LITHIUM ION SECONDARY BATTERY

摘要

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery that can suppress Li deposition at an electrode end portion.SOLUTION: A lithium ion secondary battery includes a positive-electrode mixture layer 12 and a negative-electrode mixture layer 22 facing the positive-electrode mixture layer 12. The positive-electrode mixture layer 12 includes a main surface 12a and an inclined end surface 12b crossing the main surface 12a. The negative-electrode mixture layer 22 has a first region 22a extending along the boundary between the main surface 12a and the inclined end surface 12b, and a second region 22b which is continuous with the first region 22a and located farther away from the inclined end surface 12b than the first region 22a. In a direction D perpendicular to the extension direction of first region 22a, the width W1 of the first region 22a ranges from not less than 1 time to not more than 10 times of the width W2 of the inclined end face 12b. The amount (g/cm) of the negative electrode active material per unit area in the first region 22a is larger than the amount (g/cm) of the negative electrode active material per unit area in the second region 22b.SELECTED DRAWING: Figure 5