Wise cofounder Taavet Hinrikus is the latest big-name investor to back batteries, taking part in the €37.6m Series D round for Estonian startup Skeleton Technologies.

Skeleton, which is developing ultracapacitors and a “SuperBattery” that will charge electric vehicles in seconds, is fast becoming one of Europe’s big bets in batteries, having raised more than €200m from investors.

What does Skeleton develop?

Much of the investor focus on batteries has so far been around gigafactories, like Northvolt, Britishvolt and Verkor, which will make massive numbers of batteries for the legions of electric cars that carmakers are planning to roll off their production lines. Car manufacturers and the EU have backed these projects heavily, keen that Europe should not become dependent on US or Chinese manufacturers.

Skeleton is trying to solve a different problem, the charging time of batteries — an issue that any impatient EV owner can relate to. The lithium-ion batteries rolling out of gigafactories still take hours to charge.

This is an obvious issue for car manufacturers. Tesla has managed to cut its batteries’ charging times to around 30 minutes at its Supercharger stations, is poised to cut it further after it bought ultracapacitor company Maxwell Technologies for $218m in 2019.

Ultracapacitors, also called supercapacitors, provide a burst of energy for a short amount of time (often little more than a few minutes) and can be charged even faster. They can also be recharged about a million times, compared with only about 1,000 for batteries. They are already used in places where lithium-ion batteries are impractical, like in trams or in industrial machinery which only operate in short bursts, as well as in combination with batteries.

Skeleton says it’s working with European automotive companies, industrial equipment manufacturers, truck fleet operators and aerospace contractors for its SuperBattery.

Is graphene the answer?

Skeleton’s ultracapacitor is based on patented curved graphene, which it refers to as a “next-gen supermaterial with extraordinary properties that could revolutionise all sorts of industries”.

This supermaterial that Skeleton is using has also opened the door for developing a SuperBattery, which is half way between an ultracapacitor and a battery. It can be charged in seconds like an ultracapacitor, but lasts for 15 minutes. That doesn’t sound very useful, but according to the industry and investors there is a need for this.

“We are not the silver bullet for all of the issues on the market”

It’s not just quicker to charge than lithium-ion batteries but also lighter and doesn’t contain harmful chemicals or toxic metals — making it more sustainable.

“But we are not the silver bullet in terms of solving all of the issues on the market,” says Skeleton’s chief executive and cofounder, Taavi Madiberk.

According to Skeleton, the slow discharge of energy in batteries has led to those systems being oversized by up to six times to meet power needs. The Skeleton SuperBattery may be able to fill the technology gap in the energy storage market, delivering peak power within 15 seconds while still being able to support up to 15 minutes of constant power.

So when will we see this SuperBattery on the market?

According to Madiberk, the process of bringing the SuperBattery to market is “going according to plan”, meaning it should be available for manufacturers next year.

“We are already working with some of the largest global automotive companies and industrial players. And with this round, we are focusing on scaling our manufacturing capabilities because the demand far exceeds what we can make using our first facility,” Madiberk says.

Skeleton is a part of the European Battery Alliance and, like Tesla, has based its manufacturing facilities in Germany. Last year the German government gave Skeleton €51m to help scale up production in its facility outside Dresden.

The company’s development of curved graphene seems to be enough to make a range of investors enthusiastic, including industry experts like Bengt Wahlqvist, the founder of Swedish battery company CTEK in Sweden, who is one of the latest investors.

The Estonian company has also managed to intrigue tech founders like Taavet Hinrikus, cofounder of Wise and first employee at Skype, as well as some of the founding team of Dutch unicorn Adyen.

“I am convinced that the next generation of battery technologies — the ones that will allow us to achieve our climate goals — will be enabled by materials innovation. Skeleton’s team has a proven track record of bringing R&D to real-life products, which is why investing in the company was an obvious choice for me,” Hinrikus said.

Mimi Billing is Sifted’s Nordic correspondent. She also covers healthtech, and tweets from @MimiBilling