Data for the publication "In Situ Observation of Room-Temperature Magnesium Metal Deposition on a NASICON/IL Hybrid Solid Electrolyte"

Datasets are obtained from X-ray diffraction (XRD), Rietveld analysis, Scanning electron microscopy (SEM), Electrochemicla impedance spectroscopy (EIS), Nudged Elastic Band (NEB), Chronopotentiometry (CP), Linear sweep voltammetry (LSV), X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDS). <strong>Abstract:</strong> Secondary batteries using multivalent cations as ionic charge carriers have attracted increasing attention in recent years due to the high theoretical energy density provided by multi-electron redox reactions. However, the high charge density of these cations inevitably leads to sluggish kinetics of ion migration at room temperature, which poses a challenge for the development of solid-state batteries using multivalent ions. Here, we prepared a magnesium ion conducting hybrid solid electrolyte (HSE) consisting of a new NASICON-structured material, Mg0.5Sn2(PO4)3, and a small amount of Mg ionic liquid. The HSE shows superior room-temperature ionic conductivity of 1.11 · 10−4 S cm−1 and an activation energy of 0.36 eV. Due to good compatibility of the HSE with the magnesium metal anode, symmetric MgǀHSE|Mg cells show stable Mg plating and stripping behavior at room temperature. Using in situ electrochemical scanning electron microscopy measurements the room temperature growth-induced fracture of the HSE was observed, giving unequivocal evidence for magnesium deposition. These results may serve as starting point for understanding the magnesium deposition mechanism on solid electrolyte in solid-state batteries.