3 ms·
There is a somewhat equivalent to that for batteries: Coulomb’s law [1]. The energy contained in a battery increases exponentially the closer the anode and cath
by ricw 7y ago
There is a somewhat equivalent to that for batteries: Coulomb’s law [1]. The energy contained in a battery increases exponentially the closer the anode and cathode are to each other.
Due to this, scale and other reasons, we’ve seen batteries become 15-20% cheaper year over year [2] for at least the last two decades.
[1] https://en.wikipedia.org/wiki/Coulomb%27s_law https://en.wikipedia.org/wiki/Coulomb%27s_law
[2] https://data.bloomberglp.com/bnef/sites/14/2017/07/BNEF-Lithium-ion-battery-costs-and-market.pdf https://data.bloomberglp.com/bnef/sites/14/2017/07/BNEF-Lith...
- marcosdumay 7y agoWait, what? It's linear, and it only applies to capacitors. Batteries are a completely different beast. The cost reduction we have been seeing for batteries has completely different reasons, and no relation at all with that.
- ricw 7y agoDivided by distance^2 - looks inverted exponential to me. It does apply to spooled batteries, which is pretty much most modern batteries but most importantly Li-ion batteries
- thfuran 7y agoWhat you've linked has essentially nothing to do with the discussion. What the person who replied to you thought you were talking about was the equation for energy stored in a capacitor, which is proportional to inverse of distance.
- ricw 7y agoIt absolutely has. It’s basic physics and it definitely applies to batteries or in fact any static charges, which is what is being discussed.
- nitrogen 7y agoI'm not a physicist, but my understanding is that batteries do not use the electric field at all to store charge, unlike a capacitor. Batteries use chemical reactions to move electrons, not static electric charge.
- klyrs 7y ago> Divided by distance^2 - looks inverted exponential to me. As stated in the Wikipedia article you linked to, that's an inverse-square law. That's a far cry from inverse-exponential.
- adwn 7y ago> Divided by distance^2 - looks inverted exponential to me. Quadratic growth is very, very different from exponential growth – both from a theoretical as well as a practical perspective.
- marcosdumay 7y agoThe force is proportional to distance^-2, the resulting energy is proportional to distance^-1.
- magicalhippo 7y agoBatteries are electrochemical[1], and the amount of energy in them depends on the amount of active ingredients (for a given composition). I guess the distance between the electrodes affect the internal resistance which can affect the effective energy output somewhat, but primarily it's the number of molecules that can undergo redox that affects the energy stored. [1]: https://en.wikipedia.org/wiki/Galvanic_cell https://en.wikipedia.org/wiki/Galvanic_cell