Status of cell-level thermal safety assessments toward optimization of all-solid-state batteries

All-solid-state batteries are considered a promising safe battery technology for electric vehicles and energy storage power stations, and many studies have demonstrated this from the material perspective. However, all-solid-state batteries at the cell level are not immune to thermal runaway under extreme conditions, including thermal, mechanical, and electrical abuses. Therefore, further evaluation is needed to determine whether, at the cell level, all-solid-state batteries have their anticipated safety. This review summarizes the typical thermal runaway mechanisms of all-solid-state batteries, compares the thermal runaway characteristics at the cell level, and analyzes the feasibility of thermal safety improvement strategies at the material, cell, and system levels. This review provides not only a valuable reference for assessing the safety of all-solid-state batteries but also a foundation for designing safe batteries for practical applications.