US battery startups are pushing sodium-ion technology into home, vehicle, and grid storage as companies look for alternatives to lithium-ion batteries. San Diego-based Unigrid has already shipped its first 100 residential units and expects to deliver 1,000 by the end of the year, with interest coming from Spain, France, Germany, and the Netherlands.
Unigrid sells a roughly nine kilowatt-hour home battery that can store electricity when grid prices are lower and supply it later, including during periods of heavy air-conditioning use. The company listed residential batteries among its commercial products this year through its official product and launch updates.
Sodium-Ion Batteries Promise Different Trade-Offs
Sodium-ion batteries have attracted attention because their materials could eventually be cheaper and their operating temperature range can be wider than lithium-ion alternatives. The International Energy Agency says newer sodium-ion cells can retain about 90% of their capacity at temperatures as low as minus 40C.
The technology still has disadvantages. Sodium-ion cells generally store less energy for their weight than lithium-ion batteries, which means larger and heavier packs are needed for the same capacity, making them better suited to stationary storage than compact electronics.
Cost advantages have also not fully arrived. Lithium iron phosphate battery packs were trading at about $81 per kilowatt-hour last December, while Unigrid’s sodium-ion pricing was roughly $100 per kilowatt-hour, although some companies believe sodium-ion costs could eventually fall much further.
Safety remains another area of debate. Unigrid uses chromium-3 in its cathode, and University of Cambridge professor Dame Clare Grey noted that chromium-3 can form toxic chromium-6 under some conditions.
CEO Darren Tan said third-party testing had not produced chromium-6 even when the battery was deliberately overcharged. He also said the company’s battery has passed certification and safety testing for sale in Europe and is undergoing evaluations for the US market.
US Companies Target Domestic Production
China currently leads sodium-ion cell manufacturing, and several US companies still rely on Chinese cells. Unigrid, Seattle-based Emerald Battery Labs, and Peak Energy all currently source cells from China for at least some products or initial deployments.
Peak Energy has partnered with General Motors to develop a US sodium-ion supply chain for grid storage. GM said in its partnership announcement that it is investing in next-generation sodium-ion cells designed for large-scale electricity storage.
Peak aims to support a US production facility in Michigan by the end of 2028. Another US company, Alsym Energy, plans to ship hundreds of megawatt-hours of US-made sodium-ion batteries by 2027.
Companies are also targeting rising electricity demand from data centres, where sodium-ion systems could store renewable power without requiring as much cooling as some lithium-ion alternatives. Researchers caution that large-scale manufacturing remains difficult and that sodium-ion batteries still carry some fire risk despite their safety advantages.
Featured image credits: Magnific.com
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