Rechargeable lithium battery

A rechargeable lithium battery, comprising:

• an electrolyte solution comprising a non-aqueous organic solvent, a lithium salt, and an additive;
• a positive electrode comprising a positive electrode active material;
• and
• a negative electrode comprising a negative electrode active material,
• wherein the additive comprises one or more selected from a compound represented by Chemical Formula 1A and a compound represented by Chemical Formula 1B, and
• the positive electrode active material comprises a lithium nickel manganese-based oxide represented by Chemical Formula 2, and
• a charging upper limit voltage of the rechargeable lithium battery is about 4.4 V to about 4.7 V:
• wherein, in Chemical Formula 1A, R1 to R8 are each independently hydrogen, a halogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted C6 to C20 aryl group, and
• wherein, in Chemical Formula 1A and Chemical Formula 1B, R9 to R17 are each independently a substituted or unsubstituted C1 to C10 alkyl group or a substituted or unsubstituted C6 to C20 aryl group;
• LiaNixMn1-x-yAyO2±bXc Chemical Formula 2
• wherein, in Chemical Formula 2,
• 0.9≤a≤1.2, 0≤b≤0.1, 0≤c≤0.1, 0.7≤x≤0.95 and 0≤y<0.3,
• A is one or more element selected from Li, B, Na, Mg, Al, Ti, and Si, and
• X is one or more elements selected from S, F, P, and Cl.