Scientist proposes quantum über-battery Boffins in Illinois believe they have figured out how to design a battery with ten times the energy density of the best of today's lithium-ion batteries. Their challenge now: work out how to make the thing. The design is called a "digital quantum battery" and it comes from University of Illinois Director of the Center for …
... but if they did ...
Lets just assume the idea doesn't work. It's nothing like as brilliant as this guy thinks it is, and batteries made under this method are only twice as good as li-ion equivalents. Are we really so hard-done-by?
What would the weight of something like this be in comparison to li-ion? ie would it be at all practical for use in a laptop or camera, or phone, or anything at all.
... that as we are able to store more power per cubic centimeter (energy density), we are able to improve existing devices (iPhone!) and make portable versions of things currently only available with a three pin tether. Remember the first portable phones? Huge. Some of that was the electronics, some of it was the battery.
And if the charge process is quick, then this kind of battery could be used in a car. You could recharge as quickly as filling up a tank of petrol.
Simples, when you stop and think about it.
Essentially, these are far, far better ultracaps. They take 1/10th (or far less) of the time to charge compared to electrochemical cells. They have no electrolyte - The dielectric is actually an insulating vacuum. This means very low self-discharge and essentially limitless charge cycles.
The only downside I can see is that it's fairly difficult to contain a vacuum for a significant period - Which will probably be where the built-in obsolescence is added. A battery manufacturers worst nightmare is a battery that does not need replaced.
"Digital quantum battery"? I'm not sure why they call this thing a battery, when it is not. A battery is a collection of electrochemical cells. This thing is a collections of minute capacitors connected up together (probably some in series to increase the potential difference across the whole device, and some in parallel to increase current carrying capability). Also, why is it called digital? I suppose it depends on discreet, individual quantum events, but then so does an electrochemical cell if you reduce it to the limit (although, to be fair, most people don't tend to think of chemical reactions in quantum mechanical terms).
However, the biggest issue with this is going to be scaling up. It may be possible to use the same techniques as a silicon foundry, but I think there would have to be several orders of magnitude improvement in the cost effectiveness of production. Just think how much it costs to produce a single chip with an area of a few square centimetres with active layers a fraction of a micron deep. Now multiply this up by something a few hundred square centimetres in area with an active depth of maybe 10 centimetres to make a quite modest sized and capacity device. That's going to be a scaling factor of over 100,000 - and that 10 x 10 x 10cm cube will be just one of many.
We have enough trouble scaling up solar cells in a cost-effective manner, and those are essentially just a 2 dimensional scaling. This is a massive difference. Somebody is going to have to come up with a whole different way of producing these things...
So imagine your normal battery takes ten hours.
One order of magnitude quicker would take an hour.
Two would take six minutes.
Three would take 36 seconds.
Four would take 3.6 seconds.
That'd be kind of handy, if not completely ridiculous, and four is quite a low value for 'several'.
If we could make much better capacitors or at least larger, higher voltage capacitor then it would have lots of applications apart from a possible battery replacement but the title of the paper is odd, reminiscent of Bohms pilot wave theory, and it is published in an odd journal. I think a healthy dose of scepticism is a good idea.
I have posted about this before but the idea of a copasitor to take the charge quickly and a battery to store it in the long term is a very good idea as it means that the charge times are reduced to minuets.
This could then mean that milions of mobile phones are charged only for as long needed rarther than overnight. This could save a lot of CO2 being waisted as the phone charger sits trying to top up the phones battery all night when it only needed charging for say 3 hours.
This could also mean that electric cars can top up at petrol stations, rarther than having to spend the entire day in a special car parking bay with a charge post. They would have to come up with the electric equiverlant to a liter petrol can, but when they do they can sell them though the petrol garage.
I still think that the best way to store power is the form of compressed air, at least for cars. This is because you can sore the compressed air for as long as you like , compressed air tanks are easy to produce from plastic and they are llightweight.
out of Philip José Farmer's Riverworld series. The battacitor, I believe, was what he called his array of capacitors which were quickly charged and then able to release said charge in a more battery-like trickle or flow.
One assumes that were it possible + easy + cheap there would be plenty of them around by now; and that they would run on water and air; and that Detroit would have kept them off the market in order to keep us enslaved and in our petrol-fuel misery.
Bah.
Sounds very interesting, but I would be worried about the rate of discharge. Capacitors tend to be able to dump charge rapidly, which would make these devices potentially dangerous if handled incorrectly.
These would be very difficult to secure in a car after a road accident. I'd be worried of high current arcs vaporizing any metal that shorted the battery. But any stored high energy source is potentially dangerous, I guess.
Probably Really Light! But that got me thinking.... Let me show my complete lack of semiconductor fabrication knowledge. This involves me talking out my ass, which I am rather good at actually. So attend me while I put some unfounded assumptions out for public ridicule... (Just remember it's Christmas and if you're too rude to me you'll only get coal. Although you can burn your coal so that might be good.)
The article talks of 10NM spacing. This is quite close; one could say almost immaterially close such that the electrolyte isn't going to weigh much. If we then think of it as a block of Silicone, that has an atomic weight only 2 more than aluminum. So this dubious, but reasonable sounding, logic means it would weigh something similar to the same sized block of aluminum. I've never held a laptop battery sized block of aluminum but I suspect it's quite a lot less than a Li-ion pack.
My nay-saying was more of the line, that doesn't sound that dense to me! But...
And here is where my maths probably go to crap. But if we start with 1A/sec = 6.242E18 electrons (known) this should be 1.348E23 electrons / hr for a 1AH battery. That should only be around 8E24 electrons for a typical laptop battery. (this sounds wrong so maybe I've buggered it)
I have no idea how many electrons he's planning to store in these tiny capacitors, clearly not very many, possibly even one for all I know. But still, if he's talking about 10NM, that's 10E-7M. Grudgingly, I do have to admit that that could indeed add up to a useful amount of power. So maybe he's onto something. Regardless, it's probably good for programmers to do some maths that are more than increment or decrement by 1.
"I still think that the best way to store power is the form of compressed air, at least for cars"
Work on a gas is equal to volume of gas x change in pressure. Note that to do this you need to use consistant units. So under SI you;ll need m^3 and Pa
So a 40l tank with a 300 atm (0.04m^3 x 30397800Pa) gives 1215912J of energy.
1HP is 746 Js^-1.
A 100 HP motor will last roughly 16 seconds. BTW The filling (compressing) process will raise tank temperature quite a lot and coll down quite a lot on emptying (not sure if it's enough to form ice ).
It is true that rolling friction of a vehicle is substantially lower than the power needed to start and you may feel 40l is small for a tank. Run your own numbers and see if it still looks good to you.
Mine's the one with the physics text book in it.
I haven't worked through your numbers, but to calculate the energy stored in a battery you need to multiply the current by the voltage by the time (actually you need to integrate the product over time as the current and voltage will both vary, especially on a capacitor). That voltage element is missing from your calculations.
In fact it ought to be possible to work out the theoretical maximum energy available in this "quantum" storage system by just working out the number of electron volts or eV (which is a unit of energy) of the "excited" electrons compared to the ground state and multiply that by the number of electrons.
If we consider a 1 Litre volume block of silicon then that gives a theoretical maximum of 10^21 of these notional 10nm "nanocapacitors". If the excited state is around the 1eV level off the ground state, then one electron per "nanocapacitor" would give 10^21 eV. That 1 Litre of Silixon would have a mass of about 2.3Kg (about 3 times the mass of diesel of the same volume).
One Joule is about 6.24^18 eV, so that notional 1Litre of silicon with one excited electron per 10nm cube would be worth just 159 joules. That is none too impressive. To increase this to the energy density of Li-Ion batteries (say about 1200Kj per Litre for a state-of-the-art battery, or a factor approaching 10,000), then there will have to be many more electrons per nanocapacitor. Each of those 10nm "nanocapacitors" will have around 5 x 10^4 silicon atoms, so with 4 electrons in the outer shell of a silicon atom, there are about 2 x 10^5 electrons available per 10nm "nanocapacitor".
So, if we could somehow, magically get all the available electrons in a 1L cube of silicon into excited states 1eV above ground then we might beat current energy densities of Li-Ion batteries (by volume) by a factor of 20. However, that's a tall order (and I'm not sure what the excited energy state would be - I vaguely remember that the forward bias on a silicon rectifier is 0.6V so it might be 0.6eV per electron for the jump to the conduction band. It's been a long, long time since I did any of this stuff...
"This could then mean that milions of mobile phones are charged only for as long needed rarther than overnight. This could save a lot of CO2 being waisted as the phone charger sits trying to top up the phones battery all night when it only needed charging for say 3 hours."
This is nonsense. I recommend you go and read David Mackay's book "Sustainable Energy - Without the hot air". It is extremely good and reveals the true facts about sustainable energy. Two quotes from this book are relevant here: "All the energy saved in switching off your charger for one day is used up in one second of car-driving." and "obsessively switching off the phone-charger is like bailing the Titanic with a teaspoon."
Lithium-Air batteries seem more likely to be mass produced than these.
While your maths seem right some of your assumptions are doubtful. I'm not sure if you have acess to more information than what was in the article but I'll start there.
You have presumed the capacitors are cubes. A reasonable guess given the lack of information. Reducing the thickness between the electrodes increases the capacitance so a thinner dielectric is a very good idea. A 1 nm thick dielectric would be a good idea. A capacitor design of 2nm electrodes and 1nm dielectric would double the capacitance. OTOH that needs the dielectric has a breakdown voltage of 1Gv/m, which is pretty substantial.
Much more doubtful is that you have assumed that each holds 1 electrons charge. Given the electron radius is roughly 2.58 x 10-15m giving roughly a *potential* 3.75x 10^12 electrons spread over the whole 10 nm square area. While it's highly implausible that you could achieve this it suggests that 1 electron per capacitor is *very* conservative.
Mine's the one with "Semiconductor devices" by Sze in the pocket.
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