FEST by Factorial Energy: status and timeline

Milestones

Next · Stellantis Dodge Charger Daytona demonstration fleet launches

Factorial Energy founded2013Complete.
Joint development agreements with Mercedes, Stellantis, Hyundai, Kia2021Complete.
Series D investment round closed ($200M from Mercedes and Stellantis)2021Complete.
UN 38.3 safety certification for 100+ Ah cellsMay 2023Complete.
Methuen manufacturing facility opens (200-MWh capacity)Oct 2023Complete.
Mercedes road testing: 1,205 km range achievedFeb 2025Complete.
Stellantis Dodge Charger Daytona demonstration fleet launchesTarget 2026Current milestone.
Mercedes production vehicle introductionTarget 2027Not yet reached.
Hyundai/Kia production introductionTarget 2028Not yet reached.

Most important updates

Upcoming

2026Stellantis Dodge Charger Daytona demonstration fleet launches (next)
2027Mercedes production vehicle introduction
2028Hyundai/Kia production introduction

Current obstacles

Dendrite suppression under high currentLithium metal anodes can grow branching dendrites that short the cell. Suppressing this at 18-minute charge rates is still being refined.
Manufacturing cost per kWhLab cells cost $200+/kWh. Automotive prices need <$100/kWh. Factorial must scale production and improve yield to 10x current levels.
Thermal runaway risk with lithium metalLithium metal is more reactive than graphite. A cell malfunction can trigger rapid heat release. Thermal management and safety architecture must be robust.

Physics limits

Electrolyte degradation limits calendar lifeEven at room temperature, the quasi-solid electrolyte slowly degrades chemically, shortening the cell's shelf and calendar life. This is a chemistry limit, not a design choice.
Lithium metal is chemically reactiveLithium burns in water and air, and reacts with almost any electrolyte. An 8–10 year vehicle warranty requires electrolyte chemistry that resists degradation, which limits energy density gains.

How it works

4 parts

Lithium anode

Metal instead of carbon

Lithium metal stores 3.8x more energy per kg than graphite. This is why solid-state cells are lighter than conventional batteries at the same energy.

Quasi-solid electrolyte

Ceramic particles in polymer matrix

Factorial's electrolyte is a composite of inorganic oxide particles suspended in a polymer binder. It conducts lithium ions but blocks harmful dendrite growth.

High-capacity cathode

Nickel-rich layered oxide

The cathode material stores more lithium per unit volume than the NMC used in conventional batteries, further improving energy density.

Manufacturing

Coating and assembly in Methuen

Factorial coats anodes and cathodes with the quasi-solid electrolyte, then assembles cells in a climate-controlled facility in Methuen, MA.

Spec sheet

Spec	FEST
Energy density	375 Wh/kg^R (reported)
Cell format (demo)	77 Ah pouch cells^R (reported)
Fast-charge time (15→90%)	18 minutes at room temperature^R (reported)
Cycle life (lab)	600+ cycles^R (reported)
Anode material	Lithium metal^R (reported)
Operating temperature range	−30 to +45°C^R (reported)

^R reported by the company

Update log

5 updates

About Factorial Energy

The team behind FEST

Factorial Energy

Solid-state battery, FEST, energy storage

Factorial Energy develops solid-state lithium-metal batteries with quasi-solid electrolyte. FEST delivers 375 Wh/kg energy density and fast charging for automotive and aerospace applications.

Factorial raised $244M from Mercedes-Benz, Stellantis, Hyundai and Kia for solid-state battery development.
FEST delivers 375 Wh/kg energy density, 600+ cycles and 18-minute fast charging.
Stellantis launched Dodge Charger Daytona demo fleet in 2026; Mercedes and Kia pilots underway for 2026–2027 introduction.

factorialenergy.com (opens factorialenergy.com)Company profile →

Founded: 201313 yrs
Headquarters: United States
Status: Private
Valuation: $1.3BprivateJun 2026
Staff: ~200Jan 2026
Raised: $300M3 rounds
Last round: Manufacturing expansion · $50M2023
Works in: EnergyBatteriesVehicles
Coverage: 1 program · 5 updateslatest 1 Jan 2026checked 10 Oct
Lead investors: Mercedes-BenzStellantis
Customers: Mercedes-Benz (opens mercedes-benz.com)Stellantis (opens stellantis.com)Hyundai Motor Group (opens hyundai.com)Kia (opens kia.com)
People: Siyu HuangCEOHector Abruna (opens en.wikipedia.org)Co-founder

FEST

Milestones

Most important updates

Upcoming

Current obstacles

Physics limits

How it works

Metal instead of carbon

Ceramic particles in polymer matrix

Nickel-rich layered oxide

Coating and assembly in Methuen

Spec sheet

Update log

2026

Feb 2025

Oct 2023

May 2023

2021

About Factorial Energy

Current obstacles

Physics limits

How it works

Metal instead of carbon

Ceramic particles in polymer matrix

Nickel-rich layered oxide

Coating and assembly in Methuen

Spec sheet

Update log

2026

Feb 2025

Oct 2023

May 2023

2021

About Factorial Energy