Technology

'Massless' battery promises a 70% increase in EV range

Carbon fiber structural battery developed at Chalmers University of Technology, Sweden
Carbon fiber structural battery developed at Chalmers University of Technology, Sweden

Researchers say they've built and tested a 'structural battery' that packs a device or EV's chassis with energy, saving a ton of weight. It could unlock smartphones as thin as credit cards, laptops at half the weight and a 70% boost to EV range.

EVs rely heavily – pun intended – on large lithium-ion batteries to cover long distances. Researchers at Chalmers University of Technology wondered if they could build a battery that doubles as the load-bearing material holding the car together, and shed some weight.

As part of their work on what they call 'massless energy storage,' the research team in Sweden has developed a battery made of a carbon fiber composite. It promises similar stiffness to aluminum, while also being capable of storing a fair bit of energy – enough to be used commercially.

The carbon fiber-based battery promises to store energy, and support loads just like aluminum

Carbon fiber, of course, is incredibly light, strong, and rigid – and thus a popular, if expensive, structural and exterior material in performance cars – as well as a critical material in aerospace applications, in which every gram counts.

But it can also serve as an effective electrode material when electrochemically engineered for that purpose. The Chalmers team, led by Professor Leif Asp, has been working on this for years, having initially published a study demonstrating this property of carbon fiber with a specific arrangement of crystals in 2018.

Researchers Zhenyuan Xia, Richa Chaudhary and Professor Leif Asp have been working on this massless energy storage concept for years

The new battery design has an energy density of 30 Wh/kg, which is... not great by automotive standards. For reference, the 53 kWh battery pack in a Hyundai Ioniq 6 is rated at 153 Wh/kg (links to PDF).

But that's the energy density of a battery pack sitting in a box; you've got to add on the weight of the entire car's structural chassis to make it a fair comparison, as this carbon fiber structural battery is designed to replace the whole frame, shaving substantial weight off the overall vehicle, while freeing up space to boot.

EV and device manufacturers can do what they like with this new equation, either shooting for significantly lighter products, or filling the freed-up space back up with more cells to boost overall energy storage.

The results could be revolutionary in practice. "We have made calculations on electric cars that show that they could drive for up to 70 percent longer than today if they had competitive structural batteries," says Asp.

The team's latest prototype is nearly three times as stiff as previous iterations, with an elastic modulus of 70 gigapascal, up from 25. The team says it's now as rigid and capable of supporting weight as aluminum, while weighing far less.

What's on the inside?

The battery design uses carbon fiber in both the anode and cathode, where it also serves as a reinforcement and a current collector. That negates the need for current collectors made of heavy materials like copper, as well as conflict metals like cobalt in the electrode design.

Carbon fiber features in both the positive and negative electrodes of this battery design

Plus, this battery uses a semi-solid electrolyte instead of a liquid one to move lithium ions between its terminals. As such, it's less flammable, and safer to use – although the team admits there's still some issues getting ions through the electrolyte quickly enough for high-power applications. More research is needed there.

Yes, this is another lab battery, and as such, these next-gen EVs and devices are still some years away – but mass production and commercialization is very much in the works.

Back in 2022, the university teamed up with Gothenburg-based VC firm Chalmers Ventures to spin out a new company called Sinonus. The company appointed a new CEO in June to propel its mission to commercialize massless energy storage, with a view to change how we build cars, gadgets, and even wind turbine blades.

"One can imagine," says Asp, "that credit card-thin mobile phones or laptops that weigh half as much as today, are the closest in time. It could also be that components such as electronics in cars or planes are powered by structural batteries. It will require large investments to meet the transport industry's challenging energy needs, but this is also where the technology could make the most difference."

Source: EurekAlert

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14 comments
Nobody
So what happens in an accident? How would a battery be replaced or could it be? How could an electric vehicle be recycled? Would this make electronic items even more expendable?
Rick O
It would be interesting to see how it reacts after taking damage from impacts or stress fractures from frame loading. People are very hard on their vehicles, and if a battery that is part of your frame goes bad, it's much more difficult to replace than a battery pack.
*Joe*
I guess EVs are already considered disposable since batteries cost so much to replace, but making the frame the battery ensures they go straight to the junkyard.
davidmiller
I do like the idea of thinner laptops and phones that use no, or less conflict materials. However, if you make a car frame of this stuff, you engineer irrepairability into the heart of the machine. Imagine what will happen to your car insurance rates if an accident means you have to throw the entire device into the landfill.
rgbatduke
I have a few issues with this as an idea. First, energy stored in the battery in sufficient quantity to, say, drive a car 1000 miles is also enough energy to cause a massive explosion, whether it is stored as gasoline, in Lithium batteries, or in carbon fiber batteries. Gasoline cars burn or explode in collisions that reach the gas tank. Lithium batteries can burn or explode with nearly equivalent violence, but they can be packed in and fused to at least try to prevent this.

What's going to happen when a car crashes into a lightweight carbon fiber body storing an equivalent amount of energy? Does it all get released at once? Does it burn? What happens when the car body is pressed up against passengers on the inside by the collision? Are they electrocuted? Fried? I'm a long way away from trusting this as a model for future cars, although it may well find uses elsewhere.
vince
Its been said in the oast that eventually future airplanes will all be powered by skin of the plane. In other words no physical batteries just thicker bodies and skin that use this kind of carbon fiber enhanced energy storage. That shoukd eventually make jet planes obsolete amd plabes that can fly 1500 miles and able to reach any point in the US with 2 hops.
Bob B
I can see this working for phones and other easily replaceable devices, but in a car? No. When one fender bender requires "replacing the entire structure of the car/battery", the cost of insurance will be ridiculous, if even available.
PAV
I wish I had a clearer picture of how they intend to make that energy available to the motor.
paul314
If they just replace the part that's recognized as frame in most cars, not the outer mashable body panels, they'll get a little less range, but much of the repairability issue will become moot. Most metal-framed cars are totalled if they get into a collision bad enough the bend/kink the main part of the frame, because the engine/steering/suspension no longer line up. They'd still need energy-absorbing non-battery material front and back for crashes. But. If they're going for a whole new body design, they might well be able to engineer connections between frame parts that would shear in a collision and absorb energy while preserving the battery parts...
Karmudjun
Very nice article. Very inane comments.
So Carbon Fiber structural batteries are that much closer to production levels, but not quite. They are less flammable, less prone to explosions? How is the energy delivery? Can they be recharged quickly or are they slow release and refill batteries? As range extenders, having five or ten Amp Hours along with the battery pack would help today, but as tweaks come down the pike, the capability of using structural members as battery will improve things. Of course body shops will have to learn to cut and splice batteries as structural members - who would throw any of this away? Even old Tesla batteries have 90% plus capabilities left!!!!