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Skeleton Technologies to partner with Marubeni to bring its graphene SuperBattery to Asian automotive market

Skeleton Technologies, the largest European manufacturer of ultracapacitors, and Marubeni Corporation, one of Japan’s largest conglomerates with more than €50 billion of annual revenue, signed a strategic cooperation agreement to support commercial scale-up and customer acquisition for Skeleton’s new generation of ultracapacitors—called the SuperBattery—in the Asian automotive sector. The technology can serve the fast-growing electrified vehicles and hydrogen transportation markets.

The SuperBattery promises 10 times more energy density than current generation ultracapacitors, a reduction in cost by 90%, a 15-second charging time, a lifetime of more than 200,000 cycles and will excel at 10-15 minute applications.

Skeleton Technologies partnered with the Karlsruhe Institute of Technology to complete the development of the SuperBattery.(Earlier post.) The key differentiator for the SuperBattery is Skeleton’s patented Curved Graphene carbon material, enabling the high power and long lifetime of ultracapacitors to be applied in a graphene battery.

Enabling carbon-neutral electrification is a key priority for Marubeni Corporation. Skeleton Technologies fits perfectly in our portfolio as they fill the gap for high-power, extremely long high-cycles, and efficient energy storage devices. The company has validated its competitive advantage in real-life applications and has shown strong commercial traction. We are delighted to back Skeleton because we see that, besides their technological advantage, they are going after scale as evidenced by their participation in the €3-billion ‘European Battery Innovation’ project alongside companies such as Tesla and BMW.

—Masayuki Omoto, COO of Next Generation Business Development Division of Marubeni Corporation

Marubeni Corporation is a major conglomerate keen on advanced technology businesses and now becomes a key strategic partner for Skeleton Technologies. Our cooperation will drive the Asian automotive market’s adoption of our technology in the near future as the cost down will be much faster than for lithium-ion batteries. Our main focus is on electrified vehicles and hydrogen transportation markets because our products allow them to function more efficiently and drive their costs down.

—Taavi Madiberk, CEO and co-founder of Skeleton Technologies

Skeleton Technologies is currently investing in technology development and scaling up a new product line for the automotive sector. The cooperation with Marubeni covers Asia, excluding China and India, and will offer new resources to commercialize Skeleton’s graphene-based SuperBattery. This new energy storage solution is the ideal complementary technology for lithium-ion batteries and hydrogen fuel cells, improving overall system efficiency and performance.

While having a strong focus on the expanding electrified and hydrogen-based transportation market, Skeleton and Marubeni will also cooperate on new applications of Skeleton’s patented curved graphene material, the key enabling technology behind Skeleton’s ultracapacitors’ performance advantage.

Marubeni Corporation has also made an equity investment in Skeleton Technologies, on top of the €41.3 million ($48.5 million) Series D financing round announced by the company in November 2020.



Aha! Found Skelcap's data sheet!
On the previous article here on the technology I was very sniffy as their site did not seem provide specs, but it is here now:

Specific Energy 5.1-6.8Wh/kg
Practical Specific power 21-27W/kg

As can be seen, with specific energy some 50 times or so lower than lithium ion batteries, this is not about replacing them, above all in mobile applications.

What rather surprises me is that the power does not sound great either.

Wiki gives the specific power of LFP batteries at around 200W/kg:

Of course the cycle life of capacitors is many orders of magnitude more than lithium though.

If someone can give more technical insight in 'why choose capacitors' that would be helpful, as I am not seeing a lot here, although I have Maxwell ones in my own car for stop start.

Applications appear to be limited.


You mis-read the units.  Practical specific power 21-27 kW/kg



Aha! Excellent! I managed to read straight past that, but did at any rate express surprise at what sounded like very low power.

If their cost claims are also correct, this will enhance a host of applications.


Indeed.  Likely not hybrid vehicles, because you'd need 100 kg or so to store the full kinetic energy of a car moving at highway speeds and batteries do fine for that.  But start-stop mild hybrids?  Feathering wind turbines in a power outage?  A natural.


I mis-estimated.  It would take more like 35 kg.


They mention 10-15 minute applications as being of particular interest.
Their site gives a number of applications they are looking at:

Interestingly, for most applications the links say '
For 12v lead acid batteries, it just says 'contact us'

I think that may indicate that they are planning an early release in this field, no doubt combining lithium with the capacitors, as the ~720Wh from a 12V car battery is too much to cover with just capacitors.


Oh, no argument.  A cold PbSO4 battery is current-limited.  But slow-charge an ultracap from it, and you can kick over an engine even on a subzero day.


Hmmm.  Other possibilities include managing the rest of the electrical system, e.g. running the alternator at max when braking to recoup energy that would otherwise be lost, and killing the alternator on acceleration to minimize accessory drag while feeding the system bus from the caps.


They are getting up to lots of tricks with hybrids here in Europe, and are going to 48v to enable that, such as cruising on the flat with periodic engine cut outs.

These will make them easier but it seems to me that initially they are going to do a straight replacement for the 12v systems.

Account Deleted

Good observations everyone. In case you missed this post about the Skeleton Technologies SkelStart module, it verifies your comments.
The 12 volt brochure shows how the lead acid battery handles "hotel loads" only.


Thanks gryf.
Acute and informed as always.

From that it sound like they are looking at heavier vehicles than cars as the initial 12v application - they are talking about 'large diesel engines'


Hmm, I happen to have one of those.  It might be a good thing for me.

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