Stabilization of LiCoO2 Cathodes in High Voltage Lithium Metal Batteries Through 2‐(Trifluoromethyl)Benzamide (2‐TFMBA) Electrolyte Additives

Abstract Increasing the charging cutoff voltage of LiCoO 2 to 4.6 V is significant for enhancing battery density. However, the practical application of Li‖LiCoO 2 batteries with a 4.6 V cutoff voltage faces significant impediments due to the detrimental changes under high voltage. This study presents a novel bifunctional electrolyte additive, 2‐(trifluoromethyl)benzamide (2‐TFMBA), which is employed to establish a stable and dense cathode–electrolyte interface (CEI). Characterization results reveal that an optimized CEI is achieved through the synergistic effects of the amide groups and trifluoromethyl groups within 2‐TFMBA. The resulting CEI not only enhances the structural stability of LiCoO 2 but also serves as a high‐speed lithium‐ion conduction channel, which expedites the insertion and extraction of lithium ions. The Li‖LiCoO 2 batteries with 0.5 wt% 2‐TFMBA achieves an 84.7% capacity retention rate after enduring 300 cycles at a current rate of 1 C, under a cut‐off voltage of 4.6 V. This study provides valuable strategic insights into the stabilization of cathode materials in high‐voltage batteries.