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A scientific accident that could change the world

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Re: A scientific accident that could change the world

#51

Post by mapt »

buster wrote: post #19
BenoitEssiambre wrote: post #12

Earlier quoted context omitted.

ok so here is the only real data I could find. At the end of the paper: "The LSG-EC can exhibit energy densities of up to 1.36 mWh/cm3 , a value that is approximately two times higher than that of the AC-EC" 1.36 mWh/cm3 = 1.36 Wh/L If we assume that 1 L of it weights very roughly 1kg. We get 1.36 Wh/kg. From wikipedia: "The amount of energy stored per unit weight [in ultracapacitors] is generally lower than that of…

There is a big miscalculation: Graphene seems to be extremely light weight. 1 liter of graphene will definitely not weight 1kg. Wikipedia [1] only gives measures for m²: Graphene is very light, weighing only about 0.77 milligrams per square meter. [1] https://en.wikipedia.org/wiki/Graphene

A square meter of a single-atom-thick layer of graphene isn't very relevant. Expect the final product to have a volumetric density in the neighborhood of graphite or diamond.

Re: A scientific accident that could change the world

#52

Post by whitewhim »

ratsbane wrote: post #7

Am I the only one to think "hey, I could try this at home?" 1) prepare carbon slurry 2) pour on dvd 3) etch with LightScribe DVD drive... 4) Peel of graphene layer ...? I wonder what, exactly, goes into the carbon slurry and if it's necessary to etch a particular pattern with the LightScribe.

After reading several papers on this I think that the hardest issue would depositing the GO and electrolytic layers on a CD substrate. Although there are some fairly reliable and not terribly difficult methods I doubt many would have the materials at home. I would love to try this but I'm a poor student. I may see if I can locate some GO onthe chem labs this summer when no ones around.

Re: A scientific accident that could change the world

#53

Post by mapt »

ergest wrote: post #15

I don't know much about the technology of this, but I used to play with capacitors during my teenage years and if this works even half as advertised it would be truly life altering. We could have "hybrid" solutions of a capacitor combined with a battery with the capacitor acting as a buffer to improve battery life.

Hybrid solutions are hypothetically very nice, but as I understand it in reality the large battery banks associated with a gas-tank-like range, and the relatively minor amount of power the motors can actually put out, means that short-term power density isn't actually much of a problem.

Re: A scientific accident that could change the world

#55

Post by philwelch »

Tomdarkness wrote: post #30
samstave wrote: post #18

Earlier quoted context omitted.

When was the last time you walked around with a magnetic tape or floppy disc? Now - what happens if you put your wallet full of credit cards on it?

To be honest, magnetic strips on credit cards are redundant in a fair proportion of the world as well, especially Europe, although with a notable exception of the US which seems to be seriously lagging behind in this area. I live in the UK and it has easily been over 6 years since I have been anywhere where the magnetic strip has been read rather than using chip & pin (EMV).

I visited the UK late last year and can confirm that your card readers can still read the magnetic stripes on our outdated American credit cards if they absolutely have to.

Re: A scientific accident that could change the world

#57

Post by Someone »

mbell wrote: post #49
dmethvin wrote: post #6

Earlier quoted context omitted.

In the comments they mention about 1/4 the energy density of a lithium ion battery, so yes they don't compete on that measure. But full charging can happen in a minute or two, and you could top up a charge in seconds. Perhaps public areas would have inductive chargers on the wall; you'd just walk over and hold your phone or tablet up to it for a few seconds. Airline tray tables could have an inductive charger built i…

I've heard this argument a few times: "It charges so fast that the density doesn't matter". What often gets missed is that for it to charge fast, you need to provide a lot of power, a lot more than any current changer and laughably more than any inductive system can provide. Lithium Ion batteries can already max out the power offered by the 10W charger that comes with the iPad and charging off computer USB is often s…

Also, you would need customers brave enough to charge that tiny device they are holding in their hands at 1000W. A mobile has about the surface area of a 100W incandescent, so if charging is 90% efficient, your mobile would have to radiate about as much heat as such an incandescent would do in about 3 seconds. It won't get as hot as that lamp, because your phone has a larger heat capacity, but I doubt it would stay cool, either. Given the effect of heat on current batteries, I guess designers would want that phone to irradiate waste heat rapidly.

And that's when everything goes well. You would also need companies brave enough to risk the potential lawsuits if something goes wrong (user wears a pacemaker? Has some metal in his hand, e.g. in a tattoo? Charging accident releases heat that lights clothing?)

Re: A scientific accident that could change the world

#58

Post by derekp7 »

mbell wrote: post #49
dmethvin wrote: post #6

Earlier quoted context omitted.

In the comments they mention about 1/4 the energy density of a lithium ion battery, so yes they don't compete on that measure. But full charging can happen in a minute or two, and you could top up a charge in seconds. Perhaps public areas would have inductive chargers on the wall; you'd just walk over and hold your phone or tablet up to it for a few seconds. Airline tray tables could have an inductive charger built i…

I've heard this argument a few times: "It charges so fast that the density doesn't matter". What often gets missed is that for it to charge fast, you need to provide a lot of power, a lot more than any current changer and laughably more than any inductive system can provide. Lithium Ion batteries can already max out the power offered by the 10W charger that comes with the iPad and charging off computer USB is often s…

Maybe the charger could also have a super capacitor in it, and would charge it up over time. Then when you hook up your device, you would be getting capacitor to capacitor charging. After all, if these things can charge up fast, then they can also discharge fast.

Re: A scientific accident that could change the world

#59

Post by lostlogin »

philwelch wrote: post #55
Tomdarkness wrote: post #30

Earlier quoted context omitted.

To be honest, magnetic strips on credit cards are redundant in a fair proportion of the world as well, especially Europe, although with a notable exception of the US which seems to be seriously lagging behind in this area. I live in the UK and it has easily been over 6 years since I have been anywhere where the magnetic strip has been read rather than using chip & pin (EMV).

I visited the UK late last year and can confirm that your card readers can still read the magnetic stripes on our outdated American credit cards if they absolutely have to.

Unfortunately both types die with exposure to magnetic fields - I accidentally too mine into an MRI scanner. This may not Oruro at a lower field strength with the chip type however.

Re: A scientific accident that could change the world

#60

Post by mbell »

derekp7 wrote: post #58
mbell wrote: post #49

Earlier quoted context omitted.

I've heard this argument a few times: "It charges so fast that the density doesn't matter". What often gets missed is that for it to charge fast, you need to provide a lot of power, a lot more than any current changer and laughably more than any inductive system can provide. Lithium Ion batteries can already max out the power offered by the 10W charger that comes with the iPad and charging off computer USB is often s…

Maybe the charger could also have a super capacitor in it, and would charge it up over time. Then when you hook up your device, you would be getting capacitor to capacitor charging. After all, if these things can charge up fast, then they can also discharge fast.

That would work, but you'd need to use about 0 gauge wire between the devices. If you tried that with something the size of a lightning cable you'd have a decent chance of vaporizing the wire/connectors.
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