Data for the publication "MgB2Se4 Spinels (B = Sc, Y, Er, Tm) as Potential Mg-Ion Solid Electrolytes – Partial Ionic Conductivity and the Ion Migration Barrier"

Description Datasets

Datasets are obtained from X-ray diffraction (XRD), Rietveld analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR) spectroscopy, electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), chronopotentiometry (CP) and linear sweep voltammetry (LSV).

Abstract

The magnesium chalcogenide spinel MgSc~2~Se~4~ with high Mg-ion room-temperature conductivity has recently attracted interest as solid electrolyte for magnesium ion batteries. Its ionic/electronic mixed-conducting nature and the influence of the spinel composition on the conductivity and Mg^2+^ migration barrier are yet not well understood. Here, results from a combined experimental and computational study on four MgB~2~Se~4~ spinels (B = Sc, Y, Er, Tm) are presented. The room-temperature ionic conductivities (σ~ion~ = 2x10^–5^–7x10^–5^ S cm^–1^) of the spinels are accurately measured, as electron transport is effectively suppressed by purely Mg-ion conducting electrode interlayers. Using the same approach, reversible Mg plating/stripping as well as good electrochemical stability are achieved. Driven by the good accordance of the computationally and experimentally obtained Mg^2+^ migration barriers E~a~(th) and E~a~, respectively, further periodic density functional calculations are performed on the MgB~2~Se~4~ spinel system, revealing the role of trigonal distortion on the migration path geometry and E~a~(th). These findings provide deeper understanding how to reach small Mg^2+^ migration barriers E~a~ in the MgB~2~Se~4~ spinels.