Rechargeable lithium battery

Manufacture of A Positive Electrode

[0091]A positive active material layer composition was prepared by mixing polyvinylidene fluoride (PVdF), carbon black, and a mixture of 80 wt % of LiCoO2 and 20 wt % of LiNi0.5Co0.2Mn0.3O2, in a weight ratio of 4:4:92 and dispersing the obtained mixture in N-methyl-2-pyrrolidone. The positive active material layer composition was coated on a 20 μm-thick aluminum foil, dried, and compressed to manufacture a positive electrode.

Manufacture of a Negative Electrode

[0092]A negative active material layer composition was prepared by mixing polyvinylidene fluoride (PVdF) and a mixture of 90 wt % of graphite and 10 wt % of Si—Fe alloy (a mole ratio of Si:Fe=4:6) (CV4, 3M) in a weight ratio of 8:92 and dispersing the resulting mixture in N-methyl-2-pyrrolidone. The negative active material layer composition was coated on a 15 μm-thick copper foil, dried, and compressed to manufacture a negative electrode.

Preparation of an Electrolyte Solution

[0093]An electrolyt

[0095]A rechargeable lithium battery cell was manufactured according to the same method as Example 1 except for preparing the electrolyte solution by adding an additional 3 parts by weight of LiB(C2O4)F2 based on 100 parts by weight of the mixed solvent.

[0096]A rechargeable lithium battery cell was manufactured according to the same method as Example 1 except for using a separator manufactured as follows.

[0097]The separator was manufactured by coating a coating material prepared by mixing 2 parts by weight of Al2O3 (having an average particle diameter of 200 μm) and 5 parts by weight of polyvinylidene fluoride (PVdF) based on 100 parts by weight of a substrate on one surface of the polyethylene substrate.