Síntesis y caracterización del Mg(BOB)2 como electrolito para baterías recargables de iones de magnesio

Abstract

The solvent-free process of obtaining the magnesium bis(oxalate)borate salt (Mg(B(C2O4)2)2, Mg(BOB)2) was carried out, which is potentially viable for use as an electrolytic material in rechargeable magnesium ion batteries (RMIB). The synthesis used was by solid-state, where, in the first step, its three precursors were manually mixed in an agate mortar homogeneously: oxalic acid, boric acid, and magnesium hydroxide with a molar ratio of 4:2:1, respectively. In the second step, to avoid prolonged exposure to ambient humidity because hygroscopic compounds were used, they were dried in a vacuum oven at 60 °C for a continuous hour, followed by a heat treatment at 110 °C for 3 h to eliminate residual water prior to the synthesis temperature of 150 °C . The synthesized Mg(BOB)2 was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results obtained by Fourier transform infrared spectroscopy (FTIR) within the wave number range of 4000–400 cm−1 confirmed the presence of the functional groups of Mg(BOB)2, identified by their characteristic absorption bands: C=O, C-O-B-O-C, O-B-O, and B-O. In addition, the Mg(BOB)2 powder was used to prepare a liquid electrolyte with the solvent tetrahydrofuran (THF) and was evaluated in three-electrode cells as well as in prototype half-cells, characterized with cyclic voltammetry (CV) curves.