Understanding the characteristics of high-voltage additives in Li-ion batteries: Solvent effects

Calculations are made of the ionization potential (IP) and the oxidation potential (Eox) values of 108 organic molecules that are potential electrolyte additives for the overcharge protection of lithium-ion batteries (LIBs). The calculated Eox values are in close agreement with the experimental ones, where the root-mean-square deviation is 0.08 V and the maximum deviation is 0.15 V. The molecules exhibiting high Eox (>4.5 V) show one of the following two features: (1) IP > 7.70 eV or (2) IP < 7.70 eV with a relatively large molecule size. Consideration of bulk solvent effects, in particular the electrostatic attraction between solute and solvent, is crucial in determining Eox. Considering its accuracy and reliability, the density functional calculation is recommended as a useful tool for screening electrolyte additives for LIBs.