CATL's New Sodium-Ion EV Battery Works In -40 Degree Cold

CATL's second-generation sodium-ion cells can reportedly discharge normally even at -40 degrees Celsius (-40F as temperature scales converge).  Depending on the make and model, EV batteries perform the best between 60F to 110F. The operating range can go much higher or lower, but that affects performance and range. Sodium-ion battery production is in its nascent stage, but several battery makers, including BYD, CATL and Northvolt are betting on them for certain low-energy density applications.

China is reaching new heights in diversifying the battery chemistries used in electric vehicles. The country is already leading in subcategories of lithium-based chemistries, like nickel-manganese-cobalt (NMC), nickel-aluminum-cobalt (NCA) and lithium-iron-phosphate (LFP). Earlier this year, state-run utility company China Southern Power Grid even deployed sodium-ion batteries for stationary energy storage. Now CATL, the world's largest battery maker, claims to have unlocked new levels of extreme weather performance with sodium-ion batteries.

The role of sodium ions is similar to lithium ions, where charge-carrying ions travel between the positive and negative electrodes during the charge and discharge cycles. Studies suggest that sodium-ion batteries could eliminate the pesky traits of lithium-ions: There’s less risk of thermal runaway, they can operate at varied temperatures and crucially, the cost of sodium hydroxide, a key raw material, is far lower than lithium-hydroxide. (Although battery companies have reached better economies of scale with lithium-ions.) 

Sodium-ion batteries have already entered production in China. Cars that use them include the Yiwei EV produced by Volkswagen-backed JAC and the JMEV EV3. Speaking at the World Young Scientists Summit, CATL chief scientist Wu Kai said that its second-generation sodium-ion cells can discharge normally even at -40 degrees Celsius, as per several local Chinese media reports. That means EVs with such batteries won't lose range under frigid temperatures, which could help address some of the lingering concerns regarding the extreme weather performance of batteries. They will launch in 2025 in China, with mass production expected to begin in 2027.

Extreme heat and extreme cold are both enemies of a lithium-ion battery. In extreme cold, chemical processes within a cell slow down, as lithium-ions can't move as freely as they can under normal temperatures. Similar to how water struggles to flow through frozen pipes, electrical energy in a cold battery faces more resistance. This leads to lower driving range, longer charging times and prolonged exposure to extreme temperatures can even impact long-term battery health. At least in theory, sodium ions solve this problem as they're far more resilient.

Tesla's 4680 NCM cells in some newer Model Ys have an estimated energy density of up to 296 watt-hours per kilogram, as per some early teardowns. Sodium-ion batteries are less energy-dense. While CATL has not disclosed the energy density of the new cells, it reportedly aims to reach a figure of 200 Wh/kg—a tough goal given that even LFP batteries have only recently hit that mark. That would only be appropriate for low-range EVs or entry-level trims. Some reports also claim sodium-ion batteries are expected to replace 20-30% of LFP batteries in select applications.

A study published in the U.S. government’s National Library of Medicine calls sodium-ion batteries a “rising star.” Battery giants like CATL, BYD, and Sweden’s Northvolt are already investing in and developing these next-generation cells. So either way, one thing is clear: the future of battery chemistry isn’t headed in a single direction but will likely embrace a mix of chemistries tailored to specific use cases.