| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery that can enhance reliability over a long term without affecting normal control of the composition of a negative active material and a battery.SOLUTION: A lithium ion secondary battery has an electrode group and a battery can in which the electrode group is mounted. The electrode group has a cathode electrode having a cathode mixture layer and an exposure portion of a cathode electrode foil, and an anode electrode having an anode mixture layer and an exposure portion of an anode electrode foil, the cathode electrode and the anode electrode being flatly wound through a separator. The exposure portion of the cathode electrode foil is provided at the outside of the cathode mixture layer in the width direction, and a belt-like member sandwiched by the boundary between the cathode mixture layer and the exposure portion of the cathode electrode foil and the inner surface of the battery can is provided at the end edge of the cathode mixture layer in the width direction. |
