The development of high energy density and power density battery is of increasing importance for new generation energy storage system. However, interface instability between cathode and electrolyte remains a challenge for taking advantage of battery consistency. The use of commercial LiPF6-based electrolyte still has the limitations in optimizing interface stability to reduce material performance degradation. Here, self-developed synthetic lithium difluorobis (oxalato) phosphate (LiDFBOP) additive acts as “interface modifier” is adopted in the traditional electrolyte system. The resulting optimized electrolyte formulation exhibits improved electrochemical properties and self-discharge inhibition at high temperatures. Time-of-flight secondary ion mass spectrometry 
(TOF-SIMS) and density functional theory (DFT) calculation is applied to detect the LiDFBOP effect mechanism and distribution of main components of the interface film. It can be demonstrated that the participation of LiDFBOP can lead to a change in the composition of the interface film, which increases the number of components that facilitate the transport of lithium ions. The analytical means for additive effect obtained from this work offer a new opportunity to make an in-depth analysis of film components between cathode and electrolyte.