They buried the information that sodium battery has about 60-70% of the energy density of lithium ones. So yes the winter loss in mileage is less but the total is smaller to begin with. That is why the car mentioned only has 300 miles of range when lithium in good weather can do over twice that.
After finishing its cold weather tests at -40 Fahrenheit in Inner Mongolia, the world's biggest battery maker, CATL, and Changan have announced the first mass-market EV with a sodium-ion battery. The sedan can be charged at arctic temperatures, and the Na-ion pack doesn't lose capacity.