Over the subsequent few years, the batteries that go into electrical autos are going to get low cost sufficient that an EV ought to price not more than an equivalent-sized automobile with an inside combustion engine. But these EVs are nonetheless going to weigh greater than their gas-powered counterparts—notably if the market insists on longer and longer vary estimates—with the battery pack contributing 20-25 p.c of the entire mass of the automobile.
But there’s a answer: flip a few of the car’s structural elements into batteries themselves. Do that, and your battery weight successfully vanishes as a result of no matter powertrain, each automobile nonetheless wants structural elements to carry it collectively. It’s an method that teams around the globe have been pursuing for some time now, and the thought was neatly defined by Volvo’s chief technology officer, Henrik Green, when Ars spoke with him in early March:
What we’ve got discovered… simply to take an instance: “How do you integrate the most efficiently a battery cell into a car?” Well, for those who do it in a standard means, you set the cell into the field, name it the module; you set numerous modules right into a field, you name that the pack. You put the pack right into a automobile after which you will have a standardized answer and you may scale it for 10 years and 10 manufacturing slots.
But in essence, that is a fairly inefficient answer by way of weight and area, and so forth. So right here you could actually go deeper, and the way would you straight combine the cells right into a physique and do away with these modules and packs and stuff in between? That is the problem that we’re working with in future generations, and that can change the way you essentially construct cars. You might need thought that point of adjusting that may have ended, nevertheless it has simply been reborn.
Tesla is thought to be engaged on designing new battery modules that additionally work as structural components, however the California automaker is fashioning those structural modules out of traditional cylindrical cells. There’s a extra elegant method to the thought, although, and a gaggle at Chalmers University of Technology in Sweden led by professor Leif Asp has just made a bit of a breakthrough in that regard, making every part of the battery out of supplies that work structurally in addition to electrically.
The structural battery combines a carbon fiber anode and a lithium iron phosphate-coated aluminum foil cathode, that are separated by a glass fiber separator in a structural battery electrolyte matrix materials. The anode does triple obligation, internet hosting the lithium ions, conducting electrons, and reinforcing every part on the similar time. The electrolyte and cathode equally assist structural hundreds and do their jobs in shifting ions.
The researchers examined a pair various kinds of glass fiber—each leading to cells with a nominal voltage of two.Eight V—and achieved higher outcomes by way of battery efficiency with thinner, plain weave. The cells utilizing this development had a selected capability of 8.55 Ah/kg, an vitality density of 23.6 Wh/kg (at 0.05 C), a selected energy of 9.56 W/kg (at three C), and a thickness of 0.27 mm. To put at the least a kind of numbers in context, the 4680 cells that Tesla is shifting to have an vitality density of 380 Wh/kg. However, that vitality density determine for the cylindrical cells doesn’t embody the mass of the structural matrix that surrounds them (when used as structural panels).
Speaking of structural hundreds, the best stiffness was additionally achieved with plain glass fiber weave, at 25.5 GPa. Again, to place that quantity into context, it is roughly just like glass fiber-reinforced plastic, whereas carbon fiber-reinforced plastic will likely be round 10 occasions higher, relying on whether or not it is resin transfer molding or woven sheets pre-impregnated with resin (referred to as pre-preg).
Professor Asp’s group is now working to see if swapping the cathode’s aluminum foil for carbon fiber will improve each stiffness (which it ought to) and electrical efficiency. The group can be testing even thinner separators. He hopes to achieve 75 Wh/kg and 75 GPa, which might end in a cell that’s barely stiffer than aluminum (GPa: 68) however clearly a lot lighter.
Building electrical cars and even airplanes out of structural composite batteries remains to be a longer-term challenge, and even at their greatest, structural battery cells could by no means method the efficiency of devoted cells. But since they’d additionally change heavier steel constructions, the ensuing automobile must be a lot lighter general.
Meanwhile, Asp thinks different merchandise could see the advantages sooner. “The next generation structural battery has fantastic potential. If you look at consumer technology, it could be quite possible within a few years to manufacture smartphones, laptops, or electric bicycles that weigh half as much as today and are much more compact,” Asp mentioned.
Listing picture by Marcus Folino