Massless battery promises 70% increase in EV range

September 12, 2024

The world’s strongest battery, developed by researchers at the Chalmers University of Technology in Sweden, is paving the way for massless energy storage that could help build credit-card-thin mobile phones or even increase the range of electric vehicles by as much as 70 percent, a press release said.  
 
Even with the recent rise in the adoption of EVs, the transition to a future where transportation is electrified and free of fossil fuels remains unsure. Long-haul transport using ships and airplanes needs energy-dense fuels that are light to carry but can deliver large amounts of energy. 

Batteries, on the other hand, deliver far lower energy than fossil fuels but are much heavier. This further increases the weight that a ship or airplane has to carry onboard, making energy transition difficult.  
 
Structural batteries are a possible solution to the problem since they shoulder load-bearing functions in a device and are no longer deadweights that must be carried around. In the case of a vehicle, this also reduces energy consumption, which translates into a higher range.  
 
Developing structural batteries
 
A research team led by Leif Asp, a professor of Material and Computational Mechanics, Industrial and Materials Science at Chalmers, has been researching the use of carbon fibers for structural batteries. 

In 2018, the team confirmed that carbon fibers could store electrical energy and be used as electrodes in lithium-ion batteries. By 2021, the team had developed this battery’s strength and electrical capacity to deliver an energy density of 24 watthours per kg (Wh/kg), which was further increased to 30 Wh/kg in recent reports.  
 
While this is far from the storage capacity of standard lithium-ion battery packs, structural batteries do not have to attain these higher capacities to be truly effective.  
 
“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,” said Asp in a statement. 

Carbon fiber as electrodes
 
The structural battery developed at Chalmers is made from composite material and uses carbon fibers for both positive and negative electrodes. In previous iterations of the battery, the core of the positive electrode was made from aluminum foil. On this occasion, the researchers coated the carbon fibers with lithium iron phosphate (LFP).  
 
Carbon fiber’s role is not limited to being an electrode; it also acts as reinforcement, a current collector, and a scaffold for lithium to build on at the cathode while acting as an electrical collector and active material at the anode. This allows the battery to be built without using materials like copper or aluminum, which helps with weight reduction.  
 
The lithium ions in the battery are transported through a semi-solid electrolyte, reducing the fire risk. However, it cannot deliver high power yet, an area the team is focusing on now.  
 
The researchers have also increased the stiffness of the battery pack, which enables it to carry loads like aluminum but at a much lower weight. “In terms of multifunctional properties, the new battery is twice as good as its predecessor—and actually the best ever made in the world,” added Asp. 

“One can imagine that credit card-thin mobile phones or laptops that weigh half as much as today, are the closest in time. 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,” Asp concluded in the press release.