Solid-state battery technology could prove a game-changer for electric vehicles (EVs), improving safety and performance while reducing costs. But the market remains nascent and developers have yet to reach any sort of scale. US-based Factorial believes that is about to change.
The company has been making steady progress with its proprietary solid-state platforms FEST (Factorial Electrolyte System Technology), and facilities in the US and Korea are ramping up capacity. It has secured joint development agreements with such big-name players as Mercedes-Benz, Stellantis, Hyundai and Kia, and the first models powered by its cells are set to hit the roads in public trials in 2026. “It’s not easy for any next-generation cell maker to reach this stage,” says Factorial Chief Executive Siyu Huang. “We are probably the furthest along among all the other players.”
Solid-state hits the streets
The Stellantis partnership with Factorial serves as a clear example of solid-state batteries’ growing significance in the EV landscape. The automaker invested US$75m in Factorial back in 2021, and the two have been working closely ever since.
The latest development will see Stellantis launch a demonstration fleet of new Dodge Charger Daytona models incorporating Factorial’s solid-state batteries in 2026. The new Charger Daytona is based on the STLA Large platform, which is intended to underpin two million vehicles across the Dodge, Jeep, Chrysler, Alfa Romeo and Maserati brands, opening the door for future solid-state deployments.
“By integrating Factorial’s innovative battery solution into the STLA Large platform we are validating its potential to enhance our EV line-up, ensuring customers benefit from improved performance, longer driving ranges, and faster charging times in the coming years,” commented Ned Curic, Stellantis’ Chief Engineering and Technology Officer, speaking at the initial announcement in October 2024.
The milestone has been some time in the making. “It’s been a year of discussion followed by two years of testing,” Huang tells Automotive World. The fleet is intended to run in real-world conditions, driven by non-professional drivers. The choice of the Dodge Charger Daytona is notable, as this is a performance-branded model. “For this segment, it’s important to have a battery with not only high energy density but also high-power,” she observes.
The batteries to be used in the Charger Daytona offer a specific energy density of more than 390Wh/kg. In comparison, most of today’s state of the art lithium-ion batteries offer 260-280Wh/kg. “For us, 390Wh/kg is not so much the ceiling as the floor,” she says. “It’s where we started with our B-sample. There’s a lot of potential even moving beyond 450Wh/kg, which is a different part of the S-curve in terms of the technology ramp-up.”
Factorial is also working on just such a 450Wh/kg battery with Mercedes-Benz. Dubbed Solstice, the new battery should be able to extend EV range about 80% beyond today’s average. With potential applications in both EVs and consumer electronics, Solstice is expected to become available by the end of the decade.
Generally speaking, energy density improvements allow for both extended range and vehicle weight reduction. “We can design around the customer needs, but the most acute problem for the EV market right now is weight,” Huang says. She estimates that EVs are on average between 1,000 and 3,000 pounds heavier than their combustion engine counterparts and carry considerable cost premiums. “Anecdotally, OEMs say that every pound of weight saved equates to a US$5 saving in vehicle costs. If we can reduce 1,000 pounds, that’s potentially a US$5,000 saving per vehicle—quite substantial.”
Focus on US and Europe
The demo fleet will begin operation in 2026, but neither partner has indicated how long it will run before it gets the final green light. “That depends on how the demo goes,” Huang concedes. “We need to secure data on just how much energy efficiency the batteries can achieve in the real world, and the impact on weight, performance and power. Conservatively, it could take three to four years after the 2026 initial launch before we can ramp up to mass production. That said, there could be opportunity to go even earlier than that.”
Stellantis is the first automaker to publicly announce deployment of a demo fleet, but Factorial is in talks with other players about demonstration potential. Without going into details, Huang only states: “Historically, we have considerable support from our shareholders Mercedes and Stellantis. There is also a tremendous amount of interest from other automotive OEMs.”
While interest in solid-state grows, so too will the competition. CATL, BYD, QuantumScape, and ProLogium are just a handful of the other solid-state hopefuls jockeying for a slice of the market. But Huang is confident that Factorial has a key role to play. “We’re a US player, very focused in the US and European markets, with a healthy shareholder base,” she emphasises. “Most of the other solid-state players are heavily backed by Asian shareholders, which puts them in a different place considering today’s geopolitical environment.”
Given the change in administration, the US market faces considerable uncertainty in its near-term EV roadmap. But while the Trump government is widely expected to roll back government support for EVs, it could also increase trade barriers, particularly against China. In that sense, domestic capacity and an American and European investor base are indeed valuable assets.
