Finnish Startup's Solid-State Battery Excels in Extreme Heat Tests

Finnish startup Donut Lab is making strides in battery technology with its solid-state battery, which has recently undergone rigorous testing to evaluate its performance under extreme heat conditions. Conducted by the VTT Technical Research Centre of Finland, the tests aimed to determine how well the battery could withstand high temperatures, a known challenge for traditional lithium-ion batteries.

The tests involved a 3.6V/26 Amp-hour solid-state battery, which was evaluated at three different temperatures: 20 degrees Celsius (room temperature), 80 degrees Celsius, and 100 degrees Celsius. To simulate real-world conditions, the battery was placed under physical pressure using a steel plate and positioned on a heatsink within a temperature-controlled chamber. At room temperature, the battery delivered 24.9Ah, establishing a baseline for comparison.

Remarkably, the battery's performance improved at higher temperatures. At 80 degrees Celsius, it delivered 27.5Ah, representing 110.5 percent of its room-temperature capacity. At 100 degrees Celsius, the battery provided 27.6Ah, or 107.1 percent of its performance at room temperature. Despite the extreme heat, the battery continued to function and could be recharged, although the physical pouch lost its vacuum seal, likely due to the high temperatures.

These results suggest that Donut Lab's solid-state battery becomes more efficient at elevated temperatures, a significant advantage over traditional lithium-ion batteries, which can suffer from thermal runaway and other issues when exposed to heat. Solid-state batteries, often considered the "holy grail" of battery technology, use dry conductive materials instead of liquid electrolytes, reducing the risk of fire and improving energy capacity.

Traditional lithium-ion batteries are vulnerable to extreme heat, which can cause the liquid electrolytes to vaporize and potentially catch fire. High temperatures can also degrade the liquid, shortening the battery's lifespan or causing it to swell. In contrast, Donut Lab's solid-state battery uses a solid ceramic or polymer material, enhancing its heat tolerance and efficiency. The study by VTT demonstrated that heat reduces the internal resistance of the solid electrolyte, facilitating easier ion movement and increased capacity.

However, the report leaves some questions unanswered. VTT did not confirm the specific chemistry of Donut Lab's battery, accepting the company's claims at face value. Additionally, the tests did not address the "dendrite issue," a potential problem in solid-state batteries where microscopic growths can cause electrical shorts. Donut Lab has indicated that it will address these concerns in future independent tests as part of its "I Donut Believe" series.