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Skeleton Technologies launches new range of high-performance ultracapacitors; up to 111 kW/kg and 9.6 Wh/kg; hybrid truck application coming

Skeleton Technologies (earlier post) has launched a new range of cylindrical ultracapacitors that offers specific power performance of up to 111 kW/kg (SC450, 450F) and specific energy up to 9.6 Wh/kg (SC4500, 4500F) with ESR as low as 0.075 mΩ (SC3000, 3000F)—the highest performance cylindrical cell ultracapacitors in the market.

Through the use of its patented graphene material, the new series features a capacitance of up to 4500 farads (the SC4500 cell). By contrast, the closest competitor product has a capacitance of 3400 farads. Skeleton claims this is the single biggest increase in energy density for ultracapacitors in the past 15 years.

New Skeleton cylindrical ultracapacitors
Name Capacitance
(Farads, F)
Spec. power
Spec. energy
SC450 450 2.85 0.18 111 5.8 0.102 0.079
SC650 650 2.85 0.154 97 6.4 0.136 0.103
SC1000 1000 2.85 0.090 95 5.9 0.237 0.178
SC1500 1500 2.85 0.079 81 6.5 0.318 0.232
SC3000 3000 2.85 0.075 52 7.2 0.524 0.390
SC4500 4500 2.85 0.09 41 9.6 0.526 0.390

Skeleton Technologies uses a patented material synthesized from inorganic compounds that has curved graphene layers allowing for better conductivity and higher surface area. Skeleton says that the energy density achieved by the SkelCap 4500 series will allow it to maximize opportunities in the heavy transportation and industrial markets where weight and space are at a premium.

Skeleton Technologies ultracapacitors have already been chosen by the European Space Agency, where their use is expected to lead to significant cost savings by reducing the volume of heavy batteries required for energy storage. Next month, the company will be announcing the first ultracapacitor product for the hybrid truck market.

The new range has been designed for mass-market applications and the needs of systems engineers. The format has been developed to meet the industry standard of a 60 mm diameter cylindrical cell. Skeleton Technologies had previously offered prismatic cells, which are more compact in modular arrangements but more expensive to produce.

Skeleton Technologies has also achieved one the lowest ESR (equivalent series resistance) levels on the market at 0.095 mΩ. This factor is crucial as it greatly increases the efficiency of the cells by reducing the amount of energy that is lost as heat. For example, if a 3900A current is run through the SkelCap 4500 cell, it will lose only 0.30 joules per farad, whereas competing products can lose as much as 1.00 joules per farad.

The ultracapacitor market is dominated by organic precursor carbon from coconut shell. It is the successful development of a graphene-based carbon that is allowing us to set new records for product performance. We have set ourselves an ambitious technology development target of 20 Wh/kg by 2020, which is comparable with battery-level energy density. With the launch of the SkelCap 4500 range we are already halfway towards that goal.

—Volker Dudek, Chief Technology Office at Skeleton Technologies

In the last month, Skeleton Technologies secured €9.8 million (US$11 million) in Series B financing with a strategic investor in the electrical equipment market to ramp up the deployment of their graphene ultracapacitors.



HOLY CRAP! at 111kW/kg and an energy density of nearly 10Wh/kg....these things are massively powerful! This could allow Toyota to stay with Supercaps for their WEC 24hour of Le Mans racers and jump up to the 8MJ category next year.

I'd love to see them do it. They'd only need about 10kg of supercaps to get the regen they'd need to capture and expend 8MJ per lap...and it would give them LITERALLY 1,489hp to boost them out of corners...assuming the electric motor could handle it of course :)

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It can be used for power weapons. Lasers and magnetic rail-guns etc.


I doubt Toyota stand any chance against Porsche at next year Le Mans, unless they implement exhaust energy recuperation (as Porsche and Audi do, F1 cars as well).
I don't know what percentage of recovered battery energy in Porsche cars comes from braking, and what % from turbine generator.
Put it this way: If Porsche were able to fully charge 8 MJ battery just from regen braking, why would they use turbine generator?
This year in Le Mans (398 laps, Porsche winner), Toyota cars were 8 laps behind, which means their average laps were 2% slower.
The Toyota system may be more competitive at some circuits with shorter straights, more frequent braking, but not at Le Mans. Even then there is a lot of wasted energy in exhaust as engine works at full power during acceleration out of corners, allowing e-boost to last longer, i.e. full speed is reached quicker.
There is another possibility that Porsche switched from 6 MJ to 8 MJ (A123) battery so that bigger battery could provide just more power, or to stress it less so it is less likely to fail during the race.


Totally agree about them needing an MGU-H if they want to compete with Porsche. However, Toytota is saying that they've finally decided to finally give up on the naturally aspirated engine. If they go with a turbo now, then they'd have a chance to use the waste gate for energy recovery as well. That doesn't mean they WILL, but they've certainly got the blueprint of how to do it from watching Porsche :)

But to be honest, I'm a big Porsche fan so I hope they dominate for a long time! But it would be cool to see if Toyota could keep some interesting new tech coming into the series and they're the supercap users.


Now that I think about it, the high power version of A123 batteries used in F1 and WEC put out over 20kW/kg. And the speculation is that Porsche are getting about 450hp from that system...so they've probably got something north of 25kg of batteries in that 919 as well.
Would be interesting to know the real specs on that system instead if estimating.

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