Factorial Energy, Mitsui Kinzoku Sign Agreement to Industrialize All-Solid-State Solstice Batteries

07:46 AM EDT, 09/17/2026 (MT Newswires) -- Factorial Energy (FAC) has entered a joint development agreement with Mitsui Kinzoku to support the industrialization and scale-up of its all-solid-state Solstice battery platform, the company said Thursday. Factorial Energy said it will be responsible for cell design, process development, supply chain qualification, line integration and manufacturing validation. Factorial's Solstice platform uses sulfide-based solid electrolytes and dry cathode processing, it said. Shares of Factorial Energy were 1.6% higher in Thursday premarket activity.