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.

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.

New Skeleton cylindrical ultracapacitors Name Capacitance

(Farads, F) Voltage

(V) ESR

(mΩ) Spec. power

(kW/kg) Spec. energy

(Wh/kg) Weight

(kg) Volume

(L) 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.