Lithium-excess cation disordered rock-salt materials have received much attention because of their high-capacity as a candidate for cathodes for lithium-ion batteries.The ultra-high specific capacity comes from the coordi-nated charge compensation of both transition metal and lattice oxygen.However,the oxygen redox at high voltage usually leads to irreversible oxygen release,thereby degrading the structure stability and electrochemical performance.Lithium-excess Li1.14Ni0.57+0.5xTi0.19-0.5xMo0.10O2-xFx(x=0,0.05,0.10,0.15,and 0.20)with different amounts of fluorine substitution were synthesized.Among them,Li1.14Ni0.620Ti0.140Mo0.10O1.85F0.15 exhibits a lower capacity decline,better rate performance,and lower structure damage.The effects of fluorine substitution on the electrochemical property and structural stability were systematic studied by x-ray photoelec-tron spectroscopy and in situ XRD etc.Results show that fluorine substitution reduces the average valence of the anion,allowing a larger proportion of low-valent redox active transition metals,increasing the transition metal redox capacity,inhibiting irreversible oxygen release and side reaction.Fluorine substitution further improves the structural stability and suppresses lattice deformation of the material.