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As many videos are telling about the future when batteries would be exchanged by supercapacitors, which would charge fast and with larger power density. How much amount of these capacitors with what specifics would be needed for this?

SamGibson
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Mikul Rai
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    Your question, as written, is unanswerable. The amount of capacitors required to replace batteries depends on the characteristics of the specific battery system. If you can list some specific performance criteria (e.g. Joules of energy stored, allowable self-discharge, maximum current, voltage) then an answer may be possible :) – abb Oct 29 '19 at 05:09
  • @SamGibson - it's definitely a duplicate, but the original question is 9 years old... I'm sure the technology has changed since then. – joribama Oct 29 '19 at 06:13
  • @joribama not really. Lithium Batteries have gotten bigger and lower-loss, and exactly the same happened to supercaps. Since the answer doesn't try to give an exact numerical analysis: nope, the technology itself hasn't changed. – Marcus Müller Oct 29 '19 at 07:58
  • Supercaps can have high charge & discharge rates but ENERGY mass and volume densities are inferior to any commonly used battery technology. Garglabet knows about achieved densities. Even Lead Acid has far better energy density than supercaps. || Consider: An 18650 LiIon 3300 mAh cell provides about 12 Wh of energy. For a capacitor to contain the same energy it's capacitance would need to be C = 2E/V^2 = 2 x 12Wh x 3.6 MJ/Wh /1.44 =~ 60 megaFarad. Not something you'll see in an 18650 form factir cap ant time soon. Probably :-) – Russell McMahon Oct 29 '19 at 09:34
  • Supercaps and Ultracaps (I know of some that are 3000F / 2.7V) are really useful in things such as regenerative braking where the amount of energy being returned to the system is enormous and has a short duration that a battery simply could not handle. These devices are complementary to batteries in many applications rather than a replacement. – Peter Smith Oct 29 '19 at 09:41
  • @joribama - Hi - Agreed, I did notice that the linked question was old. My specialism is not in this area, however, for the reasons explained by *Marcus*, and due to the very general nature of this question, I thought it was still a *likely* duplicate. If anyone has better answers to this question than those which are *currently* in the linked duplicate, then if they add them to that linked question it can become a "canonical" Q&A for this type of general "supercaps vs. batteries" question, accumulating updated answers as new information becomes available. – SamGibson Oct 29 '19 at 12:24
  • @SamGibson - fair enough :^) – joribama Oct 29 '19 at 18:39

1 Answers1

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As many videos are telling about the future when batteries would be exchanged by supercapacitors, which would charge fast and with larger power density.

Telling is easy.
Doing is harder

How much amount of these capacitors with what specifics would be needed for this?

Energy capacity just requires enough stuff.
Energy density is (much) harder.

Supercaps can have high charge & discharge rates but ENERGY mass and volume densities are inferior to any commonly used battery technology. Garglabet knows about achieved densities. Even Lead Acid has far better energy density than supercaps.

Consider: An 18650 LiIon 3300 mAh cell
This provides about 3.6V x 3 Ah = provides about 11 Wh of energy.
For a capacitor to contain the same energy it's capacitance would need to be
C = 2E/V^2 = 2 x 11Wh x 3.6 MJ/Wh /1.44 =~ 55 megaFarad.
Not something you'll see in an 18650 form factor cap any time soon.
Probably :-)

Russell McMahon
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