Pie In The Sky? Electric Vehicles Could Store Electricity In Carbon Fiber Body Panels

This one sounds a bit like a Jules Verne story. Researchers at the Chalmers University of Technology in Sweden claim carbon fiber can act as an electrode if small changes are made in how it is manufactured. Is that big news? Let’s look at what it could mean to the world of transportation.

1. Electric cars and trucks could be made of carbon fiber instead of steel or aluminum. That means they could be up to 50% lighter than equivalent vehicles today, which would dramatically boost their efficiency.
2. If their exterior panels are able to store electricity, those cars and trucks could use smaller, lighter, and cheaper batteries, or might need no battery at all in some cases. Lower battery costs would offset the higher cost of carbon fiber.
3. Airplanes account for a large percentage of carbon emissions from the transportation sector. The weight of batteries is a major stumbling block to the electrification of aircraft today. Carbon fiber that stores electricity might prove to be critical to the development of electric airplanes.

Image courtesy Chalmers University of Technology

Leif Asp, professor of material and computational mechanics at Chalmers, says, “A car body would then be not simply a load-bearing element, but also act as a battery,” he says. “It will also be possible to use the carbon fiber for other purposes such as harvesting kinetic energy, for sensors or for conductors of both energy and data. If all these functions were part of a car or aircraft body, this could reduce the weight by up to 50 percent.”

Not all carbon fiber is created equal, says Asp. Some has large, highly oriented crystals and is twice as strong as steel. That type of carbon fiber does not conduct electricity well. However, other types of carbon fiber have poorly oriented crystals. They are about as strong as steel but have good electrochemical properties. They also have the additional benefit of being less costly to manufacture.

“We now know how multi-functional carbon fibers should be manufactured to attain a high energy storage capacity, while also ensuring sufficient stiffness,” Asp says. “A slight reduction in stiffness is not a problem for many applications such as cars.”

The researchers are exploring how to use the new technology with several automobile and aircraft manufacturers. For airplanes, the carbon fiber might need to be slightly thicker than it would be for automotive use to compensate for its decrease in rigidity, but making it thicker also increases its energy storage capacity.

“The key is to optimize vehicles at system level — based on the weight, strength, stiffness and electrochemical properties. That is something of a new way of thinking for the automotive sector, which is more used to optimizing individual components. Structural batteries may perhaps not become as efficient as traditional batteries, but since they have a structural load bearing capability, very large gains can be made at system level,” Asp says. “In addition, the lower energy density of structural batteries would make them safer than standard batteries, especially as they would also not contain any volatile substances.”

If the whole idea of vehicles that are also batteries seems a little far fetched to you, remember that virtually all of the cockamamie ideas dreamed up by Jules Verne — nuclear powered submarines, sending people to the moon — became a reality eventually. The idea of battery-powered cars was dismissed by many people as a joke ten years ago. We never know what the future might have in store. Structural batteries could play an important role in decarbonizing the transportation sector.