Toward Operando Structural, Chemical, and Electrochemical Analyses of Solid-State Batteries Using Correlative Secondary Ion Mass Spectrometry Imaging

The global transition from fossil fuels to green energyunderpinsthe need for efficient and reliable energy storage systems. Advancedanalysis and characterization of battery materials is not only importantto understand fundamental battery properties but also crucial fortheir continued development. A deep understanding of these systemsis often difficult to obtain through only pre- and/or post-mortemanalyses, with the full complexity of a battery being hidden in itsoperational state. Thus, we have developed an operando methodology to analyze solid-state batteries (SSBs) structurallyas well as chemically before, during, and after cycling. The approachis based on a specially designed sample holder, which enables a varietyof electrochemical experiments. Since the entire workflow is performedwithin a single focused ion beam scanning electron microscope equippedwith an in-house developed magnetic sector secondary ion mass spectrometer,we are able to pause the cycling at any time, perform analysis, andthen continue cycling. Microstructural analysis is performed via secondaryelectron imaging, and the chemical mapping is performed using thesecondary ion mass spectrometer. In this proof-of-concept study, wewere able to identify dendrites in a short-circuited symmetric celland to chemically map dendritic structures. While this methodologyfocuses on SSBs, the approach can directly be adapted to differentbattery systems and beyond. Our technique clearly has an advantageover many alternatives for battery analysis as no transfer of samplesbetween instruments is needed and a correlation between the microstructure,chemical composition, and electrochemical performance is obtaineddirectly.