The invention relates to a rechargeable lithium battery including a positive electrode including a positive active material, a negative electrode including a negative active material, and a non-aqueous electrolyte including a non-aqueous organic solvent and a lithium salt. The positive electrode has an active-mass density of about 3.7 to 4.1 g/cc, and the non-aqueous electrolyte includes a nitrile-based compound additive, a non-aqueous organic solvent, and a lithium salt.