Why this startup thinks its supercapacitor tech is key to hybrid electric vehicles

Skeleton Technologies is investing millions to scale production of its patented curved graphene ultracapacitors.
Written by Kalev Aasmae, Contributor

Supercapacitors, or ultracapacitors, are an alternative to rechargeable batteries, offering quicker charge and release times but lower capacity.

Image: Marek Metslaid/Skeleton Technologies

Estonian manufacturer Skeleton Technologies' new production line in Saxony, Germany, can produce up to 4,000,000 supercapacitor cells per year, which, according to the company, makes it the biggest in Europe.

The new facility should make it easier for Skeleton Technologies to serve its customer base, which includes German automotive manufacturers, global engineering companies, and also the European Space Agency.

Supercapacitors, also known as ultracapacitors, are an alternative to rechargeable batteries, offering quicker charge and release times but lower capacity.

Skeleton's success in the field is based on its patented curved graphene, which, according to the company, is one of the key factors in achieving the superior energy density of supercapacitors compared with competitors that use organic pre-cursor materials, mostly carbon made from coconut.

The firm's co-founder and COO, Oliver Ahlberg, tells ZDNet that although there is always a scale-up process involved when first starting a factory, the new facility is already well within the capacity at which the company plans to operate.

"Over the summer we will, however, build a new tower for the slurry mixing equipment that will further improve the process speed and efficiency," he added.

Ahlberg says the patented curved graphene-based ultracapacitors provide four times the power density and up to twice the energy density of its competitors, which include manufacturers such as Maxwell Technologies, Ioxus, and LS MTRON.

"Ultracapacitors are already the more economical choice for many applications, especially where the power need doesn't exceed 30 seconds. However, we are hard at work also increasing the energy density," Ahlberg says.

"Ultracapacitors will never fully replace batteries, but increased energy density will open doors to a significantly higher number of uses for ultracapacitors, like 48V automotive mild hybrid [engines]. The road to fully electric will have a hybrid stepping stone in between, and we think that ultracapacitor-based hybrid systems will be the key."

Skeleton Technologies was founded eight years ago by then 22-year-old Ahlberg and 20-year-old Taavi Madiberk, who together bought some intellectual property from a group of Estonian scientists with a view to helping them commercialize ultracapacitor technology.

Within a few years it has become one of Estonia's biggest startup success stories and a rare example for the country of a firm developing and manufacturing physical high-tech products and competing as one of its market's largest participants globally.

Ahlberg pointed out that a great advantage that Skeleton has over its competitors is that it is the only full value chain manufacturer in the ultracapacitor industry.

"What this means is that we have a patented raw material, curved graphene, and patented manufacturing processes protecting the full value chain from raw material to ultracapacitor cells, modules, and finally, complete plug-and-play energy storage systems."

One example of this kind of a full system is the Kinetic Energy Recovery System for heavy transportation.

"The KERS capture braking energy and uses the captured braking energy for acceleration in trucks, or lifting in port cranes. The system is sold as a complete installation and can be retrofitted to existing trucks and cranes," he says.

"We've reached savings of 25 percent in fuel consumption and related emissions for trucks and more than 40 percent for port cranes, so the KERS has huge potential for energy savings in the transportation industry."

The continuing rapid growth of the company is fuelled by the funding announced in February. The European Investment Bank (EIB) signed a €15m ($16.6m) 'quasi-equity' financing with Skeleton Technologies. In total, the company has raised €41.7m ($46.3m). Over €6m of the new loan is invested in the facility in Germany, and the company plans to invest more in production to bring the price per unit down.

"R&D is the foundation Skeleton Technologies was built on, and we'll keep investing significant amounts in R&D to stay ahead of the pack and to provide our customers with the best possible ultracapacitor-based solutions," Ahlberg says.

"We'll also need to emphasize the importance of scaling production to meet the demand and to lower the price per unit to be competitive in the marketplace."

The company is also on a hiring spree, having almost doubled the employee headcount to 90 in less than two years.

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