| 摘要 |
PROBLEM TO BE SOLVED: To provide a secondary battery capable of sufficiently exerting the effect of a magnetic field applied to a negative electrode active material to achieve excellent output performance.SOLUTION: A secondary battery according to the present invention has a porosity ratio (A1/A2) of 0.74 or higher, where A1 represents the porosity of a positive electrode mixture layer, and A2 represents the porosity of a negative electrode mixture layer. A negative electrode active material has an aspect ratio of 2 or higher, the negative electrode mixture layer has a mixture density lower than 1.5 g/cm, and the perpendicularity of the negative electrode active material in the negative electrode mixture layer is equal to or higher than 1.1. The perpendicularity is represented by m1/m2, where m1 represents the number of particles of the negative electrode active material satisfying 60°≤&thetas;n≤90°, where &thetas;n represents the inclination from the surface of a negative electrode collector, and m2 represents the number of particles of the negative electrode active material satisfying 0°≤&thetas;n≤30°, where &thetas;n represents the inclination from the surface of the negative electrode collector, out of the total number of particles of the negative electrode active material per unit area of the negative electrode mixture layer. |
