The electrode/electrolyte interfaces play an important role in the electrochemical reaction kinetics to alleviate the severe polarization and voltage hysteresis in lithium primary batteries. Herein, C5F5N is proposed as an electrolyte additive to tune the characteristics of the electrode/electrolyte interfaces. The Li/CFx primary battery with C5F5N additive exhibits an excellent discharge‐specific capacity of 981.4 mAh g−1 (0.1 C), a remarkable high‐rate capability of 598 mAh g−1 (15 C), and an outstanding energy/power density of 1068.7 Wh kg−1/24362.5 W kg−1. It also shows remarkable storage performance with 717.2 mAh g−1 at 0.1 C after storage at 55 °C for 2 months. The excellent performance of the Li/CFx batteries is closely related to the improved and stable Li3N/LiF‐rich homogeneous interfaces induced by the C5F5N additive, which results in uniform distribution of Li+ flux, facilitated electrochemical kinetics, and increased rate capability of Li/CFx battery. Therefore, C5F5N is expected to be a promising electrolyte additive, and the related electrode/electrolyte interface engineering provides an effective and facile strategy to increase the performance of the lithium primary battery.