Sodium ion is a better fit for houses and grid storage than vehicles or consumer electronics.
- charge twice as fast as lithium ion
- have double the number of charge cycles
- cost substantially less
- be substantially safer
- and more environmentally friendly
I think it would be the clear preference for all but the highest performance vehicles.
Note that Tesla is also trying to reduce cost in moving to 4680 cells [1]:
> the main reason Tesla is using 4680 batteries at the moment is to cut manufacturing costs, rather than any of the other pie-in-the-sky advantages announced on Battery Day a few years back.
> A Model Y's 4680 pack, for instance, is US$3,600 cheaper to manufacture than one with 2170 cells, but even then Tesla is only halfway through with the cost reduction potential of the new technology. It has yet to master and scale the dry-coating cathode method which would bring the pack's cost down US$5,500 compared to the 2170 battery.
[1] https://www.notebookcheck.net/Tesla-4680-vs-2170-battery-cel....
However the price advantage is more than enough. After a short googling, it appears that I could buy right now a battery large enough to supply the energy for one day for my house (5 kWh), either as sodium-ion for $650 or as lithium-iron phosphate for $5000 (with very similar specifications for endurance and size).
The former I could buy at any time, for the latter I would have to save money for some months to be able to afford it. That is a large enough advantage.
$1000 per kWh was the first price that I have found for a 5 kWh LFP battery and I am lazy now to search for a cheaper one, so this is a real price, even if it is likely not the best price.
For a much larger battery, a quick search shows EUR 20000 for 50 kWh, i.e. EUR 400/kWh (though this price is older and now it might have increased). It is normal for the price per kWh to decrease at very large capacities.
Also, the fact that LFP were cheaper than this a decade ago is irrelevant, because googling about their price finds that "lithium prices have surged over 700% since the start of 2021, which has led to a big jump in battery pack prices" (written in May 2022).
However, Na-ion batteries for solar energy storage have certainly already hit the market, e.g.:
https://www.alibaba.com/product-detail/SUNPOK-48V-5kwh-Sodiu...
EDIT: After an extra search, I have seen an offer for a LFP 5 kWh battery @ $2000, so it looks like the $400/kWh price is available for lower capacities too. Nevertheless, this price is less reliable than the higher prices seen initially, because it is only for some kind of pre-order with unknown delivery time.
https://www.currentconnected.com/product/sk48v100/
You can easily find other brands for less than $300/kWh, and plenty of review/teardowns on youtube.
Edit: adding "Typical capacity at 80% DOD @.5C Rate is over 7000 Cycles" so if you bring your battery to 7000 80% cycles at 0.5C you got 28000 kWh out of it, so 0.059 USD/kWh out of the battery (and you still have 4 kWh usable in the battery so many more cycles).
Therefore, the current price for Na-ion batteries is only 3 times less than LFP (the endurance and lifetime are claimed to be about the same for Na-ion and LFP).
Still, this price ratio of 3 remains a significant difference and it is very likely that in the future the price of Na-ion will decrease at a much higher rate than the cost of the mature lithium-based batteries, when more manufacturers will begin to make Na-ion batteries.
If they had a Tesla Megapack as a buffer for example the transformer wouldn’t be the bottleneck as the output is greater from the Megapack.
In other words, most cars.
"Americans remain resistant to the lure of EVs, which are still unaffordable": https://arstechnica.com/cars/2022/11/only-1-in-3-americans-w...
Not sure where this is the case. Here, the 250kw chargers are plentiful, but cars average closer to 120kw because of the charge curve. We're still battery limited most of the time.
Time will tell if sodium batteries can be competitive, I don't know that it's clear yet.
A significant disadvantage is the lower energy density of the sodium battery chemistry. Implications include faster discharge/lower range if the physical dimensions are the same as a lithium battery, or if optimized for more range/power, then it would be a larger and heavier pack vs lithium with the costs that entails.
This lower energy density is one of the main reasons it has been considered more suited to stationary application because the extra space and weight is less problematic than in a mobile applicaiton
There's this assumption that all the negative qualities of road are down to malignable user behavior issues. It's an unusually hostile way to view the problem.
This is false[1]. Stopping distance increases as the square of speed, and therefore safe following distance also. This and other effects mean that 80 mph is well down on 30 mph.
Theoretically capacity should be independent of speed[2], but in practise it seems to decrease at high speeds because most drivers are careful.
1. Plot of safe capacity vs speed: https://www.researchgate.net/figure/Safe-road-capacity-for-c...
2. https://civilengineering-softstudies.com/57-traffic-capacity...
The second arrives at an equality that I don't fully understand, but applying it's formula shows about a 2.6x greater spacing requirement when moving from 30mph (8.5 ft) to 80mph (22.8 ft). Which is close to what the two second rule would tell you when going from 30mph (88 ft) to 80mph (234 ft).
Interestingly, if you look at actual braking distances, then for 30mph (45 ft) to 80mph (320 ft) shows a 7x change in distances. So, the above advice relies on the fact there will be no fixed obstructions in the road and that anything in front of you will have to brake as hard as you do.
Perhaps this is why pedestrians still do so poorly on the roads, but it also makes me suspicious that you can just apply this formula equally to 30mph traffic and 80mph traffic. The hazards are different, the road duty cycle is different, traffic controls exist on one and barely on the other.
Even so.. using the basic 2.6x capacity reduction factor going from 30mph to 80mph, you're getting a 2.6x capacity increase from the change in speed. As soon as you add _one_ additional lane, the 80mph road makes a bunch of sense.