Hybrid Organic–Inorganic Functionalized Dodecaboranes and Their Potential Role in Lithium and Magnesium Ion Batteries

Abstract

Currently, development of rechargeable Mg ion batteries is an important and hot topic of research. For its development, the major challenge is to find suitable stable electrolyte anions, which possess solubility in low-polarity solvents. In this context, new organic and hybrid organic–inorganic functional derivatives of closo dodecaborane dianion, namely B12X122– (X = −C≡CH, −C≡C–CN, and −C≡C–BO), are proposed here using density functional theory. The second excess electron in B12(C≡C–CN)122– and B12(C≡C–BO)122– is very strongly bound with the ΔE2 value of 4.90 and 5.14 eV, respectively, in the gas phase, which is almost six-times higher than that of B12H122– (0.81 eV). The various other factors responsible for the high stability of these predicted dianions have been explained in detail. We have explored the implications of these stable dianions as electrolytes in the Li and Mg ion batteries, and the results are found to be highly promising. Among all the dianions considered here, B12(C≡C–BO)122– and B12(C≡C–CN)122– are the most suitable choices as the electrolyte of the Li and Mg ion batteries, as the Li+/Mg2+ salt of these two dianion requires very less energy to dissociate into corresponding cation and anion. In addition, the oxidation potential of B12(C≡C–BO)122– and B12(C≡C–CN)122– dianions versus Mg2+/Mg is very high (12.91 and 12.58 V, respectively). Present work reveals that it is possible to design desired multiply charged stable anions for appropriate applications through suitable organic–inorganic functionalization.