Researchers from Chalmers University of Technology in Sweden have produced a structural battery that performs ten times better than all previous versions. It 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 other technology.
From: Chalmers University of Technology
March 22, 2021 -- The batteries in
today's electric cars constitute a large part of the vehicles' weight, without
fulfilling any load-bearing function. A structural battery, on the other hand,
is one that works as both a power source and as part of the structure – for
example, in a car body. This is termed ‘massless’ energy storage, because in
essence the battery’s weight vanishes when it becomes part of the load-bearing
structure. Calculations show that this type of multifunctional battery could
greatly reduce the weight of an electric vehicle.
The development of structural batteries
at Chalmers University of Technology has proceeded through many years of
research, including previous discoveries involving certain types of carbon
fibre. In addition to being stiff and strong, they also have a good ability to
store electrical energy chemically. This work was named by Physics World as one
of 2018’s ten biggest scientific breakthroughs.
The first attempt to make a structural
battery was made as early as 2007, but it has so far proven difficult to
manufacture batteries with both good electrical and mechanical properties.
But now the development has taken a real
step forward, with researchers from Chalmers, 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. Its multifunctional performance is ten times
higher than previous structural battery prototypes.
The battery has an energy density of 24
Wh/kg, meaning approximately 20 percent capacity compared to comparable
lithium-ion batteries currently available. But since the weight of the vehicles
can be greatly reduced, less energy will be required to drive an electric car,
for example, and lower energy density also results in increased safety. And
with a stiffness of 25 GPa, the structural battery can really compete with many
other commonly used construction materials.
“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,” explains Leif Asp, Professor at Chalmers and leader of the
project.
Super light electric bikes and consumer
electronics could soon be a reality
The new 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, in
an electrolyte matrix. Despite their success in creating a structural battery
ten times better than all previous ones, the researchers did not choose the
materials to try and break records – rather, they wanted to investigate and
understand the effects of material architecture and separator thickness.
Now, a new project, financed by the
Swedish National Space Agency, is underway, where the performance of the
structural battery will be increased yet further. The aluminium foil will be
replaced with carbon fibre as a load-bearing material in the positive
electrode, providing both increased stiffness and 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. The new project
is expected to be completed within two years.
Leif Asp, who is leading this project
too, estimates that such a battery could reach an energy density of 75 Wh/kg
and a stiffness of 75 GPa. This would make the battery about as strong as
aluminium, but with a comparatively much lower weight.
“The next generation structural battery
has fantastic potential. If you look at consumer technology, it could be quite
possible within a few years to manufacture smartphones, laptops or electric
bicycles that weigh half as much as today and are much more compact”, says Leif
Asp.
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.
“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 Leif Asp.
Read the article in the scientific
journal Advanced Energy & Sustainability Research:
A Structural Battery
and its Multifunctional Performance
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