Powder bismuth-based anode material for magnesium-ion batteries and its properties

Abstract

In this work an intercalation anode material synthesized on the base of the powdered bismuth is presented. The uniformly distribution of carbon paste suspension over the substrate surface was found out by scanning-electron microscopy. The regularities of electrochemical intercalation and deintercalation of magnesium ions into the electrode created on the base of powdered bismuth in a solution of 0.25 mol/L Mg(N(SO₂CF₃)₂)₂ on the base of acetonitrile were studied. The cyclic voltammograms with the results of scanning electron microscopy and atomic emission analysis indicate that in the cathode area the reduction processes proceed with the formation of an intermetallic compound – Mg_xBi_y; two peaks were observed at the reverse course which were conceivably corresponding to two-stage magnesium oxidation. According to cyclic voltammograms by the difference in the potential of peaks in the forward and reverse directions it was established that the processes of reduction and oxidation of magnesium ions into intercalation material were irreversible. The diffusion coefficients of intercalation and deintercalation into the electrode material were calculated using the Rendles-Shevchik equation; they were 3.12·10^-11 sm²/s and 1.85·10^-11 sm²/s, respectively. X-ray diffraction (XRD) results demonstrated the cubic structure of the bismuth crystal lattice with altered parameters corresponding to inter-metallide formation. At galvanostatic cycling of the synthesized anode material a capacity of up to 104 mA·h·g^-1 at current load 1C was achieved. Such results can be a good indicator for the development of magnesium-ion power sources.