In a recent article at PV Magazine, we got our first look at the new “massless” battery technology. They call their carbon fiber batteries “massless” not because they literally have zero mass (that’s physically impossible by our current understanding of physics), but because they add no mass to a vehicle that wouldn’t be there already.
Tesla and Structural Battery Packs
As many readers know, Tesla plans on introducing structural battery packs at some point in the near future. By using the battery pack’s container and the battery cells themselves for rigidity, the overall weight of the vehicle can be reduced. Advantages include greater range per kWh of battery pack installed, better handling, and great potential for simplified vehicle assembly (which should reduce cost).
Tesla is not the only company working on this, and its bonded cell approach is not the only approach that researchers and engineers are pursuing. Way back in 2007, researchers at the Chalmers University of Technology in Sweden started working on lightweight battery cells with not only good electrical properties, but good mechanical properties, too. As they developed carbon fiber batteries, they figured out that it wasn’t just good mechanically for a battery, but that it was also strong enough to serve as part of the structure of a vehicle. That’s when everything changed for the researchers.
The battery comes in several parts, layered. There’s a carbon fiber negative electrode, an aluminum film-supported positive electrode, and a glass fiber (GF) separator, all working together to form a structural battery electrolyte (SBE) matrix material. Each of these layers makes the others structurally stronger. This means that the carbon fiber batteries, or battery cells, can not only assist in bearing loads, but bear the loads directly, and be a true part of the vehicle’s structure.
“The battery has an energy density of 24 Wh/kg, meaning approximately 20 percent capacity compared to comparable lithium-ion batteries currently available,” the researchers said. “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.”
Solar Vehicles Will Be The Greatest Beneficiary Of “Massless” Carbon Fiber Batteries
One area where this will make a big difference is in solar-electric vehicles. As we’re learning from Aptera, powering vehicles from the sun is all about efficiency. The more efficient the solar panels are, the more energy the car can produce by itself. The lighter, more aerodynamic, and less resistant to rolling a vehicle is, the less energy will be needed to move it along the road. The tension between these two numbers (solar energy generation and energy needed to run) determines how useful a solar vehicle can possibly be.
A true structural battery would make the vehicle lighter and would also help reduce rolling resistance, and both of these factors increase the vehicle’s efficiency. This means that even with current solar technology, the vehicle would get more range from the sun daily.
Featured image provided by Aptera.
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