Factorial Energy
Table of Contents

⚠ Disclaimer: This entry may be incomplete, out of date, or inaccurate. It is AI-maintained on a best-effort basis. Do not rely on it as a sole source — verify claims independently using the sources listed below.

Summary

Factorial Energy is a Cambridge, Massachusetts-based solid-state battery developer with two platforms: FEST®, a semi-solid hybrid-electrolyte platform whose 77 Ah cells Stellantis verified in lab testing at 375 Wh/kg, and Solstice™, an all-solid-state platform developed with Mercedes-Benz using a dry cathode process. It began trading on Nasdaq (FAC) on 8 June 2026 after a merger with the SPAC Cartesian Growth Corp III, and reported its first quarterly results as a public company on 11 August 2026. Named backers and partners include IQT, Mercedes-Benz, Stellantis, Hyundai and Kia; it is also pursuing drones, aerospace and robotics.

Key Facts

  • HQ: Cambridge, MA, USA
  • Type: Public (Nasdaq: FAC, warrants FACWW) since 8 June 2026; merger valued at about $1.3 billion with about $110 million in gross proceeds (Electrek)
  • Platform 1: FEST® — semi-solid (quasi-solid hybrid) electrolyte; Stellantis the primary partner
  • Platform 2: Solstice™ — all-solid-state, dry cathode process; company claims up to 80% higher energy density than conventional lithium-ion and stable operation up to 90°C; Mercedes-Benz the primary partner (BusinessWire). No independent performance data has been published for Solstice.
  • Verified FEST® cell data (Stellantis, April 2025): 77 Ah, 375 Wh/kg, 15% to over 90% charge in 18 minutes at room temperature, operation from −30°C to 45°C, over 600 cycles progressing toward automotive qualification (Stellantis)
  • Vehicle demonstrations: a lightly modified Mercedes-Benz EQS reportedly drove over 1,200 km (745 miles) on one charge in September 2025; FEST® integrated into a Dodge Charger Daytona demonstration vehicle with Stellantis (Nasdaq, SEC)
  • Manufacturing: company says FEST® is compatible with up to 80% of existing lithium-ion manufacturing equipment (Electrek); Philenergy (KOSDAQ-listed equipment maker) MOU for Solstice™ scale-up (BusinessWire)
  • Key partners: Mercedes-Benz, Stellantis, Hyundai, Kia, IQT, Karma Automotive, POSCO Future M, Philenergy

What It Is / How It Works

FEST® is a semi-solid electrolyte, sometimes called a gel or hybrid electrolyte, positioned between conventional liquid electrolytes and fully solid ceramics. It targets the core trade-off in the solid-state space: fully solid electrolytes offer the best safety profile but are hard to manufacture and show high interface resistance, while liquid electrolytes process easily but are flammable and limit the cell to graphite anodes.

Factorial uses FEST® to enable a lithium metal anode (roughly ten times the theoretical capacity of graphite) while staying processable on conventional cell-making lines. The company says up to 80% of existing lithium-ion equipment can be reused, which would lower capital cost and learning curve for OEM partners; this has not been audited independently.

Solstice™ is a fully all-solid-state design with a dry cathode process that avoids hazardous solvents and energy-intensive drying steps. The February 2026 MOU with Philenergy covers laser notching, precision stacking, winding and modular factory design for Solstice™ scale-up; financial terms, timeline and whether the MOU is binding were not disclosed.

In March 2026 Factorial announced strategic investments from IQT, which supports expansion into drones, UAVs and mobile robotics, and from POSCO Future M, named as a battery supply chain partner alongside Philenergy (BusinessWire). Karma Automotive and Factorial announced a joint programme in February 2026 to integrate FEST® cells into Karma’s Kaveya, planned for late 2027, with the aim of validating the cells in a production passenger vehicle environment (Electrive).

Notable Developments

  • 2026-08-11: Factorial reports Q2 2026 results and holds its first earnings call as a public company; detailed figures are in a shareholder letter on its investor site, which this review did not retrieve. (SEC)
  • 2026-06-30: Shareholder letter published, recapping FEST® and Solstice™, Mercedes-Benz and Stellantis milestones, and target markets of aerospace, energy storage and mobility. (Nasdaq)
  • 2026-06-08: Begins trading on Nasdaq (FAC) after merging with Cartesian Growth Corp III. (Electrek)
  • 2026-03-10: Announces strategic investments from IQT and POSCO Future M to expand into drones, UAVs and mobile robotics. (BusinessWire)
  • 2026-02-26: MOU with Philenergy on Solstice™ manufacturing scale-up. (BusinessWire)
  • 2026-02-05: Karma Automotive and Factorial announce a joint programme for the Kaveya; reported as the first commercial solid-state programme in the US. (Electrek)
  • 2025-12: Announces plan to list on Nasdaq via a merger with Cartesian Growth Corp III; non-binding MOU with POSCO Future M on all-solid-state materials. (Electrek)
  • 2025-09: Mercedes-Benz modified EQS with Factorial cells covers over 745 miles (1,200 km) on one charge. (Electrek)
  • 2025-04-24: Stellantis verifies 77 Ah FEST® cells at 375 Wh/kg. (Stellantis)

Key People

Siyu Huang — CEO and Co-Founder

  • LinkedIn: linkedin.com/in/siyu-huang-6b126412
  • Role: CEO, leads technology strategy and OEM partnerships
  • Education: Uppsala University (chemistry) → Cornell University (PhD Chemistry, 2012; MBA)
  • Career (reverse-chronological):
    • Factorial Energy / Lionano (2013–present): co-founded Lionano as a Cornell spinout; rebranded to Factorial Energy in April 2021; CEO throughout
    • Johnson & Johnson (approx. 2012–2013): Marketing Leadership Development Program
  • Notes: Cornell connection shared with CTO Alex Yu (both PhD Cornell chemistry; both had Uppsala University affiliations before Cornell). The technology originated in Héctor Abruña’s Cornell electrochemistry lab.

Alex Yu — CTO and Co-Founder

  • LinkedIn: linkedin.com/in/alex-yu-96703719
  • Role: CTO; co-founded Lionano/Factorial; holds key battery technology patents
  • Education: Xiamen University (BS Chemistry) → Uppsala University (thesis, Photochemistry) → Cornell University (PhD Chemistry, 2014)
  • Career (reverse-chronological):
    • Factorial Energy (May 2022–present): CTO; also served as President 2020–2022
    • Lionano SE Inc. (2019–2020): CEO
    • Lionano Inc. (2013–2019): CEO / co-founder
  • Notes: ⚑ Shared background: Both Siyu Huang and Alex Yu completed work at Uppsala University and earned PhDs in chemistry from Cornell before co-founding the company together.

People — Last Reviewed: 2026-10-20

Supply Chain Position

Factorial operates at the Cell Manufacturing layer. Upstream, POSCO Future M is both a strategic investor and the counterparty to a non-binding MOU on cathode and silicon anode materials for all-solid-state cells; the lithium metal anode ties to Lithium, and the Solstice™ sulfide-based route implies a lithium sulfide dependency (see Sulfur). Downstream partners include Stellantis, Mercedes-Benz, Hyundai, Kia, Karma Automotive and IQT.

Claim Verification

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

Status: Partially verified (OEM lab verification, cell level)

Supporting sources:

Refuting / questioning sources:

  • None identified; the verifier is a commercial partner and an investor rather than an independent laboratory, and results are at cell level.

Summary: Energy density is the best-supported claim, verified by a partner OEM; no independent third-party laboratory result has been published.

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

Status: Partially verified (OEM lab verification)

Supporting sources:

Refuting / questioning sources: None identified.

Summary: Charging performance is confirmed by a partner OEM in lab testing; not independently replicated.

Claim: Over 1,200 km (745 miles) on one charge in a modified Mercedes-Benz EQS

Status: Unverified (partner-run test)

Supporting sources:

  • Electrek (June 2026) — Mercedes-Benz ran the drive and said usable energy rose 25% with weight and size roughly unchanged

Refuting / questioning sources:

  • Electrek (June 2026) — no independent verifier of the drive is named, and the vehicle was lightly modified

Summary: A single partner-run road test; no independent measurement or repeat results are published.

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

Status: Unverified

Supporting sources:

Refuting / questioning sources:

  • No independent manufacturing audit has been published, and no production ramp has demonstrated the figure at scale.

Summary: A plausible design principle for a semi-solid electrolyte, but a company claim until demonstrated in production.

Sources

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