.