TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Electrolyte: The electrolyte comprises (vol.%): modified polyether silicone oil (1 - 70, preferably 5 - 50), and carbonate (preferably cyclic carbonates (30 - 95, preferably 50 - 90) and/or linear carbonates (preferably 5 - 70, preferably 10 - 65)). The electrolyte additionally comprises a carbonate-modified silicone oil and fluoroethylene carbonate.Preferred Components: The silicone oil has a flash point of greater than or equal to 120degreesC. The cyclic carbonate is a fluorinated cyclic carbonate and present an amount of 0.1 - 25 (preferably 0.5 - 10) vol.%. The lithium salt comprises at least one selected from LiPF6, LiBF4, Li(N(SO2C2F6)2), Li(B(OCOCF3)4), Li(B(OCOC2F5)4), LiPF6 and/or Li(N(SO2C2F5)2). The lithium salt is included at a concentration of 0.5 - 2 mol/l. EXAMPLE - A solution was prepared by mixing LiPF6 (1.3 mol/l) with mixing solvent of diethyl carbonate (DEC) and ethylene carbonate (EC) in a volume ratio of 70:30. The modified polyether silicone oil including CH3-Si(CH3)2-O-Si((CH3)(CH2-CH(CH3)CH2-O-(CH2CH2O)2-CH3))-O-Si(CH3)2-CH3 (10 mass%), was added to prepare an electrolyte (test). A comparative (control) electrolyte was prepared in similar manner of the test electrolyte, without addition of the modified polyether silicone oil. A positive electrode including LiCoO2 for a positive active material, polyvinylidene fluoride for a binder, carbon black for a conductive agent on an Al foil for a current collector, and a negative electrode including graphite for a negative active material and polyvinylidene fluoride for a binder on a Cu foil current collector, were spirally wound while positioning a polypropylene separator between the positive and negative electrodes. The positive electrode, negative electrode, and separator were inserted into a battery case, and then the test/control electrolytes were injected. The injecting holes of the battery cases were sealed to fabricate the test/control batteries with designed charge and discharge capacity of 820 mAh. The test/control battery cells were charged at 0.2C to the cut-off voltage of 4.2V under constant current and then charged for 9 hours under constant voltage. Then the battery cells were discharged at 0.2C to the cut-off voltage of 2.75V. Initial discharge capacity of test/control battery cell was measured and found to be 866/879 respectively. Result for overcharge test of test/control battery cell was found to be No rupture/rupture respectively. Thus, the results showed that the rechargeable lithium battery cell including the test electrolyte showed high initial capacity and high safety at overchage, as compared to the control.