In the story I only included the "summary" number--that they had achieved 100 F/g, but if you click on the report link you can get the rest of the numbers the researchers report. Here's a few examples from the report:
"single-walled carbon nanotube (SWCNT) thin film and achieved specific capacitance of 33 F/g and a high specific power of 250 kW/kg with an organic electrolyte...improved the graphene synthesis technique and reported a simple activation with KOH of microwave exfoliated graphite oxides and thermally exfoliated graphite oxides to achieve specific capacitance around 200 F/g in organic electrolyte...After laser reduction, the...ultracapacitor offered a specific capacitance of 265 F/g in an organic electrolyte with a wider operating voltage window of 3 V...sheet resistances of the SWCNT and composite thin films were 440.2 and 90.5 Ω /sq at room temperature, respectively...the capacitance of SWCNT and composite ultracapacitors can be estimated as 110 and 40 mF. The thin film of carbon nanostructures has the weight of 1.1 mg and surface area of 1 cm 2. Therefore, the specific capacitances of SWCNT and composites ultracapacitors were calculated as 100 and 36 F/g, respectively...According to Galvanostatic charging/discharging measurements, the specific capacitance of ultracapacitors was approximately calculated as 95 F/g for composites and 28 F/g for SWCNT...
Wow, Colin, I've read a lot of your articles over the years and I can't think of any that I would describe as 'fluffy'. I sympathize with the desire to get hard information, but it also has to be accessible to people that do not specialize in that field. Following an extra pointer to get to the research paper is a small step to take for those who are.
@Larry: Wow, Colin, I've read a lot of your articles over the years and I can't think of any that I would describe as 'fluffy'.
How about cuddly? LOL
I agree with you -- a lot of people just want to be provided with a high-level view, not burried under mounds of techno-babble -- the purpose of thsi type of column is to make folks aware of what's going on -- so long as it then links to the main report with all the numbers, I think it's perfect -- that way the folks who want the numbers know where to go to gorge themselves :-)
By no means is "fluffy" synonymous with Colin Johnson's journalism! - which I've been reading with great delight over more years than I care to count. Thank you for all that very informative work, Colin.
My problem was that I somehow missed the report link and what was posted was the same in a couple of other sources I'd already seen. The energy density of these devices seems to be most respectable.
I would like to know what the lifetime of these ultracapacitors is versus a rechargable battery. If it is infinite, then we should be moving forward to replace the batteries in electric vehicles with ultracapacitors. I would also like to see common rechargable batteries like AA cell NiMH that can have a drop in ultracapacitor replacement. I would pay more if it would last forever.
This is what I was thinking when I was reading the article. Going along the article, I get a sense that ultra capacitor may be a complement to the battery. It helps speeding up charging by storing and the ultra capacitor will then put the charge to battery for longer storage. I could be wrong. Nonetheless, I do like the article giving me a view of what's going on. I think it can be a to-be-continued article that the application of ultra capacitor and how ultra capacitor empowering the other technology can further be investigated.
From the density information of these new graphene based supercapacitors it looks like it may be possible to build these supercapacitors in the form factor and the capacity to match the rechargeable batteries that are currently used in EVs.
If that happens then EVs will get a major push as these supercapacitors can get recharged in no time and also are helpful in fast acceleration - thw two factors which are currently lacking in Evs vs the gasolene vehicles
It will hold true for the vehicle batteries but at the same time on the other hand this will be of benefit in case of sensor networks as well, in very less time the and lights the batteries can be charged to work overnight.
With such ultra capacitors and rechargeable paper batteries with high energy density, probably next portable will have one page battery, another page display and third page printed processing unit connected through edge binding!
Mr Johnson, don't take this personally, you are just feeding off what I think is a misperception of society that much invention and discovery is by mistake.
How is any of:
"... when the research team found that both could be easily synthesized by vaporizing a hollow graphite rod filled with a metallic catalyst powder with an electric arc. By thoroughly mixing the two materials to form an ink, the team was able to roll the film onto paper -- a common separator for high-capacity commercial capacitors"... a mistake?
A mistake is when you are carrying Ajak, ammonia, some alumina shavings and a power tool, trip and drop it all in Fido's water dish, and aftertaking the plugged in power tool out of the water and while you are running to flip the breaker back on, Fido trys to get a drink and is vaporized by the stored energy in the water bowl mix except for his right paw and the last third of his tail. That is an accident.
These guys were obviously going down a specific path which lead them to try the above method. Even if it was true the guy who discovered penicilin had the fungus randomly end up in his dish, he wouldn't have recognized what was going on if he wasn't on the path of that discovery.
I think hard work and genius should be recognized for what it is.
It's a great article Mr. Johnson except for that one perception of mine.
Just to clear up a perception that I see in the comments, above. An Ultracap is not a direct replacement for a battery. Batteries are electro-chemical ENERGY storage devices and rate limited as to how fast you can charge and discharge them. Ultracaps are POWER devices, the RATE of ENERGY charge and discharge. There is an overlap where they can be substituted for each other. In theory, an Ultracap can be charged (and discharged) instantaneously, and in fact system safety design has to include series resistance (or equivalent) with an ultracap to limit the charge/discharge rate (which you would not do with a battery).
For now, the size of an ultracap to replace a battery leaves something to be desired as well. But where you can benefit from near instantaneous charging (or discharging), it is finding a niche (e.g., the 90 second rechargeable cordless drill). In the mean time, look for hybrid applications with an ultracap as the external interface for instant charging (POWER) backed up by a battery for long life (ENERGY).
Finally, we still have a couple orders of magnitude to go before an ultracap or battery can replace fossil fuel in cars on the basis of power/energy density. And, yeah, the reliability is a risk for now. It's reasearcy, not a product announcement, which means it will be a while before these ever get to where you can buy one.
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.