The electrochemical stability of the UiO66-MgIL ionogel electrolyte and the sandwich-type layered UiO66-MgIL|MgB2Se4|UiO66-MgIL pellets against Mg metal was measured via linear sweep voltammetry (LSV). For this purpose, asymmetric cells were assembled using Mg foil as counter as well as reference electrode and stainless-steel current collectors as working electrode. Then, starting from the open circuit voltage (OCV) the oxidation/reduction current was recorded to 5 V/-5 V (vs. Mg 2+ /Mg) with a scan rate of 0.1 mVs -1 /-0.1 mVs -1 . As shown in Figure , at room temperature, the oxidation current starts to grow in the range of 3.7 V to 3.9 V, while the reduction current increases significantly starting from -1.1 V to -1.3 V for all cells. Since the current profiles of the sandwich-type cells and the reference cell without spinel layer are quite identical, the UiO66-MgIL appears to limit the stability window, meaning the spinels themselves have possibly a larger range of electrochemical stability. Interestingly, all reduction current profiles show two peaks, which may be attributed to a two-step reduction of UiO66-MgIL electrolyte. At a temperature of 60 °C (Figure ), the reduction peaks merge with each other and the stability windows shrink (start oxidation: