Rational Design of Mono- and Dianions as Superacids Through π-Hole Interaction: Implications for Lithium and Magnesium Ion Batteries

Nature helps generate multiply charged negative ions in abundance. Such negatively charged ions are stable as crystals with charge compensating cations, but in solution, they are protected with solvent molecules. In the gas phase, such multicharged anions are not stable due to strong electrostatic repulsion between the extra electrons. Therefore, the generation of multicharged anions without the influence of environment has been of great interest. The DFT calculations reveal that the π-hole interactions can stabilize the anion of acid using the selenoaldehydic group attached to the cyclopentadiene ring to make them superacids. This strategy helped to generate the stability of dianions without any influence of environmental conditions. It is known that most electrolytes used in Li-ion batteries contain halogens, which are, however, toxic in nature. The designed superacids can also be exploited as lithium ion batteries. These stable dianions showed the binding energies of lithium ions (5.8 and 63.6 kcal/mol) at M06-2X/6-311+G(2d,p) level of theory and can be considered as an efficient electrolyte in lithium ion battery. The study was extended with magnesium ion, which also showed promise to function as an efficient electrolyte in a magnesium ion battery using such anions.