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The data set comprises a series of measurements of electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) for the purpose of characterizing the microstructure of lithium and sodium metal, as well as electrochemically deposited alkali metals at solid-solid interfaces. Electrochemical impedance spectroscopy (EIS) and galvanostatic electrochemical data were collected using a VMP300 potentiostat manufactured by Biologic (France). Scanning electron microscopy (SEM) images were obtained using a high-resolution field-emission Gemini SEM 560 instrument from Carl Zeiss Microscopy GmbH (Germany), and microstructural analysis was conducted using a Symmetry 3 EBSD detector from Oxford Instruments (United Kingdom).    

The data set is structured in accordance with the figures presented in the corresponding manuscript, which is linked in the respective record for reference. 


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The following section provides an overview of the data and file types contained within the specified zip folder. 

Figure 1.zip: SEM images of different lithium and sodium metal foils. File type .tif

Figure 2.zip: EBSD maps of different lithium and sodium foils. File type .h5onia

Figure 3.zip: EBSD maps of electrochemically deposited lithium and sodium at SS|LPSCl, Cu|LLZO and Al|NZSP interface and the corresponding galvanostatic potential profiles. The folder contains data with file type .h5onia, .txt, .xlsx.

Figure 4.zip: In situ EBSD maps of electrochemically deposited lithium at Cu|LLZO interface and electrochemical dissolution of sodium at a Na|NZSP interface and their corresponding galvanostatic potential profiles. The folder contains data with file type .h5onia, .txt.

Supplementary Information Figure 1.zip: EBSP from pattern matching of sodium and Lithium. File type .bmp.

Supplementary Information Figure 2.zip: EBSP from pattern matching of sodium with different phases including Na, Na2O and Na2O2. File type .png.

Supplementary Information Figure 3.zip: EBSD maps from different spots of a sodium foil. File type .h5onia

Supplementary Information Figure 4.zip: EBSD maps of quenched sodium over time. Each time point has been analyzed at several points. File type .h5onia

Supplementary Information Figure 5.zip: Data structure notation. File type .txt.

Supplementary Information Figure 6.zip: EBSD maps of cross-sections of quenched sodium at different times and spots. File type .h5onia

Supplementary Information Figure 7.zip: Data structure notation and EBSD maps of cross-sections of sodium after a second milling of cross section by FIB. File type .h5onia and .txt.

Supplementary Information Figure 8.zip: Data structure notation, SEM images and EBSD maps of cross-sections of sodium foil  File types .h5onia, .txt and .tif.

Supplementary Information Figure 9.zip: Electrochemical impedance spectroscopy data before and after deposition of lithium and sodium at SS|LPSCl, Cu|LLZO and Al|NZSP interface.  File type .txt, .xlsx.

Supplementary Information Figure 10.zip: EBSD maps of cross-sections of electrochemically deposited sodium before and after warm up. File type .h5onia

Supplementary Information Figure 11.zip: Data structure notation. File type .txt.

Supplementary Information Figure 12.zip: EBSD maps of cross-sections of electrochemically deposited lithium at Cu current collector and quenched lithium foil. File type .h5onia

Supplementary Information Figure 13.zip: SEM images of surface of NZSP and LLZO. File type .tif

Supplementary Information Figure 14.zip: SEM images of preparation process for in situ EBSD analysis of electrodeposited Li at the Cu|LLZO interface. File types .tif and .png.

Supplementary Information Figure 15.zip: Data structure notation and EBSD maps of re-polished Li|LLZO interface after the in situ EBSD experiment have been finished. File type .h5onia and .txt.

Supplementary Information Figure 16.zip: Data structure notation, FSE images and EBSD maps of in situ deposited sodium at a Na|NZSP interface. File type .h5onia, .txt and .jpg. 

Supplementary Information Figure 17.zip: SEM images of Na|NZSP cross-section during in situ electrodeposition of sodium at a Na|NZSP interface using different detectors, namely FSE, LE-BSE and SE. File type .jpg and .tif.



### Information for data file type for EBSD 


All EBSD data are given in a HDF4 file format (.h5onia). The data can be excess via Oxford instruments AZtec ecosystem as well as with third-party software. 

A detail description of the structure of the file format can be found via the following link: 

https://github.com/oinanoanalysis/h5oina