New sodium-ion battery skips mechanical cooling with 97.9% efficiency

I’ve been hearing about these for a few years now. Huge if they work out at a large scale.

interestingengineering.com/energy/unigrid-sodium-ion-battery-tech

according to their product page, the charge rate for a single cell seems to max out at 3C, which could be a pretty big obstacle to grid-scale deployment. unless that’s a problem that can be fixed with a different arrangement; i’m not too up on how to build batteries.

I assume 3C is a 20 minute charge?

1 C is defined relative to 1 hour for full discharge and 3 C means a 3x faster discharge rate (full capacity can safely be discharged in 1/3 hour, or you can discharge 3 cells sequentially in an hour). Good lithium cells tend to be above 5C, can reach 10C for peak load or if cooled.

For a large enough battery it doesn’t really matter, but for dense portable ones a lower C rating means you have to discharge from more cells simultaneously to maintain a given output. That makes it more complicated, and you have less headroom to the battery’s maximum Watt output if you need to accelerate a car hard suddenly.

The comment I am responding to is about charge rate, not discharge rate