Scientists at UC Santa Cruz (UCSC) and Lawrence Livermore National Laboratory (LLNL) have reported the first example of ultrafast 3D-printed graphene supercapacitor electrodes that outperform comparable electrodes made via traditional methods. Their results open the door to novel, unconstrained designs of highly efficient energy storage systems for smartphones, wearables, implantable devices, electric cars and wireless sensors.
Using a 3D-printing process called direct-ink writing and a graphene-oxide composite ink, the team was able to print micro-architected electrodes and build supercapacitors with excellent performance characteristics. The results were published online January 20 in the journal Nano Letters and will be featured on the cover of the March issue of the journal.
"Supercapacitor devices using our 3D-printed graphene electrodes with thicknesses on the order of millimeters exhibit outstanding capacitance retention and power densities," said corresponding author Yat Li, associate professor of chemistry at UC Santa Cruz. "This performance greatly exceeds the performance of conventional devices with thick electrodes, and it equals or exceeds the performance of reported devices made with electrodes 10 to 100 times thinner."
LLNL engineer Cheng Zhu and UCSC graduate student Tianyu Liu are lead authors of the paper. "This breaks through the limitations of what 2D manufacturing can do," Zhu said. "We can fabricate a large range of 3D architectures. In a phone, for instance, you would only need to leave a small area for energy storage. The geometry can be very complex."
This would obviously have applications in mobile phones as well as wearables and IoT devices, but what other applications would this empower? Would this be of use in automotive or home power applications? -Ed.
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A number of companies are developing advanced supercapacitors in the hopes of replacing or augmenting lithium-ion batteries:
Dr Donald Highgate, director of research at Superdielectrics Ltd, says a material he originally developed for soft contact lenses is also surprisingly good at holding an electrostatic field. [...] Dr Highgate is working with Bristol and Surrey universities to develop supercapacitors using the new polymer and hopes that they could eventually rival, or even surpass, lithium-ion (li-ion) batteries - so long as they manage to replicate prototype performance on a large scale.
[...] Taavi Madiberk, chief executive and co-founder of Skeleton Technologies, a supercapacitor maker based in Estonia, Germany and Finland, says his products incorporate layers of graphene - a single layer of carbon atoms arranged in a hexagonal lattice - and other carbon-based materials in its supercapacitors. These layers have a huge surface area - just 1g of graphene can cover 2,000 sq m, says Mr Madiberk. This allows them to hold on to a lot more power.
[...] But he acknowledges that in the short-term, combining supercapacitors with li-ion batteries is probably the best way to enjoy the best of both worlds, particularly in electric vehicles. Ulrik Grape, chief executive of NaWa technologies, another supercapacitor maker based in the South of France, agrees, saying: "Supercapacitors don't store as much energy but their response is instantaneous. So a supercapacitor could handle acceleration and energy recovery under braking - taking care of the stressful part of a battery's life - possibly doubling or tripling a battery's life expectancy."
(Score: 3, Insightful) by Covalent on Tuesday February 23 2016, @03:18PM
The power density reported in the Nano Letters paper (>4 kW/kg) is higher than that of Lithium Ion batteries (closer to 1kW/kg), so these could output their energy 4 times faster. But nowhere does it mention the energy density, and it doesn't give the data needed to calculate it either, so I'm guessing this was done at very low voltage. Nice proof of concept, but if this was a real energy storage game changer, they'd be shouting it from the rooftops, not hiding it behind a paywall.
You can't rationally argue somebody out of a position they didn't rationally get into.
(Score: 3, Insightful) by c0lo on Tuesday February 23 2016, @04:03PM
From the original nanolett FA**:
The cyclic voltammograms indicate they scanned the 0-1V range, but I suspect the gel they used is similar to Maxwell supercapacitors [wikipedia.org] - if so, the max voltage is 2.7V and they managed, without any optimization of the capacitor geometry, to put together something that is at par with the current energy densities. in supercapacitors.
Ummm... regarding:
** a few days ago, SN run a story about how scihub nested in the darknet. One comment posted the .onion link
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by Immerman on Wednesday February 24 2016, @12:48AM
Not quite. They're still discuss power density, what's missing to translate that to energy density is *time*, voltage isn't relevant. That pulse of energy may have only lasted a small fraction of a second.
As an extreme example - Let's say someone made a capacitor that could deliver 1 megawatt from something the size of a AA battery. Incredibly impressive in it's fashion, but if it only takes a millisecond to discharge then it only actually stored less than 0.28 Watt-hours of energy [1], maybe one-tenth as much as a cheap alkaline cell.
[1] 1,000,000MW*0.001s * (1h/3600s) = 0.2777Wh. In reality considerably less than that, since power output would reasonably be expected to decay exponentially with time as it discharged.
(Score: 2) by c0lo on Wednesday February 24 2016, @02:11AM
Maybe if you tell me what exactly don't you get from a maximum volumetric energy density of 0.14 mWh/cm^3 (at the power density of 49.48 mW/cm^3), I could help you better.
Beg you pardon? Last time I checked, the voltage difference between two points was defined as the energy required to move a charge of 1C between the two points.
Since then, maybe there was a revolution in physics that overthrew the oppressive definitions of the measure units, so you may be right.
Other than that, if you don't have other solutions, I suggest you to search SN for scihub's onion location**, stick the DOI number in their search box and enjoy all the details by yourself
--
** no, the non-onion scihub won't show you the full text of the original FA
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by Immerman on Wednesday February 24 2016, @07:39AM
My mistake, not sure why I saw power density instead of energy density, I could have sworn I double checked your quote.
I stand by the fact that voltage is not particularly relevant to the discussion. Knowing the voltage might give you some insight into potential applications and improvements, but it's not like you can safely extrapolate properties beyond the limits tested, especially in regards to a nanoscale engineered mechanical structure. And in regards to GPs low voltage objection - even if true it's nothing that putting a bunch of capacitors in series wouldn't fix.
Finally, According to https://en.wikipedia.org/wiki/Energy_density, [wikipedia.org] Lithium-ion batteries have an energy density around 1.8MJ/L (.9 to 2.6), or about 504mWh/cc, and supercapacitors around 14mWh/cc. So basically these supercapacitors offer a fairly typical energy density for supercapacitors, which is about 30x lower than lithium-ion batteries.
Hmm, rereading, I think I may have gotten a false impression from a punctuation error. In the context of the original poster's comparison to Li-ion, I read
>at par with the current energy densities. in supercapacitors.
as suggesting they had a achieved a similar capacity to Li-ion. In supercapcitors.
Also your definition of voltage is missing two vital components - time and resistance. Any nonzero voltage will move 1C charge across any resistance given enough time. 1V is defined as the potential that will move 1C across 1 ohm in one second. (1V = 1A * 1ohm)
(Score: 2) by c0lo on Wednesday February 24 2016, @08:16AM
Ah, I see. Indeed, the context is supercapacitors, not batteries.
Mmmm... yes and no.
Yes, the supercapacitors are limited to 2.7V max with the current techno level.
No... assuming they find a gel that can push the voltage higher, the same electrodes with the new gel will have a higher energy density because the supercap can now be charged at higher voltage
Mind you, TFA is not about a new supercapacitor technology, it's about a new way of printing macroporous graphene/GO electrodes with regular pore patterns.
They used the supercapacitor as a test that their technology is not worse than others (and discovered that's slightly better in performance).
Mmmmm... yes and no. Historically, it was the unit of electrical charge and the second that defined the unit of current (as a derived unit). At that time, the volt definition was exactly the energy required to move a charge between the two points - no time, no resistance.
Because the amount of charge is hard to measure directly, later the fundamental/derived role was switched, making the Ampere as fundamental (easier to measure based on the magnetic interaction). The Volt is now defined [wikipedia.org] based on the Ampere (fundamental) and the Watt (derived).
So yes, to define the Volt you need the Ampere (maybe a time integration, because instantaneous power is again hard to measure), but definitely you don't need the Ohm.
Resistance unit - ohm - is again a derived unit, based on the Volt and Ampere (without voltage or current, one cannot define resistance).
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by Immerman on Wednesday February 24 2016, @10:53AM
Yes, higher voltages would obviously improve energy density; but do you have any reason to conclude that electrolyte breakdown was the reason they couldn't push the capacitors farther, rather than say, structural electrode failure at a much lower voltage?
It makes no sense to define voltage in terms that don't have a time component, 0.0001 V is more than sufficient to move even 10000C of charge any distance, if you give it long enough.
Perhaps you're thinking of the definition in which 1V is the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it? In that case you're still introducing a reference time component (1s) embedded in the energy definition ( kg*m^2/s^2), even though you're not explicitly stating it.
(Score: 2) by c0lo on Wednesday February 24 2016, @11:46AM
Yeap, pretty sure is the electrolyte, not the electrodes. Wikipedia [wikipedia.org]
Maxwell super/ultra/capacitors can reach as high as 3000F (right, Farads. Not milli, not micro. 3000 F***ing Farads), but go only to 2.7V.
A clip [youtube.com] with charging one of only 370F with a supply able to deliver 3A at 2.5V - takes 6 minutes to reach 2.3V.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by Immerman on Thursday February 25 2016, @03:19PM
That link is about supercapacitors in general, I' talking about *this particular* supercapacitor creation technique. There's no reason to assume the limiting factor is the same unless explicitly stated.
(Score: 2) by c0lo on Thursday February 25 2016, @09:48PM
Mate, I told you to go read the original FA from scihub, that is still my recommendation (and that's final).
You'll learn from that the authors did not intend to create a novel supercapacitor but a novel way to print macroporous electrodes with a regular distribution of the pores.
They used the supercapacitor field of technology just to validate that this technique is not worse than the currently available methods.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by Gravis on Tuesday February 23 2016, @04:06PM
why does it need to meet your arbitrary standards? any improvement is welcome as it may inspire further improvements. now go sit in the corner. (＃｀д´)ﾉ
(Score: 3, Insightful) by ikanreed on Tuesday February 23 2016, @10:27PM
The reason he's saying what he's saying is that there are specific purposes people tend to imagine supercapicitors fulfilling, when that word is used, and chief among those is replacing rechargeable batteries. And if the energy density is substantially lower than batteries, then the advantages: near infinite charge cycles, high power output, more environmentally friendly, etc, won't make up for them.
(Score: 2) by Gravis on Tuesday February 23 2016, @11:07PM
The reason he's saying what he's saying is...
i know why he's saying it but i'm asking him why he thinks his expectations are important with a rhetorical question that implies it does not.
you have wasted everyone's time. now go sit in the corner. (＃｀д´)ﾉ
(Score: 2) by ikanreed on Tuesday February 23 2016, @11:14PM
Oh, so your attitude is less "that concern is invalid" more "how dare someone other than me have an opinion? WHAT IMPUDENCE"
(Score: -1, Offtopic) by Anonymous Coward on Tuesday February 23 2016, @03:56PM
We can just print this, right?
Application: the recent hydrogen-supercapacitor car.
(Score: 4, Informative) by c0lo on Tuesday February 23 2016, @04:27PM
TFA is not about inventing a new supercapacitor, but inventing a process in which the electrodes can be 3D printed. Various techs/chemistries may be used on top of it.
The resulted electrodes are macroporous, with a pore size of 1000um(=1mm if I'm not mistaken). The "ink" is a mixture of graphene nanoplatelets, graphite oxide fumed silica and resorcinol-formaldehyde (R-F) solution - the last one is for the purpose of obtaining a gel. Yes, of course, water based.
They 3D-printed the stuff under an organic solvent (2,2,4-trimethylpentane) to avoid the water evaporation collapsing the 3d-printed structure.
They extruded the stuff to form sort of a stack of lattices - one set of extrusions on X direction, the next on Y direction and so on. After gellation (85C overnight), they dried it in supercritical CO2 (to avoid gel collapse), calcined at approx 1000C (to remove the resorcinol-formaldehyde gel and let only the grafene/GO/silica skeleton) and eliminated the silica using diluted hydrofluoric acid.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: -1, Offtopic) by Anonymous Coward on Tuesday February 23 2016, @06:29PM
My UAV runs off a 3D PRINTED, GRAPHENE supercapacitor!! The buzz is very loud!!
(Score: 1, Offtopic) by SanityCheck on Tuesday February 23 2016, @08:17PM
Is it the buzz of the supercharge discharging?