Substituent-Stabilized Organic Dianions in the Gas Phase and Their Potential Use as Electrolytes in Lithium-Ion Batteries

Using density functional theory and a hybrid exchange-correlation functional, a systematic study of the stability and electronic structure of neutral and multiply charged organic molecules, B_nC_6−nX₆ (n=0, 1, 2; X=H, F, CN) and B_nC_5−nX₅ (n=0, 1; X=H, F, CN) is performed. The results show that in addition to the aromaticity of the molecules, substituents play an important role in stabilizing the organic dianion complexes. In particular, it is demonstrated that CN groups are responsible for the stability of organic dianions as it has recently been found to be the case in B-cage compounds such as B₁₂(CN)₁₂ ²⁻ and CB₁₁(CN)₁₂ ²⁻. It is also shown that the stable organic dianions B₂C₄(CN)₆ ²⁻ and BC₄(CN)₅ ²⁻ might be halogen-free electrolytes in Li-ion batteries.