Comprehensive Safety Assessment of All-Solid-State Batteries: Using Calorimetry, X-Ray Radiography and Blast Testing Techniques

In the context of the energy transition, researches on batteries are devoted to improving their energy density, i.e. their autonomy and their safety, particularly in relation to the risk of fire. Among the different types of battery, all-solid-state batteries are promising because of their high energy density. A ceramic or a glass electrolyte replaces some traditional components of lithium-ion batteries as the liquid electrolyte and the polymer separator.<br/>However, safety concerns related to ASSBs have remained relatively unexplored. This investigation is focused on understanding the behaviour of reassembled all-solid-state batteries subjected to overheating abuse. Specifically, two batteries compositions: Gr|LLZO|NMC811 and Li|LLZO|NMC81 are studied. The first cell aids in comprehending the impact of the electrolyte (liquid or solid) safety and the second enables to assess the safety of a reconstructed lithium-metal all-solid-state cell.<br/>An innovative approach to assess the safety of all-solid-state cell in-development has been devised. This approach incorporates three distinct techniques: calorimetry, X-ray radiography and blast testing. This methodology could significantly contribute to the development of future battery technologies. Ensuring the integration of safety concerns right from the beginning is crucial, encompassing both cell performance and safety aspects.<br/>Substituting liquid electrolyte with a solid electrolyte, the initiation and the maximal temperatures remain unchanged. It reduced by 10 % the heat released and reduced by 40 % the amount of gas released and the duration of thermal runaway. Using solid electrolyte no prevent from thermal runaway.<br/>Substituting liquid electrolyte with a solid electrolyte and substituting the lithiated graphite with a lithium-metal foil, the initiation temperature remains unchanged. The maximum temperature is at least increased by 40 %; the amount of gas and the duration of thermal runaway are decreased by 90 % and 95 %. Furthermore, the Li|LLZO|NMC811 cell is not an explosive but a 188 mbar aerial pressure has been measured. It corresponds to an mass equivalent TNT of 2.7 g.<br/>Furthermore, the characteristic parameters of thermal runaway are different. Therefore, the means to mitigate its thermal runaway are different and should be taken into account when all-solid-state batteries are developed.<br/>The impact of blast wave on the casing and battery pack integrity should be taken into when all-solid-state batteries are developed.<br/>To conclude, all-solid-state batteries are neither safer nor less safe than lithium-ion batteries. However, their the characteristic parameters of thermal runaway are different. This work underlines the importance of evaluating the safety of all-solid-state batteries with respect to users and the environment.