It's 10 times more everything, just like every other battery breakthrough in the last several decades. AND, you get to use it as a building material?
- Sounds too good to be true: Check
- Sounds like every other "big" breakthrough: Check
- Article light on science and heavy on assertions: Check
- Skepticism engaged: Check
The claim is:
__This battery holds 10x more charge per kilo of material than previous attempts at STRUCTURAL (massless) battery materials__.
To be specific, this material holds only _ONE FIFTH_ the charge of what your smartphone's battery can hold per kilo of battery. No laws of thermodynamics is being broken and this is not at all about battery chemistry. It's all about the 'physics' of construction materials: About how this stuff is made in the factory and layered. The basic battery chemistry going on is not much different from what's been available for years - the interesting part is how this material encases it.
You can't make a car by building the chassis out of smartphone batteries. But the promise of this paper is that you CAN build the car chassis out of this battery, and even if this battery is only 20% as effective, a car chassis is rather large, and you needed it anyway, so every drop of power you can store in the chassis itself was effectively 'free' - hence the somewhat hyperbolous 'massless' terminology.
(This is not a claim that the batteries described in the article are a fire hazard - I don't know)
I guess a full discharge first.
But what about your accident, and the jaws of life? Will they conduct? Will the wrenched apart car have conductive edges?
In the Teslas, the power system is shunted through a single disconnect point... Cutting that line isolates the battery from the rest of the vehicle.
In Waymo cars, firefighters needed to be made aware that high-power electrical conduit and liquid cooling channels go up through the pillars, which are usually empty of energized components or contain only low-power channels (for things like overhead lights).
This doesn't happen organically. Manufacturers were happily iterating toward a different optimum before regulation forced their hands.
https://www.nytimes.com/2015/11/27/automobiles/50-years-ago-...
I'm not sure if most modern EVs have manual disconnect switches on the main power cables where they meet the batteries or if you're just expected to wear rubber gloves and use non-conducting wrenches to unbolt the cables. I'd expect any modern EV will at least have contactors to connect the battery to the motor controller (these are basically electrically actuated switches, like a mechanical relay), which will be disabled when the car is off. In general, though, I'd expect the main power cables to be something that doesn't need maintenance and mechanics can generally steer clear of.
I hope they develop a mechanism that allows exchange of the battery and can bear load without the battery with some sort of mechanical movement that can shift the load to a more permanent structure (not that this is necessarily a good idea either but proposing an option). Or, perhaps the battery never needs changed, and by that I mean the life of the product lasts as long as it would with a replaceable battery. They can't just redefine the life of the product as the life of the battery to get around this (unless the life if the product was already defined by the life of the battery for a long time before).
I'm betting once EVs start making their way into fleets, you'll find your 300k mile, low maintenance, minimal electronics American/German brand.
I'm in the middle of converting a Mazda RX-8. Just got the motor/clutch/transmission assembly (mostly) in place last weekend. It's kind of fun, but it's also a lot of work. It seems like a tremendously inefficient way to get the car I want: electric, no phone-home or over-the-air update capability, ability to control how everything works, easy to fix, manual transmission, modern safety features. I thought about buying a Model 3, but decided it was a lot of money for something that wasn't quite what I want. 200+ mile range would have been nice though; it's hard to get that in a conversion without making it unreasonably heavy.
It's a bit of a trade-off. To use Tesla as an example, they take the approach of just putting a massively overpowered motor in each car so that they can overcome the lack of a low gear. That works fine, but the kind of parts you need in that sort of system are expensive. Not just the motor, but the motor controller and the batteries have to handle that much power.
A different approach is to just have a normally-sized motor and an ability to shift gears. It should make for a lighter, more efficient car. (Though you also lose some efficiency in the gearbox.) The conversion I'm doing has a 120 horsepower motor, and it's going into a car that's about 3,000 pounds. I won't win any 0-60 races with a Model S, but it'll probably handle corners better and generally be more fun to drive, not to mention be about 1500 to 2000 pounds lighter.
I'm willing to concede that wanting an EV with a stickshift may be an unpopular opinion, but it's hard to know if there's a market for that kind of thing until someone starts manufacturing it. (And I don't mean the Taycan, I mean something that some ordinary middle-class person might buy.) It seems kind of a shame that we have all these legacy car companies that know how to build transmissions, but none of them seem interested in using that as an advantage they have over Tesla for that part of the market that want an electric car but would rather drive a manual transmission.
Sounds like a very educational project.
I wouldn't be so quick to just brush off Tesla engineering as having bad tradeoffs, or make assumptions about the fun of cornering, but I'm sure the project will be an eye opener and maybe will lead you to test drive an M3P sometime.
Definitely it's hard to beat an RX8 with cornering but that's before you load it down with batteries.
Edit: I had some doubts about your weight claims but I wasn't thinking about the fact that you are losing the engine weight, which puts you pretty far ahead! Sounds like a cool project.
I did actually consider buying a Model 3, and even put down a thousand dollars to preorder back when it was announced. I test drove a dual-motor version (I would have gotten the single-motor version, but it's what they had). The acceleration is fun. Otherwise it seemed like a solidly built yet kind of generic car. In the end, the main things that kept me from buying it were Tesla's secretive nature when it comes to service information and the prospect of some minor component failing and bricking the car (like that flash chip soldered to a giant motherboard that had issues in early models) after the warranty expires, and the price being a bit more than I cared to spend on a car. Awhile later a friend showed off a Ford Ranger pickup truck he'd converted with an electric motor and I thought: hmm, this isn't actually as expensive or difficult as I thought, maybe I should do a conversion...
The weight breakdown is something like this: the RX-8 is about 3,000 pounds stock. The rotary engine is about 300 pounds with all its accessories attached. The dual-shaft version of the Netgain Hyper9 AC motor I'm using is 130 pounds. The exhaust system is maybe a hundred pounds or so removed. The gas tank is another hundred pounds or so (when full). I'm adding about 450 pounds of lithium iron phosphate batteries, which gets me about 27kwh and maybe 100 miles of range if I'm lucky. (Used Tesla cells have a lot better energy density and are actually reasonably priced, but they wouldn't have fit very well in the places I wanted to put them. They're also a bit more dangerous than LFP cells and require liquid cooling.) I'm also adding in some weight for battery boxes and the motor mount and motor/transmission adapter. In the end I figure the car'll be about 200 pounds heavier or so, and most of that weight is very close to the ground.
Drones? Military drones or aircraft? (The paper mentions ARL) Quite possibly. What this promises is that anywhere you would have a strut or panel made from carbon fiber as a load-bearing element, you can have it store some energy for you as well.
Why not cars?
Let's say that it's 10% for structure and 30% for batteries.
If you decrease energy density of batteries several times now they take up let's say 90% of the car mass and the only thing you saved was 10% :)
Also, even if it’s only 10% weight you are saving, that sounds pretty good to me!
You toss the car in a landfill and stamp out a new one in the factory.
So probably better for drones and things that have a short lifetime anyway.
So you could literally make the frame 2x lighter with carbon fiber and put that 50% of weight in batteries getting you 2x+ more capacity.
Cars more likely as it's roughly on par with aluminum. Still the cost will be way more than plain aluminum or even steel body.
They're called Structural batteries (or [micro]structural super/ultracapacitors)
"Carmakers want to ditch battery packs, use auto bodies for energy storage" (2020,) https://arstechnica.com/cars/2020/11/carmakers-want-to-ditch...
Having said that, the car chasis is not juuuust about holding up a roof and the humans inside. You also have to handle impact stresses, you don't want it discharging on the poor inhabitants as the car is being hit, etc.
This sounds like a step, out of many, the the direction of lighter cars or aircraft that are electrically powered. It also doesn't have to be the only tech. If we can eliminate say 20% of the battery weight by making the frunk/trunk casings out of this material, some other inner parts of the car, we can use it as part of the solution.
> The battery has an energy density of 24 Wh/kg, meaning approximately 20 percent capacity compared to comparable lithium-ion batteries currently available. But since the weight of the vehicles can be greatly reduced, less energy will be required to drive an electric car, for example, and lower energy density also results in increased safety. And with a stiffness of 25 GPa, the structural battery can really compete with many other commonly used construction materials.
This seems a bit more believable. Whether it'll actually be used in that manner is to be seen, but this seems more down to earth. And while the article seems to put emphasis on using it to save weight, it's probably more effective to use it to add capacity while maintaining weight.
Aircraft, though... Aircraft already have "wet wings", which are fuel tanks. If the battery provided some of the wing's structural strength, that might work. Probably worth trying in military drones first.
Has the article been changed since you posted this comment? Because the article I've seen was pretty clear:
"Its multifunctional performance is ten times higher than previous structural battery prototypes. [...] The battery has an energy density of 24 Wh/kg, meaning approximately 20 percent capacity compared to comparable lithium-ion batteries currently available."
A battery strong enough to be a structural component, at the cost of 80% of its capacity-per-unit-weight, doesn't sound so hard to believe.
Going further with the battery news cynicism idea, batteries have steadily improved over the last 50 years, to an amazing degrees, because of steady breakthroughs causing small improvements. It is why we can have iphones and tesla today.
"times less" is division.
• "90% less than x" does not equal "10% of x"
• "90%" does not equal "0.9 times"
• "0.9 times less" means multiplication and subtraction (x - 0.9x) but "1.1 times less" means division (x / 1.1)
This is one of those cases where we know from the context what was meant but that isn't the same as what was said. Normalizing this abuse of language introduces unnecessary special cases and discontinuities for readers/listeners to deal with and creates ambiguity in situations where one of the two interpretations is not so obviously wrong as it is here. It's better to keep the rules simple: ratios, percentages and "times" always involve multiplication by the original value, and "more" and "less" refer to addition and subtraction. There should be a deterministic 1:1 correspondence between the phrasing and the formula.
That's much easier than dealing with people who calculate percentages wrong or say ambiguous things about large increases.
This is human language, of course, so you can be as over-complicated, inconsistent, and ambiguous as you want and generally count on sufficiently smart listeners/readers to decode the resulting mess into something intelligible based on context. It's not good style, and it encourages innumeracy and presents math as being more complicated than it should be, but it will usually get the job done.
That's 20% as dense (1/5 the density), not 20% less dense (4/5 the density).
As for replacing the chassis—a Tesla Model S has 1,200 lbs of batteries, and the aluminum chassis weighs 410 lbs. Assuming this new material replaces the aluminum pound-for-pound, that would store enough energy to displace about 82 lbs of ordinary lithium ion batteries for a ~5% reduction in total weight. If the energy density were somehow on par with lithium ion then it would save 410 lbs, or 25% of the total weight.
“... produced a structural battery that performs ten times better than all previous versions”"The battery has an energy density of 24 Wh/kg, meaning approximately 20 percent capacity compared to comparable lithium-ion batteries currently available. But since the weight of the vehicles can be greatly reduced, less energy will be required to drive an electric car, for example"
"the researchers did not choose the materials to try and break records – rather, they wanted to investigate and understand the effects of material architecture and separator thickness." - this implies there may be a lot of room for improvement with this design.
The Fastest Sports car! [1]
[1] with a 3.2-liter horizontally opposed flat 6-cylinder engine
But then that's not what it is about. The breakthrough is (oversimplifying here) that they invented a way to whack a bog-standard smartphone battery into the middle of a bunch of layers of building material, such that about 20% of the weight of the end product is battery, whilst the material is still strong enough to not cause a Samsung Galaxy Note style oopsie when structurally compromised, and to be strong enough to build with, and to have some of the mass of the battery improve the structural integrity of the whole, even.
The idea being: Take your tesla. Take the batteries out. Smash em to paste. Remove ~20% of the atoms from the chassis materials and replace them with your paste.
Voila - made your car 20% lighter.
I think there might be lots more low hanging fruit, their cars weigh quite a bit.
https://cleantechnica.com/2020/02/19/bloombergnef-lithium-io...
The problem is we don't really know what multifunctional performance means or how it's defined, but maybe this is a common metric in battery technology?
edit: I skimmed the actual paper linked in the article and it doesn't mention a 10x improvement.
"Structural battery composite materials, exploiting multifunctional constituents, have been realized and demonstrate an energy density of 24 Wh kg−1 and an elastic modulus of 25 GPa. Their combined electrochemical and mechanical properties outperform all previous structural battery materials reported in the literature. "
But even there, I feel like you can't just sum things up and say "LiIon are 10x better than Nickel Cadmium" there's a whole range of requirements.