Factorial and Mitsui Kinzoku Join Forces to Accelerate Solid-State Battery Production

Solid-state batteries just moved closer to the factory floor. Factorial Energy, the US-based battery developer, announced a partnership with Japan's Mitsui Kinzoku to build out full-scale manufacturing processes and accelerate the technology's shift into commercial production — a step aimed at clearing the toughest hurdle the industry faces.

Why the Future of Electric Vehicles Needs Industrial Alliances

No single company can develop every battery component alone. Factorial is building an alliance of specialized firms, each handling a distinct part of the materials and component chain. The goal is to reach commercial-scale output faster than keeping everything in-house ever could. Mitsui Kinzoku will supply a sulfide-based solid electrolyte called A-SOLiD, a material it developed specifically for solid-state cells, while also refining cell manufacturing processes for high-volume production. Factorial, for its part, will keep leading cell design, manufacturing development, supply chain qualification, production line integration, and manufacturability validation.

How Solid-State Batteries Differ from Lithium-Ion

Conventional lithium-ion cells rely on a liquid electrolyte. Solid-state replaces that liquid with a solid material — a fundamental change that lifts energy density and improves thermal stability, which could eventually translate into longer-range and more efficient EVs. The real challenge isn't the concept. It's scaling cell production while preserving high performance and cutting costs at the same time. That's exactly what this alliance is designed to tackle.

Real Numbers That Back the Technology

The new partnership follows concrete results Factorial already posted. In 2025, the company and Stellantis validated FEST automotive cells rated at 77 Amp-hours and 375 Wh/kg energy density, with a charge from 15% to over 90% in roughly 18 minutes under test conditions. Those figures show clear progress on both rapid charging and energy density — the two metrics the entire industry is chasing.

Commercial production is still some distance away. What matters here is that solid-state batteries are moving from research labs toward real factories, and that transition is precisely what the electric vehicle market needs to deliver longer range and better efficiency to drivers.