alt Hacker NewsThis article is about a sodium-ion battery which is a different chemistry to the one BYD claimed those results on (that was LFP).
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.
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"Sodium-ion is exciting because..."
Well it is exciting, but not for the reasons you think. More like a Michael Bay movie exciting...there is nothing practical about this design. Most of the cost will be safety systems designed to prevent the battery from being exciting and even then a crash will likely set them off. Pure Na-ion probably isn't viable and certainly isn't viable in a car. Maybe mixing in some Na into the Li-ion to stretch the small amount of Lithium but even then you are significantly increasing the volatility of the battery.
This isn't a practical step, its an act of desperation from people who don't want to admit that large scale electrification is a dumb idea. We electrified everything that made sense to electrify a half century ago.
What sodium ion lacks in energy density, it actually partially gains back in the reduced need for cooling. The same properties that make it work across a larger temperature range also mean that you don't need a lot of (or any) cooling/heating to condition the battery. That means less weight is used for that and less energy is needed for running a heat pump.
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.