Patent ID: 8338022

Claim:
A lithium secondary battery comprising: a positive electrode formed by disposing a positive-electrode mixture layer containing a positive-electrode active material and a positive-electrode binder, on a surface of a positive-electrode current collector; a negative electrode formed by sintering a negative-electrode mixture layer containing a negative-electrode binder and a negative-electrode active material containing silicon and/or a silicon alloy, disposed on a surface of a negative-electrode current collector, a separator disposed between said positive electrode and said negative electrode; and a nonaqueous electrolyte; wherein an electrode unit obtained by setting said positive electrode and said negative electrode opposed to each other through said separator and rolling them around a rolling core in a spirally rolled state is placed in a cylindrical battery container and wherein a minimum curvature radius of said negative-electrode mixture layer opposed to said positive-electrode mixture layer through said separator in said spirally rolled state is 2.0 mm or larger, wherein, in the portion of said negative-electrode mixture layer having a curvature radius of 2.5 mm or smaller and opposing to said positive-electrode mixture layer through said separator, said negative-electrode mixture layer is provided on only one face of said negative-electrode current collector and is rolled so as to place said negative-electrode current collector in the inner side and said negative-electrode mixture layer in the outer side and said positive-electrode mixture layer is provided on only one face of said positive-electrode current collector and is rolled so as to lace said positive-electrode mixture layer in the inner side and said positive-electrode current collector in the outer side, and in the portion of said negative-electrode mixture layer having a curvature radius of greater than 2.5 mm and opposing to said positive-electrode mixture layer through said separator, said negative-electrode mixture layer is provided on both faces of said negative-electrode current collector, and wherein said minimum curvature radius of said negative-electrode mixture layer is determined by a diameter of said rolling coil.