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DOE puts out comparison papers at times, but I haven't looked in a while.

"The energy density of sodium ion batteries is low.It is only 100-150Wh/kg, while the energy density of lithium energy is 120-180Wh/kg. This means that for batteries of the same size, sodium-ion batteries can store much less energy than lithium-ion batteries.Jan 2, 2024"

https://www.dnkpower.com/will-sodium-batteries-replace-lithi...

That's 20% less, not "much less".

Furthermore, we're decades into lithium optimization, and sodium is yet quite young. Being within 20% so early in the game is remarkable!

Depends on where you get your numbers:

“The density of sodium batteries is still relatively low, between 140 Wh/Kg and 160 Wh/kg, compared to lithium-ion battery’s 180 Wh/Kg–250 Wh/Kg.”

https://www.flashbattery.tech/en/sodium-batteries/

Depends on whether you're talking about a single battery cell or a pack.

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