Comment by maxnevermind
18 hours ago
I thought the main advantage in comparison with LFP is the lower price(long term) and better sub-zero performance?
18 hours ago
I thought the main advantage in comparison with LFP is the lower price(long term) and better sub-zero performance?
Nope. Almost all batteries I see for LFP have heaters for them at too low temps (around freezing 0C/32F). Where as sodium ion can discharge at -25C
Discharging is not the issue with LiPo4 or other lithium tech. They can work up to negative temperatures without any issue. They can go down to -20°C (-4°F).
The problem is charging the battery at negative, as this damages the internal structure. So you need to heat up the battery (aka, you discharge by warming up heating elements), until you hit the right point. And then you can charge up, what will create heat and thus allow for non-damaging charging.
Some even have a fun trick, where if your going to a EV station with your car (end point route on your build in sat nav). They can start to pre-drain the battery if its really too cold, to warm up the batteries even more. So by the time your at the charger, the batteries are on temperature. I forgot what brand did it that way, seen that feature years ago.
What is different is that Sodium-Ion batteries can charge from negative (i think it was -10°C), as they do not suffer from the same damaging effect.
Nearly all EVs now do "battery preconditioning" when on the way to a charger. They would be pretty unusable without, I know one person had a model that didn't have it (this was a few years back) and he could barely pull more than 10kW in winter from public chargers, vs 100kW+ in summer at the exact same chargers.
Tesla do this if they know they're navigating to a charger.
There's a yttrium-containing variety of LFP that's supposed to work better at lower temperature (down to -45 C). But yttrium itself is quite expensive ($35/kg).
LFMP variant of LFP with added magnesium mostly solved this. Presently it is not as long-lasting as LFP so is not suitable for home batteries, but it covers typical lifespan of a car and solves the issues with cold climate.
lithium batteries can usually discharge below 0C, it's the charging at sub-zero temperatures that kills them.
Lithium can discharge just fine at -25C without heaters.
Charging it at or around 0C will destroy it extremely rapidly due to electroplating of lithium.