Sodium-ion is exciting because it has the potential to have less degradation over time, much less sensitivity to cold and less reliance on rare earth metals. Could also end up significantly cheaper. However it has struggled to reach the same energy densities and so hasn’t been practical thus far.
This seems like a big step towards it being a practical technology choice for certain models, if it bears out.
Another thing here is that volumetric density matters more than weight density in cars. Space comes at a premium and while weight affects efficiency somewhat, it pales in comparison to aerodynamics and rolling resistance. The difference between the best and the worst cars on the road is at least 3x. You have some heavy, brick shaped, monstrosities that barely do 1.5 miles per kwh and then you have some cars with low drag coefficient that easily do 5-6 miles per kwh. Even swapping tires can add meaningful range. Weight reductions help a bit but the difference between the best and worst energy densities on a 60kwh battery is probably 1-2 big passengers in terms of weight.
Peak energy makes sodium ion batteries for energy storage. Their pilot batteries are deployed in a desert. High temperatures during the day, freezing temperatures at night. They use only passive cooling without any moving parts (fans, pumps, etc.). Aside from that being impressive, that also lowers maintenance cost because it reduces the amount of stuff that actually needs servicing.
Sodium ion gains back volume because it doesn't need cooling. At the cell level, they are worse but at the pack level, it starts looking pretty decent. Anyway, there are multiple sodium ion batteries on the road now in China. It's practical right now. The rest is just the widening technology gap the US and EU have with China. We'll just have to wait a few years for local manufacturers to catch up. Some models with these batteries will probably start making it to the EU in the next two years or so.
-20 Celsius just happens to be a temperature for which a retention ratio was specified in the parent article, and not the limit of the operation range.
For -20 though, it can happen each year in 4 season temperate climates and north of that.
The 1000km range likely has more to do with the efficiency of the drivetrain and the aerodynamics of the car more than the battery tech. kWh is an absolute value that is fungible and the Denza has a 122.5 kWh battery pack, which means its getting 5mi/kWh. For perspective my Rivian R1S gets ~350 miles on a 135 kWh pack which is about 2.5mi/kWh (so about half that)
The only part of the battery tech that could affect range is the weight. Sodium batteries are typically much heavier than Li-on. I believe the Denza uses LFP, which means it's likely somewhere else on the car that they're gaining improvement in the range - not from the battery tech. That being said, the battery tech definitely affects the charge/discharge rates.
Weight is a pretty low factor for cars, sub-percent (aging wheels did a comparison using a pickup empty versus loaded with a pallet of shingles, though with a more efficient vehicle the influence of weight probably shows up more).
Energy density (amount of energy per unit of volume) is a much bigger factor than energy specificity (amount of energy per unit of mass), it means you can either cram more energy in the same volume for more range, or have a lower vehicle with better aero.
So they have 2 essential advantages over LFP, retention of capacity to much lower temperatures and their cost will become significantly lower when their production technology will be more mature, because they not only do not use lithium, but they also do not use other expensive substances, e.g. nickel or cobalt.
Doesn't the charging speed affect how much regenerative braking can be done? If you have to stop fast enough or the battery is sufficiently hot/full/etc. then one that can't charge as fast requires more of the energy to be lost.
Braking is the reverse of accelerating so the rate is about the same for the same acceleration (positive or negative).
It’s really only if the battery is extremely close to full that this is a potential issue, and that’s assuming the manufacturer either has little to no buffer, or didn’t take this in account and won’t regen into (some of) the buffer.
If the battery is hot and you want to accelerate, increasing the 0-60 time from 3 seconds to 10 seconds isn't a problem for ordinary usage. If the battery is hot and you want to stop, increasing the stopping time isn't acceptable so the car is going to use the friction brakes instead.