Donut Lab’s solid-state battery could barely hold a charge after getting damaged

Donut Lab's solid-state battery lost about 55% of its energy capacity after sustaining damage from a prior heat test that broke the pouch's vacuum seal, but it did not catch fire or experience thermal runaway. Independent tests at Finland's VTT Technical Research Centre showed sharp drops in efficiency and significant swelling, yet Donut Lab considers the graceful failure a safety win over conventional lithium-ion batteries. However, the startup has still not conducted a proper long-term cycle test or obtained independent verification of its claimed 400 Wh and 100,000-cycle specs.