Skeleton Technologies at $1B: EIC Accelerator Supercapacitor Maker

On 14 October 2026, Skeleton Technologies announced a "9-digit" investment round led by Siemens that it says values the company at more than $1 billion, money meant mainly for factories and research in the United States, according to the company's announcement. ESS News reported the same valuation, noted that the round size was not disclosed, and added that Siemens takes a minority stake plus exclusive global rights to sell Skeleton's high-power storage products to data-centre customers. Six years earlier, the company's German subsidiary had been one of the Green Deal winners of the EIC Accelerator pilot, with a grant-only award for X-CAP, a project to put metal oxides into ultracapacitor electrodes and build a cell between a supercapacitor and a lithium-ion battery.

The funded entity is Skeleton Technologies GmbH, listed in Großröhrsdorf, Saxony, in the European Commission's list of companies selected at the 19 May 2020 cut-off, which names no other beneficiary for X-CAP. The GmbH belongs to Skeleton Technologies Group OÜ, a holding company registered in Tallinn in February 2013, according to the Estonian e-Business Register. The group was founded in 2009, according to its own press release and ERR News.

A Grid and AI Power Supplier in 2026

Skeleton is active and growing. The group's consolidated revenue rose from €23.58 million in 2024 to €29.23 million in 2025, and its net loss fell from €20.80 million to €10.03 million, according to the 2025 annual report filed in the Estonian e-Business Register in August 2026. The report notes that 2025 revenue includes compensation from a customer for the early termination and change of a contract. Cash fell from €82.30 million to €65.80 million, and the balance sheet carried €75 million in convertible loans plus €9.5 million in accrued interest.

The company now presents itself as a power-systems supplier for AI data centres. Its GrapheneGPU system smooths the power swings of GPU clusters, and the annual report says first industrial-scale deliveries to AI data-centre customers took place in 2025. In May 2026 the group announced a €33 million first close of a pre-IPO round with Axon Partners Group, SmartCap and Taiwania Capital, bringing its venture funding to €392 million ahead of a planned United States listing in 2027, according to its release; ESS News repeats the €392 million total. Skeleton has named no hyperscaler customer, and no US site, capacity or start date has been disclosed.

The Technology: Supercapacitors With More Energy

Ultracapacitors, also called supercapacitors, store charge on the surface of their electrodes. That lets them charge and discharge in seconds and survive hundreds of thousands of cycles, but it caps how much energy they hold. X-CAP set out to break that limit by adding redox-active metal oxides to the electrodes, through "hybrid materials and composite materials", according to the project's CORDIS report. The target was a cell for one to 15 minutes of storage that would fill the gap between ultracapacitors and lithium-ion batteries in vehicles, grid support and lead-acid replacement.

Skeleton's base material is Curved Graphene, a carbon it makes itself in Germany. Since 2025 the group has run two plants: a €220 million supercapacitor factory in Markranstädt near Leipzig, which it says supplies Siemens, General Electric and Hitachi Energy for European grids, according to its opening release, and a SuperBattery plant in Varkaus, Finland. The 2025 annual report puts Leipzig's capacity at up to 4.4 million supercapacitors a year, against the 12 million cells a year named in the opening release; the two figures could not be reconciled from public sources.

What X-CAP Promised, and What the Record Shows

X-CAP ran from 1 August 2020 to 31 December 2022 with a total cost of €3.61 million, of which the EU paid €2.527 million, according to CORDIS. It was not Skeleton's first SME Instrument money: the Estonian company had a €50,000 feasibility study in 2014 (SKLCarbon) and a €2,488,762.50 Phase 2 grant from 2016 to 2018 to scale up its carbon production (SKLCarbonP2).

The X-CAP report set the targets: energy cost below €250 per kWh, power above 10 kW/kg, energy density above 50 Wh/kg, an operating range of -40°C to +70°C and a lifetime above 200,000 cycles, with the technology moving from TRL 6 to TRL 8 and being developed and produced in Großröhrsdorf. Its final report, covering the period to December 2022, still described the technology as being at TRL 6 and said TRL 8 was "expected" at the end of the project. It said Skeleton was working on product development with customers in mining and heavy off-road transport, and claimed "100x faster charging" than standard lithium-ion batteries.

Those are the same markets and the same claim Skeleton used in October 2022, two months before the project ended, when it launched the SuperBattery with Shell as partner in a mining consortium, according to its launch release. Skeleton has not publicly labelled the SuperBattery as the X-CAP product, so the link rests on these matching descriptions. The launch release specified 50,000 cycles, a quarter of the X-CAP target, and planned mass production for 2024. In 2020 the company had also announced a SuperBattery development deal with the Karlsruhe Institute of Technology and a €1 billion letter of intent with an unnamed automotive OEM, according to its release; no resulting automotive contract has been announced.

Production went to Finland, not Saxony. Skeleton bought the assets of a bankrupt battery maker in Varkaus in May 2023 for pilot production, according to its release, and opened the factory officially in November 2025 after a €50 million investment, according to the company and the EIT. ERR News reported a €25 million plant with another €25 million planned, 37 staff and a capacity of 250,000 SuperBatteries a year; the company gives €50 million and more than 65 staff in Finland. The cells use niobium oxides from CBMM, a Brazilian niobium producer that invested in Skeleton in 2023. In Saxony, the existing site was in Großröhrsdorf, according to Skeleton's 2023 release; Skeleton shut its Dresden-area plant to move to Leipzig, ERR News reported, and the GmbH moved its registered seat from the Dresden to the Leipzig court register in January 2025, according to North Data.

1. Metal oxide hybrid cell developedDeliveredCORDIS final report; SuperBattery launched October 2022.
2. TRL 6 to TRL 8 within the projectLateFinal report still at TRL 6; industrial production in Varkaus from 2025.
3. More than 200,000 cyclesNot achievedSuperBattery specified at 50,000 cycles.
4. Below €250/kWh and above 50 Wh/kgNot shownNo cost or energy density figure published.
5. Production in GroßröhrsdorfNot achievedMade in Finland; Dresden-area plant closed.
6. Electric and hybrid vehicle marketShiftedVarkaus output marketed for AI data centres, grid, mobility and defence.

The Money

Revenue has more than tripled since the X-CAP award, but the group has not made a profit in any year shown. Revenue was €9.02 million in 2020, €12.85 million in 2021, €20.95 million in 2022 and €23.40 million in 2023, according to the consolidated annual reports. Growth almost stopped in 2024, when the Leipzig factory missed its start because the equipment supplier Manz ran into financial trouble and could not deliver, ERR News reported in September 2025, citing the annual report; Skeleton also cut 20 of its roughly 100 jobs in Estonia that year.

Equity investors have covered the losses. A €108 million round in October 2023 brought in Siemens Financial Services, Marubeni and CBMM and took total funding above €300 million, according to Skeleton's announcement. Public money has followed the factories: a grant of nearly €7 million from the EU's Just Transition Fund for Varkaus, according to Skeleton's release, and Innovation Fund support confirmed by the European Commission's Finland representation. The annual report puts the Innovation Fund award for Varkaus at €79 million and a second one, for a German supercapacitor project confirmed in 2026, at €81 million.

Why It Matters for Europe

The EU has paid for Skeleton's manufacturing through several channels: three SME Instrument and EIC grants, the Just Transition Fund in eastern Finland and the Innovation Fund in Finland and Germany. The European Commission describes the Varkaus plant as supporting the stability and self-sufficiency of Europe's energy system. Skeleton argues that its supercapacitors use no lithium or cobalt and that it is the only fully European company covering the high-power storage value chain from raw material to systems, according to its Leipzig release; that claim is the company's own.

The 2026 Siemens deal adds a question for that European case. Skeleton says it will invest more than $200 million in scale-up and research in Silicon Valley and build US cell production, and Siemens gets exclusive global rights to sell its products to data centres, according to ESS News. In May 2024 Skeleton also announced a €600 million plan for research in Toulouse and a SuperBattery factory in Occitanie, according to its release; a French subsidiary exists, but no French factory site or start date has been announced since.

The Verdict

Skeleton Technologies and the EIC were not asked for comment for this article. It is based on public records and published statements, linked throughout.