Assessing the Safety of Solid-State Technologies: What Can We Learn from a Coin Cell

All-solid-state lithium batteries equipped with lithium metal anodes offer a promising energy density potential critical for next-generation electric vehicles. Despite notable advancements in the performance of these emerging battery technologies, safety assessment remains a major challenge due to the lack of effective diagnostic techniques. This original study introduces a recently developed experimental setup designed to trigger thermal runaway in cells with very low capacity (10 mA h). A UV–Vis spectrometer is employed to analyze the light emitted by the flame, enabling the determination of flame temperature and the emission peaks of elements involved in the reaction. By comparing garnet-type and sulfide-based electrolytes, this work provides valuable insights into the reaction pathways leading to thermal runaway in both solid-state battery technologies and contributes to a comparative evaluation of their mutual safety potential.