Marubeni Corporation, one of the biggest Japanese conglomerates, has announced additional funding for an Estonian DeepTech startup, Skeleton Technologies. The deal amount is not disclosed.
Marubeni first invested in Skeleton in March 2021, buying close to 1% of the company. Since then, the startup has raised additional funds and progressed on several key projects, including a supercapacitor factory and SuperBattery development.
Advancing energy storage
Skeleton Technologies specialises in manufacturing supercapacitors, which are advanced energy storage devices that offer better capabilities compared to traditional batteries. Also known as electric double-layer capacitors (EDLC), they possess low internal resistance. It allows them to charge and discharge rapidly at high currents while maintaining a long service life of up to one million cycles and ensuring exceptional safety.
The company is currently preparing mass production for a groundbreaking storage battery called the SuperBattery. This innovative battery utilises Skeleton’s proprietary electrode technology and materials to enhance storage capacities while retaining the advantages of supercapacitors.

Honda CR-V Hybrid Racer powered by Skeleton’s supercapacitors
Skeleton’s novel products have garnered significant interest from various sectors, including grid energy storage, electric vehicles, battery railcars, and electric ships. For example, Shell is already working with Skeleton to develop a heavy-duty electric mining truck as part of its efforts to electrify mine transportation trucks completely. Other clients include Siemens and General Electric.
Besides long life, high levels of safety and impressive power, SuperBattery has a lower environmental impact compared to other storage batteries, emitting less CO2 throughout its lifecycle from manufacturing to disposal. Its mass production is expected to start in 2024.
Estonia and Japan: cooperation that drives innovation
Estonia and Japan are quite far apart, but they both share a passion for innovative solutions, although with a different approach. Japan, the world’s third-largest economy, capitalises on its massive industrial base. Estonia moves forwards as an invention factory and testbed for new solutions.
Skeleton’s deal is a perfect illustration of their possible synergy. Marubeni has been a strategic partner of Skeleton since its initial investment in 2021 and has recognised the strong demand for SuperBattery in various industrial sectors in Asia, particularly in Japan and Korea. That includes automotive, power grid, transportation, and mining operations. Marubeni is ready to support Skeleton’s growth by providing additional funding and resources, enabling them to expand their global marketing efforts, the company says.
Combining the expertise and scale of a Japanese corporation with Estonian innovations, this investment contributes to the global energy transition. It’s also a sign of the growing presence of Estonia abroad. Previously, Estonian company Auve Tech sold its new-generation self-driving vehicle, MiCa, to Japan, in a historic deal. In 2022, Estonia and Japan also signed a digital cooperation agreement.
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