Comment by MarsZebra
16 hours ago
Aren't sodium higher density (at least in terms of energy per weight) than LiFe?
Maybe you're right in terms of energy per volume. Sodium are very light weight in my experience.
16 hours ago
Aren't sodium higher density (at least in terms of energy per weight) than LiFe?
Maybe you're right in terms of energy per volume. Sodium are very light weight in my experience.
No.
The ratio of the stored charge per mass is 23/7 = about 3.3 times higher for lithium than for sodium (7 and 23 are the atomic masses of lithium and sodium), and the voltage can be higher by around 10% for lithium, leading to an even higher energy per mass ratio.
Nonetheless, both sodium and lithium are only a small fraction of the mass of lithium-ion batteries and sodium-ion batteries, so the difference in stored energy per mass is much smaller than for the pure metals.
In practice that means that today LFP batteries and sodium-ion batteries have about the same energy per mass ratio (and similar prices), with both having a lower specific energy than the more expensive NMC lithium-ion batteries.
For now, sodium-ion batteries are very new, so they are still a little more expensive than LFP, but eventually they will be significantly cheaper.
Already now, they have important advantages, so there are applications for which they are preferable even when still more expensive, e.g. where it must be possible to charge them at very low temperatures or where it must be possible to discharge them completely.
No, sodium batteries are less energy dense.