CATL’s new sodium-ion battery no longer fears extreme cold

Chinese CATL, the world’s biggest battery maker, claims a breakthrough in developing its second-generation sodium-ion (Na-ion) batteries. These batteries still perform well at minus 40° Celcius, which could make them an even more exciting alternative to current lithium-ion batteries, LFP or NMC.

CATL envisions these batteries becoming the cheapest alternative, costing less than lithium iron phosphate (LFP) batteries in the long term. The utmost advantage of Na-ion batteries is the natural abundance of sodium. Sodium hydroxide, a critical raw material, is far cheaper than lithium-hydroxide.

More stable and safer

In addition, Na-ion batteries are said to be more stable and safer (non-flammable), but so far, they haven’t offered the same energy density (which determines an EV’s range greatly). However, CATL said in 2021 that its first-gen sodium-ion batteries were approaching 160 Wh/kg and that it aims at 200 Wh/kg.

Closing that gap is not as easy as it looks, as LFP batteries only recently took the hurdle of more than 200 Wh/kg density. Tesla’s 4680 NCM cells, as used in newer Model Ys, have an estimated energy density of up to 296 watt-hours per kilogram. NMC batteries use a combination of nickel, manganese, and cobalt, which are rare and expensive but offer longer EV ranges in premium models today.

Still more expensive than LFP

While CATL hasn’t revealed new density figures yet, chief scientist Wu Kai confirmed the battery should be available from 2025, but mass production is expected no sooner than 2027. Although Na-ion promises to be cheaper than mass-produced lithium-ion (LFP) batteries, today, they’re still more expensive due to limited production capacity.

“The sodium-ion battery has a working principle similar to the lithium-ion battery. Sodium ions also shuttle between the cathode and anode. However, compared with lithium ions, sodium ions have a larger volume and higher requirements regarding structural stability and the kinetic properties of materials,” CATL explains. “This has become a bottleneck for the industrialization of sodium-ion batteries.”

CATL already said in 2021 that it improved both cathode and anode materials, “which enables the abundant storage and fast movement of sodium ions, and also an outstanding cycle performance.”

The next challenge will be to scale up production to current LFP production levels to bridge the cost gap. Due to their lower density – hence shorter EV ranges – these batteries will be primarily intended for lower-cost EVs or smaller applications.

70% of the cost of today’s LFP batteries

CATL is not the only battery maker focussing on cheaper Na-ion batteries. China’s second-biggest battery maker and top-selling automaker, BYD, started constructing a factory for sodium-ion batteries in the Xuzhou region in January of this year.

The plant will be scaled up to produce 30 GWh annually, with packs primarily intended for use in scooters, motorcycles, and smaller vehicles. BYD said that the development of its sodium-ion batteries entered the second stage around (reducing) costs and its bill of materials)(BOM) cost is expected to be on par with LFP batteries in 2025 and  will be less than 70% of the cost of these batteries in the long term.”