US Start-ups Bet on Sodium-Ion Batteries to Rebuild Domestic Supply Chain

Amid scorching European heatwaves, demand for home battery storage surged, prompting a US-based company to recognize the potential of its domestic manufacturing ambitions. San Diego-headquartered Unigrid, which produces nine kilowatt-hour sodium-ion batteries for residential use, has seen a spike in orders from Spain, France, Germany, and the Netherlands. Co-founder and CEO Darren Tan reported that the company has delivered its first 100 units and anticipates shipping 1,000 by year’s end, driven by homeowners seeking to store grid electricity at lower rates for use during peak air conditioning periods.

Sodium-ion technology has garnered attention from energy experts as a potentially lower-cost and safer alternative to dominant lithium-ion cells. These batteries are believed to be less prone to ignition and capable of operating in extreme temperatures, including lows of minus 40C. However, the sector faces internal debate regarding optimal designs, and several American firms have recently struggled. Currently, China maintains a leading position in sodium-ion manufacturing, presenting a significant hurdle for US competitors.

The primary incentive for these startups is the prospect of producing batteries using entirely US-sourced materials. This contrasts sharply with the lithium-ion industry, where China controls a substantial portion of the global lithium extraction and manufacturing supply chain. Despite this strategic goal, Unigrid currently relies on Chinese-made sodium-ion cells, with Tan noting the flexibility to switch suppliers as domestic production capacity evolves.

Concerns have been raised regarding Unigrid’s use of chromium-3 in its cathode. Professor Dame Clare Grey, co-founder of Nyobolt at the University of Cambridge, warned that under certain conditions, chromium-3 could transform into chromium-6, a known carcinogen. While Ivana Hasa of the University of Warwick acknowledged this risk at high charge states, she suggested it could be mitigated through voltage control and noted promising safety test results. Tan dismissed toxicity concerns as exaggerated, stating that third-party tests failed to generate chromium-6 even when cells were overcharged, and that the product holds European certification while undergoing US evaluations.

Pricing for Unigrid’s sodium-ion batteries currently sits at approximately $100 per kilowatt-hour, compared to roughly $81 per kilowatt-hour for lithium iron phosphate (LFP) batteries last December. Although some companies project costs could eventually drop to $30 per kWh, analysts caution that such reductions may be years away. Additionally, sodium-ion batteries remain less energy-dense than lithium equivalents, making them better suited for large-scale grid storage than portable electronics.

Other US firms are also entering the space. David Bell, CEO of Seattle-based Emerald Battery Labs, predicts sodium-ion could capture 80% of the market. The company is currently utilizing Chinese cells for 12-volt auxiliary vehicle batteries supplied to commercial fleets, with plans to develop new anodes for US-produced cells. Meanwhile, California and Colorado-based Peak Energy announced a partnership with General Motors in June to establish a US supply chain, targeting a Michigan production facility by late 2028.

Drew Buckley, CEO of Oregon-based ESS Tech, highlighted the booming electricity demand from data centers as a key opportunity. He suggested sodium-ion batteries could offer a cost-effective solution for distributing renewable energy to these facilities, requiring less cooling than lithium alternatives. ESS Tech is collaborating with Alsym Energy, which aims to ship hundreds of megawatt hours of US-made sodium-ion batteries by 2027. Experts note that while mass production remains challenging and fire risks cannot be entirely eliminated, success in this sector could enhance energy security and help reduce the cost of renewable storage.