Designing stable closo-B12 dianions in silico for Li- and Mg-ion battery applications

Abstract

Ligand engineering based on a closo-B₁₂-cage has been practiced in this work to design a series of stable gas-phase dianions [B₁₂(ECX)₁₂]²⁻ (E = N, P, and As; X = O, S, and Se) via ab initio calculations. The calculated second electron affinities ranging from 1.2 to 3.4 eV indicate that these dianions are electronically stable against electron auto-detachment. Their electronic structures were analyzed based on molecular orbitals and natural bond orbitals. We found that in these designer dianions, the ECX ligands bind the B₁₂-cage via B–E covalent interactions. We simulated the photoelectron spectra of these dianions and discussed the potential application of [B₁₂(NCX)₁₂]²⁻ (X = O, S, and Se) salts as electrolytes in Li- or Mg-ion batteries.