Discovering that carbon fibers can work as battery electrodes, storing energy directly, opens new opportunities for structural batteries, where the carbon fiber becomes part of the energy system. The use of this type of multifunctional material can contribute to a significant
Passenger aircraft need to be much lighter than they are today to be powered by electricity. A reduction in weight is also very important for electric vehicles (EVs) to extend the driving distance per battery charge.
Leif Asp, professor of material and computational mechanics at Chalmers, conducts research into the ability of carbon fibers to perform more tasks than simply to act as a reinforcing material. They can store energy, for example.
“A car body would then be not simply a load-bearing element, but also act as a battery,” Asp 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%.”
Asp headed up a multidisciplinary group of researchers who recently published a study on how the microstructure of carbon fibers affects their electrochemical properties – their ability to operate as electrodes in a lithium-ion battery.
The researchers work with structural
Researchers studied the microstructure of different types of commercially available carbon fibers and discovered that carbon fibers with small, poorly oriented crystals have good electrochemical properties but
“We now know how multifunctional 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 market is currently dominated by expensive carbon fiber composites whose stiffness is tailored to aircraft use. There is
In the study, the types of carbon fiber with good electrochemical properties had a slightly higher stiffness than steel, whereas the types whose electrochemical properties were poor were slightly more than twice as rigid as steel.
The researchers are collaborating with automotive and aviation companies. Asp explains that for the aviation industry, it may be necessary to increase the thickness of carbon fiber composites to compensate for the reduced stiffness of structural batteries. This would, in turn, also increase their energy storage capacity.
“The key is to optimize vehicles at
He continues, “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.”
Chalmers University of Technology