Low Li+ binding affinity: An important characteristic for additives to form solid electrolyte interphases in Li-ion batteries

Calculations are made of the lowest unoccupied molecular orbital (LUMO), chemical hardness (η), dipole moment (μ), and binding energy with a Li+ ion for 32 organic molecules that are electrolyte additives for solid electrolyte interphase (SEI) formation in lithium-ion batteries (LIBs). The results confirm that both the LUMO and η values are critical indicators of suitable SEI formation. The μ values of the additives are generally smaller than those of widely used solvents in LIBs. It is found that a low Li-ion binding affinity may be an important characteristic for SEI-forming additives. Li+ binding affinity is proposed as a factor in the computational screening process used to obtain promising additives.

Research highlights► Low Li-ion binding affinity is a predominant characteristic. ► The weak binding of Li+-additive makes the Li+ desolvation reaction easier. ► We propose the Li+ binding affinity as a screening factor.