Testing says Donut Lab’s solid-state battery can handle (extreme) heat.

Like the first test This was also conducted by the state-owned VTT Technical Research Center in Finland. The team set out to determine how well Donut Lab’s cells would hold up under extreme heat, which is known to negatively affect traditional lithium-ion batteries. The results show that the Finnish startup’s solid-state battery can not only discharge power under conditions up to 100 degrees Celsius (212 degrees Fahrenheit), but that it is actually gaining capacity.

The group tested the 3.6V/26Ah solid-state battery under three different temperatures: 20°C for a baseline at room temperature; “High temperature” at 80°C; and “extreme heat” at 100 degrees Celsius. To ensure the battery was working properly during testing, VTT applied physical pressure to it using a steel plate and placed it on the heatsink inside a temperature-controlled chamber.

At room temperature, the cell delivered 24.9 amps, which was the benchmark for other tests. At 80°C, performance actually improved, delivering 27.5 amps, or about 110.5 percent of its capacity at room temperature. At 100°C, the cell delivered 27.6 amps, or 107.1 percent of its room temperature performance. While the battery was still functional and could be recharged afterwards, the physical bag lost its vacuum seal, likely due to extreme heat.

VTT found that the solid-state cell has already become more Effective at higher temperatures, saving more energy than at room temperature. Even at a temperature of over 100°C (a temperature that would be too dangerous for many standard batteries), the cell continued to provide power and could still be recharged.

Solid-state batteries, often referred to as the “holy grail” of batteries, have eluded researchers for decades. Most electric vehicle companies use “wet” lithium-ion batteries, which use liquid electrolytes to move power. But these batteries can be slow to charge, can freeze at subzero temperatures, and contain flammable materials that could be dangerous in the event of an accident. Solid-state packs are made of a “dry” conductive material that can hold more power without any of the thermal runaway problems of a traditional battery. This could mean electric cars with longer range, shorter charging times, and better performance under extreme conditions.

Lithium-ion batteries with liquid electrolytes are more susceptible to extreme heat. If a liquid battery becomes too hot, the liquid can vaporize and catch fire – a process called thermal runaway. At high temperatures, the liquid can decompose, reducing battery life or causing it to swell dangerously.

By replacing the flammable liquid with a solid ceramic or polymer material, Donut Lab says it can improve the battery’s ability to withstand extreme heat, which could mean better efficiency. As we saw in the VTT study, heat actually reduces the internal resistance of the solid electrolyte, allowing the ions to move more easily. That’s why the battery capacity actually increased at 80°C and 100°C.

But before you start popping open the champagne, keep in mind that the report doesn’t address some basic questions about Donut Lab’s solid-state battery. First, VTT does not confirm the chemistry of the packaging, but simply takes it seriously. Second, the test did not address what edge Contributor Tim Stevens points to the “dendrite problem,” where microscopic stalagmites growing from the anode to the cathode across the solid-state electrolyte can cause a short circuit. Perhaps Donut Lab will address this in subsequent independent test results, which are part of its findings “I Don’t Believe” series..