Storedot’s ‘100-in-5’ cells are under validation with leading automakers

Israel-based StoreDot is developing extremely fast-charging Lithium-ion cells for electric vehicle batteries that can provide a range of 100 miles within 5 mins of charging. Its strategic investors and partners include Daimler, BP, VinFast, Volvo, Polestar, Ola Electric, Samsung, TDK, and its manufacturing partner is EVE Energy. The company aims to be mass-production ready by 2024. In this chat with CEO Doron Myersdorf, we learn more about their technology, approach and market readiness.

Where is StoreDot in the process of achieving ‘100-in-5’ cells?

The technology is ready, and we are shipping the 30Ah samples. These cells can deliver 1000 cycles and 300 Wh/kg performance. The cells are currently in testing with multiple car makers around the world. So in terms of technology readiness, we are there. The process of being integrated into a vehicle takes a year or two. We have already started that validation process.

What are the major milestones that your company has been able to achieve so far?
  • We reached our first milestone of best-performing energy density almost two years ago. We are now at 300 Wh/kg, i.e. 700 Wh/litre.
  • The next challenge was to hold this energy density steady and keep improving on the fast-charging cycle life. In the beginning, we had only 20 to 40 cycles until the battery reached 80% performance, which is not sufficient for the vehicle. The minimum cycle life demanded by an OEM was 800 consecutive cycles of extremely fast charging. We have now passed the threshold of 1,000 consecutive cycles of extremely fast charging.

If a vehicle can do 300 miles per charge, we are good for 300,000 miles or 460,000 kilometres which provides the minimum requirement for the warranty of the vehicle.

What cell specifications and form factors are the automakers currently testing?

At present, we are shipping 30Ah pouch cells. The dimensions are 300 mm by 100 mm. Some European OEMs are pushing for prismatic cells, and some Americans are using pouch, but they would like it a little larger. Tesla, for example, is looking at cylindrical. So, we can customise different form factors as we move to our B samples. But for this phase of the A sample testing, we are only shipping the pouch cells.

What materials or tech innovations are helping you achieve safe and fast charging?
  • First and foremost is the replacement of graphite in the anode. We totally replace graphite with Silicon as the only active material. This Silicon is actually nano silicon that enables the ions to be diffused faster.
  • Silicon has the challenge of being amorphic – it’s like a balloon that kind of inflates and deflates when you charge and discharge. So, it was a major challenge to protect Silicon during high-power charging. We control the swelling and shape of these particles with an organic coating and some propriety materials.
  • We also use a new proprietary electrolyte that would react well and move the ions into the active material in an efficient fashion.
  • Additionally, the entire cell design, with thin layers of the anode and the cathode, reduces the resistance and allows for extremely fast charging.
For your 2024 target, what price premium do you expect these cells to command?

In general, the cost is very similar in terms of its structure. The silicon by itself is not expensive. It’s actually the second most abundant element on earth after oxygen. However, we need to process it for nanotechnology, and that adds a few percentage points to the cost to deliver the benefit of extremely fast charging. For 2024, we are targeting roughly USD 80 per kWh, which is comparable with graphite or slightly premium.

What kind of validation have you received from the OEMs to date?

We are in the early phases of the OEM validation process with multiple companies like Daimler, Volvo, Polestar, VinFast and many others. We have received some early positive feedback on our claims. Further validation, such as stress tests in high temperature, low temperature, nail penetration, swelling during storage etc., need long-term testing. This is why we say 2024 until we can actually integrate this solution safely into the vehicles.

Have these stress tests, nail penetration test etc., been performed at your end?

Of course. In order to ship cells by air, you need to undergo UN 38.3. It is a standard of about 30 different safety tests; if you do not pass, you cannot ship the cells. We have already passed these tests. But some of the further tests relate to the battery pack itself and not just the cell. This is where we might have challenges with heat dissipation when you have many of these cells together; the cooling design needs to be aligned with the challenges we see in the pack. And this is the work we need to do together with the OEMs.

Are you going to work on the BMS, thermal management side of the pack as well?

We are a relatively small startup with 120 people. Even though we are global, it’ll be difficult for us to own the pack design or the BMS. We have a team of engineering experts working with the OEMs to provide consulting advice on how to best use our technology. But we don’t take ownership of the BMS or the pack.

You recently said that solid-state batteries are at least a decade away from mass production. Were you talking about your own roadmap, or was it a general statement?

It was both. Tens of billions of dollars of investments are going into battery factories with the traditional coating process. Our roadmap is aligned with our belief that a full solid-state solution has many challenges. Even though one can show developments in the lab, the industry is far from having a cost-effective solution that is commercially viable. In many configurations of solid state, you need to apply high pressure to enable the charging, and there is a very high resistance for fast charging. For us, fast charging is critical, and I believe it’ll become more and more critical for everyone. I think solid-state solutions will not be in vehicles in the coming decade. They will be in other smaller applications, maybe in drones or some buses that can be charged slowly overnight. But the premise of having a production-ready solid-state battery at a reasonable cost by, say 2025 is not realistic.

Can you share your initial plans for production?

We have a joint venture with our investor Eve Energy in China. So, this is where we are currently producing, but we’ve also started production in Korea, and we are ramping up some capabilities in Europe as well. So, we are going to stagger production very carefully.

The A samples are being produced in China, but once we move to the B samples, depending on who it’ll be with, we’ll finalize additional manufacturing locations.

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