Provided are an electrolyte for a rechargeable lithium battery including a non-aqueous organic solvent, a lithium salt, and an additive, wherein the additive is a composition including a first compound and a second compound, the first compound is a cesium salt compound, and the second compound includes a second compound represented by Chemical Formula 1A or Chemical Formula 1B, and a rechargeable lithium battery including the same.
Details of the above Chemical Formula 1A and Chemical Formula 1B are as described in the specification.