| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a compact and high capacity cylindrical lithium ion secondary battery that has a simplified structure of an electrode group. <P>SOLUTION: In the cylindrical lithium ion secondary battery including a positive electrode and a negative electrode, a separator disposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte, and having the electrode group rolled up with the use of a core, the electrode group has a radius of curvature of 2.0 mm or less at an outermost circumference, the positive electrode and the negative electrode each comprise a mix containing an active material which is formed on both surfaces of a collector, the electrode group has the negative electrode at an innermost circumferential portion, the negative electrode has no mix formed on an inner side of rolling at the innermost circumferential portion and has a radius of curvature of 0.2 mm to 0.6 mm, and the positive electrode has an active material amount in the mix formed on an inner side of rolling of 40% to 91% of an active material amount in the mix formed on an outer side of rolling. <P>COPYRIGHT: (C)2013,JPO&INPIT |
