The newly structural cell consists of a carbon fibre electrode and a lithium iron phosphate electrode separated by a fibreglass fabric, all impregnated with a structural battery electrolyte for combined mechanical and electrical function. Image credit: Marcus Folino
“Previous attempts to make structural batteries have resulted in cells with either good mechanical properties, or good electrical properties. But here, using carbon fibre, we have succeeded in designing a structural battery with both competitive energy storage capacity and rigidity.”– Leif Asp, Professor at the Division of Materials and Computational Mechanics of Chalmers University of Technology, Leader of The Project
Researchers from Chalmers University of Technology in collaboration with KTH Royal Institute of Technology in Stockholm, presenting a structural battery with properties that far exceed anything yet seen, in terms of electrical energy storage, stiffness and strength that performs ten times better than all previous versions. A new structural battery contains carbon fibre that serves simultaneously as an electrode, conductor, and load-bearing material.
Their latest research breakthrough paves the way for essentially ’massless’ energy storage in vehicles and in the longer term, it is absolutely conceivable that electric cars, electric planes and satellites will be designed with and powered by structural batteries.
Structural battery composites can’t store as much energy as lithium-ion batteries, but have several characteristics that make them highly attractive for use in vehicles and other applications. When the new battery becomes part of the load bearing structure, the mass of the battery essentially ‘disappears’. Illustration by: Yen Strandqvist
The research team at Chalmers University of Technology has spent many years investigating the idea that batteries can double as structural components to save on weight in vehicle design. Carbon fiber is a key pillar of this research, due to its excellent and well-known mechanical properties, along with its ability to act as an electrode material when engineered in the right way.
In 2018, the scientists published a study describing a form carbon fiber with just the right arrangement of crystals to offer both the required stiffness for vehicle construction and the necessary electrochemical performance for energy storage system. As part of their efforts to translate this research to real-world applications, the researchers have now produced a carbon-fiber-based structural battery that performs ten times better than any previous version.
The battery has an energy density of 24 Wh/kg, approximately 20% capacity compared to comparable lithium-ion batteries currently available. Since the weight of the vehicles can be greatly reduced, less energy will be required to drive an electric car and lower energy density also results in increased safety. With a stiffness of 25 GPa, the structural battery can really compete with many other commonly used construction materials, and that such a battery could reach an energy density of 75 Wh/kg and a stiffness of 75 GPa by estimation. This would make the newly battery about as strong as aluminium, but with a comparatively much lower weight.
The new structural battery has a negative electrode made of carbon fibre, and a positive electrode made of a lithium iron phosphate-coated aluminium foil. They are separated by a fibreglass fabric, which in an electrolyte matrix. The aluminium foil will be replaced with carbon fibre as a load-bearing material in the positive electrode, providing both increased stiffness and its energy density. The fibreglass separator will be replaced with an ultra-thin variant, which will give a much greater effect—as well as faster charging cycles.
This new project is expected to be completed within two years and funding has come from the European Commission’s research program Clean Sky II as well as the US Airforce.
“We are really only limited by our imaginations here. We have received a lot of attention from many different types of companies in connection with the publication of our scientific articles in the field. There is understandably a great amount of interest in these lightweight, multifunctional materials,” says Prof. Leif Asp
Source : Chalmers University of Technology
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