This year, the EV field has seen many advances, in both industry and academia, in the direction of structural batteries.
Arguably, the biggest roadblocks to widespread mainstream adoption of electric vehicles are range. Currently, you can expect to get about 300 miles on a single charge in a “top-tier” electric vehicle, which is undoubtedly good––but not where we want to be.
Edmund’s EV range test top four results with EPA estimates and Edmunds testing. Image used courtesy of Edmunds
The challenge of increasing vehicle range has a few key angles to choose from:
- Figure out a way to recharge batteries quicker.
- Create larger capacity batteries.
- Decrease a vehicle’s weight.
Often, the latter two can go hand in hand––more energy-dense batteries can mean better capacity and less weight.
One technology looking to address range issues in this capacity is the structural battery, which has seen a lot of improvement in 2021.
Structural Batteries = Massless Storage?
Traditionally a battery is a standalone component whose only function is to provide the rest of the vehicle with power. In this scheme, batteries are a catch-22 since the vehicle’s weight dramatically impacts the range of a battery, but the battery itself contributes significantly to the vehicle’s weight.
A high-level overview of a structural battery in an EV. Image used courtesy of IEEE
A very clever way to get around this is the idea of the structural battery––a battery that works both as a power source and as part of the vehicle’s mechanical structure. Researchers have coined this method as “massless energy” since the battery serves as the structure, making the system’s total weight plus battery equal to just the structure’s weight as a whole.
Making Massless Storage “10x Better”
The first highlight-able news in the field came earlier this year when researchers at the Chalmers University of Technology announced a new battery that is “10x better” than previous attempts.
According to their paper, the researchers explain that their new battery works with “a negative electrode made of carbon fiber and a positive electrode made of a lithium iron phosphate-coated aluminum foil which are separated by a fiberglass fabric in an electrolyte matrix.” The result is a structural battery with an energy density of 24 Wh/kg, which is about 20% the capacity of Li-on, and stiffness of 25 GPa, which is comparable to other construction materials.
The components of Chalmers research team’s structural battery. Image used courtesy of Asp et al
The research is now being financed by the Swedish National Space Agency, with clearly defined improvements. Namely, the researchers plan to replace the aluminum foil with carbon fiber and replace the fiberglass separator with an “ultra-thin variant.” With these changes, the researchers predict they could achieve an energy density of 75 Wh/kg and stiffness of 75GPa, which is comparable to aluminum.
Beyond the scope of academia, structural batteries are also working towards more marketable solutions.
Massless Storage in the Real World
Formula 1 spinoff Williams Advanced Engineering (WAE) has recently made headlines relating to structural batteries moving out of academia.
This week they’ve announced that they’ll be partnering with Italdesign to launch their EV platform together. At the heart of this collaboration is WAE’s proprietary structural battery technology, which they claim can provide world-class vehicle weight and chassis stiffness.
Crossover concept from WAE and Italdesign. Image used courtesy of WAE and Italdesign
According to WAE, their structural battery works by having “front and rear chassis structures mount to the carbon composite case. Crash loads can be transferred via internal reinforcements to the integral side sills.”
WAE and Italdesign’s battery case design. Image used courtesy of WAE and Italdesign
This design results in a higher profiled cross-section which achieves high torsional stiffness. While more technical details about the battery are being kept under wraps, the company feels optimistic about its offer.
Massless Energy for EVs
If achievable, structural batteries could be the technology that finally allows EVs to achieve mainstream adoption in ways yet seen. With movement happening in both academia and industry, we can optimistically expect that day to arrive sooner than later.