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Comment by JoeAltmaier | Hacker News Reader

Gotta be dead-heavy? Sodium is atomic weight 22, while Lithum is 7. Three times as heavy? Or is the electrolyte too small a fraction to matter much.

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There is very little actual lithium in li-ion batteries. This will not be a problem.

For those wondering: 0.6 grams of lithium out of 45 grams for an 18650 battery, or about 1.3% by weight.

Thanks! I just looked that up and was going to post. Beat me to it!

So it is very different - a li-ion battery anode is a tiny part of the battery. A lead-acid battery, its a much larger component.

Makes we wonder why li-ion AA batteries weigh so much less than Nimh rechargeable. What’s the difference?

All of the nickel maybe?

Hm. There's a lot of lead, in a lead-acid battery. Must be very different.

Even if it wasn't ... If the energy density and mass density of a sodium battery are between lead-acid and lithium-ion, then an equally capable battery would weigh somewhere in-between.

I would think there would be use cases where weight isn't necessarily a consideration- like grid storage for solar energy

Shipping maybe. If sodium cells are safer than lithium then they can be shipped by airplane which would benefit a lot from reduced weight.

Planes are much more expensive than ships. Unless you're shipping livers for transplant, you probably want to ship by ship.

They're more likely to be more dangerous.

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