Battery can be used as physical structure

“We have created a battery made of carbon fibre composite that is as stiff as aluminium and energy-dense enough to be used commercially, claimed Chalmers researcher Richa Chaudhary.

First revealed with KTH Royal Institute of Technology in 2018, by 2021 the material was achieving 24Wh/kg, and now it has climbed to 30Wh/kg.

This is still well under ~200Wh/kg from conventional lithium ion batteries, but the university argues that its technology offsets its low energy density by reducing the weight of the rest of the vehicle.

The technology is lithium iron phosphate, with structural carbon fibre used in both the positive and negative electrodes – an earlier version had an aluminium foil positive electrode.

The electrolyte is semi-solid instead of liquid “which is challenging when it comes to getting high power, and for this more research is needed”, said the university.

Its elastic modulus is between 25 and 70GPa – hence the “as stiff as aluminium” claim, but it weighs less that aluminium, according to Chalmers.

“In terms of multi-functional properties, the new battery is twice as good as its predecessor  – actually the best ever made” said project head Professor Leif Asp, who has been researching structural batteries since 2007. “We have made calculations on electric cars that show that they could drive for up to 70% longer than today if they had competitive structural batteries.”

A company has been spun-out to exploit the technology: Sinonus, based in Borås, Sweden.

“There is a lot of engineering work to be done before the battery cells step from lab manufacturing to being produced on a large scale,” said the university.

For more information, ‘Unveiling the multifunctional carbon fiber structural battery‘ is available in Advanced Materials, and can be read in full without payment.