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Sweden’s Calmers University of Technology says it has made a breakthrough with the development of so-called structural batteries. The batteries are said to be ten times more efficient than previous models. This was announced in a press release today.

The main difference between a structural battery and a lithium-ion battery (as commonly used in e.g. electric cars today) is that a structural battery is part of the bodywork. In fact, the battery is the car.

Chalmers University accomplishes this feat with the help of carbon fibers, as in carbon. This is a plastic that is already regularly used in the automotive and aviation industries because it is lightweight and extremely strong. A third property of carbon is that it can serve as an energy storage medium and an electrical conductor. Yet so far, this property has hardly been used. Chalmers’ invention could therefore change all this.

20 percent

Research into structural batteries has been going on since 2007. However, the problem has always been that the electrical properties of the applied materials in particular still leave much to be desired.

The battery that Chalmers has now developed in conjunction with the KTH Royal Institute of Technology (Stockholm, Sweden) has an energy density of 24 watt-hours per kilogram. If you compare that to a normal lithium-ion battery, that amounts to a capacity of about 20%.

Which may not sound like much. But, as mentioned, the advantage of carbon is that it can be used in the construction of a car or a bicycle. Whereas lithium batteries are just extra ballast.

Consumer electronics

“In earlier attempts to make structural batteries, the cells either had good mechanical properties or good electrical properties. Not both at the same time. But now, we have managed to design a structural battery with a competitive energy storage capacity as well as rigidity by using carbon fibers,” explains Professor Leif Asp of Chalmers University.

As a matter of fact, he says, the battery is suitable not only for cars, but for e.g. electric bicycles and consumer electronics as well.

In Chalmers’ structural battery, carbon forms the negative pole, while the positive pole comprises aluminum foil coated with lithium iron phosphate. The two electrodes are separated by glass fiber reinforced plastic (GRP) that serves as the electrolyte.


Chalmers University expects to increase the efficiency of the battery even further over the coming years. The research is essentially still in its infancy. It will be followed up in a newly launched project funded by the Swedish National Space Agency Rymdstyrelsen.

Among other things, the idea is to replace the aluminum foil with carbon. Also, in the case of the GRP, work is being done on thinner versions. This should have even better properties and capabilities for faster charging. This project will run for about two years.

Asp thinks that this could yield a battery that is heading towards 75 kilowatt hours per kilogram. That would then be an improvement by a further factor of three. Asp: “The next generation of structural batteries has enormous potential. It is quite possible that in a few years we will be able to build smartphones, laptops and electric bikes that weigh half as much as current models and are more compact,” Asp says.

Also check out our archive on batteries here.