Data for the publication "High Room-Temperature Magnesium Ion Conductivity in Spinel-Type MgYb2Se4 Solid Electrolyte"

Description Datasets Datasets are obtained from X-ray diffraction (XRD), Rietveld analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), nuclear magnetic resonance (NMR) spectroscopy, electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), chronopotentiometry (CP) and linear sweep voltammetry (LSV), flame atomic absorption spectrometry (FAAS), and total reflection *X*-ray fluorescence spectrometry (TXRF). Abstract We present three magnesium selenide spinels, MgSc~0.4~Y~0.4~Er~0.4~Tm~0.4~Yb~0.4~Se~4~, Mg~0.75~Sc~2~Se~3.5~Br~0.5~ and MgYb~2~Se~4~, as potential solid electrolytes (SE) for magnesium batteries. In particular, the latter spinel exhibits a room-temperature ionic conductivity exceeding 10^–4^ S cm^–1^ and a low Mg^2+^ migration barrier of 364 meV. The high ionic mobility is attributed to the low magnesium insertion energy revealed by density functional theory (DFT), which indicates a weak binding interaction between magnesium ions and the host lattice. Furthermore, likethe two multicomponent spinels, MgYb~2~Se~4~ exhibits lower electronic conductivity compared to previously studied MgB~2~Se~4~ spinels (B = Sc, Y, Er, Tm) and a good electrochemical stability, making it a strong candidate for Mg^2+^ SE applications.