Assessing the thermal runaway characteristics of solid-state lithium batteries based on thermochemical reaction properties at material level

Solid-state batteries using solid electrolyte have attracted considerable attention in recent years as the most promising solution to the safety issue of lithium-ion batteries. Despite the verified thermal stability of a variety of solid electrolytes, the safety characteristics of practical solid-state batteries are still uncovered and argument has emerged about severe exothermic reactions in solid-state chemistry. In this perspective, key thermochemical reactions in solid-state chemistry related to battery safety are summarized and analyzed to assess the safety characteristics of solid-state batteries, compared with conventional lithium-ion batteries. The overall hazard degree is assessed through the evaluation of total heat release from battery thermal runaway, and the specific change of thermal runaway characteristics due the alterations of battery chemistry is predicted through the difference of thermochemical reactions. The importance of solid phase interfaces for the safety of solid-state batteries is further discussed. The assessment in this perspective provides a confidence of the enhancement of battery safety through solid-state battery chemistry, and urges comprehensive investigations into the safety aspects of solid-state batteries from materials to cells, modules, and systems level.