Peak Energy, an energy-storage startup, received $55 million in funding to scale up production of sodium-ion batteries that the company is positioning as an alternative to the widely used lithium-ion technology.

The Series A funding round was led by Xora Innovation and joined by existing backers Eclipse Ventures and TDK Ventures, according to a statement Wednesday. Peak plans to use the support in part to build a US factory that’s expected to open in 2026.

Peak’s technology uses sodium ions that are sourced from natural rock salts and brines, such as soda ash, that are easily available and cheaper than lithium, the industry standard. Sodium batteries can have a longer cycle life, according to chief executive officer Landon Mossburg, so they have a longer lifespan than than lithium-ion versions.

“Sodium-ion batteries are a major advancement for large-scale energy storage,” Mossburg said in an interview. “They can last as much as 15,000 cycles compared to lithium-ion’s 8,000.”

Interest in the technology took off in 2022 when lithium prices climbed, prompting supply-chain concerns. Lithium batteries are also prone to fires when they’re damaged. However, sodium-ion designs have less energy density and aren’t well suited for the booming electric-vehicle market, according to Yiyi Zhou, an analyst with BloombergNEF. Recent declines in lithium prices have also made the dominant technology more competitive.

Peak’s management team has a strong clean-energy background, with executives that worked previously at Tesla Inc., SunPower Corp. and Northvolt AB. The company plans to offer long-duration storage systems for grid-scale storage. Another company, Natron Energy Inc., opened this year a sodium-ion battery plant in Michigan, targeting data centers.

“Most grid storage lasts two to four hours, but there’s a demand for 10-hour systems,” said Cameron Dales, Peak’s president. “Sodium-ion could offer a more cost-effective solution for large-scale storage.”