General Motors‘ venture arm led a $108 million Series B round in Peak Energy, a California developer of passively cooled sodium-ion battery systems for the grid, deepening the carmaker’s push into stationary energy storage.
Burlingame-based Peak said on Wednesday the round was oversubscribed. Maverick Silicon, Infinite Capital, Eclipse, Xora Innovation and LG Technology Ventures also took part.
Neither company disclosed Peak’s valuation after the deal or how much GM Ventures contributed.
“GM Ventures is investing to help Peak Energy continue to scale this innovative technology because we believe it has significant potential in the energy storage market as a safe, cost-effective solution using abundant, domestically sourced materials,” Kevin McCabe, President of GM Ventures, said in a statement.
The new round brings Peak’s disclosed funding to at least $173 million. That includes a $10 million seed round led by Eclipse with TDK Ventures in October 2023 and a $55 million Series A led by Temasek’s Xora Innovation in 2024.
The Series B is nearly twice the size of the Series A. Eclipse and Xora Innovation are the only investors named in both rounds.
The total excludes a strategic investment GM Ventures made in June, whose size was not disclosed. Peak did not say whether that stake was folded into the Series B.
4 Months After the Cell Deal
The round comes four months after GM and Peak announced a partnership on June 9 to develop sodium-ion cells built for grid storage.
Under that agreement, GM develops the cell in its Michigan battery labs and keeps exclusive manufacturing rights, while Peak integrates it into its own storage systems, according to Peak.
“At GM, we know that the application should determine the battery, and for grid-scale stationary storage, sodium-ion is the right solution,” Kurt Kelty, GM’s Vice President of Battery, Propulsion and Sustainability, said at the time.
In a blog post the same day, Kelty said GM would be “prototyping sodium-ion cells purpose-built for stationary storage this year at our Wallace Battery Cell Innovation Center” in Warren, Michigan.
“Our next-generation sodium-ion cell development will drive energy density higher, with the potential to outperform more mature chemistries, including LFP, over time,” he wrote.
In September, Kelty told CNBC that GM was building a domestic supply chain for the cell over the next two to three years, and the broadcaster reported that GM did not expect commercial production until around 2029.
Kelty has framed the project as a way to “leapfrog” Chinese battery makers rather than license their technology, a path Ford took with CATL at its Marshall, Michigan, plant.
What the Money Is For
Peak said the funding will help it scale domestic manufacturing, fulfill “over $1 billion in existing customer orders” and launch its product for data centers, where it said access to power “has become the primary constraint on growth.”
Peak’s factory timeline has already moved. At its 2023 launch, the company said it planned to open a U.S. factory in 2026. With its Series A, it said the plant was “slated to open in 2027.”
The company announced in July that it would build its first factory in Sacramento, California. The 183,000-square-foot plant is designed to produce up to 4 GWh of battery systems a year and represents up to $71 million in capital investment, Peak said.
The company expects it to create 239 local jobs over 18 months, at an average annual wage of more than $90,000.
Production and shipments are expected to begin in the first quarter of 2027. Peak also received a $10.5 million CalCompetes tax credit from California in May.
Most of Peak’s orders come from two contracts, according to Bloomberg. Jupiter Power agreed in November 2025 to buy up to 4.75 GWh of Peak systems for deployment between 2027 and 2030. Energy Vault signed a definitive agreement in February for 1.5 GWh, aimed at data center operators.
Peak has also agreed to pilot its system with RWE Americas at the utility’s lab in eastern Wisconsin, in the MISO grid region.
The Pitch Against Lithium-Ion
Peak’s systems use sodium-ion cells based on NFPP (sodium iron phosphate pyrophosphate) chemistry and no active cooling.
Peak says today’s incumbent grid batteries are built around lithium iron phosphate (LFP) cells that require active cooling to stay at safe operating temperatures.
Peak says removing cooling equipment and scheduled maintenance can cut the cost of energy by up to 20% compared with conventional storage. It also says its systems use no water and run almost silently.
Sodium-ion cells store less energy for their size and weight than lithium-ion cells, which is why they are being aimed at stationary storage rather than cars.
Peak deployed what it called the first passively cooled, grid-scale sodium-ion system in Colorado in August 2025, according to its company timeline.
Peak Leans on China for Now
Sodium-ion production remains concentrated in China. CATL said in September that deliveries of its large-scale sodium-ion storage system were beginning in China.
Peak has been buying commercial sodium-ion cells from Chinese suppliers while it builds its US factory, IEEE Spectrumreported in July.
“It’s already catalyzed in China,” Chief Executive Landon Mossburg told Bloomberg in an interview. “You just want to catalyze this supply chain as much as possible.”
Peak is shipping small volumes from a pilot line in San Francisco and puts its orders at about $1.1 billion, according to Bloomberg. The outlet cited a BloombergNEF forecast that sodium-ion demand will reach 257 GWh by 2035, from just over 1 GWh in 2025.
GM’s Storage Push
For GM, Peak is part of a broader bet on stationary storage as electric vehicle demand in the United States slows.
GM’s battery joint venture with LG Energy Solution, Ultium Cells, began making LFP storage cells at its Spring Hill, Tennessee, plant this year. Kelty said in June those cells would “serve LG’s commercial energy storage business.”
GM is also working with Redwood Materials to deploy “roughly 10,000 GM batteries into energy infrastructure,” including at Crusoe’s AI data center in Sparks, Nevada, Kelty wrote.
Peak has drawn on GM’s storage team as well. In August, it named Paul D. Menson its first Vice President of Sales.
Menson had joined GM to lead its stationary battery storage strategy, after leading US grid-scale storage sales at Tesla, according to Peak. GM booked $238 million of “EV strategic realignment” charges in the third quarter, mainly tied to resizing its battery supply chain with joint venture partners.
Tesla and Northvolt
Peak was set up in 2023. Mossburg, its co-founder, was previously President of North America at Northvolt and held leadership roles at Tesla.
Liam O’Connor, a co-founder and Chief Operations Officer, was Chief Operating Officer at Zipline and VP of Global Supply Management at Tesla. Cameron Dales, President and Chief Commercial Officer, was previously Chief Commercial Officer at Enovix.
“The investment we announce today will supercharge Peak’s ability to scale and deliver as the world increasingly turns to passively cooled sodium-ion storage to solve our energy needs,” Mossburg said in the statement.
