US Start-ups Push Sodium-Ion Batteries Toward Domestic Production

European heatwaves have driven homeowners to seek storage solutions, prompting San Diego-based Unigrid to ramp up sales of its 9 kWh sodium-ion battery for residential use. Co-founder and CEO Darren Tan says the firm has shipped 100 units and plans to reach 1,000 by the end of the year, with orders coming from Spain, France, Germany and the Netherlands. The battery uses sodium-ion cells made in China, but Unigrid hopes future models will incorporate U.S.-produced cells to create a fully domestic supply chain.

Critics note that the cathode contains chromium-3, which could form carcinogenic chromium-6 under extreme charge conditions, though Unigrid claims extensive testing has not reproduced the conversion. Industry peers such as Emerald Battery Labs, Peak Energy with GM, and Oregon-based ESS Tech are also pursuing sodium-ion technology, eyeing data-center power demand and the prospect of cheaper, safer grid storage.