BYD / Denza z9 gt claim 10-70% in 5 mins, 97% in 9 mins. With a range of ~1000km this seems to crush these results? I don't know enough about this space to know if I am missing something here, but would love to know because something about this feels more exciting than i think i am grasping. anyone know?
> With a range of ~1000km this seems to crush these results<p>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)<p>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.
I see no charge rate numbers so there is no way to compare. however, these sodium batteries are cheaper, do not require lithium, and are operable at lower temperatures of -20C/-4F. Sounds like a bit of a win and opens the door for battery options in cars.
And the fire safety risks are significantly reduced (thermal runaway is much harder). They can also be transported and stored completely discharged, something not done with lithium ion batteries because of it degrades them much more than regular usage.
The sodium-ion batteries are said to work satisfactorily down to -40 Celsius = -40 Fahrenheit.<p>-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.
This article is about a sodium-ion battery which is a different chemistry to the one BYD claimed those results on (that was LFP).<p>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.<p>This seems like a big step towards it being a practical technology choice for certain models, if it bears out.
The range claims depend on the size of the battery pack. The Denza has a larger pack than what is quoted in the article. Also, the Chinese CLTC range ratings are overly optimistic with 1000km CLTC being ~820km WLTP or ~700km EPA.