World's first solid-state battery retains 97.7% charge after 10 days

Finnish startup Donut Lab has released the results of a third independent test conducted by the VTT Technical Research Centre of Finland, demonstrating that its solid-state “Donut Battery” retains 97.7% of its charge after being idle for 10 days. This finding addresses previous speculation that the battery might function like a supercapacitor, which typically loses charge rapidly when not in use. The test involved charging the battery to about 50% capacity, leaving it idle at room temperature for 240 hours, and then measuring the remaining charge, confirming the battery’s strong self-discharge performance and stability without any visible damage. The Donut Battery, designed for Verge Motorcycles’ TS Pro, offers a 370-mile range, five-minute charging, and an energy density of 400 Wh/kg, along with robust thermal stability demonstrated in earlier tests at elevated temperatures. Donut Lab’s CTO, Ville Piippo, emphasized that the battery behaves as expected for a solid-state battery, maintaining charge