High-Speed X-ray Visualization of the Sodium-Ion Thermal Runaway

Sodium-ion batteries (SIBs) are gaining attention as a cost-effective and abundant alternative to lithium-ion batteries (LIBs). Despite these advantages, concerns about the thermal safety of SIBs remain, with limited studies addressing this critical aspect. To fill this gap, we present a comprehensive investigation into the thermal runaway dynamics of NVPF (sodium vanadium phosphate fluoride)/hard carbon 18650 sodium-ion batteries using advanced characterization techniques. Notably, we employ high-speed synchrotron X-ray radiography to provide real-time visualization of internal processes and reactions during thermal runaway, offering insights into the battery’s behavior under extreme conditions. Complementary gas analysis techniques are utilized to explore thermal characteristics, gas composition, emitted volumes, and energy aspects associated with thermal runaway, providing an understanding of the events leading to and during thermal runaway. Comparative analyses with lithium iron phosphate (LFP) and nickel manganese cobalt (NCM) LIBs reveal that SIBs exhibit thermal safety performance comparable to that of LFP LIBs and superior to that of NCM LIBs. This study aims to contribute to the improvement of our understanding of SIB safety and to offer some useful insights for the development of safer sodium-ion battery technologies.