The Holy Grail of the Solid-State Battery
The most exciting solid-state battery of the year turned out to be an ordinary lithium-ion cell wearing a better
The most exciting solid-state battery of the year turned out to be an ordinary lithium-ion cell wearing a better name. It came from Donut Lab, a Finnish startup whose name alone might have invited a little skepticism. Instead it drew a $1.25 billion valuation. The cell, the company said, held 400 watt-hours per kilogram, roughly double what a good electric-car battery manages today; charged fully in five minutes; survived 100,000 cycles, more than the car around it could ever use; cost less than lithium-ion; and was built from nothing but green materials. It was even, they claimed, already shipping inside a production motorcycle. These were specifications that Toyota and Samsung, after years of work and billions of dollars, still cannot deliver.
The $1.25 Billion Costume
The numbers collapsed the moment anyone tested them. An investigation by Electrek, backed by a video analyst who ran the data past more than twenty battery experts, found that the miracle cell carried none of the chemistry that makes a battery solid-state. It was a normal lithium-ion cell. The former commercial chief of a partner company, Nordic Nano, took his concerns to the Finnish police, the financial regulator, and the chancellor of justice, alleging the specs had never been real. Most damning of all, leaked emails showed Donut Lab asking its own supplier to send measurement results that would match the promises it had already made to investors. The chief executive eventually conceded that the headline cell was not in the motorcycles, and that the unit handed to testers was “not even the cell that’s going to be shipped.”
Donut Lab is an outlier in its brazenness, not in its instinct. The solid-state battery is the most wanted and least delivered technology in the car business, and that gap between desire and delivery is a near-perfect habitat for exaggerators, relabellers, and the occasional fraud.
What a Solid-State Battery Actually Is
A normal lithium-ion battery is a chemical sandwich with a liquid centre. Ions shuttle back and forth through that liquid electrolyte, which has two unfortunate habits: it is flammable, and it tends to sprout tiny metal needles called dendrites that can pierce the cell and start a fire. Every laptop that has ever puffed up and every EV that has ever burned on a motorway owes the experience to that liquid.
A solid-state battery throws the liquid out and replaces it with a solid: a ceramic, glass, or polymer layer the ions pass through instead. Two things follow. The solid does not burn, so you could in principle drive a nail straight through the cell and it would sit there unbothered. And it lets the battery use an anode, the electrode that stores the charge, made of pure lithium metal rather than bulky graphite, which packs far more energy into the same weight.
Add it up and you get the prize the whole industry is chasing: roughly double the range, half the weight, and a battery that does not catch fire when you crash. For an industry whose entire future runs through the battery pack, that is close enough to a magic bullet that anyone claiming to have built one gets applause first and scrutiny much, much later.
A Unit of Time That Never Elapses
The catch is that this particular grail has been almost within reach for the better part of two centuries.
Michael Faraday was poking at solid electrolytes in the 1830s. Toyota and Panasonic started serious work on solid-state for cars around 1990. For the past decade in particular, the technology has lived in a state of permanent imminence, forever stuck on what one industry writer called the eve of mass production. Toyota promised production cars by 2025. Samsung said the breakthrough was just around the corner. The American startup QuantumScape sent its share price soaring on the promise, then quietly walked its commercial target from 2024 to “samples” in 2025 to “field testing” in 2026.
Follow battery news for any length of time and you learn to read “two years away” as a unit of time that never actually elapses. The deadlines slide, the press releases recycle, and the cars on the road keep running the same liquid chemistry they ran on ten years ago. That is the ground the Donut Lab story grew out of, because when the future has been described as nearly here for fifteen years, one more confident voice claiming it has finally arrived sounds less ridiculous than overdue.
Why It Is So Hard
The delays are not laziness but the mark of a problem that is genuinely, stubbornly physical.
Picture the liquid electrolyte again, soaking into every nook of the electrodes like water into a sponge, touching everything, carrying ions everywhere. Now replace it with a solid. A solid only touches what it is pressed against, so the ions have far fewer paths to travel, and the battery chokes. It gets worse with use: every time the cell charges and drains, the electrode swells and shrinks, peeling away from the solid layer and opening microscopic gaps. The most energy-dense candidate material, silicon, balloons by about 300% as it cycles, cracking itself apart in the process. Building something that is both rich in energy and able to keep solid pressed against solid for thousands of cycles is one of the meanest problems in materials science, and throwing money at it has not made it quick.
Then there is the bill. The chairman of the battery maker Svolt has put the cost of a true all-solid-state cell at five to ten times that of liquid lithium. The battery is already more than 30% of an EV’s price, so multiplying that figure by five prices the car out of every garage except a billionaire’s. CATL, the biggest battery maker on the planet, scores the technology’s maturity at four out of nine, expects only limited production around 2027, and does not see real mass production before about 2030.
It Still Is Not Vaporware
Here is the twist that should keep the cynics honest: the thing actually works.
Mercedes-Benz dropped a solid-state pack from a startup called Factorial into an EQS and reported a single-charge run of 749 miles. That is not a lab figure under perfect conditions; that is roughly London to the Scottish Highlands and most of the way back, on real roads. QuantumScape’s cells are running in a Ducati electric race bike through its tie-up with Volkswagen. Solid Power is building a sulfide-based cell with BMW. These are real machines from companies that know how to build cars, and they prove the chemistry holds up outside a sealed laboratory.
That is what makes the field so hard to read, because the dream is not a lie. The serious players are out of the lab and into pilot production, the last stage before the real thing. The honest verdict is that solid-state is real, expensive, and slow, and that the affordable version sitting in a normal family car is still years off. The distance between “it works” and “you can buy it” is precisely where the marketing likes to plant its flag.
How the Word Lost Its Meaning
Because the genuine article is so close and so costly, a cheaper stand-in has slipped into the gap, and it is hollowing the term out from the inside.
A number of Chinese carmakers, including MG’s parent SAIC, are already putting semi-solid-state batteries into cars you can buy. A semi-solid cell keeps a little liquid in the mix to keep the ions moving, which makes it genuinely better than standard lithium-ion and, crucially, ready years ahead of the fully solid version. One analyst called it cheating the timeline, beating Toyota and Volkswagen to market with something almost as good. Fair enough. The problem is the badge: these are routinely sold as “solid-state,” and the buyer almost never hears the “semi” that does all the work.
So “solid-state battery” is drifting toward the fate of “natural” and “artisan,” words that still sound like a promise but have stopped meaning much. When a spec sheet says solid-state now, it might mean a true ceramic cell off a pilot line, a semi-solid hybrid with liquid still in it, or, in the Donut Lab case, a bog-standard lithium-ion cell in a costume. Three very different things, one increasingly meaningless word, and only one of them the grail.
How to Read the Spec Sheet
A few questions separate the real thing from the marketing.
Look first for the word “all.” A true cell is “all-solid-state”; drop the “all” and you are often looking at a semi-solid hybrid. Ask who tested it, and whether they measured the two numbers that actually matter, energy density and cycle life, rather than something flashier and easier. Ask the price, because a genuine all-solid-state cell that somehow undercuts lithium-ion would be a miracle on top of a miracle, and miracles deserve more scrutiny, not less. And distrust on sight any product that claims to have won on energy, charging speed, lifespan, cost, and safety all at once, because in battery chemistry pushing one of those almost always drags down another. That trade-off is the entire reason this has taken fifty years.
The solid-state battery is coming. Mercedes has driven it across most of Britain, CATL is building toward 2030, and the laboratories are not bluffing. What is not coming yet is a cheap one, or a fast one, or one that does everything its loudest salesmen swear it already does. The grail is real. Most of what gets sold under its name is not.
Sources
Electrek: Donut Lab’s “Solid-State” Battery Exposed as Regular Li-ion in Damning Investigation
Tom’s Hardware: Startup’s “Miracle” Solid-State Battery Actually Uses Lithium-Ion Chemistry
kr-asia: Despite Renewed Hype, Solid-State Batteries Remain Years From Mass Production
Undecided with Matt Ferrell: Solid-State Batteries, Hype vs. Reality
