Is the “Holy Grail of Batteries” finally ready to bless us with its existence?

Earlier this year, a relatively unknown startup emerged from Finland He made a startling announcement: I have finally solved the problem of solid state batteries.

Not only that, but Donut Lab, a subsidiary of Verge Motorcycles, said its solid-state battery — long considered the “holy grail of batteries” for its high-density, durable, fast-charging capabilities — will go into production later this year.

Battery experts were understandably skeptical. After all, solid-state batteries are one of those technologies, along with Artificial general intelligence and Hyperloopwhich always seems two years away. While most legitimate efforts in this field – whether academic or commercial – have some level of published research or well-known names, Donut Lab seems to have appeared out of nowhere, with no well-known researchers or prior presence in the field. This lack of traceability immediately raised concerns about the startup’s credibility.

“I can’t say they haven’t,” said Eric Waxman, director of the Maryland Energy Innovation Institute and an expert in solid-state batteries and solid-oxide fuel cells. “All I can say is they haven’t proven they did it.”

These doubts seem justified, especially when you consider how many other people were chasing the dream of a solid state. Did we really believe that this mysterious startup had beaten Toyota, Stellantis, and the entire nation of China? The odds were against her.

Donut Lab seems to have anticipated this skepticism, launching a website last February called idonutbelieve.com It will serve as a platform to deploy independent tests to verify that its solid-state battery is real and amazing. Over the course of several weeks, the startup published third-party results from Finland’s state-owned technical research center VTT, which it said proved its battery was what it said it was: Fast shipping, High energy density solid state battery Which It wasn’t actually a super capacitor in disguise.

“Resistance will not go away when we present the evidence,” Marko Lehimäki, CEO and co-founder of Donut Lab, said in a video. “It will intensify as this new technology poses a threat to established players in the industry.”

But Donut Lab is still dropping the ball on some key information. At CES last January, the startup said its solid-state battery had an energy density of 400 watt-hours per kilogram, nearly double that of typical lithium iron phosphate (LFP) batteries in production. Not only that, it can be fully charged in five minutes, has a practically unlimited lifespan of 100,000 charge cycles, is unaffected by heat and cold (negative 30°C and 100°C), and contains no rare earth elements, precious metals or flammable liquid electrolytes.

Much of this remains unproven. Even after publishing five independent testing reports from VTT, the startup has yet to demonstrate three of the most important metrics: chemistry, density, and cycle life.

The risks are incredibly high. Imagine an electric car that could travel 700-800 miles on a single charge, and had no risk of catching fire due to the replacement of flammable electrolytes with a solid material.

In lithium-ion batteries, the movement of liquid electrolytes generates heat, and in certain cases, this can descend into a “runaway thermal” effect that results in a fire. In comparison, solid-state batteries will make it safer to quickly draw power from the battery (or add it back to it), which means you can theoretically charge an electric car faster. It could also mean, structurally, that less space would have to be devoted to temperature control, which could allow companies to squeeze more battery cells into the same volume.

After reviewing the donut battery tests, Waxman said there are still major concerns. During extreme heat tests, for example, the bag surrounding a donut battery It lost its vacuum seal. Gas generation inside batteries — resulting from processes such as electrolyte decomposition or the release of oxygen — can cause swelling and rupture of the battery case. But without knowing the exact chemistry of the cell, it’s difficult to determine how important it is for a donut battery to malfunction.

Putting the donut battery aside for a moment, solid-state batteries have struggled to make it from the lab to the assembly line due to well-documented problems. These batteries often suffer from the formation of metal cracks called dendrites which cause short circuits. Think of them like the cracks that form in the sidewalk when a tree root grows underneath.

Dendrites have been a thorn in the side of battery developers since the 1970s. One reason lithium-ion batteries have become so ubiquitous, while other methods have stalled, is that the commonly used graphite anodes are less prone to dendrite formation.

But new discoveries could help engineers finally overcome these obstacles. A research team from MIT recently A study published in nature She found that chemical reactions caused by high electrical currents that weaken the electrolyte also make it more susceptible to the growth of dendrites. For this reason, the development of stronger electrolytes alone has not solved the decades-old problem of dendrites. This could point to the importance of developing more chemically stable materials to finally fulfill the promise of solid-state batteries.

Progress has already been made – where else? — In China. Last month, CATL, which controls nearly 40 percent of the global battery market, filed a patent application for solid-state batteries with an energy density of 500 watt-hours. according to Chinese car newsthe battery maker is already planning small-scale production in 2027. But cells for cars likely won’t be ready until the end of the decade.

Other Chinese companies are accelerating ahead. The automaker FAW said recently The 500 Wh/kg “liquid-solid-state” lithium-rich manganese cell was ready for vehicle integration.

China is already laying the groundwork for mass production by the end of the decade, and by that point it hopes the technology will be mature. Why not? This country has taken the development of electric vehicles and batteries seriously for years, allowing it to monopolize the market on much of the global supply.

Different companies take different approaches. For example, Honda is committed Sulfur-based electrolytes Although alternatives are emerging. last October, Toyota announced “The world’s first practical use of all-solid-state batteries in battery electric vehicles” by 2027 or 2028. Mercedes, using a prototype battery from Startup Factorial, has managed to get an EQS electric sedan with a real-world range of 749 miles.

“Companies likely have a ways to go,” said Alevtina Smirnova, director of the Collaborative Research Center for Solid-State Electrical Energy Storage at the NSF Industrial University. “Because there is no comparison between what is happening now in China and what is happening here in the United States.”

For its part, Donut Lab is not concerned about the doubts surrounding its claims. On April 1, Lehtimäki posted a new video addressing some of the controversy surrounding its solid-state batteries. He also revealed that Donut Lab has created a second, more production-ready version of its battery that will begin shipping to customers later this year.

There was a crucial admission: the widely discussed “100,000 cycles” figure was a design goal, not an experimentally verified result. Actual testing was conducted over shorter cycles, with expectations extrapolated based on known variables such as charging rate, temperature and usage conditions.

He then turned to a near-term project: the latest drop of Donut Lab merchandise, including a foil-covered bucket hat.