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Lithium is the third lightest element in the world, sodium is the 11th”
Serioisly!!!.....the chemistry of the battery material is not just lithium, it’s a compound of other metals and oxygen.
You have all sorts of combinations, LiCoO2, LiFePO4 (iron phosphate chemistry), LiMn2O4, Li2MnO3 (manganese chemistry), then you have lithium nickel manganese cobalt chemistries (LiNiMnCoO), lithium titanate chemistries, nickel cobalt aluminum oxide (LiNiCoAlO), lithium sulphur, lithium tin and chemistries not involving lithium at all.
Sodium is only ~3 x heavier than lithium. You need look at the total weight of the cathode/anode. Some of the above chemistries rely on cobalt and nickel and manganese in varying molecules ratios. Cobalt and nickel are about 2.6 x as heavy as sodium. This weight argument is facile. What is important is the energy density and the fact that about 3.5% of the weight of sea water comes from dissolved salts. Cheap, pure and easy to extract. If you are a North American battery maker there is no problem sourcing salt from the sea, you don’t have to get involved with land locked hard resources in unstable jurisdictions where you have very little influence. I can’t see why the “visionary” Elon Musk didn’t embrace this vision earlier.
The lastest sodium chemistries involve carbon coupled with an air-stable Na0.9Cu0.22Fe0.30Mn0.48O2 layered cathode. Carbon has about one fifth of the weight of Cobalt and Nickel and is also a lot easier to source along with the other compounds in this chemistry. The energy density of the Na battery in the below article is ~240 Wh kg-1 . This exceeds the current energy denisties of commercial cars. The Tesla model 3 is reported as ~222 Wh kg-1 . While there is a strong motivation to move away from difficult to source cobalt and lithium, scientists and the world will keep working to find the best and final solution. Chances are it won’t look like anything we see today. Disruption can come from anywhere.Esh
https://phys.org/news/2018-09-carbon-material-na-storage-capacity.html
