Sodium-ion batteries: Why US start-ups are racing to break China's grip

The battery pivot

If you’re watching your utility bills spike during heatwaves, you’re not alone. San Diego-based startup Unigrid is cashing in on that pain, selling nine-kilowatt-hour home batteries that let you store power when it's cheap and drain it when your A/C is working overtime. CEO Darren Tan says they’ve already shipped their first 100 units, with 1,000 more slated for delivery by year-end.

The secret sauce? Sodium-ion tech. Unlike the lithium-ion batteries in your phone, these are cheaper to build, handle extreme temps better, and have a lower fire risk. For the U.S., this is a major W because it opens the door to a 100% domestic supply chain—something we currently lack with lithium, where China holds all the cards.

The toxicity tea

It’s not all sunshine and rainbows. Unigrid’s tech uses chromium-3 in its cathode, which some experts worry could oxidize into the toxic, cancer-causing chromium-6. Professor Dame Clare Grey from the University of Cambridge called out the move, saying that if you’re selling safety, you shouldn’t use materials that raise red flags.

Tan is pushing back, calling those concerns "overblown." He claims third-party stress tests couldn’t force the battery to generate chromium-6, even under extreme overcharging.

Can the US compete?

Real talk: China is currently the main character in sodium-ion manufacturing. Most US companies, including Seattle-based Emerald Battery Labs and California’s Peak Energy, are currently relying on Chinese cells to get their initial products off the ground. But the goal is to shift that manufacturing stateside.

Peak Energy has already teamed up with General Motors to aim for a Michigan-based production facility by 2028. Oregon-based ESS Tech is also in the game, eyeing large-scale energy storage deployments by 2027 to feed the massive electricity demand coming from data centers.

Why it matters

With data centers gobbling up power and driving emissions, we need cheaper, safer storage to manage renewable energy. If these startups can scale production and clear the safety hurdles, they could make electricity way more efficient and keep your monthly energy costs from staying rent-free in your nightmares.