Sepion Technologies raised $10 million in a Series B round led by Fine Structure Ventures. The funds will drive U.S. polymer production scale-up, fulfill commercial orders, and expand its polymer-coated battery separator technology.
Sepion Technologies has closed a $10 million Series B funding round, led by repeat investor Fine Structure Ventures and featured strategic participation from W. L. Gore & Associates and Syensqo Ventures, joined by Volo Earth Ventures, Chailease, Catalus Capital, Impact Science Ventures, and ACVC Partners. Proceeds will scale U.S.-based polymer production, fulfill existing commercial purchase orders, expand product lines, and strengthen quality systems and operations.
What is Sepion Technologies?
Sepion, founded in 2015 in the San Francisco Bay Area by CEO Peter Frischmann and co-founder Brett Helms, develops ultra thin polymer coatings and membrane technologies for lithium-ion battery separators and next generation cell chemistries. Its core innovation replaces conventional ceramic coatings on polyolefin separators with proprietary, atomically selective polymer layers. These coatings permit lithium ions to pass while blocking harmful transition metals (nickel, cobalt, manganese, copper, iron) that migrate from the cathode and degrade the anode, causing capacity fade, safety issues, and reduced cycle life. The result is a drop-in solution that integrates seamlessly into existing battery manufacturing lines without retooling.
Key performance advantages include up to 5% higher volumetric energy density, lighter cell weight (eliminating dense ceramic layers can reduce vehicle mass by ~10 kg in EVs), faster charging capability, and improved durability and thermal stability. The technology also supports high nickel or manganese-rich cathodes, low cost chemistries, and emerging formats such as lithium-metal anodes, all while maintaining compatibility with current production infrastructure.
The company operates a 25,000 sq ft pilot facility in Alameda, California, equipped with a slot-die coater capable of 330 mm-wide coated separators, a dry room for cell assembly (proven at 2 Ah, scalable to 20 Ah), and annualized capacity reaching 500,000 m² of coated separator plus 1 MWh of prototype cells. It is already producing material on commercial scale lines and running multiple concurrent qualification programs with leading global battery manufacturers for electric vehicles, stationary energy storage, and consumer electronics applications.
Funding history shows steady progression toward commercialization. Early support included a seed round led by Creative Ventures. In November 2021, Sepion closed an oversubscribed $16 million Series A, also led by Fine Structure Ventures, to accelerate lithium-metal battery commercialization. Non dilutive capital followed, notably a $17.5 million grant in October 2024 from CALSTART and the California Energy Commission’s PowerForward ZEV Battery Manufacturing Grant Program. That award funds construction of a dedicated separator manufacturing facility in West Sacramento’s Capitol Innovation District. The plant targets initial annual output of 50 tons of proprietary polymer and 50 million square meters of coated separator, enough for roughly 50,000 EVs, with production slated to begin in 2027 after Phase I construction and validation. It directly addresses projected domestic separator supply shortfalls and aligns with U.S. priorities for supply chain security and clean energy manufacturing jobs.
The Series B builds directly on these foundations. The $17.5 million grant handles facility capex and infrastructure, while the new equity capital focuses on polymer synthesis scale-up, order fulfillment, product line extensions, and operational readiness. Strategic investors bring deep domain expertise: W. L. Gore & Associates contributes membrane and porous material know-how (core to its ePTFE technologies), and Syensqo Ventures supplies advanced polymer and specialty chemicals capabilities, ideal partners for ramping high performance coatings. The repeat leadership from Fine Structure Ventures and continued involvement from climate focused and institutional backers (Volo Earth, Impact Science, ACVC) underscore sustained confidence in Sepion’s technical roadmap and path to revenue.
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In the broader battery ecosystem, this round is strategically significant. Separators represent a critical, high volume component whose performance directly limits cell energy density, safety, and cost. Traditional ceramic-coated separators have reached diminishing returns on thickness and weight; Sepion’s polymer approach delivers measurable gains without the manufacturing complexity of solid state or entirely new cell formats. By enabling longer life cells with manganese-rich cathodes and supporting next generation chemistries, Sepion helps battery makers meet EV range, cost, and durability targets while mitigating supply risks from overseas ceramic materials.
Customer traction, evidenced by active qualifications and purchase orders, signals commercial readiness. The U.S.-centric manufacturing strategy positions Sepion to capture incentives under the Inflation Reduction Act and to serve OEMs seeking domestic content. With production scaling targeted for 2027, the company is transitioning from pilot validation to volume supply, a pivotal inflection point for deep tech hardware ventures.
Risks remain execution focused: achieving cost effective polymer production at scale, securing full customer design wins post qualification, navigating competition from established Asian separator leaders, and managing the capital intensive nature of battery-component manufacturing. However, the combination of proven drop-in compatibility, demonstrated performance uplift, strategic investor alignment, and secured grant backed infrastructure substantially de-risks the path forward.
The $10 million Series B accelerates Sepion from qualified prototypes to commercial delivery. It solidifies the company’s role as a U.S.-based innovator in advanced battery materials, directly contributing to higher performing, safer, and more affordable energy storage systems essential for widespread electrification. With purchase orders in hand and manufacturing capacity coming online, Sepion is well positioned to capture share in the rapidly expanding global separator market while strengthening domestic supply resilience.
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