During the development of high-capacity, ultra-stable battery electrode materials, battery performance, and safety issues are proved to be related to the properties of the electrolyte used. The employment of electrolyte additives is to improve the battery electrolyte properties. Representative commercial two-electrode LiCoO2//graphite pouch cells are used to study electrolyte additives represented by fluoroethylene carbonate (FEC) to improve the electrochemical stability of a commercial pouch full cell. The study reveals that a 1.5% FEC electrolyte additive has the best stability in the voltage range of 3.0-4.2 V.