A novel design for the combination of electrochemical atomic force microscopy and Raman spectroscopy in reflection mode for in situ study of battery materials

The emergence of functional materials, especially energy materials made up of various structures with different properties, requires the development of complementary or integrated characterization technologies. The combination of atomic force microscopy and Raman spectroscopy (AFM-Raman) offers a powerful technique for the in situ characterization of physical properties (AFM) and chemical composition (Raman) of materials simultaneously. To further extend the potential application in the battery's field, we here present an electrochemical AFM-Raman (EC-AFM-Raman) in the reflection mode, developed by designing a novel structure including water-immersion objective lens-based optics for high-sensitivity Raman excitation/collection, optical level detection for AFM imaging in the solution, and a dual-cell for electrochemical reaction. EC-AFM imaging and Raman measurement can be realized simultaneously. Dynamic morphologic evolution and phase transition of the LiMn2O4 particles during cyclic voltammetry measurement were successfully observed. This technique will provide the possibility of probing physicochemical phenomena of the battery materials and other surface/interface processes such as the formation of the solid electrolyte interphase layer.