Solid-state battery from US cell maker hits new milestone

While Chinese manufacturers have burst out in front of the pack with semi-solid-state battery achievements, other manufacturers around the world are working hard to get their own cells developed and validated. Based in Massachusetts, Factorial Energy has been working on its lithium-metal quasi-solid-state technology for over a decade, attracting backing and collaboration from major automakers like Stellantis, Mercedes-Benz and Hyundai. It’s aiming for a long-range, energy-dense battery that costs the equivalent of lithium-ion units and rolls off the same production lines. This month, it sent out its first round of B-samples to Mercedes-Benz for further testing and development.

Factorial first revealed its 100-Ah solid-state cell at CES 2023 in collaboration with Stellantis, advancing on from the smaller cells it had shown previously. It began shipping the first 100-Ah A-samples to global automotive partners in October of last year and has now delivered over 1,000 A-sample cells to Mercedes-Benz alone.

Now Factorial has announced shipment of the first 106-Ah B-sample cells to Mercedes, calling it the world’s first announced shipment of B-sample solid-state battery cells to a global automotive OEM. The “announced” qualifier in that particular “world first” leaves open that other B-sample cells have been shipped but not announced, but either way, the company is making steady progress and moving into the next stage of testing.

Battery cells and other automotive components go through a multi-stage testing and development process from A to D samples ahead of production. Following the A-sample, a rough initial working prototype of a full-size commercial cell, B-samples are a more mature prototype subject to more rigorous testing.

“The B-samples will be integrated into modules and battery packs for extensive testing and optimization,” Factorial said of this month’s shipment. “This crucial phase involves validating the module and pack designs against Mercedes-Benz’s strict performance specifications. Additionally, this step will confirm the robustness of Factorial’s supply chain and its manufacturing processes, ensuring scalability for future vehicle testing.”

Factorial’s cells rely on “Factorial Electrolyte System Technology”, with a lithium-metal anode, quasi-solid electrolyte and high-capacity cathode. The company says reliance on lightweight lithium metal currently enables an energy density up to 391 Wh/kg, well above the 300-Wh/kg ceiling of current-gen lithium-ion technology and more than double the 160-Wh/kg high-end capacity of typical lithium-iron-phosphate (LFP) batteries. The quasi-solid electrolyte improves safety in comparison to the liquid electrolytes in lithium-ion.

Factorial is ultimately aiming for vehicle ranges over 600 miles (966 km) per charge from a 90-kWh battery that drops around 30% in weight and size compared to a conventional lithium-ion pack. The FEST batteries are also designed to be produced using the same equipment used to produce lithium-ion batteries, with minimal changes.

In October 2023, Factorial opened a battery manufacturing facility in the Boston suburb of Methuen, Massachusetts. It expects the facility to be the largest solid-state manufacturing plant in the US when up and running at full 200-MW capacity.