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Advance In Super/Ultra Capacitor Tech: High Voltage and High Capacity
fyngyrz writes: Ultracaps offer significantly faster charge and discharge rates as well as considerably longer life than batteries. Where they have uniformly fallen short is in the amount of energy they can store as compared to a battery, and also the engineering backflips required to get higher voltages (which is the key to higher energy storage because the energy stored in a cap scales with the square of the cap's voltage, whereas doubling the cap's actual capacitance only doubles the energy, or in other words, the energy increase is linear.) This new development addresses these shortcomings all at once: considerably higher voltage, smaller size, higher capacitance, and to top it off, utilizes less corrosive internals. The best news of all: This new technology looks to be easy, even trivial, to manufacture, and uses inexpensive materials — and that is something neither batteries or previous types of ultracaps have been able to claim. After the debacle of EEStor's claims and failure to meet them for so long, and the somewhat related very slow advance of other ultracap technology, it's difficult not to be cynical. But if you read TFA (yes, I know, but perhaps you'll do it anyway) you may decide some optimism might actually be called for.
We're getting to a point where the issue isn't just how much energy we can store in how little space, and how readily we can use it, but also how stable that medium is and how gracefully it fails when mishandled. Cellphone batteries are already pretty scary when punctured, imagine something holding several times as much energy.
A bullet may have your name on it but splash damage is addressed "To whom it may concern."
Capacitors. [...] If they finally obeyed Moore’s Law by squeezing themselves down to the microscale
They never disobeyed Moore's law since Moore's law is about transistor density..
CLI paste? paste.pr0.tips!
You said it. We want a lot of energy in a hand-held format. But it's dangerous.
That energy will get hacked for purposes both good and bad, and the bad purposes will include explosions.
-kgj
What's not to like?
You said it. We want a lot of energy in a hand-held format. But it's dangerous.
Do you have any comprehension of the amount of energy stored in a tank of gasoline? A lot of energy stored is not in and of itself dangerous. What matters is the means by which that energy can be released. Your body stores a huge amount of energy but there is no easy way to release that energy rapidly. Diesel has even more energy than gasoline but good luck igniting it. You can drop a lit match on diesel fuel and nothing will happen. Now do batteries and ultracaps have their own unique failure modes? Sure. But it's not hard to demonstrate that the chances of an explosion are pretty minimal.
That energy will get hacked for purposes both good and bad, and the bad purposes will include explosions.
Do you see a lot of exploding cars outside of fictional movies? Causing an explosion normally requires a criminal act typically involving external explosives. It's not actually a very easy thing to cause an explosion. (thank goodness) In most cases even if there is a catastrophic failure the car merely burns, it doesn't explode. I actually trust the engineers working on this stuff and I've worked with companies building battery packs for cars and other high energy applications over the years. They are pretty well aware of the possible failure modes and what to do about them. Explosions aren't something they are overly worried about.
Cellphone batteries are already pretty scary when punctured, imagine something holding several times as much energy.
One of the problems with capacitors charging rapidly is that they can also discharge very rapidly too so any failure would not be graceful. However I'm not sure there is much reason to be optimistic yet for these devices. The article mentions that the way they get high voltages is by connecting the capacitors together. This means they connect them in series which will significantly reduce the actual capacitance since capacitors in series add like resistors in parallel.
Cellphone batteries are already pretty scary when punctured, imagine something holding several times as much energy.
You ARE something that holds several times as much energy. The energy density of animal fat is roughly the same as that of gasoline and both are FAR higher than the energy density of a lithium-ion battery. Whether something is scary has very little to do with the amount of energy it holds. It is the rate and circumstances in which it can be released that matters.
That said, if something hits me hard enough to puncture my cell phone battery while I'm carrying my phone, the battery combustion is probably the least of my concerns. I'm likely much more concerned with whatever just speared or shot me.
Well, yes, the amount of energy stored goes up as the square of voltage for a given capacitance. However, for a given dielectric getting twice the voltage requires twice the thickness and cuts the charge in half -- so the energy per unit volume is unchanged.
Which shouldn't be surprising since the energy is stored in the dielectric by (e.g.) straining the molecular structure of the material.
The biggest reason for going to higher voltages is to reduce the interconnects, which get enormous at low voltages and high currents. (Cross-sectional area goes up inversely with the square of voltage for any acceptable IR loss, which is why long-distance power lines run at scary voltages.)
Lacking <sarcasm> tags,
Energy stored is C * V * V / 2. Telling us C without V is sort of like measuring the capacity of a gas tank by giving you the length, but leaving out the depth and width.
They report capacitances in the 1000 millifarads for a "centimeter scale" device.
If the maximum voltage is 1V, then we have an unimpressive energy storage of 0.5 J in their "centimeter scale" device.
AAA batteries can store about 5000 J, by contrast. To match that, these would need to be charged to 100V.
Without the V number this article is disappointingly uninformative.
--PM
Why can't we use these things in cars?
We already do use them in cars.
Imagine being able to recharge your car faster than you could fill it up with gas.
Not quite that simple. There is a serious heat issue to deal with when you are transferring that much electric power over wires even if the power is available. Filling up something like a Tesla safely in less than 3 minutes is not as easy as it sounds. You can't just pump more juice over the same wires. You start getting into needing superconductors to handle the juice unless you have wires the thickness of your arm.
Stations could add solar panels for some additional "free" electricity, etc.
That would be a LOT of solar panels. I'm not sure you appreciate the amount of power we are talking about here. A few solar panels on the roof would add so little power it would barely be measurable.
Do you have any comprehension of the amount of energy stored in a 3-oz bottle of distilled water?. E=mc^2. If I didn't slip a decimal, the blast radius should run to approximately 6 miles.
Exactly my point. The energy density of a substance is almost irrelevant to the discussion. What matters is whether there is a means to release that energy catastrophically. In most cases there is no easy way to do it. We don't see cell phones detonating. We don't see cars exploding. We don't see laptop batteries going ka-boom. Worst case we normally see is a comparatively gentle and slow combustion. Damaging sure but hardly an explosion.
The idea of having a cheap consumer device that can so easily etch any bitmap with such fine detail intrigues me. I wonder what else you could etch. If there was a coating for circuit boards that these lasers could etch that would be really cool. Pop a board in your CD burner amd minutes later have a perfectly etched board.
If they had an electrolyte that worked in this application they wouldn't be talking about all the possible choices. They would tell us what worked.
"For this solid electrolyte, we have plenty of choices. We can use gelled polymer electrolytes, made by swelling a polymer matrix with an electrolyte solution, or we can solidify ionic liquids by adding polymers or silica nanopowder. This nonleaking design, together with a virtually unlimited number of charge and discharge cycles, means that our supermicrocapacitors will likely outlast all other electronic devices on the chip. Such long life will be particularly useful whenever it is inconvenient or dangerous to open things up to replace a power source, as in pacemakers, defibrillators, and other medical implants."
Electrical and magnet fields occur in 3 dimensions, not one. They can talk about the gap between the fingers of their layout, but their effective average gap in 3D is probably closer to PI*center_distance/2 which gives a lesser result for the expected capacitance. Their max voltage with a given electrolyte is limited to the closest edge, but that is not how a physicist would compute expected capacitance.
From here
The DVD-burner graphene etching technique to produce supercaps is several years old -- but it looks like they're continuing to work on it. Good to see the technique hasn't been abandoned.
I'd never heard of it.
Using a DVD burner for constructing microcircuitry is a GREAT hack. Should be trivial to do resistors and wiring with it. If somebody can figure out how to do fast thin-film transistors it would put microcircuit fabrication within easy reach of hobbiests.
Sure the scale would be far larger than microchips. But for a lot of stuff that's just fine.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way