Solid state battery hits the market

[Pdf27]

Seems relevant...

Yesterday, I wrote a very brief LinkedIn post about solid state batteries (SSB). I expressed significant doubts that a small, unnamed Finnish startup could develop SSB with such parameters:
400 Wh/kg
Full charge in five minutes
Designed for 100,000 cycles
Lower cost than lithium-ion
etc.

I tried to find more information and discovered that it is probably not SSB, but an 'electrostatic bipolar capacitor', which I believe is "mistakenly" referred to as SSB.
Finnish Carbon Nano acts as a supplier of an "energy storage solution" (I can't put it any other way) for this unnamed Finnish startup. Their online presentation states parameters such as 50,000 cycles and 400 Wh/kg, which closely match the specifications of the so-called SSB from an unnamed company. However, this is not SSB; it is an "electrostatic bipolar capacitor".
This is likely a supercapacitor, which only achieves an energy density of 10-30 Wh/kg, so I am very curious (and many scientists who work on the development of supercaps), how is it possible to achieve the energy density of 400 Wh/kg.

I took a very close look at the profiles of the people behind Carbon Nano, and none of them has experience in SSB development. There is not a single peer-reviewed paper or even one relevant patent from these Finnish companies related to solid state batteries or even battery chemistry!

A statement from an unnamed small Finnish startup amazed the media by claiming they developed an SBB with a cycle life of 100,000 cycles, which damages the reputation of all companies and scientists working on real SSB development. I noticed that a lot of familiar faces, including bloggers, CEOs, and journalists, were led to believe this is about SSB; it is 99% not about SSB.

The main difference between SSB (rechargeable) and supercapacitors lies in their energy storage methods: Solid state batteries rely on reversible chemical reactions (redox) to achieve high energy density by storing energy in chemical bonds, whereas supercapacitors utilize an electrostatic mechanism (electric double layer) for quick charging and discharging, resulting in lower energy density and minimal chemical alteration.

This is the reason I placed a red flag on these Finish startups.

[Pdf27]

No I'm not talking about little planes, I mean 500km+ transport for 100s of PAX.

Yes, I mean ask him! That’s the end goal, he isn’t working on general aviation from what I recall.

Sorry, missed this - haven't been on here much recently because the ICE debate is just getting too depressing.

At the moment state-of-the-art is ~100 miles or so on a certifiable aircraft, and the theoretical limit on Li-ion chemistry is about 2-4x this. It isn't hugely sensitive to aircraft size - if you double the weight of the aircraft you double the energy demand, so if you double the battery size the range stays pretty much the same. The problem is that short hops tend to have limited passenger demand, so justifying large aircraft is hard. That means battery powered aircraft are probably going to be under CS-23 (19 pax maximum) - there are projects to build much larger aircraft, but I haven't seen a credible one yet. This is simply because certifying a CS-25 aircraft is eye-wateringly expensive and can't be justified without a very large market.

If you want to use electricity to power a long-ranged aircraft, the current plan for the industry (out to 2050) is to carry some sort of fuel which reacts with atmospheric oxygen to provide energy. There is an ongoing debate as to what this will be - the US is leaning towards Sustainable Aviation Fuels (SAF), Europe had been leaning towards Hydrogen but has been hedging it's bets more recently. Both fuels can be manufactured from renewable electricity - SAF using green hydrogen to either hydrogenate agricultural waste or combine with direct air captured CO2 to form a liquid fuel.

What we are seeing - and is a large part of my day job - is hybridising thermal engines to reduce fuel burn by sharing power between fuel and battery. The level of hybridisation varies, mostly by aircraft range, and with smaller aircraft what we're seeing is the use of what are essentially giant APUs which act as range-extenders on a pure battery mission when you have to divert or to stretch battery life for longer flights, directly cutting fuel burn.

[Craiglxviii]

No I'm not talking about little planes, I mean 500km+ transport for 100s of PAX.

Yes, I mean ask him! That’s the end goal, he isn’t working on general aviation from what I recall.

Sorry, missed this - haven't been on here much recently because the ICE debate is just getting too depressing.

At the moment state-of-the-art is ~100 miles or so on a certifiable aircraft, and the theoretical limit on Li-ion chemistry is about 2-4x this. It isn't hugely sensitive to aircraft size - if you double the weight of the aircraft you double the energy demand, so if you double the battery size the range stays pretty much the same. The problem is that short hops tend to have limited passenger demand, so justifying large aircraft is hard. That means battery powered aircraft are probably going to be under CS-23 (19 pax maximum) - there are projects to build much larger aircraft, but I haven't seen a credible one yet. This is simply because certifying a CS-25 aircraft is eye-wateringly expensive and can't be justified without a very large market.

If you want to use electricity to power a long-ranged aircraft, the current plan for the industry (out to 2050) is to carry some sort of fuel which reacts with atmospheric oxygen to provide energy. There is an ongoing debate as to what this will be - the US is leaning towards Sustainable Aviation Fuels (SAF), Europe had been leaning towards Hydrogen but has been hedging it's bets more recently. Both fuels can be manufactured from renewable electricity - SAF using green hydrogen to either hydrogenate agricultural waste or combine with direct air captured CO2 to form a liquid fuel.

What we are seeing - and is a large part of my day job - is hybridising thermal engines to reduce fuel burn by sharing power between fuel and battery. The level of hybridisation varies, mostly by aircraft range, and with smaller aircraft what we're seeing is the use of what are essentially giant APUs which act as range-extenders on a pure battery mission when you have to divert or to stretch battery life for longer flights, directly cutting fuel burn.

Thanks Paul. So we’re talking essentially REEV aircraft with IFEP architecture?

[Pdf27]

More suggesting it's actually a supercapacitor:

Here is everything we currently know about the Donut Lab solid state battery!

The claims for their cells include:

~100,000 charge cycles
Potentially ~50 million miles of use (!?!)
400 Wh/kg
5 minute charge time (~12C)

Here is what I saw at CES:

Displayed cells and modules were 3D-printed mockups, not live cells
The team would not discuss chemistry or manufacturing, increasing scepticism
Strong industry interest (~600 enquiries on day one)

Here are some key technical clues.

Battery:

Can be made in any shape (even structural components)
Claims no lithium (at all)
Voltage can be tuned to match existing systems
Supports very high current with constant current charging
Manufacturing appears to be stacked / pressed, not traditional jelly-roll cells.

Production claims:

1 GWh this year, 10 GWh next year
Comparable to a full EV gigafactory (bold claim!)
Available test data showed unusual charging voltage
Lifespan claims align more with capacitors than electrochemical cells.
Evidence points toward a capacitor-like system, not a conventional battery.

Finland connection:

Manufacturing planned in Finland.
Donut Labs has ties to Nordic Nano, a Finnish company working on printed, shape-agnostic solid-state energy storage.
Claimed 400 Wh/kg and 50,000+ cycles
Technology described as electrostatic bipolar capacitors

My current take:

This may not be a “battery”, but a super (ultra?) capacitor.
Some claims seem plausible, others feel extremely optimistic.
Extraordinary claims need extraordinary proof.

I hope it works out, but it needs some serious backing up with third party tests.

(Full youtube video available here: https://lnkd.in/eGjX3sMD)

[Pdf27]

Thanks Paul. So we’re talking essentially REEV aircraft with IFEP architecture?

Varies by range:

• Short hops - up to 1h / 100 miles - battery only (BEV).
• Longer hops - up to 3h/250 miles (diversion requirements are very restrictive hence the mismatch between endurance and range, and smaller aircraft don't want to sacrifice a seat to fit a toilet) - battery with range extender (REEV).
• Most applications - above 250 miles or so - thermal engine with battery boost (PHEV).

[Craiglxviii]

More suggesting it's actually a supercapacitor:

Here is everything we currently know about the Donut Lab solid state battery!

The claims for their cells include:

~100,000 charge cycles
Potentially ~50 million miles of use (!?!)
400 Wh/kg
5 minute charge time (~12C)

Here is what I saw at CES:

Displayed cells and modules were 3D-printed mockups, not live cells
The team would not discuss chemistry or manufacturing, increasing scepticism
Strong industry interest (~600 enquiries on day one)

Here are some key technical clues.

Battery:

Can be made in any shape (even structural components)
Claims no lithium (at all)
Voltage can be tuned to match existing systems
Supports very high current with constant current charging
Manufacturing appears to be stacked / pressed, not traditional jelly-roll cells.

Production claims:

1 GWh this year, 10 GWh next year
Comparable to a full EV gigafactory (bold claim!)
Available test data showed unusual charging voltage
Lifespan claims align more with capacitors than electrochemical cells.
Evidence points toward a capacitor-like system, not a conventional battery.

Finland connection:

Manufacturing planned in Finland.
Donut Labs has ties to Nordic Nano, a Finnish company working on printed, shape-agnostic solid-state energy storage.
Claimed 400 Wh/kg and 50,000+ cycles
Technology described as electrostatic bipolar capacitors

My current take:

This may not be a “battery”, but a super (ultra?) capacitor.
Some claims seem plausible, others feel extremely optimistic.
Extraordinary claims need extraordinary proof.

I hope it works out, but it needs some serious backing up with third party tests.

(Full youtube video available here: https://lnkd.in/eGjX3sMD)

Be interesting if so, my understanding is that weight doesn’t scale well at all for supercaps.

We looked at these in Nissan Advanced Technologies, the idea was to fit each door latch with a small supercap to give the door latch unlocking power in the event of a crash severing power lines.

We went from that to, well could we not distribute supercaps around the car to remove the starter battery… then quickly found the answer was, “No, no you can’t”.

[Pdf27]

Be interesting if so, my understanding is that weight doesn’t scale well at all for supercaps.

Correct, in the same way that the number of charges without loss in capacity and power density don't scale well with batteries.

There's two options here:

1. Everything is as reported and this small start-up get Nobel Prizes all around.
2. Values are not as reported / claimed and it's all vapourware.

[Micael]

Auto-translated from Finnish:

Donut Lab has had the Donut Battery's features measured by one of Europe's leading research organizations - will publish a series of measurement reports in the coming weeks
20.2.2026 09:00:00 EET | Donut Lab | Press release

Ice







Donut Lab has commissioned the internationally renowned VTT Technical Research Centre of Finland to measure the properties of the company's announced world's first mass-produced solid-state battery under independent research conditions. The results of the measurements will be published in a series on Donut Lab's channels, with the first part being published on Monday, February 23 at 3 p.m.

The measurements carried out by VTT focus on the technical characteristics and performance of the Donut Battery.
The measurements carried out by VTT focus on the technical characteristics and performance of the Donut Battery. Photo: Donut Lab
Technology company Donut Lablaunched in early JanuaryAt CESthe world's first 100% all -solid-state battery , immediately available for mass-produced vehicles. The battery's exceptional properties have sparked a huge debate among industry experts around the world.

Donut Lab wants to provide more information about the features it promises through research, which is why the company has provided a batteryFor VTT, the Finnish Research Centre for TechnologyVTT, owned by the Finnish state, is one of Europe's leading research organizations.

“The Donut Battery has attracted enormous interest from both the media and industry experts since our launch. Such an extraordinary innovation has naturally aroused not only excitement but also a lot of speculation and doubt – how is this possible? It really is possible, and now we want to reveal the technical features through more detailed measurements,” says Marko Lehtimäki, CEO of Donut Lab .

Donut Lab will publish a video series about the research results on its own social media channels andOn the I Donut Believe websiteThe company will also publish the full measurement reports on its website. The first part of the video series will be published on Monday, February 23 at 3:00 p.m.

“Donut Lab’s battery technology is unprecedented, and its introduction to the market has sparked much discussion and shaken up the global automotive industry, as larger players in the industry have been trying to develop a similar solution for years. For our part, we will continue the discussion with a video series starting next week, where we will delve into the battery’s technical features and performance,” says Ville Piippo , CTO of Donut Lab .

Compared to traditional lithium-ion batteries, solid-state batteries are significantly safer and more efficient. Solid-state battery technology has been touted as the next big leap in electric mobility for years. The Donut Battery enables longer range, lighter structures, and unprecedented flexibility in vehicle and product design. The environmentally friendly and safe Donut Battery does not contain flammable liquids and is not prone to heat escape in extreme conditions.

[Micael]

Donut Lab Brings the Receipts: Finland’s VTT Lab Verifies Donut Lab’s 0–80% Solid-State Charge in 4.5 Minutes.

Last week, I shared how Donut Lab was facing heavy skepticism over their claims of a production-ready solid-state battery. Today, things are starting to get much clearer, which makes believing in this a bit easier. The VTT Technical Research Centre of Finland, a government-owned lab, just released independent test results. For those of us living with EVs, the data is worth a close look.

Here is what the lab actually proved regarding charging performance and why it matters:

•The 5C Test (Under 10 Minutes): To put this in perspective, a typical EV today takes about 30 to 60 minutes to charge from 10% to 80% at a fast charger. In the first phase of testing, the lab pushed the cell at a 5C rate. Even with very basic cooling, the battery reached 80% state of charge in less than 10 minutes. When they removed the cooling to let it run hotter, it finished the full 0–100% charge even faster, in just over 12 minutes.

•The 11C Test (The 4.5-Minute Mark): This is the extreme speed test. An 11C rate is roughly 11 times faster than the battery's standard hourly capacity. The cell hit a 0–80% state of charge in exactly 4.5 minutes. This is about five times faster than the best fast-charging performance we see on the road today.

•The Thermal Advantage: In most batteries, heat is the enemy. It forces the car to slow down the charging speed to protect the cells. With the Donut Lab cell, the opposite happened. As the temperature climbed to 89°C during the 11C test, the battery’s internal resistance actually dropped. This allowed it to maintain that extreme charging speed for longer without having to "throttle" or slow down.

If this tech scales to a full battery pack, it turns a charging stop back into a refueling stop. It is fast enough that by the time you walk inside to use the restroom, your car is already ready to go.

Independent verification from a state lab is a massive hurdle to clear. If this is a scam, they deserve an Oscar for the level of detail. If it is true, they deserve a Nobel Prize.

What is your take?

The official report:
https://pub-fee113bb711e441db5c353d2d31 ... 092_26.pdf

[gtg947h]

Hmm, interesting.

I wonder, though, how many times you can do that before bad things happen (i.e. what impact does fast charging have on battery life)?

What does the degradation curve look like for SoC vs time and temperature, and depth of discharge vs cycles? I'd like to see test data on this, not just claims.

How prone is this design to thermal runaway and other spectacular failure modes?

And I know it's early, but how easy is it to make compared to cell-based construction (e.g. Tesla packs)?

[Pdf27]

IMG_2606.jpeg

IMG_2605.jpeg

[Micael]

More test results are said to be coming, this is the first in a series. They’ve got a countdown to the next one to be released going here: https://idonutbelieve.com/
(A bit theatrical I admit but I understand the desire to hype it up as much as they can.)

[kdahm]

What about heat generation during charge and discharge? How does it react when put into big packs? At 90% efficiency, that's 30-40 Wh/L that needs to be removed, or enough to cause a Rapid Unscheduled Incendiary Situation if it's in a vehicle and the cooling system doesn't work. For that matter, can a normal cooling system even work under that heat rate?

[gtg947h]

What about heat generation during charge and discharge? How does it react when put into big packs? At 90% efficiency, that's 30-40 Wh/L that needs to be removed, or enough to cause a Rapid Unscheduled Incendiary Situation if it's in a vehicle and the cooling system doesn't work. For that matter, can a normal cooling system even work under that heat rate?

From: https://electrek.co/2026/02/23/donut-la ... -charging/

The charging speed results are legitimately impressive.

At 11C with two heat sinks, the cell reached 80% state of charge in 4.5 minutes, with the surface temperature climbing from 26.5°C to a peak of 63°C. At 5C with a single heat sink, the cell charged fully with temperatures rising from 27°C to 61.5°C. At 5C with two heat sinks, the peak temperature was only 47°C from a starting point of 23.4°C.

But here’s where it gets interesting. During the 11C test with only a single heat sink, the configuration closest to minimal thermal management, the cell’s surface temperature hit the 90°C safety cutoff, forcing VTT to interrupt the test. After a four-minute cooling period, the cell was strapped more tightly to the heat sink to improve thermal contact, and the test was restarted.

That 90°C incident matters. Donut Lab has marketed this battery as needing no active cooling, but at 11C charge rates, even passive thermal management with a single heat sink proved insufficient. In a real vehicle, consistent 11C charging will require some thermal engineering, not a deal-breaker, but a gap between the marketing and the measured reality.

[kdahm]

Ouch. That's pretty bad, especially for a 14mm thick cell. Now let's think about getting rid of that sort of heat in a 900mmx700mmx200mm battery package, even with internal liquid cooling passages. Then there's getting rid of all of that heat in the liquid before recirculating it.

Something tells me that's going to be downplayed in the releases and journal articles. Not insoluble, but a pretty major problem.

[Paul Nuttall]

Quite a long article

https://cleantechnica.com/2026/02/23/do ... o-critics/

There has been a frenzy of response to Donut Labs’ announcement of the world’s first solid-state battery. Donut Labs produced a response video to critics. The video says everyone jumped the gun, and independent testing is coming. It drops hints all over the place. It tells their strategy and why they elected to reveal information the way they did. In my opinion, it is completely consistent with a small company attempting to survive in a world of larger players. I don’t believe they are lying. I am sorry. This is all I have to offer those only interested in an executive summary. Others, read on. There might be something useful or entertaining beyond the headline. Some may even enjoy the writing. I do have a private reputation as a muckraker and a writer. I think that may no longer be a secret. Yes, I do more than technical writing. And, yes, I have a ton of skeptics throwing spaghetti at me. No matter. I’m used to it. It comes with the territory.

The Story

When Donut Labs announced the world’s first production solid-state battery, I knew what would happen. The response came slowly at first, then grew like a breaking wave.

One could hardly expect the world’s largest companies researching solid-state batteries for years without result to stay silent while an upstart stole their thunder and limelight. You could see the panicked response as they struggled to explain why, out of the blue, an unknown threatened to grab the crown and brass ring before they did. Experts now had to explain to the click-hungry social media crowd and to their own corporate bosses and investors how they lost the race to an upstart, and why it took them so long and yet they still have not accomplished what this company claims. It causes severe changes in plans, and apologies to Tom, whose expertise and expressions I admire, but it does not mean companies will change plans — because they have NIH, the “not invented here” principle. That is, companies will not necessarily all flock to get Donut Labs tech. Some of them will stubbornly refuse any outside tech in favor of their own despite pressure. Others will attempt to steal it, and more on that later.

I spent my entire career in the tech industry observing the interplay between technology companies, news organizations, and startups in Silicon Valley. None of this kind of claim, counterclaim, and inter-company rivalry is new to me. On the contrary, it is to be expected in industries in which the stakes are in billions and the advancements come rapidly, year by year, and month by month. I wrote recently about the social media storm regarding recent sodium-ion advancements, and the stark difference between projections of sodium-ion production timelines and CATL’s announcement of the Naxtra battery. One must tread carefully when making statements about what cannot be done. Exaggerations come in both directions.

When I heard reports that major companies expressed skepticism, I was not surprised. Years ago, I wrote a story about the Tesla Semi, titled “Does Tesla Semi Break the Laws of Physics?” I proved that it was technically possible based on known empirical data and readily available information to conclude that it was possible to make an electric truck with the specifications and performance claimed. The story title was based on a response from a large, well established company that expressed skepticism. I could not verify cost claims, only performance. That kind of math and research is normal for senior design engineers. The makers of the Semi might not choose to make the vehicle that way, but they could, and I could only assert that it was possible, not predict what tradeoffs they might make. It is possible to predict what is technically possible, not what human events and behavior will follow. When the vehicle was built, and the test results agreed with my calculations, it was no surprise to me. Technology is not magic to me. I know how the sausage is made.

As an experienced design engineer, my career has been spent attempting to justify my designs in design reviews, and have them sent into production in a venture of great cost and investment risk. No one took my sole word for it. I had to prove it with months of simulations, data, and screening. It took a huge amount of effort by me and others to give birth to those products in the real world. It is with this background that I viewed the endless torrent of social media opinion and speculation following Donut Labs’ announcement.

As a design engineer, I know there are two general responses to claims of novel product performance. One is opinion, and the other is based on ideas and facts. The latter is the first order of business for me. It has been my professional practice to sort that out. I am familiar with doing necessary diligence to prove a design production worthy, but as a design engineer, I know the only way to silence critics is to produce a successful product. I have agonized over the prospect of failure versus success many, many times. After years of experience, I learned how to deal with it and became comfortable with it, comfortable enough to trust myself and realize I could make mistakes, but I would be a fool if I did not trust myself instead of a horde of critics. Select your critics wisely.
What Donut Labs Device Isn’t

Right off, some of the responses to Donut Labs were speculative opinion and false. Donut Labs storage technology is not a supercapacitor. This one is easy. Capacitors work on physics that depends on a simple equation.

E=½CV²

where E is energy, C is capacitance, and V is voltage.

Donut Labs declared an operating range of 2.5 to 4 volts. Capacitive storage relies on voltage squared for greatest energy. Capacitor voltage storage does not use small voltage swings. It uses the most voltage it can endure to optimize energy. Normally, that voltage is in hundreds of volts, limited by the dielectric strength of the insulator material between the plates of the capacitor. This idea is a non starter if Donut Labs is making a drop-in replacement for the lithium batteries it previously had in the Verge motorcycle. That is too much evidence pointing toward the idea of a capacitor being a nonstarter. You can forget that.

The fact that this idea has circulated and has legs in social media circles is testament to the fact that news organizations of the past with large professional screening staffs are now officially a thing of the past, replaced by a social media fray hungry for clicks and not overly concerned with journalistic reputation. No doubt, the idea will persist long after this article debunks it and the product becomes an every day reality, but you cannot completely stop rumors with fact. My advice to journalists without technical backgrounds in this matter is, don’t take sides. If you are not an expert in something, do something else. Do journalism. Report what you find, hopefully in a balanced way. Taking sides and changing your mind back and forth is bad form. Don’t lay shade on CleanTechnica either. I might not like it. It might be a game changer. Game changer and holy grail are two phrases that may soon be banned by English teachers. Don’t mess with them.
We Couldn’t Do It, So Neither Could You

It should come as no surprise that self-interest dictates that companies that could not succeed at solid-state technology might respond by saying it is impossible. Sure enough, they did. I don’t want to further embarrass them, but a response sans proof is just another unsubstantiated claim. It is not just bad form to do it that way, it is a bad idea. Making uninformed claims without full knowledge is apt to end with egg on the face. The fact that one party could not do it is not proof that another party could not. It is only proof that the measures they took failed. Without knowledge of exactly what Donut Labs did to achieve true solid-state batteries and other performance claims, it is not possible to come to any conclusion based on particular measures. When and if full disclosure and reveal of Donut Labs is available, then we can fully test and determine. Without that, the only path forward is using generally based known physical laws and information. Since all parties are attempting to create designs that must be based on physical principles, and we are entering the territory of new knowledge and advancement, this is a matter of learning, not just measurement or speculation.

What Do We Know?

We know few things we can firmly base conclusions on. Unfortunately, there are very few things we do have. We’ve only had the announcement and statements of the company, pictures, and video as clues to the story. Now we have the response video from Donut Labs. The statements of the company combined with those leave a trail of bread crumbs that lead to the most likely results. We can test the self-consistency of the claims and likelihood of possibilities, and guesstimates.

The Claims

The videos reveal much information. It is not a lithium battery. It does cost about the same as lithium batteries or lower. It works on a voltage range compatible with lithium, from 2.5V to about 4V. It is planned as a drop-in replacement for a lithium battery, although exact details are not available. The stated voltage range is greater than lithium (about 3V to 4V). It works up to 100°C and down to -40°C. In videos, they have said, that is as far as they have extended testing. That means it could be more. It has double the energy density (400 Wh/kg) of the best LFP and about 50% more than average NMC. If it fits into a space replacing the prior lithium packs and the range is doubled, it has something like double the volumetric energy density as well. How could this be?

For starters, there are batteries that have high energy density at that level and beyond today. CATL’s condensed batteries are capable of 500 Wh/kg. The recently announced semi-solid state batteries in FAW EVs are claimed capable of more than that as well. These both have some measure of planned production. There is more than just a possibility batteries can achieve those specifications.

There is a small video showing high-speed charging in five minutes. Some of the Donut Labs people are using Verge motorcycles with the advanced battery. Can a battery do 12C charging? Oh, yes, certainly. A123 Labs was doing 25C years ago. Bill Dube and Eva Hakkonen used them years ago on the Killacyle to set electric drag race records. I met Bill and Eva. Nice people. Battery people wear non-conductive, non-metallic rings. LFP batteries are capable of excessive peak currents, like 60C for short periods of time. In the videos, Donut Labs says they do the 5 minute, 12C charging, but that is only if they are thermally managed with liquid cooling. For the Verge motorcycle which is air cooled, they do 5C. This is consistent information.

The battery is claimed to have a cycle life of 100,000. I have to say, I don’t care. If it were a measly 25,000, it would be good enough. Seriously. How does anyone know a lifetime of 100,000 cycles? Present day battery testing does elevated temperature and limited laboratory cycles to project lifetime. Higher temperature increases aging, allowing accelerated testing. Accurate coulombic testing has been pioneered for some time by Jeff Dahn and others. It works. It means the total charge is measured accurately to determine how much charge is lost over cycling. Let’s not waste time over whether it is 25,000 or 100,000 cycles. Some people even thought 25,000 is the highest previously. It isn’t. Recently defunct Natron Energy claimed 50,000 cycles. Why is that? In concession to the TLDR crowd, it comes down to how stable the materials are. This education comes courtesy of Shirley Meng, foremost battery educator and researcher. If so inclined, you owe it to yourself to absorb her teachings.

The miracle of modern intercalating batteries is that they shuttle ions, ionized atoms, or molecules (big bowling balls), not electrons (little peas), back and forth from cathode to anode. The anode and cathode must retain intact structures for the life of the battery. The structure of the cathode makes tunnels like bowling ball receivers at the bowling alley that allow ions to park themselves in a regular, crystal-like structure, in rows. As the ions pass through the anode and cathode, they may expand the structure or undergo other transformations that modify them and reduce their capability. If those structures are stable, the battery life can be quite long. This is the story with lithium titanate, which has been known for many, many years. The idea that batteries can have very high cycle life is not new, only the particular claim. For my part, this is nearly irrelevant, because if they only had cycle life of 50,000, it would hardly be a disaster. How do they know? They probably tested it in the ways everyone tests batteries. Did they test correctly? I don’t know. We will find out when independent testing is done. Is it likely to be high cycle life? Yes. Will it matter. Not much.

What about high temperatures? 100C is pretty high. That is the temperature of boiling water. It doesn’t just survive that temperature, it works at that temperature. It better not have a paper label on it. We do know that sodium-ion batteries can endure several hundred degrees C without becoming a conflagration. Other sodium-ion batteries work up to 70C.

In reality, the claims are not that far beyond the realm of possibility and beyond what people familiar with batteries are aware of. Their performance is a shock to lay people unfamiliar with tech, and researchers and companies trying to achieve those levels who are unable to succeed. The battery performance is not entirely beyond the realm of possibility compared to known batteries, but we do not have the data, and we do not know how rigorously it was tested and measured. It is very common for product specifications to be tightened for yield. It would not strike me as unusual if the final production cells had tighter specs. The Wh/kg will still be near that level, but the temperature range and cycle life may be less for production. 400 Wh/kg is for pouches, 350 Wh/kg is for prismatic. I don’t expect those numbers to change that much.

We know a few other details that are interesting. There is some production. It is assembled by machines, not by hand. One of their products is a powered trailer used to lower truck fuel consumption. They created a battery storage trailer to charge the other trailers, because no adequate charging infrastructure was available to charge their trailer product demos. The storage needed to do that is sizable, in the 10 MWh realm. This is consistent with at least some factory production. The claim of one GWh production is about the size of a good pilot line. Finland has a reasonable level of battery infrastructure.
What About Solid State?

This is the biggest mystery in all of it. CATL, BYD, Toyota, and others have struggled without success for many years. In the wake of the Donut Labs announcement, predictably, the others have responded with plans in the near future or limited production, anything that feeds the limitless hunger of the social media piranha frenzy. It is important to understand why solid state is so difficult. I mentioned the regular, cage-like crystal structure of the cathode and how expansion and contraction could damage it. Solid state has one more problem. It is solids, not liquids. That cathode and the anode both have a bumpy surface. Any solid electrolyte is composed of solids. A liquid can fill the pores, gaps, and bumps. Up until now, efforts have been made to force the solids into contact with high pressure. This has not been a production-worthy, low-cost approach. There are low quantities available from Quantumscape for example. Whatever anyone does, it has to solve the problem mating an uneven solid surface to a solid. Some of the attempts have failed because solid structures that expand and contract can crack. The result has been short cycle life.
What Could It Be?

There is a video that guesses what it might be and does find some useful information about the company. I give Miss GoElectric credit for digging up facts. The speculative part is interesting for detectives and might be entertaining, but probably has some mistakes in it. There are some patents and there was a deal with another company, Nordic Nano. What could fit from the clues? Let me be direct. The voltage range from 2.5V to 4V is a dead ringer for a sodium-ion battery. We know from Naxtra that a sodium-ion battery can have a self-formed, or anodeless, construction. That improves performance. We know if we pay attention to Shirley Meng, a researcher’s goal is to do both a self-forming anode and solid state. We also know from her teachings that if this is done, 400 Wh/kg values are expected. We also know that sodium-ion tech has extended temperature range operation, in liquid electrolyte, and that solid state will improve that. We know that sodium-ion tech has impressive safety, and high temperatures will not cause it to explode or burn rapidly. So, is there anything really that unbelievable about it being a solid-state, sodium-ion battery? No, not really. It is not the sodium part of it, or the performance that is so unusual. The only part we have not seen any particular knowledge of is solid state. So that is what we need to talk about. Any tech can be solid state. It can be sodium, lithium, or others. Solid state is only about the electrolyte. If it has a self-forming anode, the anode is not the issue. The cathode is. Then we need to know what type of cathode. We already know TAQ is a kind of cathode that is more than capable of 400 Wh/kg, for one. That does not mean this is what they used, but it does lend credibility to the possibility of such performance. How they get the solids in contact is the key mystery. There is no way they are going to reveal it. Every major company in the world wants to know, and some of them probably have detectives in the field trying to discover it.

That is all we really know. The speculation about Donut Labs’ solid-state battery being a scam is overdone. Let’s wait until more is revealed. Don’t call it a scam until the independent testing is done. There is too much evidence that they are not lying. If it was a scam artist, promising product and giving timelines would be the worst way to do it. Giving too many details would be a poor choice. Leave scams for the experts like Elizabeth Holmes and Trevor Milton. The last thing they would want to do is give a date for independent testing.

[Paul Nuttall]

https://cleantechnica.com/2026/02/23/do ... v-battery/

The Finnish technology startup Donut Lab launched a new solid-state EV battery at the Consumer Electronics Show in January, billing it as “the world’s first solid-state battery that is ready for use in OEM vehicle manufacturing.” With a full charge in five minutes and 400 Wh/kg of energy density, it seemed too good to be true. However, for any skeptics out there, Donut Lab is posting a new video series along with supporting material that explains the results of an independent assessment at the VTT Technical Research Centre of Finland.

Find the videos beginning on Monday, February 23rd at 2 pm CET at I Donut Believe. Donut Lab plans to publish the VTT reports there as well. Also check out a deep dive into the details by CleanTechnica’s Christopher Arcus here.

Solid-State EV Batteries Are Coming For Your Gasmobiles

Regardless of the recent squishiness in the US market, the vehicle electrification trend continues apace globally, and solid-state batteries are among the innovations that will help accelerate uptake. In contrast to conventional lithium-ion EV batteries with liquid electrolytes, the solid-state formula offers faster charging, longer range, enhanced safety, and more freedom from environmental and ethical complications in the automotive supply chain.

Donut Lab has already enlisted the European electric motorcycle maker Verge Motorcycles to showcase the new battery in its Verge TS Pro and Ultra two-wheelers. With the release of the VTT assessment, Donut Lab aims to prove that Verge is just the beginning.

“Unlike conventional lithium-ion batteries, the Donut Battery experiences minimal capacity fade over its lifetime, with a design life of up to 100,000 cycles, offering practical longevity that far exceeds existing technologies,” Donut Lab explained at the CES launch, while noting that the new battery avoids the fires attributed to dendrites, which are the fernlike growths that can emerge in liquid electrolytes.

“Performance has been rigorously tested across extreme conditions,” Donut Lab continues. “At –30°C, the battery retains over 99% of its capacity, and when heated to temperatures exceeding 100°C, it continues to retain over 99% capacity with no signs of ignition or degradation.”

“The Donut Lab solid-state battery is made entirely from abundant, affordable, and geopolitically safe materials, does not rely on rare or sensitive elements, and demonstrates a lower cost than lithium-ion,” they add for good measure.

Verge Motorcycles & The Solid-State EV Battery Of The Future

Verge has a footprint here in the US, so keep an eye out for the TS Pro and Ultra sporting the new battery. In a press release dated January 5, Verge said that it expects to begin deliveries to customers within the next few months.

“The company has become the first in the world to introduce solid-state battery technology into production motorcycles — marking a significant milestone not only for two-wheeled transport, but for electric vehicles more broadly,” Verge says of itself, noting that the new solid-state battery provides almost double the range per charge, while also charging much faster.

In a press statement, Verge CEO Tuomo Lehtimäki further teased the idea that two-wheelers are just the tip of the EV iceberg. “The use of solid-state battery technology to motorcycles in production is a historic breakthrough shaking up the entire automotive industry,” Lehtimäki said.

“Current battery technologies typically support only thousands of charging cycles, whereas Verge’s solid-state battery lasts for the entire lifetime of the motorcycle,” Verge also points out. “The upgraded battery pack does not affect the motorcycle’s price, making it a highly cost-effective option for customers as well.”

As described by Verge, the standard battery pack offers 217 miles of range, with ultra-fast charging enabling 186 miles in ten minutes. With an optional range-extended battery pack, riders get up to 370 miles on a single charge.

Donut Lab’s advanced motors have also surfaced on the CleanTechnica radar, and they make an appearance in the TS Pro, too. “Its next generation Donut 2.0 motor is 50% lighter than its predecessor while delivering the same power and torque (737 lb-ft), enabling significantly improved efficiency, stability, and handling,” Verge explains.
EVs Just Keep Getting Better

Whether or not Donut Lab can make the leap into four-wheeled electric vehicles remains to be seen. However, the company has already given itself a headstart with its “Donut Platform,” described as a “fully integrated EV hardware and software stack.”

“It includes our motors, battery modules, the “Brains” (our onboard control unit), and vehicle software — designed to work seamlessly together,” Lehtimäki told CleanTechnica in an interview last September.

“It supports a wide range of vehicles and enables faster, more flexible EV development,” Lehtimäki added, taking note of the platform’s modular design and emphasis on simplicity.

Lehtimäki also elaborated on the company’s in-wheel Donut Motor. “By eliminating gearboxes, driveshafts, and differentials, it reduces unsprung weight and simplifies vehicle design,” he explained.

“With a larger diameter and minimal active materials, we’re able to achieve higher torque and power density — essentially, more power and torque per kilogram — than conventional motors,” he added.

As for the future of the vehicle electrification movement here in the US, that’s still an open question. However, millions of EVs are already on the road, and a new survey from JD Power shows that the vast majority of EV drivers will consider buying or leasing another EV. That suggests consumer choice will continue to sustain EV sales over the rough patch of the Trump years.

JD Power has been asking EV drivers if they will consider getting another EV since 2021. In the latest survey, published on February 18, 96% of EV owners said yes — a new record high for that question.

While noting that EV market share dipped after the premature demise of the $7,500 federal tax credit last September, JD Power’s executive director of EVs, Brent Gruber, underscored the “steadily growing customer satisfaction among owners of new EVs.”

“Improvements in battery technology, charging infrastructure and overall vehicle performance have driven customer satisfaction to its highest level ever,” Gruber stated.

“What’s more, the vast majority of current EV owners say they will consider purchasing another EV for their next vehicle, regardless of whether they benefited from the now-expired federal tax credit,” he emphasized.

Although US automakers sharply rolled back their near-term EV plans after the federal tax credit ended, Slate Auto and several other newcomers are still moving forward with their production plans, and Ford recently affirmed its plans for producing a next-generation affordable electric pickup truck.

[Paul Nuttall]

More news

https://cleantechnica.com/2026/03/05/do ... 0-celsius/

Speculation that the Donut Lab battery is not real are diminishing as independent lab data shows 100° Celsius performance. Speculation that the battery may be lithium run into difficulty explaining how a battery can work at 100° Celsius. In the independent tests, the thin membrane surrounding the pouch breached. If the contents were a standard lithium-ion with liquid electrolyte, there would have been significant outgassing and the organic electrolyte would have caught fire.
The Battery Is Real

Attention is now focused on what it could be, and the speculation continues. Once again, there are so many different stories, and the quality of analysis on social media has a wide range. It is time to admit the truth. Donut Lab is not lying. It is not a liquid electrolyte. It is solid state. It is time to listen to what Donut Lab says.

More can be learned from Donut Lab than by speculation. As I said before, we can make inferences based on what we know is fact. We cannot make inferences based on what we do not know or have never experienced before. The Donut Lab high-temperature battery tests place us in new territory, where no other intercalated battery has been before. That is one reason for resistance and disbelief. The reaction from other battery competitors has quieted and has turned from “if we can’t do it, you cannot either” to “if we cannot do it, how on Earth did they do it?” The latter is less audible as well.

The time for speculation is over. It does work at 100° Celsius. It does charge at 11C. Donut Lab battery performance is extraordinary. There is more to be gained by listening to what Donut Lab says than by speculation. Donut Lab is telling the truth. Yes, the claims are not full engineering specifications including all conditions and limits. Claims like this are normal for this stage of development. In the tests, Donut Lab’s battery performed well at 100°C and retained full function when returned to room temperatures. There are more questions. There are more weeks of independent testing to come, results revealed once a week. Patience is the order of the day. Now a few myths must be laid to rest.
It Is Not A Production Lithium-Ion Battery

It does not contain a liquid organic electrolyte.

How do we know the battery does not contain liquid organic electrolyte? During tests, the thin pouch enclosure was breached. Donut Lab stated it is a solid electrolyte, and any NMC battery in production today (using a liquid organic electrolyte) exposed to 100° temperatures that breached its package would have caught fire. We know that Donut Lab did its own tests and sent its batteries to independent labs before this round of testing. The CTO is not gambling.

Does it have to be a lithium battery? Not really. Battery cell maximum voltage can be altered by doping, adding a small amount of another substance to a chemistry.

“Doping is a potent and often used strategy to modify properties of active electrode materials in advanced electrochemical batteries. There are several factors by which doping changes properties critically affecting battery performance, most notably the voltage.”

The maximum voltage can be raised and charge curves changed. It is possible that different chemistry charge curves could look alike and yet follow electrochemistry rules. The fact that similar chemistry charge curve voltage is unusual is not proof it cannot happen. Donut Lab is telling the truth. It does not contain a liquid electrolyte and it is not a production NMC lithium-ion battery. I think it is time to stop doubting and start listening.
The Sunwoda NMC Battery Is Not A Counterargument

There is an argument made that the Sunwoda battery proves that an NMC battery could survive 11C testing. It could at low temperatures, but not at 90C and not with a ruptured pouch. Further, the Sunwoda battery attains 11C by sacrificing energy density. The energy density is only 102 Wh/kg. It shaves the cathode and anode down to the thinnest possible width to reduce the distance ions need to travel. This increases ion flow and reduces internal resistance, resulting in faster charge. It does not meet the criteria of a contradiction to Donut Lab’s claims. It is an outlier and not representative of most standard NMC batteries. None of this changes the fact that no NMC or other production lithium battery could duplicate the tested performance of Donut Lab’s battery. There are no intercalating lithium batteries that duplicate the performance over the range of temperature used, from -30°C to 100°C.
What Did Donut Lab Say? It Is Not Lithium

We do not have to search far for that. Marko answered to an interviewer.

Interviewer: Operating in whatever temperature…

Marko: and also the environmental and supply chain concerns that people always had for electric vehicles…

Interviewer: lithium, cobalt… whatever…

Marko: All of that is gone.

And we know more from CTO Ville Piipo who also says this is “non-lithium” at about 26:26.

He also says: “We’ve been doing like third party analysis or validations in recent years, but that is more for our own sanity checks…”

Knowing that Donut Lab already measured the batteries and had prior third party testing, there is little risk in further independent tests made public. They already know what the results will be. It is only us, the viewers, that have any suspense in awaiting the outcome. That leaves viewers scratching their heads, guessing what the battery is.
Why Is Solid State So Difficult?

In a nutshell, the problem with solid-state batteries has been keeping solid materials in contact despite expansion and contraction. The cathode, anode, and electrolyte are all solids. They are powders composed of small grains. Contact between them is limited, unlike with a liquid electrolyte. There can be voids at the boundaries. Up until now, solid-state batteries have required very high pressures to maintain good contact and conductivity.

Donut Lab’s battery does not require heavy pressure to maintain performance. What are possible solutions? An electrolyte can begin as a liquid and get pressed to fill voids, and then be secured in place by becoming a solid, or semi solid like a soft glue or polymer. When that sets, a solid is in place that meets the requirements. For now, the solid electrolyte is unknown.
What Else Do We Know?

Another battery type that matches some of the characteristics of Donut Lab’s solid-state battery is sodium-ion. Low- and high-temperature performance looks similar. But at high temperatures, Donut Lab’s battery goes even further. The safety of both is high. The cost of both is low. Both are made of commonly available materials. Neither contains lithium. Sodium-ion batteries have high cycle life, and Natron’s sodium chemistry was claimed to have a cycle life of 50,000 cycles. Donut Lab’s battery has an energy density of 400 Wh/kg, while liquid electrolyte sodium-ion batteries have an energy density of 175 Wh/kg. Sodium-on is also capable of C rates of 5. The differences are the higher temperature, higher energy density, faster charging, and more extreme cycle life. Could solid-state render a sodium-ion battery with greater energy density and fit the final piece of the puzzle? We know there are some cathode materials used with sodium-ion, like TAQ, that allow high energy densities.

“Altogether, these allow the construction of SIB cells built from an affordable, sustainable organic small molecule, which provide a cathode energy density of 472 Wh kg–1 electrode when charging/discharging in 90 s and a top specific power of 31.6 kW kg–1 electrode.”

“These figures underscore the potential of this technology to compete with and eventually surpass existing lithium-ion batteries in various applications.”

This does not prove Donut Lab’s batteries are sodium-ion. It does suggest that there are pathways to performance similar to them.

[Paul Nuttall]

and some more

https://cleantechnica.com/2026/03/04/do ... od-enough/

The furor over the claims made by Donut Lab for its “solid state/not so solid state” battery continues unabated. This week, it released new testing data for its breakthrough battery that purports to show it worked admirably at temperatures of 80º C and 100º C — performing better at higher temperatures than it does at room temperature — and yet the controversy continues.

In an effort to combat the negative publicity, the company has created the I Donut Believe website, where it assembles all the test results that support its claims. To date, they all originate from VTT, the Finnish state research institute, which has been asked to counter the skeptics by providing independent validation of the company’s claims.

The website introduces itself this way: “This website serves as the platform for publishing validation results and technical documentation related to the Donut Solid State Battery. Donut Lab has commissioned the internationally renowned VTT Technical Research Centre of Finland to conduct independent measurements of the battery’s performance and key characteristics.

“Unless otherwise stated, all tests presented here have been conducted by VTT. Full reports will be published alongside detailed video documentation that walks through the procedures, showcases the test setups, and explains the results.”

My colleagues Tina Casey and Christopher Arcus have written several articles lately that support the company’s claims. According to the company, its battery has an energy density of 400 watt-hours — nearly double that of typical lithium-ion cells, a five-minute charge time, an operating range of -30º C to 100º C, a 100,000 cycle lifespan, and zero rare earth materials.

This week, Donut Lab released new data from VTT from testing at 80º C and 100º C. Are those results enough to quell the doubts about this new battery technology? Not even close. As InsideEVs reports, “Once again, the data is raising as many questions as it answers.”
The Results Of The Second Testing Protocol
Donut Lab
Credit: VTT

Electrive says VTT tested a Donut Lab cell with a nominal capacity of 26 Ah and a nominal energy content of 94 Wh according to the datasheet, in a Weiss LabEvent T/110/40/3 climate chamber using a PEC ACT0550 cell tester. Unlike the first test series, the results of which were published last week, VTT placed a 2.4-kilogram steel weight on the cell this time to apply mechanical pressure. The temperature sensor, critical for the high-temperature tests, was positioned underneath the cell between the cell and the aluminium heat sink used in the first test.

The test series comprised three charge-discharge cycles, beginning at 20º C in the climate chamber. After a one-hour stabilization period, VTT charged the cell at a constant current of 24 amperes until it reached 4.15 volts. Charging then continued at 4.15 volts until the current dropped to 1.2 amperes, or 0.05 C. For the first test, VTT discharged the cell after one hour at a constant 14 amperes until the voltage fell to 2.7 volts. This procedure determined a capacity of 24.9 Ah for the cell.

After fully recharging the cell using the standard procedure outlined above, VTT increased the temperature in the climate chamber to 80º Celsius and maintained it at that level for two hours. At that temperature, VTT discharged the cell at 24 amperes down to 2.7 volts to determine its capacity under elevated temperature conditions.

Following a one-hour stabilization period at 20º C, VTT recharged the cell and held it at full charge for one hour. It then conducted a reference discharge at 20º with a current of 12 amperes down to a cell voltage of 2.7 volts.

For the third test, VTT heated a fully charged cell under the same experimental conditions to 100º C and kept it at that temperature for two hours. It subsequently discharged the cell at 12 amperes down to 2.7 volts. The institute then reduced the temperature back to 20 degrees Celsius and, after one hour, recharged the cell completely. Detailed measurement data are available in the VTT report.

“Under the specified conditions, the cell was successfully discharged at +80° C with a current of 24 A, achieving a discharge capacity corresponding to 110.5 percent of the initial discharge capacity at +20° C with the same current. After discharge, the cell could be charged normally, and no observable changes were detected,” VTT wrote. “The cell was also discharged at +100° C with a current of 12 A, achieving 107.1 percent of the reference discharge capacity measured at +20° C with the same current. After discharge, the cell could be charged normally.”
Finding The Silver Lining

In a statement, Donut Lab said, “The test measuring battery performance at high temperatures has shown that the Donut battery is extremely heat resistant and even delivers improved performance at elevated temperatures.”

“The full capacity of the battery was utilized at both 80º and 100º C with excellent results. Discharge at a 1C rate at 80 degrees and at a 0.5C rate at 100 degrees was possible without any temperature increase,” added Ville Piippo, CTO of Donut Lab. “The battery characteristics remained unchanged even at 100 degrees, and after recharging it functioned flawlessly, confirming the convincing performance of the Donut battery even under extremely hot conditions. This demonstrates that the battery is exceptional not only in terms of performance but also in safety.”

Sounds pretty good, doesn’t it? Yes, it does, except for a few things. Donut Lab says it has created a solid-state battery, but VTT through a curveball into the testing report, saying only that it conducted tests on an “energy storage device provided by the customer […] identified by the customer as a solid-state battery cell.” Hardly a ringing endorsement of the company’s claims.

In addition, VTT reported that during the second high-temperature test, the pouch cell labelled DL2 lost its vacuum after the 100º C test. However, what would normally be considered damage Donut Lab said was proof of success. “The battery and its active materials remained fully functional even after the outer cell casing lost its vacuum at 100 degrees.”

“Conventional lithium-ion batteries are highly sensitive to heat and their maximum operating temperature typically lies around 60 to 70 degrees Celsius. At high temperatures, the risk of cell damage increases, reducing service life,” said CTO Piippo. “In addition, high temperatures can accelerate reactions inside the cell and, in the worst case, significantly increase the risk of thermal runaway. The Donut battery starts from a fundamentally different position, as it contains no flammable liquid electrolytes, and therefore the maximum operating temperature is higher.”
Not Breaking Any Laws

Assuming all that is true, Eric Wachsman, a professor at the University of Maryland’s Department of Materials Science and Engineering who specializes in solid-state batteries and solid-oxide fuel cells, said the insufficient data does not represent real-world usage in automotive applications. “The cells are not violating any law of thermodynamics,” Wachsman told Suvrat Kothari of InsideEVs. “But the data presented leaves a lot to be desired for many reasons.”

Wachsman said the pouch issue was a potential red flag. The loss of vacuum may indicate that the cell lost its “hermetic seal,” the barrier that keeps outside air away from the sensitive internal chemistry. “Pouch cells will tend to expand due to internal pressure as they can give off gas during cycling. It’s clear they experienced excessive swell after a few cycles,” he said after comparing the fast-charging images from last week’s test to this week’s high-temperature results.

Whether this is a major safety issue or something that’s expected on solid-state cells remains unclear. However, the broader consensus is consistent among experts. Neither test reveals meaningful pack-level performance over the thousands of cycles that actually matter for real-world use. “To be commercially relevant, the cells need to be stable with less than 10 to 20 percent of capacity fade for thousands of cycles,” Wachsman said. “Without that, the tests are essentially meaningless.”

And so the beat goes on. Is the Donut Lab battery solid state? Is it ready for prime time? Is it a genuine breakthrough or just a sideshow? We take no position on any of this controversy, but our readers, who are all well above average, may wish to express their opinions in the comments.