Sodium has greater density than lithium, while most other materials used in a battery have similar densities regardless if sodium or lithium is used, so if a Na-ion battery and a LFP battery have about the same mass and stored energy, it is likely that the sodium-ion battery has a smaller volume.
that doesn't check out, capacity depends on surface area, if the element that is on the surface is heavier then, all other things equal, the battery will be heavier for same kWh.
Sodium would need to be more efficient to be lighter, which it isn't
The maximum deliverable power depends on electrode area, through the maximum current density.
The capacity of storing energy does not depend at all on area, but only on the mass of sodium contained in the battery and on the efficiency of using it (i.e. between full discharge and full charge not 100% of the sodium or lithium is cycled between the 2 oxidation states, but a fraction, e.g. 90%).
Any battery has both an energy density and a power density, which are weakly correlated and the correlation may have opposite signs, i.e. for some batteries it may be possible to increase the power density if the energy density is lowered and vice-versa.
For a given stored energy in kWh, the required mass of sodium is several times greater than the corresponding mass of lithium, by a factor that is the product of the atomic mass ratio with the ratio between the battery voltages. The voltages are similar, with a slight advantage for sodium, so the required mass of sodium is about 3 times the corresponding mass of lithium.
If the complete batteries have about the same mass, that means that other components of the sodium-ion battery are smaller and/or lighter.
It is all about cost and efficiency... There is a classic 1913 electric vehicle that ran NiFe packs for many years, and were only replaced because the container rotted away. Sustainable storage costs real money, but has existed for over a century. =3
I have no idea about the characteristics of these new sodium-ion batteries, but there is a great likelihood that they auto-discharge much faster than LFP batteries.
This means that if you do not use the car for some time, you may need to recharge it before you can use it again. This may be a problem if the car is left far from a charger.
CATL's Naxtra cells apparently have a c rating of 5C. Which boils down to about 12 minutes for a full charge with the right charger. So, as fast or faster than LFP would be the answer here.
100% is a soft limit in many batteries. The battery management system actually prevents you from charging too much. Pushing it too far can damage the battery so they don't let you completely charge it.
A lot of EV drivers optimize to minimize waiting time. Mostly you try to charge while you are doing something else (sleeping, working, eating, shopping, etc.). So, you are not actually waiting for it and sitting in the car bored.
Charging speeds are non linear. The last few percent take a bit more waiting. But you don't actually have to charge the battery to 100% all the time. Two 10-80% charge breaks might be a lot less less time than one 10-100% charge break and it will get you a lot more miles.
When you are driving long distance, you can plan to top up while having breaks, lunch, etc. Just top it back up to whatever the time allows. You don't have to drive the battery to empty either. And destination charging is a thing as well.
You can trade off not having to stop for a bit more against the charging time. Charging to 100% at night is a good use of time. Because you are probably sleeping/resting. Interrupting your journey to do the same is probably not a great use of your time. Two 10-80% charge breaks might be a lot less less time than one 10-100% charge break and it will get you a lot more miles.
Of course on longer journeys, planning for 45 minute charging breaks is a lot more annoying than planning for 15 minute charging breaks. Which is what 5C charging should enable given the right cell and charger combination. With a normal EV (medium sized battery) that's once every 3-4 hours roughly. A bit longer if your car is more economical with the battery. That's actually not a horrible frequency for taking a short break. Even if you drive a petrol car.
And if you are really anxious about that, get an EV with a bigger battery. 300 miles. 400 miles. There are even some 500 mile batteries in some cars now. It will cost you of course. Financially it's probably not a great choice for most people.
Most people posting about 80% seem to talking about charging at home. If you are charging overnight, why are you restricting charge level if it doesn’t really matter to longevity? Is it just left over advice that no longer applies?