Summary

Factorial Energy is a Cambridge, Massachusetts-based startup developing the FEST® (Factorial Electrolyte System Technology) semi-solid electrolyte platform for high-performance lithium-metal batteries. The company’s cells have been independently validated at 375 Wh/kg with Stellantis and are under joint development with Mercedes-Benz, Hyundai, and Kia. As of early 2026, Factorial is expanding its addressable market beyond automotive into drones and robotics.

Key Facts

  • Founded: 2019
  • HQ: Cambridge, MA, USA
  • Type: Private (SPAC merger filing in progress as of 2026)
  • Stage: Pre-IPO; $75M from Stellantis (2021); approximately $1.1B pre-money valuation at SPAC filing
  • Technology: FEST® semi-solid (quasi-solid/gel hybrid) electrolyte platform
  • Cell format: Large-format (77 Ah validated); designed for automotive pouch cells
  • Validated energy density: 375 Wh/kg (77 Ah FEST® cells, Stellantis validation, 2025)
  • Validated charge rate: 15% to 90% SoC in 18 minutes at room temperature (4C+)
  • Operating range: −30°C to 45°C (with expansion potential)
  • Manufacturing compatibility: ~80% compatible with existing Li-ion production equipment
  • Cycle life (validated): 600+ cycles in automotive qualification testing (2025); full automotive cycle target ongoing
  • Key partners: Stellantis, Mercedes-Benz, Hyundai Motor Company, Kia, Karma Automotive, IQT, POSCO Future M

What It Is / How It Works

FEST® is a semi-solid or quasi-solid electrolyte — sometimes called a gel or hybrid electrolyte — positioned between conventional liquid electrolytes and fully solid ceramics. This design targets the core tradeoff in the solid-state space: fully solid electrolytes offer the best safety profile but are difficult to manufacture and exhibit high interface resistance; liquid electrolytes process easily but are flammable and limit the cell to graphite anodes.

Factorial’s approach uses the FEST® material to enable a lithium metal anode (which stores roughly 10× more energy per gram than graphite) while remaining processable enough to run on equipment already deployed in conventional lithium-ion factories. The company claims approximately 80% compatibility with existing Li-ion manufacturing tooling, which significantly reduces the capital expenditure and learning curve required for OEM partners to validate and eventually produce the cells.

In 2025, Stellantis validated the 77 Ah FEST® cell format in an automotive-relevant large-format pouch. Key confirmed specs: 375 Wh/kg energy density, 18-minute 15–90% charge at room temperature, operation across −30°C to 45°C, and more than 600 cycles of progress toward full automotive qualification (typically 1,000+ cycles). The cells are also rated for up to 4C discharge.

In early 2026, Factorial began pursuing adjacent markets beyond automotive, partnering with IQT (In-Q-Tel, the CIA’s strategic investment arm) and POSCO Future M (a major South Korean materials supplier) to adapt the FEST® platform for drone and robotics applications, where energy density and fast-charge are similarly high-value.

A demo fleet of Stellantis Dodge Charger Daytona vehicles equipped with FEST® cells is planned for 2026. Karma Automotive validated the cells for its upcoming Kaveya EV (targeting late 2027 launch), which promises 250+ miles of range and 0–60 mph in under 3 seconds.

Notable Developments

  • 2026-03: Factorial announces partnerships with IQT and POSCO Future M to expand FEST® platform into drones and robotics. (BusinessWire)
  • 2026-02: Karma Automotive independently validates FEST® cells for the Kaveya EV. (Electrive)
  • 2026: Stellantis Dodge Charger Daytona demonstration fleet planned with FEST® cells.
  • 2025: Stellantis validates 77 Ah FEST® cell at 375 Wh/kg, 15–90% in 18 min; 600+ cycles in qualification testing. (Stellantis)
  • 2025: POSCO Future M partnership announced for cathode and anode materials development.
  • 2021: $75 million strategic investment from Stellantis; joint development agreements in place with Mercedes-Benz, Hyundai, and Kia.
  • 2019: Founded in Cambridge, MA by Siyu Huang and others.

Key People

  • Siyu Huang — CEO and co-founder; leads technology and OEM partnership strategy
  • Randall Fong — CTO and co-founder

Claim Verification

Claim: 375 Wh/kg energy density (77 Ah FEST® cells)

Status: Verified (third-party automotive validation)

Supporting sources:

Refuting / questioning sources: None identified for the 375 Wh/kg figure specifically.

Summary: Energy density is the best-validated claim, confirmed by Stellantis in an automotive-grade large-format cell context.

Claim: 15–90% charge in 18 minutes at room temperature

Status: Verified (Stellantis validation)

Supporting sources:

Refuting / questioning sources: None identified.

Summary: Charging performance confirmed by an independent OEM partner.

Claim: ~80% compatibility with existing Li-ion manufacturing equipment

Status: Partially verified

Supporting sources:

Refuting / questioning sources:

  • No independent manufacturing audit has been published confirming the 80% figure at production scale; the claim is plausible given the gel/semi-solid approach but should be considered unverified until a production ramp is demonstrated.

Summary: Directionally credible given the semi-solid electrolyte approach; not independently verified at manufacturing scale.

Sources