
Graphene supercapacitors are 20x as powerful, can be made with a DVD burner  - evo_9
http://www.extremetech.com/extreme/122763-graphene-supercapacitors-are-20-times-as-powerful-can-be-made-with-a-dvd-burner
======
ctdonath
Underdiscussed point: one reason we want such high capacity power storage is
that recharging takes _hours_. Society has internalized long charging times as
normal. Would we fuss quite so much about run time if a recharge took seconds
instead? (Am thinking cell phones/tablets here, not the dangerously high power
issues of recharging a car in one minute flat.)

~~~
anamax
For many applications, we can get the equivalent of fast recharging by
swapping batteries. Yet, we still want long battery life because swapping is
inconvenient.

Fast recharge is also inconvenient. Just as you must have a set of batteries
to swap, you must have the means and opportunity to fast recharge. Note that a
fast recharger is probably at least as big as a set of batteries. And, I can
swap batteries in places where I can't plug in the recharger.

Yes, fast recharge is less inconvenient than slow recharge.

~~~
Tossrock
I don't think swapping batteries is a good analog for fast recharge. For one,
the cost of a kilowatt hour in AA batteries well exceeds $100, even buying in
20-count lots. From the wall, it costs less than a dollar. Swapping batteries
is also significantly more effort than plugging in a microUSB or whatever.

~~~
tjoff
Still way to cumbersome. I would love to be able to get a quick fix but I
won't trade any battery life for it.

If I'm ever around to recharge quickly I can just as well let it sit there for
a while, at least the vast majority of times. Please note how convenient it is
to charge from a USB-port, a micro usb cable is all that is needed to be able
to charge pretty much anywhere (and they are cheap enough leave one at
home/work/laptop/pocket. With a fast charger I'd have to bring it along and
plug it in everywhere - not worth it. And I most definitely would like at
least the same poor battery life that we have today, otherwise you wouldn't be
able to last a day without a charge and that it just unacceptable regardless
of how easy or fast it is to recharge.

------
Cushman
Taking the article at face value, it sounds like they're talking capacitors
with an energy density comparable to lithium-ion, and that's on the first try.
(Although just looking at the chart it looks more like at least an order of
magnitude lower.)

But we're used to being disappointed by articles about graphene... Anyone got
a reason this isn't as good as it sounds?

~~~
snewman
A key point here is the tradeoff between energy density (how much energy the
battery or capacitor can hold) and power density (how quickly the energy can
be released).

I'm not an expert, but just working from the graph in the article, the best
energy density they show for the new graphene capacitors is roughly 1/8th the
best energy density for lithium-ion batteries. What's interesting is that
capacitor has roughly 500x the power density of that battery. Or if you look
at a battery tuned for power density (lower-right end of the red arc in the
graph), there's a capacitor that can offer 200x or more power density with the
same energy density.

More simply: for low-discharge-rate applications, lithium-ion still wins,
though the new capacitors may narrow the gap a bit. For high-discharge-rate
applications, these capacitors win by a mile. (Ignoring considerations not
covered in the chart -- cost, durability, temperature sensitivity, safety,
etc.)

~~~
marshray
What's an example high-discharge-rate application where Lion could be
displaced?

Toy helicopters? EMP weapons?

Weight would be an interesting graph axis!

~~~
evgen
It is not just about high discharge. In return you also get fast recharge.
Something that can suck in a large chunk of power, hold it for a short time,
and then dump it out again rather quickly has certain advantages. Consider the
energy storage system for regenerative braking, for example, which needs to
absorb a lot of energy quickly -- the trick is then figuring out what to
discharge it into, starting a vehicle rolling is the prime candidate but there
may be other uses of an intermediate storage device like this.

In most cases I think that this will not displace Li-ion but would instead
augment the existing battery setup.

~~~
Cushman
Yeh, that's the really cool bit-- would you be okay with your iPhone only
getting an hour of battery life if you could fully charge it in a couple of
seconds?

I mean, obviously not, but it's interesting to think about.

~~~
marshray
But what about a hybrid system where you could add an hour or two of usage in
that first few seconds of charging?

Would be great during a layover in a typical US airport where you might have
to sit on the floor in a corner to use a power outlet. You could plug in for
10s to fill the cap, eat lunch while the cap charges the battery for an hour,
plug in again for 10s before you fly out having something close to a full
battery.

~~~
robocat
A cellphone battery is say 1 Amp Hour. Assume an equivalent capacitor is 3600
Amps for a second. Assume the capacitor is charged to 10x the Voltage, and is
charged in 10 seconds. That needs 36 Amps - copper wires a bit thicker than
those in a kettle cord. Bad approximations made, but right order I think.

Also there are real safety issues with something that can be charged that
fast, because it usually implies it can be discharged faster. A shorted Li ion
battery may burn, but a low-resistance capacitor will cause an explosion.
Capacitors are fun :-)

~~~
kronusaturn
An iPhone battery is roughly 1400mAh at 3.7V, which gives 5.2Wh or 18720 watt-
seconds. A standard power outlet in the US supplies 15A at 120V, for a maximum
of 1800 watts. So if you could charge your phone using the maximum power
available from a standard outlet, it would take roughly 10 seconds. A typical
laptop might take about 1-2 minutes. (That's assuming 100% efficiency, which
is unrealistic.)

~~~
ars
He's talking about the wire to the battery, not from the outlet.

------
ChuckMcM
I've got solar panels on my house. During the day, on good days, they generate
more power than I use in a 24hr period, except I'm grid tied because I can't
economically store that power.

Back when maxwell tech [1] was using them to start diesel electric locomotives
I did the math to figure out how many I would need in my house foundation to
'carry me' over from day to night, and it was an additional $128,000 and
probably 1000 sq ft of 'foundation' space to hold them.

Graphene, and other high surface area + high conductivity solutions seem like
they will make this configuration more feasible in the future. It would be
interesting to be 'off grid' but without the cost/hassle of maintaining a
bunch of batteries.

[1] <http://www.maxwell.com/>

------
th0ma5
I read this with great interest when it came across another site. I have
watched many of people explode bolts or something with homemade capacitors.
This seems to imply that a home a solution for experimentation could be
derived, but at this time it seems that while a DVD burner may be in the mix,
it is in the middle of a very advanced lab and the further processing such a
material would require for application.

------
jerf
Does anyone know or have the capability to accurately estimate what the
volumetric power density of these capacitors are (assuming they commercialize
well)? In terms of replacing cell phone batteries or something, that's what
matters, and I only see areal densities.

~~~
missing_cipher
Maybe I'm not understanding correctly, but isn't that how they're presenting
their findings(W/cm³)?

[http://www.extremetech.com/wp-
content/uploads/2012/03/energy...](http://www.extremetech.com/wp-
content/uploads/2012/03/energy-density-graphene-capacitor-640x399.jpg)

<http://en.wikipedia.org/wiki/Power_density>

~~~
morsch
Wouldn't you care more about _energy_ per volume or weight? In other words
Watt-hours/cm³.

~~~
SuperFungus
Thats the discussion. In reality, you care about both. Power density to move
the energy into and out of the cell quickly to shorten charge times and supply
thirsty loads. Energy density to run lower loads for longer.

------
1053r
These might replace other kinds of capacitors, but at the listed energy
density, there is no way they are going up against cell phone batteries or car
batteries. According to wikipedia, the lithium iron phosphate battery has an
energy density of 220 mWh/cc. These are weighing in at 1.36 mWh/cc, according
to the article.

And existing battery chemistries can already charge fast enough such that the
limiting factor for electric car recharge times is the grid. My Nissan Leaf
can charge most of the way in 25 minutes at a L3 charging station. But PG&E
levies enormous fees for people who want to pull down that kind of power, so
there isn't a single operable L3 station in the whole bay area.

~~~
aptwebapps
That's 220 Wh/L for lithium iron phosphate batteries, or 0.22 mWh/cc.

------
Tossrock
To me the most astonishing part of this article is that they can 'bake'
graphene out of graphite oxide with consumer-grade tech. Did I miss something,
or is that not a huge step forward for graphene synthesis?

~~~
jacquesm
All it takes is a pencil and some scotch tape, it does not get much more low
tech than that.

~~~
DrStalker
And if lightscribe can produce usable graphene for super capacitors an
industrial machine that does the same thing faster and better shouldn't cost
too much, and I can't see any reason why the low-tech approach can't scale up
easily.

------
jbert
What about micro-fuel cell + hydrocarbons?

The energy density of gas/petrol is fantastic. Recharge time is quick ("pour
some in").

[http://www.gizmodo.com.au/2011/12/a-gallon-of-petrol-can-
pow...](http://www.gizmodo.com.au/2011/12/a-gallon-of-petrol-can-power-an-
iphone-for-20-years/)

<http://www.mtimicrofuelcells.com/>

Sure, we have limited supplies of hydrocarbons in the ground, but to me the
key energy technology would be "synthesise hydrocarbons from water + CO2 +
energy in". i.e. stop focusing on hydrocarbons as a _source_ of energy and
start thinking of them as a 'transport' of energy.

That would also mean we can move to clean, renewable power generation without
retooling the globe's transport fleet.

~~~
karamazov
I had the chance to analyze a solid-state gas engine a few months ago, based
on this technology:

[http://web.mit.edu/newsoffice/2011/sun-free-
photovoltaics-07...](http://web.mit.edu/newsoffice/2011/sun-free-
photovoltaics-0728.html)

The solid-state engine has much lower efficiency than a regular power engine
would (a hypothetical 12%/realized 5% vs. a realized efficiency of about 30%),
but it can be made much smaller - and even at a 5% conversion rate, the energy
density just blows everything else out of the water. Aside from being energy
dense, it's also much cheaper than high-end lithium-ion batteries; and unlike
regular fuel-cells, the technology is just based on regular photovoltaics, and
is relatively easy to manufacture.

~~~
jbert
Awesome, so we'll have the tech to consume the hydrocarbons, but where is the
production side?

What do we need to be able to hook up a nuclear power plant, a supply of clean
water and a big air pump and starting sucking in H2O+CO2 and piping out
CnH(2n+2) and pumping out O2?

------
mbell
Here is a video from the author of the article on the process used

[http://www.aaas.org/news/releases/2012/0315sp_capacitor.shtm...](http://www.aaas.org/news/releases/2012/0315sp_capacitor.shtml)

~~~
drucken
Youtube version of same video: <http://www.youtube.com/watch?v=_oEFwyoWKXo>

Yes, it is very informative/clarifying.

------
robomartin
I'll preface this by saying that I want my next vehicle to be electric.

Here's my concern with regards to electric cars: There's a huge difference
between failure modes of electric vs. gasoline powered vehicles in crash
scenarios.

In a great deal of cases a crash with a gasoline-powered car results in no
spills or fires. No problems. In a few cases a spill might result. Fires are
only a factor when gasoline vapors are involved.

If a pure electric vehicle has a range equivalent to that of a gasoline-
powered vehicle, say, 200 to 300 miles, this means that it is storing a
tremendous amount of energy. Also, due to i-squared-c losses it is very likely
that the system will be a high voltage system (hundreds of volts).

In the case of a bad accident this energy could be released violently. There
might come a day when we hear of an entire family electrocuted to death in
their car after a crash. I hope this never happens, but I have a feeling it
could.

As I see it this is the PR problem with the technology: Huge amounts of energy
that could do serious damage if something goes wrong. In contrast to that, a
gas tank is a relatively harmless device.

Yes, there are safety measures that can and are being utilized, like fusible
links between batteries and intelligent management systems. Still, it doesn't
take much at, say, 500 volts, to cause a lot of damage quickly. As someone who
has worked with and designed very high power DC motor controls and have tested
many designs to destruction I have to say that this is an area that really
needs to receive a tremendous amount of attention.

The last thing the industry needs is the media devoting weeks to cover how a
family got fried in their electric car while the fire department was powerless
to aid them until the batteries fully discharged (which could take a long
time). That would be a truly horrific sight to behold and a potential
industry-killing event. Close your eyes and imagine that for a moment. Then
imagine trying to convince someone who saw that on TV to buy an electric car.

Super-capacitors could help in this regard in very meaningful ways. If we
could get battery packs to be small enough that leaves a lot of room for
creating a crash and intrusion protection barrier around the battery.

Today battery packs are very large and heavy. And, while I am sure that a lot
of work has gone into safety, they could be made far safer if the batteries
had higher energy capacities.

The other way super capacitors might be able to help could be as paradigm
shift enablers. Picture the case of not needing a range of 300 miles. For most
of us, 60 miles might be enough. If that battery pack is small enough gas
stations could morph into battery pack swap stations. The fact that a super-
capacitor has a useful life of tens of thousands of cycles means that there
would be no concern of receiving someone's almost-dead battery. The cost of
re-fueling would include some amount of money to deal with packs near or at
their end of life. If you did need to go farther maybe cars could be designed
with room for a second range-extension pack or some other means to connect a
larger battery pack.

From a safety standpoint, I want to see the kinds of tests companies like
Volvo and Mercedes are known for: Fling a car through the air and roll it
multiple times. In other words, extreme stuff that is unlikely to happen in
most accidents. After the tests the cars have to remain in a state that is
safe enough for egress as well as for rescue personnel to approach, touch and
render aid.

In other words, electric cars have to be better in terms of safety than
gasoline powered vehicles.

~~~
jberryman
Driving any sort of car has such a high likelihood of killing you and your
whole family in so many dozens of ways, it's hard for me to see how the
battery issue is something to get hung up on (not that any safety improvement
isn't a good thing).

But I agree that a death-by-car-electrocution scenario would be big news, and
not a good thing for electric car makers.

~~~
JoeAltmaier
A capacitor could internally short, releasing all of its energy at once.
Imagine all of the gasoline in your car going off at once. Its a bomb. That's
quit a different scenario from other car-crash situations.

We've all seen the laptop-going-nuclear videos when Li-Ion batteries short.
This could be worse, given the high discharge potential mentioned in the
article.

~~~
jamesaguilar
> That's quit a different scenario from other car-crash situations.

Only if it happens frequently. If it happens in one of ten thousand fatality
accidents, you won't even be able to see it in the statistics.

~~~
robomartin
...but you will see it on TV. And that is what will stop the industry on its
tracks.

People are used to gasoline. They are comfortable with it, if you will.
Electricity is another matter. People fear electricity. They don't understand
it. If electric cars are seen as roving high-tension wires that can
electrocute you and your family in a crash that will be the end of the
industry. People don't care about statistics but they react very readily to
anything that triggers fundamental fears.

~~~
caf
Families have burnt to death horribly in gasoline fires, too. They don't tend
to show that kind of thing on TV at all (and I don't think that burning to
death is significantly less horrible than electrocution).

------
SuperFungus
There's quite a few practical details that weren't addressed. Whats the self
discharge of these caps? Sure, maybe they can hold a ton of energy in a small
volume but who cares if it bleeds off in 2 hours? What's the performance over
temperature? Does the capacity drop off at temperature? Does the available
power drop off? A lot of conventional supercaps can even permanently age quite
quickly at moderately high temperature.

------
forgottenpaswrd
Wow, this is fantastic news!

One of the fantastic things about grapheme is that it is so easy to work with
and abundant material.

This simple method of reduction means you could create a machine for making
long sheets of grapheme just with an uniform focusing laser bar, this means
mass scales and super cheap. Very exciting!!

------
pbrumm
I can't wait for a DIY version of this. Turning old cd/dvd's into super
capacitors.

~~~
jackalope
The discs appear to serve only as a temporary platter for holding the graphite
oxide film. Once scribed by a laser, the graphite oxide is converted to
graphene and peeled from the disc for further processing. The discs aren't
used in the capacitors. The article says that blank discs are used, but
doesn't mention if they are reused or even if they must be blank, but I get
the impression that a viable method of production probably won't depend on
wasting disposable discs.

