This study applied two in operando techniques to reveal the reaction kinetics of solid electrolyte interphase formation on electrolyte and benzimidazole salt additives. The results obtained from studying interface effects reveal changes in solid electrolyte interphase mass, reflection angle, and reflection intensity within the electrolyte additives in accordance with electron-withdrawing and electron-donating substitutions. Surface plasma resonance results reveal that the electrolyte containing the electron-withdrawing salt additive exhibited the highest rate constant (774 s−1) of the binding reaction between the benzimidazole additive and Au surface, indicating the strong reaction effects on Au. The electrolyte containing the electron-withdrawing salt additive accelerates and facilitates the dissociation reaction of the ethylene carbonate–lithium ion (EC–Li+) ionic cluster. From the quartz crystal microbalance results, the electrolyte containing the electron-withdrawing salt additive shows the greatest solid electrolyte interphase mass (14.84 μg cm−2), representing the intense dissociation reactions of the EC–Li+ ionic cluster as well as solid electrolyte interphase formation and recombination. In this study, selecting a high rate constant and high binding strength of the EC–Li+ ionic cluster on the electrode surface enhance solid electrolyte interphase formation and battery performance.