How to Eliminate EV Battery Weight

EV batteries are heavy. A 60-100 kWh battery pack can weigh anywhere between 900 to 1,500 pounds—about 20–30% of an EV’s weight. The larger the battery (in terms of energy capacity), the heavier it tends to be, which is why efforts to reduce battery weight or improve energy density—getting more power out of a smaller and lighter battery—are so important to enhancing vehicle range and efficiency.

But what if you could make that battery weight go away completely? How? By making the battery out of a material that serves a dual purpose: It not only stores and releases energy as needed but also serves as part of the vehicle’s load-bearing structure. The battery stops being a weight to be carried and becomes a carrier of weight. That’s the tantalizing promise of research at Chalmers University of Technology in Sweden.

Structural battery research

A recent development from Chalmers presents a significant leap in the field of structural batteries—materials that store energy while carrying mechanical loads. The new battery, which integrates carbon fiber as both an electrode and a load-bearing material, has the potential to drastically reduce the weight and energy consumption of electric vehicles, laptops, and mobile phones.

Chalmers' research team, led by Professor Leif Asp from the Department of Industrial and Materials Science, has been advancing structural batteries for years. Their latest prototype demonstrates a combination of improved stiffness and energy density, making it strong enough to replace traditional materials like aluminum while functioning as a battery. This new design could, for example, increase an electric vehicle's driving range by up to 70% on a single charge, thanks to the significant reduction in overall vehicle weight.

Related:Structural Batteries Could Make EVs Lighter

How the technology works

The structural battery is made from a composite material with carbon fiber serving dual roles. In the battery's anode, the carbon fiber acts as both a reinforcement and an active material, while in the cathode, it supports the structure and conducts current. The use of carbon fiber reduces the need for heavier components, like copper or aluminum, which typically serve as current collectors in traditional batteries. This multifunctional approach significantly cuts the battery’s weight and complexity.

The researchers Zhenyuan Xia, Richa Chaudhary and Leif Asp in the graphene lab at the Department of Industrial and Material Science at Chalmers University of Technology, Sweden. Credit: Chalmers University of Technology | Henrik Sandsjö

Another key feature of the new battery is its semi-solid electrolyte, which enhances safety by lowering the risk of fire. Unlike conventional liquid electrolytes, this design prioritizes safety and reliability, although further research is required to boost its power output for high-performance applications.

Why carbon fiber matters in aerospace and automotive

Carbon fiber composites are prized in both aerospace and automotive industries for their high strength-to-weight ratio. Stronger than steel yet significantly lighter, these materials are used extensively in aircraft wings, fuselages, and high-performance vehicle body panels. By reducing vehicle weight, carbon composites improve energy efficiency and handling. Their ability to bear heavy loads without adding unnecessary mass makes them especially valuable in electric vehicles and aircraft, where range and fuel economy are key concerns.

Potential applications in vehicles and electronics

While the energy density of this structural battery—currently at 30 Wh/kg—is lower than that of commercial lithium-ion batteries, its ability to function as part of a vehicle's structure makes it highly efficient for certain applications. Electric vehicles, aircraft, and even drones could see considerable performance boosts due to lighter designs that conserve energy. According to Asp, structural batteries could be a game-changer for the automotive and aerospace industries, with the potential to make electric cars drive up to 70% farther than today.

The developed battery concept is based on a composite material and has carbon fiber as both the positive and negative electrodes – where the positive electrode is coated with lithium iron phosphate. Credit: Chalmers University of Technology | Henrik Sandsjö

Beyond transportation, the technology could have more immediate applications in consumer electronics. The researchers foresee credit card-thin mobile phones or laptops that weigh half as much as current models, thanks to the integration of the battery into the device’s structure.

Next steps toward commercialization

Despite the promising progress, the structural battery is still in the lab-testing phase, with further engineering work needed before it can be commercially scaled for use in consumer goods or vehicles. To bridge this gap, Chalmers has launched Sinonus AB, a venture aimed at bringing the technology to market.

"We are seeing a great deal of interest from the automotive and aerospace sectors, but there are still significant engineering challenges to overcome," says Asp. "However, credit card-thin phones or laptops could be some of the first commercial products featuring this technology."