LAUSR

Abstract High working potential and temperature put nonnegligible threats on electrochemical stability and safety performance of lithium ion batteries (LIBs). In this paper the carbonate-based electrolyte is modified with LiF additive to improve the comprehensive properties of cells in which a metallic lithium anode is paired with a LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) cathode under the extreme conditions of high cut-off potential, high current rate or even high temperature (55 °C). The tests of self-discharge behavior and chronoamperometry present that the introduction of LiF additive contributes to relieving self-discharge of cells and side reactions on the surface of electrodes. The cells with 100 ppm exhibit the improved cyclic performance (81.6% of initial capacity 195.4 mAh g −1 ), high-rate capability (150.6 mAh g −1 at 8 C) and high-temperature performance. Additionally after 100 cycles over 3.0–4.6 V, the results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) on electrodes reveal that the cathodes in LiF-reinforced electrolyte retain more stable layered structure and more intact spherical secondary particles than those in original electrolyte.