Research progress of thermal runaway and gas explosion hazard of lithium-ion batteries for aviation propulsion

The safety of propulsion lithium-ion batteries is a technical bottleneck to restrict the operation and airworthiness certification of electric aircraft and affects the development of electric aviation worldwide. Failure events such as combustion and explosion triggered by thermal runaway of lithium-ion batteries will cause catastrophic consequences of aircraft destruction and casualties. This paper aims to introduce the latest research status on the thermal runaway explosion characteristics of aircraft lithium-ion battery from three aspects, i.e., lithium-ion battery’s thermal runaway combustion and explosion behavior, the limit of thermal runaway gas explosion and the hazard assessment of thermal runaway and gas explosion. For lithium-ion battery thermal runaway and explosion behaviors, this paper introduced the lithium-ion battery thermal runaway development process, analyzed the determination of the characteristic parameters of the thermal runaway shock and summarized the evolution of the thermal jet mechanism as well as the associated simulation and experimental methods. For the limit of thermal runaway gas explosion, the national and international testing standards for the gas explosion limit were compared and the theoretical calculation of the explosion limit of thermal runaway gas are summarized together with the introduction of the in-situ detection method of the gas explosion limit. For the thermal runaway gas explosion risk assessment, a risk assessment method of ageing lithium-ion battery is introduced by innovatively combining CT non-destructive testing technology with explosion limit in-situ testing method, from which a severity factor of gas explosion hazard is obtained. Based on the characteristics of lithium-ion battery’s thermal runaway gas explosion limit and pressure rise rate, the factors of explosion risk and severity are obtained together with the formula for the calculation of explosion risk and severity. This study shows that future research will focus on areas such as advanced diagnostic techniques, enhanced electrolyte stability, multi-scale modelling, advanced inhibition techniques, and the establishment of standardized testing processes and safety regulations. It proposes that future research should focus on areas such as advanced diagnostic techniques, enhanced electrolyte stability, multi-scale modeling, advanced inhibition techniques and the establishment of standardized test procedures and technical regulations.