US Patent 7575830 Lithium secondary battery

There is provided a lithium secondary battery with a negative electrode which comprises a negative electrode active material layer comprising alloy particles comprising silicon and tin and having an average particle diameter of 0.05 to 2 μm as an active material, and a negative electrode current collector, wherein the negative electrode active material layer has a storage capacity of 1,000 to 2,200 mAh/g and a density of 0.9 to 1.5 g/cm3 and which thereby has a high capacity and a good cycle-characteristic. Thus, a lithium secondary battery having a high capacity and a long life and so designed as to exhibit these characteristics at the same time is provided.