A lithium secondary battery including a cathode; an anode; and an electrolyte disposed between the cathode and the anode, wherein the cathode includes a cathode active material represented by Formula 1, the electrolyte includes a lithium salt; a non-aqueous solvent; and a monofluorosilane compound represented by Formula 2, wherein an amount of the monofluorosilane compound is in a range of about 0.1 percent by weight (wt %) to about 5 wt % based on the total weight of the electrolyte wherein, in Formula 1, 0.9≤x≤1.2, 0.85