Stellantis Claim Solid-State Breakthrough, But Real-World Proof Still Pending

The race to testing and perfectly integrating solid state battery technology is surely heating up globally, joining the long list of vehicle brands and battery brands such as Chery, BYD, CATL, QuantumScape is Stellantis.

According to Stellantis, they have partnered up with Factorial Energy and successfully tested Factorial’s large-sized solid-state battery cells, known as FEST (Factorial Electrolyte System Technology).

This is a big step toward making next-generation electric vehicle (EV) batteries ready for the market.

According to Ned Curic, Stellantis Chief Engineering and Technology Officer. “It puts us ahead in the solid-state battery race. But we’re not stopping—we’re aiming for even better, lighter, and more efficient batteries.”

Solid-state batteries are different from regular lithium-ion ones. They offer more energy, charge faster, and are safer. The newly tested FEST cells can store 375 Wh/KG of energy and last over 600 charge cycles — getting closer to being ready for real cars.

They can also charge from 15% to 90% in just 18 minutes at room temperature. Plus, they support high power output, which means better performance for EVs.

Factorial used advanced science and AI tools to create a new electrolyte formula. This helps the battery work in extreme temperatures - from -30°C to 45°C - solving a common problem with solid-state tech.

“Usually, improving one part of a battery means sacrificing another,” said Siyu Huang, CEO of Factorial. “But these batteries balance energy, lifespan, fast charging, and safety - all in a real car-sized unit. That’s a huge deal.”

Stellantis and Factorial are also working on lighter and more efficient battery pack designs. This will help EVs go further on a single charge and lower costs for customers.

Stellantis partnership with Factorial started in 2021 when they invested US$75 million in the company in 2021. With this new success, they plan to test these batteries in real cars by 2026. This test fleet will help prove the technology works on the road.

While Ned Curic’s remarks suggest that Stellantis and Factorial are leading the solid-state battery race, the statement echoes similar claims made by many others in the industry. Despite the technical milestones, the true test will be real-world deployment - something that has yet to be proven at scale.