It’s not, if you charge any capacity with 1C, it will take an hour. Looks like they achieved stable charging at over 4C (charging current in amperes 4x larger than stated capacity in amp-hours).
There are tons of technologies that are inherently unscalable. Or won’t be for another 50 years. Commercial unviability is one thing, but physic limitations are another matter.
A Coulomb is basically a number of electrons, so it still very much depends on capacity. The only way it could avoid capacity dependence is if the amperage varied depending on total available uncharged capacity. That in itself is unlikely because the wires that transmit the electricity can only handle so many amps before getting too hot and melting apart, so any charging system must necessarily be constructed with intended charging capacity and rate in mind from the beginning.
In this case, C refers to the current rate, not the unit Coulomb. It is a standard way of giving the current rate in battery research, and 1C is defined, as oldfart says, as the current rate required to charge that particular battery fully (to its nominal capacity) in one hour. 2C is twice this, so it is charged in half an hour, and C/2 is half this, so it is charged in two hours.
It is a convenient way of giving the current rate, because it allows a more application focused comparison (i.e. my EV battery or phone battery should be able to charge fully in one hour), but it hides the actual capacity of the battery (you have no way of knowing, without additional information, if the cell has a small or a large capacity).
ETA: The last point here is what deranger and AwesomeLowlander is getting at. You can have a very small battery with very little active material, and charge that at 10C and achieve reversible cycling for many, many cycles, and it is meaningless if it cannot be scaled to a larger cell (unless we are only considering microbatteries for example). Usually, results at a small scale is not directly transferable to larger scale, and you encounter all kinds of challenges as you scale up.
It’s not, if you charge any capacity with 1C, it will take an hour. Looks like they achieved stable charging at over 4C (charging current in amperes 4x larger than stated capacity in amp-hours).
EDIT: C is not Coulomb in this case
The point being, if it only works in the lab for minimal capacities, it’s never going to see the light of production.
How do you think batteries started out?
There are tons of technologies that are inherently unscalable. Or won’t be for another 50 years. Commercial unviability is one thing, but physic limitations are another matter.
True, but that doesn’t mean this is one of them.
That said, I think salt batteries will eclipse these.
What are you referring to when you say “salt batteries”?
https://en.wikipedia.org/wiki/Molten-salt_battery
A Coulomb is basically a number of electrons, so it still very much depends on capacity. The only way it could avoid capacity dependence is if the amperage varied depending on total available uncharged capacity. That in itself is unlikely because the wires that transmit the electricity can only handle so many amps before getting too hot and melting apart, so any charging system must necessarily be constructed with intended charging capacity and rate in mind from the beginning.
In this case, C refers to the current rate, not the unit Coulomb. It is a standard way of giving the current rate in battery research, and 1C is defined, as oldfart says, as the current rate required to charge that particular battery fully (to its nominal capacity) in one hour. 2C is twice this, so it is charged in half an hour, and C/2 is half this, so it is charged in two hours.
It is a convenient way of giving the current rate, because it allows a more application focused comparison (i.e. my EV battery or phone battery should be able to charge fully in one hour), but it hides the actual capacity of the battery (you have no way of knowing, without additional information, if the cell has a small or a large capacity).
ETA: The last point here is what deranger and AwesomeLowlander is getting at. You can have a very small battery with very little active material, and charge that at 10C and achieve reversible cycling for many, many cycles, and it is meaningless if it cannot be scaled to a larger cell (unless we are only considering microbatteries for example). Usually, results at a small scale is not directly transferable to larger scale, and you encounter all kinds of challenges as you scale up.
I know I have a “swords united” meme with C/c at the center but can’t find it for the life of me.
What solbear said. I edited my post to clarify i did not mean the SI unit.