In Situ Transmission Electron Microscopy Advancing Cathodal Dynamic Visualization in All-Solid-State Battery

All-solid-state battery (ASSB) technology is one of the most promising approaches to energy storage due to its great safety and energy density. However, the detrimental effects of cathodal structure/morphology/composition/conductivity evolution on electrochemical performance significantly restrict the development of ASSBs. To elaborately investigate these cathodal dynamic evolution processes and deterioration mechanisms of ASSBs, in situ transmission electron microscopy (TEM) technology has been extensively introduced into the ASSB research. This paper discusses the latest important scientific discoveries toward cathodal dynamic evolution in multitype ASSBs through in situ TEM and highlights key challenges for in situ TEM to analyze ASSB cathodes with a higher spatial resolution. Lastly, insights for future directions of in situ TEM monitoring multiscale electro-chemo-mechanical evolution of ASSBs are prospectively provided. This Review will deepen the fundamental understanding of cathodal dynamic mechanisms and open new opportunities for the optimization and development of in situ TEM in ASSBs.