They don’t mention the actual specific energy of the completed cells in Wh/kg. Also, “four times of WHAT?” They need to compare like-to-like, which would mean comparing to an equivalent Li-S cells.
Li-S cells usually have much higher specific energy than regular lithium ion. I doubt these cells are better, considering sodium is heavier than lithium.
The highest lithium ion cells you can get now are Amperium cells at 390Wh/kg, plus the metal anode Licerion cells at over 400Wh/kg. That’s not counting lithium sulfur which can get to 650Wh/kg (but are still stuck in the lab).
A quick google suggests Na-S cells at high temperatures are ~2.1V nominal (as opposed to 3.2V for LFP), but I lack the physics chops to parse the paper in the article to validate this. Anyway this sounds like a tiny experimental cell and for real world applications you'd want to see the Wh/kg for a fully packaged product.
> for real world applications you'd want to see the Wh/kg for a fully packaged product
Oh, absolutely, there's still a lot of stuff that could prohibit this technology from ever becoming an actual product. AFAICS, they also don't say anything about dependence an ambient temperature, for instance. It might be that this thing disintegrates as soon as it's freezing. Or, actually the most likely: that it's simply not possible to build this thing at scale with reasonable cost.
Is that for a complete cell or just an electrode? If it's not specified, you can bet it's just for the electrode. Complete cell is what matters (or to be strictly true, a full battery... but that's another story).
Plus the voltage difference... IIRC, Na-S is 2.1V compared to 3.7V nominal for Lithium-ion, high voltage versions sometimes up to 4.35V max voltage. Perhaps a factor of 2 difference in voltage, plus it's only counting a portion of the cell mass.
Isn't that quite close to the magic number which makes electric planes a viable option? 1 kW = 1 kg; Musk said something about that in a podcast I think...
Yes of course, I meant to say 1 kW·h = 1 kg; but I'm not certain if I remember correctly now; I could be off by a factor of 10 I guess. It was either 1 kg battery weight = 1 kW·h, or perhaps he said 10 kW·h had to be contained in a 1 kg battery to allow all types of air travel.
I think the 100 kW·h Tesla batteries found in the Model S/X weigh around 750 kg; so I guess electric air travel is still difficult unless a battery breakthrough happens; at least in terms of weight.
Li-S cells usually have much higher specific energy than regular lithium ion. I doubt these cells are better, considering sodium is heavier than lithium.
The highest lithium ion cells you can get now are Amperium cells at 390Wh/kg, plus the metal anode Licerion cells at over 400Wh/kg. That’s not counting lithium sulfur which can get to 650Wh/kg (but are still stuck in the lab).