Scaling the Solid-State Battery FEST

Factorial Energy has successfully scaled its technology in 40-Ah cells at room temperature.

April 27, 2023

Kami Buchholz

Factorial Energy’s 40-Ah battery cell uses the company’s FEST. (Factorial Energy)

Start-up battery developer Factorial Energy’s workforce of engineers, chemists and other technology specialists has topped 100 with recent hirings in the Asia-Pacific region. A pilot manufacturing plant for the firm’s solid-state lithium-metal batteries is slated to launch later this year. And, Hyundai Motor Co., Stellantis and Mercedes-Benz have invested in the Woburn, Massachusetts-based company and its proprietary Factorial Electrolyte System Technology, trademarked FEST. CEO Siyu Huang recently spoke with SAE Media’s Kami Buchholz. Condensed highlights of the interview:

What are the targeted benefits of FEST?

Siyu Huang, CEO of Factorial Energy. (Factorial Energy)

Our technology has three major attributes. Number one is energy density. We’re delivering approximately 20 to 50 percent higher energy density compared to today’s lithium-ion manufacturers. Number two is safety. All of the prior recalls due to battery safety situations have taken a toll, so we’ve put substantial emphasis on battery safety. Number three, our system is highly compatible with today’s lithium-ion manufacturing process, which means we will be able to save in development costs and bring this technology to market faster.

How does FEST differ from today’s Li-ion batteries?

With an up to 50 percent energy density improvement versus traditional lithium-ion, that can translate to a substantially higher driving range compared to existing electric vehicles. We have 60-plus patents and patent applications on file. The patents and pending patents address material technology, cell design and the cell manufacturing process. There are a lot of unique attributes in the solid-state materials. With a traditional lithium-ion battery, the liquid electrolyte is very volatile and more flammable between 60-75 degrees Celsius. For our system, the electrolyte is not flammable until at least 200 degrees Celsius. So that makes the system inherently stable from a material perspective, and it’s also armed with a novel cell design and manufacturing process. FEST has been successfully scaled in 40-Amp-hour cells at room temperature. The long-term goal is for FEST to be scaled in 100-Amp-hour cells.

What are key aspects of the pilot plant?

It’s a very sizable plant, 60,400 square feet. In the initial phase, we plan to produce about 300,000 pouch and large format cells per year. Our up to 200-MWh facility in Methuen, Massachusetts, will have a manual assembly line and a semi-automated pilot production line. We expect to be operational in 2023.

What about the production equipment?

Most of the equipment will be similar to what’s used today for Li-ion manufacturing. Probably less than 20 percent of the equipment will need to be modified to accommodate our proprietary process. Equipment modifications require a lot of internal engineering, and we have a great engineering and technology team. We’ve recruited many talented people with extensive battery experience. Our leadership team also has extensive experience in the automotive and battery industries.

Talk about the value legacy automakers bring to a start-up.

Mercedes-Benz, Stellantis and Hyundai are really good partners. They bring a lot of support from organizational, investment and business perspectives. Our joint development partners have provided a combined $200 million investment, giving us a substantial cash flow for pilot production capabilities and our core engineering work force. Our development partners are helping us bring the cells to the module level for vehicle integration. And they’re helping with many other things, such as the supply chain, government relations and sustainability factors. We’re really grateful to have their strong support.