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Battery technology is, according to many in the industry, advancing at remarkable rates thanks to investment and attention from the world’s biggest automakers.

So, when one small Berlin-based company appears, almost out of nowhere, claiming that its lithium-sulphur cells can deliver triple the energy density while requiring 90% less energy to produce than conventional lithium-ion cells, it certainly seems worth investigating.

That company is Theion. Founded just two years ago on the back of research by now CTO Marek Slavik, the company has ambitious plans for commercialisation. Auto Futures has been speaking to CEO Dr Ulrich Ehmes to find out what the rest of the world seems to have missed about lithium-sulphur.

Nothing New Under the Sun

Dr Ulrich Ehmes Theion Ceo
Dr Ulrich Ehmes, Theion’s CEO

“That is a very good question!” says Ehmes as we talk over a video call and ask him why no one else is using lithium-sulphur.

“There are some other companies out there and there is also research on lithium-sulphur in universities – so we are not the only ones.

“But we are very likely the only ones who are applying these new processes because the other companies and researchers often use their existing equipment – it’s always the dogma.”

For Ehmes, currently ill with COVID-19 but feeling well enough to chat, the potential for lithium-sulphur has always been present.

But, as big companies have invested billions into lithium-ion cells, they remain reticent to retool, reorganise, and retrain their factories, supply chains, and workers to take advantage of new innovations.

“The battery industry is very conservative,” he explains. “It’s copy-and-paste from Asian factories to Europe – they don’t change anything. It’s always the same.

“But, in Europe and Germany, we have quite an interesting, innovative atmosphere and startup scene, so the innovation often comes from Europe.”

That innovation, in Theion’s case, largely came from one man – Marek Slavik, the company’s co-founder and CTO. 

“Marek thought, ‘How can we bring battery capacity to the next level? What is the best material?’ says Ehmes.

“The cathode material is the key for keeping cost down and energy density up. He [Slavik] found out it would be fantastic to use the intrinsic energy density of sulphur as a cathode material as it only costs 20 cents per kilogram in comparison to €20 per kilogram for standard NMC811.”

Theion Scientist Prepares Sulphur Powder For The Next Test Build Up Of Cells...
A Theion scientist prepares sulphur powder for the next test build up of cells

NMC811 is a cathode comprised of 80% nickel, 10% cobalt, and 10% manganese. All of these materials, while effective at storing power, are rare and expensive.

“We use very easy-to-get materials,” says Ehmes.

“A carbon nanotube, sulphur is abundantly available, and thin lithium metal foil – that is all that we have. No cobalt, no aluminium foil, no copper foil. We are quite agnostic to all of these price changes occurring in the market.”

Saving Money and Commercialisation

The other side to Theion’s improved batteries is the reduced cost. 

“Sulphur is a by-product of many industries,” explains Ehmes. “For example, from the petrol industry, they take it out because they want to have fuel without sulphur, this pollutes the air when burned, so there are huge mountains of sulphur everywhere that they want to get rid of.

“Therefore, even high purity sulphur at 99.5% is so cheap to get – 20 cents per kg – and without any mining. When you look at the cost of a battery cell, one-third of a traditional cell is the cost for the cathode material. So, if that one-third is now brought down to 1%, it has a huge impact on cost.”

Theion’s cells should also be easier to recycle than traditional cells. 

“The existing setups have aluminium foil, copper foil, nickel, cobalt, manganese, liquid electrolyte, plastic foil and to separate that is crazy,” says Ehmes.

“Normally, they have a thermal recycling process. They throw everything into 2000-degrees and they separate by melting it down. So, this is crazy-expensive. In our case, it’s just sulphur, lithium, and carbon – that’s all. It’s just three materials which is much easier to separate.”

The lithium would then be recovered and used in other cells, says Ehmes. When it comes to what Theion will do with the sulphur, however, the jury is still out.

“The question is if it makes sense because the raw sulphur is so cheap and if there are ways to use the sulphur again.”

Sulfur Crystal Theion
A sulphur crystal under a microscope

Of course, with such dramatic cost and material savings compared to traditional cells, does Ehmes think that other companies will look to copy Theion?

“I can imagine so,” he says, “especially if you look at the metal prices in recent weeks – they went up dramatically, not only because of the war but also because of the demand.

“I see that there are many companies that are going away from the traditional NMC, nickel, manganese, cobalt, to other chemistries. And one of these chemistries can, obviously, be sulphur, but these companies need to be willing to change their production processes. 

According to Ehmes, this unwillingness of big companies to change their production presents a huge opportunity for companies like Theion. 

“Here I see more startups, more newcomers in the production scene of batteries, rather than established old companies,” he says. 

“For them [the old companies] it’s a bit more difficult. This has to do with existing overheads, existing technology, and it has to do with courage.”

Taking the Next Step

However, at the moment, much of this talk is hypothetical. For all of Ehmes’ and the company’s big claims, there is nothing concrete for us to see yet. 

“I’m an engineer – I don’t want to over-promise, right?” says Ehmes.

“We had our proof of concept. Now we are working to build the very first complete battery cell within the year.”

Once the small matter of actually building the compete cell is out of the way, Theion will then look to start commercialising. It will start small, looking to walk before it can run.

“We will start with a small market, not the biggest market on earth – that would be a risk. We’ll start with a small market that needs really lightweight batteries because, with each kilogram they save, they can put more payload into the device.”

That small market is, perhaps unusually, commercial rockets for satellites. 

“For each payload, they get €10,000 per kg,” explains Ehmes. “So they are changing the way they get the energy to the pump of the rocket and our battery plays a role. It will be a very small niche market but the first cells will be for them.”

Filling The Battery Test Equipment At The Lab
Filing the battery test equipment in Theion’s lab

In 2023, Theion will look at mobile devices including laptops and smartphones as well as eVTOL air taxis. Then, in 2024, long-range passenger aircraft and the automotive sector are on the horizon.

Gigafactories with large-scale production are planned in 2025 onwards.

“We need another three years to go there. But the potential is huge and then certainly we will build our first factory in Germany because there is our headquarters and there is a huge demand for batteries,” says Ehmes.

“Then, we will build more factories close to our end customers as these materials besides lithium – only 5% of the weight of the battery is lithium – so to transport this to the factory is not an issue, but all the other materials are locally available.”

Speaking to Ehmes, it’s hard not to get caught up in a heady mix of cost savings, efficiency increases, and potential implications for the various industries. However, it’s important to remember that Theion isn’t quite ready to change the world just yet. 

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