GM Backs Sodium Ion Batteries for U.S. Grid Storage

Introduction

Despite setbacks in sodium-ion battery development in the U.S., the startup Peak Energy says it can be the one to finally achieve the ambitious application of using the tech to store energy for the grid. When U.S. start-ups Natron Energy and Bedrock Materials shut down sodium-ion battery operations last year, they joined an ignominious list of more than a dozen failed Western battery companies. CATL, based in China and the world’s largest battery company, then dropped a bombshell in April, announcing it would supply 60 gigawatt-hours of sodium-ion cells to the grid storage provider HyperStrong. The largest sodium-ion battery order in history suggested China was on its way, as with lithium-iron phosphate in previous years, to dominating yet another promising chemistry.

The Colorado-based Peak Energy insists it can succeed where companies like Natron failed. Company executives say its sodium-ion tech can compete directly with low-cost lithium-iron phosphate (LFP) batteries, which currently dominate grid storage. Unlike Natron, which ran out of money and investors’ patience, Peak Energy has a giant in its corner: General Motors. Like Tesla and other automakers, GM is moving aggressively into grid storage to keep massive battery factories humming in the wake of slumping EV demand. Peak Energy has formed a partnership with the automaker to ultimately deploy sodium-ion batteries at grid scale. In July, the company announced it will build a US $71 million, 17,000 square-meter factory near Sacramento, with capacity to produce 4 GWh of sodium-ion batteries annually, enough to power 4 million homes.

Sodium-Ion vs Lithium-Iron Phosphate Batteries

As with other sodium-based designs, Peak Energy’s cells can’t yet match the energy density of LFP batteries. Company executives from Peak Energy and GM, which has partnered with Peak to codevelop and manufacture the batteries, freely admit they can’t currently compete with current LFP prices on a per-cell basis. Yet Peak Energy says its passively cooled storage system will still cost operators 20 percent less over its lifetime compared with LFP storage.

Cameron Dales, Peak Energy’s cofounder and chief commercial officer, says the company’s GS1.1 system will store energy for 20 years, over roughly 20,000 cycles, and still retain 80 percent of its capacity. For LFP, a basic durability benchmark pegs them at 70 percent capacity after 8,000 cycles.

Peak Energy’s case is helped by a booming market for energy storage, to back up AI data centers and to store excess solar and wind energy. Volatile lithium prices have major players looking for a steady alternative. Incumbent LFP batteries, Dales says, were initially designed for EVs, where cell costs and energy density are critical for driving range and affordability. But utilities and storage operators are focused on entirely different metrics. They want batteries that last the longest, at the lowest overall cost, to maximize returns and justify massive capital investments.

Passive Cooling and Temperature Tolerance

The company’s technical edge, Dales says, is its stable cells that can operate safely at temperatures roughly double the typical operating temperatures of LFP, which performs best at or near room temperature. “You need to keep an LFP cell at 25 °C, give or take, or it will rapidly degrade,” Dales says.

The generous temperature tolerance of Peak Energy’s cells allows a passive cooling system with no pricey, trouble-prone fluid cooling loops or moving parts such as fans or pumps. That makes the modular system well-suited for data centers or grid support in desolate areas, where operators are finding abundant cheap land, high potential for solar energy, and a low risk of natural disasters. “You don’t have to power a refrigerator in the desert for 20 years to keep the system operating properly,” Dales says.

The GS1.1 system stacks slender prismatic cells into modules roughly the size of a king-size mattress. A 36-module system stores 3.1 megawatt-hours. Large-scale projects might combine dozens or hundreds of units, generating enough juice to power a small city.

Supply Chain Challenges

Proponents note that sodium is the sixth-most abundant element on earth, roughly 1,000 times as abundant as lithium. And unlike lithium, which must be sourced from far-flung regions fraught with environmental or human-rights issues, the world’s largest, purest deposits of trona are found in the Green River Basin in Wyoming. Trona, which is composed of sodium carbonate, sodium bicarbonate, and water, supplies the United States with 90 percent of its soda ash, which is the basis for battery-grade lithium carbonate salt.

However, analysts note that while the raw material may be plentiful, its processing is dominated by China. “The supply chain tends to get overlooked, but it’s just a massive issue,” says Varnika Agarwal, a battery research analyst at Benchmark Mineral Intelligence. Agarwal says sodium-ion tech holds promise. But a lot has to go right for sodium ion to carve out a viable niche in the U.S. Benchmarks project that less than 1 percent of newly deployed storage in the United States will be sodium ion this year, less than 4 percent by 2030, and 5 percent globally. For now, she notes, Peak Energy is buying its commercial cells via contracts with Chinese suppliers, which dominate both processing of its raw materials-however cheap-and-abundant they may be-and cell production. The U.S. is basically just getting started, with Peak Energy’s California factory slated to come online in 2027.

NFPP Cathodes in Sodium-Ion Batteries

Natron was banking on long-shot “Prussian Blue” electrodes, a form of blue pigment that acts as a sponge to soak up and release sodium ions. Peak’s batteries, however, rely on sodium iron pyrophosphate (NFPP) cathodes, which are chemically and structurally similar to lithium-iron phosphate in an LFP battery, known for superior safety and long cycle life. NFPP is fast becoming an industry standard. CATL has also settled on NFPP for its core chemistry. This helps make Peak Energy’s cells largely “drop in,” able to be manufactured at existing battery plants such as GM’s-a huge advantage for market viability.

GM’s Testing and Validation

Kurt Kelty, Tesla’s former battery guru and a globally recognized battery expert, is now vice president of batteries and sustainability at GM. Kelty says GM is backing Peak Energy for several reasons, including his familiarity with and respect for its own former Tesla execs.

GM has been testing Peak Energy’s cells, in 170 and 190 ampere-hour formats, at its Wallace Battery Cell Innovation Center in suburban Detroit, in the same labs where GM is developing its proprietary lithium-manganese-rich battery chemistry. Kelty says the battery life of competing cells, from a full range of global producers, “falls off a cliff” during high-temperature testing. But Peak Energy’s batteries are withstanding extreme testing at up to 55 °C, with notably little effect on their lifespans. “The cell is kicking butt over everything,” Kelty says. “We can get 20 years of lifetime without a cooling system, and that’s the key.”

The batteries are showing a round-trip efficiency of 96 percent, a significant 2 to 3 percent better than LFP. (“Round trip” refers to the amount of energy a battery discharges, relative to the amount used to charge it). Eliminating active cooling, Kelty adds, allows a near-silent system that could be used in public buildings. In addition, it ditches the plumbing that’s a potential trouble spot for leaks and maintenance. “It also reduces parasitic power losses, because you’re not using power to cool the system,” Kelty says.

Peak and GM executives believe sodium-ion cells themselves will reach price parity with LFP around 2028, based in part on discussions with Chinese cathode suppliers. Sodium ion, they say, is just entering its steep slope of cost reductions, where LFP’s savings have largely been realized over 20 years.

Peak Energy’s Sodium-Ion Battery Projects

In March, Peak Energy announced it will join with RWE Americas for another pilot system near Milwaukee. That would become the first-ever use of sodium-ion backup on the Midcontinent Independent System Operator, the regional grid operator for 15 central states and Canada’s Manitoba province. Peak Energy also plans to begin supplying up to 4.75 GWh of batteries to Jupiter Power, an independent storage developer, through 2030. The deal, worth up to $500 million, includes an initial 720 MWh of storage, including in Texas, the nation’s largest single announced deployment of the batteries to date.

Ask Dales about winners and losers in battery chemistries, and he’ll tell you it’s the wrong question. In a world of planes, trains, phones, drones, and every imaginable device, it makes no sense that one “super battery” would rule them all. “Sodium ion is just another sister technology to lithium,” he says. “But instead of going higher energy density, it’s going lower energy density, and you’re paying for that with better stability and safety at a lower cost.”

This story was updated on 23 July 2026 to correct the timeline for Peak’s California facility. It is scheduled to come online in 2027, not 2028 as originally stated.

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