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“Massless” lithium-ion energy storage breakthrough could be key in mass EV adoption

Mon, 04/19/2021 - 11:28 -- Paul Crompton

Researchers from Sweden’s Chalmers University of Technology have produced a structural lithium-ion battery that performs ten times better than previous versions. 

The latest battery contains carbon fibre that serves as an electrode, conductor and load-bearing material.

The latest development from Chalmers, in collaboration with KTH Royal Institute of Technology in Stockholm, follows 14 years of research into structural batteries, including previous discoveries involving certain types of carbon fibre.

The battery— which works as a power source and as part of the application’s structure— has an energy density of 24Wh/kg, around 20% of comparable lithium-ion batteries, with a stiffness of 25GPa.

The new battery has a carbon fibre negative electrode, and a positive electrode made of a lithium iron phosphate-coated aluminium foil. They are separated by a fibreglass fabric, in an electrolyte matrix. 

The research was published in the scientific journal Advanced Energy & Sustainability

The technology could pave the way for ’massless’ energy storage in vehicles and other technology where the battery’s weight effectively vanishes when it becomes part of the load-bearing structure.

Leif Asp, professor at Chalmers and leader of the project, said: “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.”

A new project, financed by the Swedish National Space Agency, will now investigate increasing the performance of the structural battery to 75Wh/kg and a stiffness of 75 GPa. 

The aluminium foil will be replaced with carbon fibre as a load-bearing material in the positive electrode, providing increased stiffness and energy density.

The fibreglass separator will be replaced with an ultra-thin variant, which will give faster charging cycles. 

The new project is expected to be completed within two years.

Asp said: “The next generation structural battery has fantastic potential. In the longer term, it is absolutely conceivable that electric cars, electric planes and satellites will be designed with and powered by structural batteries.

“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.”

Work on structural batteries was named by Physics World as one of 2018’s ten biggest scientific breakthroughs.

IMAGE: Doctor Johanna Xu shows a newly manufactured structural battery cell to Leif Asp in Chalmers’ composite laboratory. Image: Marcus Folino

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