Dataset of "Wide electrochemical stability window of boron-doped microcrystalline diamond electrode in NaNO3 water-in-salt electrolytes"

Expanding the electrochemical stability window (ESW) of aqueous electrolytes can contribute to the high energy density of electrochemical energy storage devices and supercapacitors (SC). Here we demonstrate unique electrochemical interaction in two and three-electrode configurations of sodium nitrate (NaNO3) water-in-salt (WiS) electrolyte in a wide range of concentrations (1-12 m) with an electrode made of boron-doped microcrystalline diamond (B-MCDE, grain size ~ 1 m) deposited by a microwave plasma Chemical Vapor Deposition (CVD) process. Compared to a commercial glassy carbon electrode (C-GCE), the extension of ESW up to ~ 3 V was obtained. In the frequency range of 10 mHz - 100 kHz, the B-MCDE also demonstrated better conductive (down to Rct of 50 Ω) and capacitive (up to Cdl 3.2 µF) properties compared to C-GCE for all investigated electrolyte concentrations, where the appropriate equivalent circuit was identified. The best performance was obtained for 8 m WiS concentration at neutral pH and room temperature, whereas 12 m WiS was unstable, as confirmed by Raman spectroscopy. The expanded ESW and superior performance of B MCDE are explained by its high quality material properties and nanostructured, almost nanoporous surface (feature size < 100 nm) formed in the WiS electrolyte. The results reveal that, with a well-controlled quality, boron-doped diamond electrodes provide apparent advantages for water-in-salt SCs.Dataset contains PowerPoint presentation with several images, opj file with the raman data, SEM crossection image and zip with the SEM data.micrographs; cross sections of model simulation or prediction (MSP).