Electric vehicles (EVs) are poised to dominate the next generation of transportation, but meeting the power requirements of EVs with lithium ion batteries is challenging because electrolytes containing LiPF₆ and carbonates do not perform well at high temperatures and voltages. However, lithium benzimidazole salt is a promising electrolyte additive that can stabilize LiPF₆ through a Lewis acid–base reaction [1]. The imidazole ring is not eligible for high-voltage applications owing to its resonance structure, but in this research, electron-withdrawing (−CF₃) and electron-donating (−CH₃) substitutions on imidazole rings were investigated. According to the calculation results, the CF₃ substitution facilitates a high electron cloud density on imidazole ring structures to resist the electron releases from bezimidazole in oxidation reactions. In addition, through CF₃ substitution, electrons are accepted from the lattice oxygen (O²⁻) in Lithium-rich (Li-Excess) layer material and O⁻ is converted by electron to a great quantity, which catalyzes the electrolyte reduction and forms a new polyionic liquid solid electrolyte interphase on the cathode’s surface. Furthermore, the cycle performance tested at 60 °C and 4.8 V showed that the CF₃ substitution maintains the battery retention effectively and exhibits almost no fading compared with both the blank electrolyte and the CH₃ substitution. In addition, the results of this study confirm that bezimidazole salt greatly catalyzed the reduction of EC to a stage II reaction, and therefore less Li₂CO₃ formation was found. A possible reaction mechanism is shown in Figure 1.