Patent ID: 7575830

Claim:
A lithium secondary battery comprising: a negative electrode comprising a negative electrode active material layer comprising alloy particles as an active material comprising silicon as a major component and a negative electrode current collector; and a positive electrode comprising a positive electrode active material layer and a positive electrode current collector, wherein the positive electrode active material layer and the negative electrode active material layer satisfy the following relationships: ( C N ×D N )/( C P ×D P )≦8 C N ×D N =1,200 to 2,500 mAh/cm 3 C N =1,000 to 2,200 mAh/g D N =0.9 to 1.5 g/cm 3 C P =80 to 200 mAh/g D P =2.5 to 3.5 g/cm 3 C P ×D P =200 to 700 mAh/cm 3 where C N represents a capacity per unit weight of the negative electrode active material layer, D N represents the density of the negative electrode active material layer; C P represents a capacity per unit weight of the positive electrode active material layer, and D P represents the density of the positive electrode active material layer, and wherein the alloy particles comprise silicon and tin.