Supercapacitors vs batteries. Capacity.

[Hillhater]

Combined with the 1C in/out limits, it seems to have power behavior, voltage characteristics, and energy density an awful lot like a box of low C rate iron phosphate cells would have.

Yes, however they firmly state there is no chemical batteries involved, and have managed to convince the FAA and relavent associated authorities of that.???

 

[liveforphysics]

Combined with the 1C in/out limits, it seems to have power behavior, voltage characteristics, and energy density an awful lot like a box of low C rate iron phosphate cells would have.

Yes, however they firmly state there is no chemical batteries involved, and have managed to convince the FAA and relavent associated authorities of that.???

I've yet to see a sanctioning body test involving SEM RDX or Libz or XRF to know what salts may or may not be dissolved into the electrolyte, or coating the anode. A lithium ion double-layer capacitor further blurs between cap and LIB. It's perhaps not technically incorrect to call our industry standard lithium-ion cells a super-capacitor with intrensic ion supported recharging.

 

[Hillhater]

Im thinking along the lines that its a. "self certification".. Type process, with somebody from Kilowattlabs signing a legal airfreight declaration to say there is no Li cells involved on penalty of jail or huge fine.
Something they would not want to risk when they could simply surface ship them instead.
I would also assume that a supercap device would be shipped at 0 volt charge, which shouldnt be too hard to verify ?

 

[jonescg]

It sounds a lot like a play on words, or at least generous use of words to describe the nature of the energy storage device. If they have genuinely managed to obtain 2.7 volt, 3000 F capacitors which are the size of a Li-ion cell, why haven't we seen these products in the literature, or being certified elsewhere...?

 

[liveforphysics]

Im thinking along the lines that its a. "self certification".. Type process, with somebody from Kilowattlabs signing a legal airfreight declaration to say there is no Li cells involved on penalty of jail or huge fine.
Something they would not want to risk when they could simply surface ship them instead.
I would also assume that a supercap device would be shipped at 0 volt charge, which shouldnt be too hard to verify ?

Most assembled battery systems would require closing internal contactor or FETs to get a voltage reading. This may require connectivity to CAN network and required handshake and libraries of commands merely to check voltage.

 

[Hillhater]

It sounds a lot like a play on words, or at least generous use of words to describe the nature of the energy storage device. If they have genuinely managed to obtain 2.7 volt, 3000 F capacitors which are the size of a Li-ion cell, why haven't we seen these products in the literature, or being certified elsewhere...?

Sure , more mystery rather than explanations.!
Jonescg, can you ask Paul, via the Aeva forum, to just take a few relavent photos inside the mystery box ?
He seems happy to respond on that site.

 

[jonescg]

I've yet to see a sanctioning body test involving SEM RDX or Libz or XRF to know what salts may or may not be dissolved into the electrolyte, or coating the anode. A lithium ion double-layer capacitor further blurs between cap and LIB. It's perhaps not technically incorrect to call our industry standard lithium-ion cells a super-capacitor with intrensic ion supported recharging.

So this image popped up on facebook:


UN3499 - double layer capacitors.

So yes, it's a lithium ion double-layer capacitor. Not a supercapacitor, which is the main contention we've had thusfar. If they were true supercapacitors they wouldn't have the energy density quoted.

 

[Hillhater]

So this image popped up on facebook:
caps.jpg

UN3499 - double layer capacitors.

So yes, it's a lithium ion double-layer capacitor. Not a supercapacitor, which is the main contention we've had thusfar. If they were true supercapacitors they wouldn't have the energy density quoted.

? Whos FB page was the photo on ...KiloWattlabs, or Arvio ?
Isnt a a "Supercapacitor" a EDLC ?
Whatever the type, they are still capacitive devices are they not ?
How does this help clarify whats in the Sirius box ?

Edit:-
Further to the above ..Arvio (P Wilson ), has repeated several times..

?..... There are no lithium ion electrochemical cells in the super capacitor modules which are being used...?

..and since a Li Capacitor is clearly understood to be an "electrochemical ". device, would seem to contradict the LIC idea , ...and dont LiC's have a higher operating voltage ?.

 

[jonescg]

It was posted by Paul on a solar installers' page.

I was under the impression lithium ion double-layer capacitors were a kind of hybrid capacitor, but if that makes them a supercapacitor then so be it. The main point of contention was the way Kilowattlabs were using images of Maxwell 3000 F capacitors (non electrochemical) in their promotional material, yet there's clearly a different component inside the Sirius unit.

So yes, our plausible explanation was that there were Li-ion cells inside was not the right one, but I would also say that the definition of 'safe and not electrochemical' have been stretched...

 

[Hillhater]

Wiki suggests that "SuperCapacitor " term covers a range of posibilities ..
Electrostatic DL Capacitors
Electrochemical DL (Pseudo) Capacitors (LiC)
Combination of both in Hybrid construction.

And that UL3499 is a United Nations Material Category for shipping dangerous goods.
.....specifically capacitive devices of between 0.3 and 10.0 Wh capacity.

 

[liveforphysics]

LiC is like a lithium battery, but the ions stay in the anode just for the voltage gain.

They are damaged if discharged below ~1.8vdc.

Brief overview copied from wikipeadia:

"A lithium-ion capacitor is a hybrid electrochemical energy storage device which combines the intercalation mechanism of a lithium-ion battery with the cathode of an electric double-layer capacitor (EDLC). The packaged energy density of an LIC is approximately 20 Wh/kg generally four times higher than an EDLC and five times lower than a lithium-ion battery. The power density however has been shown to match that of EDLCs able to completely discharge in seconds.[4] The negative electrode (cathode) often employs activated carbon material at which charges are stored in an electric double layer that is developed at the interface between the carbon and the electrolyte.

The positive electrode (anode) was originally made from lithium titanate oxide, but is now more commonly made from graphitic carbon to maximize energy density. The graphitic electrode potential initially at -0.1 V versus SHE (standard hydrogen electrode) is lowered further to -2.8 V by intercalating lithium ions. This step is referred to as "doping" and often takes place in the device between the anode and a sacrificial lithium electrode. The pre-doping process is critical to the device functioning as it can significantly affect the development of the solid electrolyte interphase (SEI) layer. Doping the anode lowers the anode potential and leads to a higher output voltage of the capacitor. Typically, output voltages for LICs are in the range of 3.8–4.0 V but are limited to minimum allowed voltages of 1.8–2.2 V. If the voltage drops any lower than this lithium ions will deintercalate more rapidly than they can be restored during normal use. Like EDLCs, LIC voltages vary linearly adding to complications integrating them into systems which have power electronics that expect the more stable voltage of batteries. As a consequence, LICs have a high energy density, which varies with the square of the voltage. The capacitance of the anode is several orders of magnitude larger than that of the cathode. As a result, the change of the anode potential during charge and discharge is much smaller than the change in the cathode potential.

The electrolyte used in an LIC is a lithium-ion salt solution that can be combined with other organic components and is generally identical to that used in lithium-ion batteries.

A separator prevents direct electrical contact between anode and cathode."

 

[spinningmagnets]

I've been looking for a reference to explain the moment when capacitor design went from a capacitor to a "super capacitor". So far it "looks like" it was the moment when they went from jobs like voltage ripple smoothing to actually storing energy, and being designed from the ground up to do that. Perhaps when "double sided" capacitors were designed? which dramatically improved the capacity, but don't seem to change any other metric.

The first capacitors I began reading about was the low-ESR 50V units that we added to 12S "44V" RC motor systems, to keep the expensive ESCs from popping. https://endless-sphere.com/forums/viewtopic.php?t=22194&start=45

Those are roughly the volume of my little finger, and have 1,000 uF. Since one Farad is (*Googles furiously) 1,000,000 uF, and...The Maxwell "D-cell" 350F super capacitors I have are roughly ten times the physical volume, but...their electrical energy capacity is...100,000 more per Farad, then they are...350,000 times more capacity. So...knock off one zero to divide the D-cell volume by a tenth (to equalize volumes), and...The super capacitor has 35,000 more energy per unit-of-volume than a capacitor that is designed for the normal jobs capacitors used to do.

That being said, when comparing super capacitors to batteries, I recently saw many you tubes of cars being started by super caps, and...since SCs drain down over time, I also saw hybrid packs with 4S LiFePO4 + SCs. One video shows a fully charged 6S 350F super cap bank (no lithium added), he unplugged the spark and fuel relay, then cranked-over the 4-cylinder engine. He had shown on some cheap measuring devices that this car started with a half-second peak of 200A, and a continuous 100A to keep going. It ran for about 30 seconds at 100A on the SCs alone.

100A is pretty awesome for an ebike (IMHO), but...30 seconds is very short range (although, not bad for six D-cells). On the other hand, most of the videos were for cars in ultra-cold climates where lead-acid sags, even when new and fully-charged.

Here's one tech observation. A common strategy to increase capacity (among several strategies), is to increase the collector area per volume, and one way to do that is to use the thinnest possible separator sheets. However, the thinner the separator, the lower the break-down voltage is, so...high-Farad SCs are typically low voltage. The Maxwells are 2.7V and the Amperics are 3.0V

Luke has been an advocate for lowering typical system voltages, and emphasizing amps to get the target watts. It would be interesting to see a high-powered E-moto system as low as 13S / 48V with SC's added to handle the acceleration peaks, and the battery designed for best capacity (or failing that, maybe an E-scooter?). Many E-scooters start out as 48V, and are boosted to 72V when the lead acid dies and the owner swaps to lithium. What if he swapped to a higher KV motor (low turn-count) and added super caps to handle amp peaks?

 

[Hillhater]

Arvio continue to drip feed details of the Sirius Supercap power pack...

https://youtu.be/8MgCrdyWYoM
Charge & discharge profile curve for supercapacitor module

[youtube]8MgCrdyWYoM[/youtube]

And
https://youtu.be/fdI1ZpRhUkI. Pick it up at about 8 mins in
[youtube]fdI1ZpRhUkI[/youtube]

BUT...!!
There is a strong suspicion that rather than supercaps, we are actually dealing with 18650 LTO cells of 1.3 Ah capacity, which would fit the voltage range, capacity, performance, and cost claims,....without "magic sauce" !

 

[TheBeastie]

You can read a pretty good description of these types of Lithium capacitors here.
Lithium Ion Capacitors: An Effective EDLC Replacement
https://www.digikey.com.au/en/articles/techzone/2015/jan/lithium-ion-capacitors-an-effective-edlc-replacement

In that video HillHater posted that guy talks about the fact that these li-caps have a constant voltage like a battery and don't massively drop like a traditional capacitor. And again emphasizes its an electrostatic charge and not an electrochemical charge like a traditional battery.

He shows this off in this newly uploaded video, you can watch the multimeter manually or just look at the graph he displays which shows constant battery like voltage.
https://www.youtube.com/watch?v=aQD8hk2llN0

[youtube]aQD8hk2llN0[/youtube]


So all up as far as I am concerned what he has is all real. As he mentions hes worked hard to acquire/help develop this technology early.
Apparently home roof solar subsidies last year were $500million in Australia and its expected the subsidies for just standard roof solar in Australia will be $1.2billion by the end of 2018 so there's big money to suck out of the taxpayer thats going to be added to electricity bills in the coming years so it makes sense to have this kind of technology available for folks who want top notch stuff.

Also, he does a pretty good safety comparison video here, between his li-cap and a standard 18650.
I like this bit where he gets a standard 18650 cell glowing.. I made a Samsung 18650 cell glow like this, it was a severely deformed cell I got somehow, it looked like a forklift had run over it at the Australian post depot, it came repackaged in an official 'Australian-Post repackaged bag', I hooked it up to a battery pack anyway and it melted out of the pack and glowed for a long period of time just like this guys video shows. I have never looked at a 18650 the same way again.
https://youtu.be/Z7jjMq5UE9A?t=1m5s

 

[billvon]

In that video HillHater posted that guy talks about the fact that these li-caps have a constant voltage like a battery and don't massively drop like a traditional capacitor. And again emphasizes its an electrostatic charge and not an electrochemical charge like a traditional battery.

Those two sentences conflict with each other. If it's an electrostatic storage mechanism then it follows 1/2CV^2 and it "massively drops like a traditional capacitor." If it's an electrochemical system then the voltage will remain steadier, maintained by the electropotentials of the materials chosen for the electrodes.

 

[amberwolf]

Or it has some conversion electronics that maintain the output voltage, whether they will admit it or not.

 

[liveforphysics]

What's shown in the video would be exactly the voltage curve signature of a LTO (lithium Titanate anode) cell.

I know of no type of capacitor, ion assisted potential or not that exhibits that voltage curve for energy storage.

From a technical aspect, they are of course intrensic supercaps like all lithium ion batteries, so it doesn't bother me if they prefer to call them caps for shipping or whatever. LTO likely handles safety tests better even being a lithium ion battery vs supercaps anyway, which can get pretty excited in safety tests.

 

[Hillhater]

Or it has some conversion electronics that maintain the output voltage, whether they will admit it or not.

But it was a bench test on a single, bare "supercapacitor" component, with no associated electronics.

 

[Buk___]

Wiki suggests that "SuperCapacitor " term covers a range of posibilities ..
Electrostatic DL Capacitors
Electrochemical DL (Pseudo) Capacitors (LiC)
Combination of both in Hybrid construction.

And that UL3499 is a United Nations Material Category for shipping dangerous goods.
.....specifically capacitive devices of between 0.3 and 10.0 Wh capacity.

It's going to be mildly amusing to watch the naysayers here backtrack when this turn out to be exactly what they say it is.

 

[jonescg]

I'd never be happier to be wrong! The thing is, this is a promise of orders of magnitude more energy density than the most advanced capacitors on the market. Someone deserves a frigging Nobel Prize if they have actually done it.

It sounds like an electrochemical storage device being described as a supercapacitor...

 

[amberwolf]

But it was a bench test on a single, bare "supercapacitor" component, with no associated electronics.

Unless they're inside the module where you can't see them, in the can, casing, shrinkwrap, etc.

I've seen so many claims of so many things over the years, that then can't be substantiated, or the claimant simply refuses to even try to do a real public test, etc., that I am very skeptical of pretty much everything even a little out of the ordinary.

 

[Hillhater]

The problem is, the performance, charge/discharge curves, size, capacity, price, even appearance.....is all so much more like the commercially available LTO cells than any type of supercapacitor known to exist.
"State of the art". ,3000F supercapacitors are many orders of magnitude bigger and cost a minimum of $50 each.
So unless there has been a earthshattering , mega step change in capacitor technology and manufacturing ,...together with a equally revolutionary financial approach to marketing a industry changing product....then i will not be expecting to be surprised when the full details are established.

 

[Buk___]

The problem is, the performance, charge/discharge curves, size, capacity, price, even appearance.....is all so much more like the commercially available LTO cells than any type of supercapacitor known to exist.
"State of the art". ,3000F supercapacitors are many orders of magnitude bigger and cost a minimum of $50 each.
So unless there has been a earthshattering , mega step change in capacitor technology and manufacturing ,...together with a equally revolutionary financial approach to marketing a industry changing product....then i will not be expecting to be surprised when the full details are established.

I expect the truth will be less earth-shattering, industry changing technology and more, hiding behind the ill-defined nature of the term "supercapacitor".

As I alluded to elsewhere in this thread, there is a dichotomy in the different behaviours of two essentially quite similar products, in terms of physical construction, materials and physics; the way their capacities combine in series.

If they found a small change (or series of changes) that brought the best properties of each into a single construction, it'd be more evolution than revolution.

One could speculate that if you combined 3 layers with two different electrolytes, you might get something that has some of the properties of both.

 

[liveforphysics]

Every LIB has the intrensic supercap properties already and always has.

 

[Buk___]

Every LIB has the intrensic supercap properties already and always has.

Obviously, not all of them, or they wouldn't behave differently.