Image Credit: Yen Strandqvist/Chalmers University of Technology.
Long before Elon Musk announced that Tesla was looking to integrate batteries into the car’s structure itself to reduce the weight of energy storage, researchers were already developing structural battery solutions. What does it mean to have a “massless” battery, and what are the possible applications for this type of battery?
What are structural batteries?
Batteries can often be the singular heaviest part of a machine; in electric vehicles, battery packs can make up 25% of the entire mass. In mobile applications like vehicles or drones, this means that significant energy is used to carry the battery pack as well. Unlike fuel, which burns away and makes the vehicle lighter over time, batteries maintain their full weight and thus do not spend energy as efficiently.
This obstacle is what structural batteries hope to address. In theory, these types of batteries double as an integral load-bearing part of the machine itself. They are also dubbed “massless” batteries as they do not add any extra mass to the device or machine outside of the necessary structural elements. For instance, Tesla hopes to make the battery pack the floor of the car itself, eliminating the need for a separate car floor to house the heavy batteries.
What materials are used for massless batteries?
Unlike current batteries that are held within a protective battery pack casing, structural batteries must withstand weight independently. For this reason, they need to be made out of much more rigid and sturdy materials. A common choice among structural battery researchers is carbon fiber. It is not only a strong material that can uphold the integrity of a structure; it is also a favorable material for battery anodes due to its high ion-carrying capacity.
Although structural batteries have been under development since the 2000s, there has yet to be a viable rendition. The latest version of a massless battery, developed by researchers at Chalmers University of Technology, was ten times better than previous ones. Yet at an energy density of just 24 wh/kg, it has only 20% of a lithium-ion battery’s capacity. There is still some way to go, but the technology is certainly promising.
Applications and benefits of structural batteries
- Electric Vehicles
Electric vehicles, from cars and trucks to ships and planes, would greatly benefit from structural batteries. As previously mentioned, vehicle battery packs take up a lot of weight. Integrating energy storage into the structure itself will increase the range capacity of a vehicle, as extra energy is not needed to carry the non-load bearing battery packs. This energy savings would especially be valuable for larger vehicles like cargo trucks and even planes, as it can help address range anxiety.
Another exciting application for structural batteries is robotics. Like EVs, batteries for robotics can often constitute 20% of the space or mass of a robot, limiting the designs of robots.
Robotics researchers have been exploring how to integrate the battery into the robot’s anatomy, designing biomorphic batteries that in some ways borrow their concept from energy storage in animals. Basing their research on the way fat tissues store energy throughout the body, scientists are developing ways to distribute energy storage throughout the robot. These types of structural batteries could potentially be used in applications such as body prosthetics as well as flexible or soft robotics.
- Medicine and Microelectronics
Microelectronics is also a promising application for structural batteries, especially in medical applications and implants. Structural batteries will allow manufacturers to design these devices in even smaller formats. Battery-powered devices like pacemakers or hearing aids could be redesigned to be more comfortable and more seamlessly integrated into the body.
How battery testing can support research
High-quality, customizable battery testing technology can support the research and development of structural batteries. Arbin’s Regenerative Battery Testing Series, for instance, can test batteries according to a drive cycle, mimicking how a battery would be used in real life. This can provide scientists with a more accurate snapshot of the capabilities of a battery, facilitating and accelerating the testing and development process. Contact us to find out more.