| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a wound lithium ion secondary battery with small performance degradation. <P>SOLUTION: The lithium ion secondary battery comprises a wound electrode group having a positive electrode, a negative electrode, and a separator (1a), a shaft core around which the wound electrode group is wound, and a battery can (3) housing the wound electrode group and the shaft core (2). The lithium ion secondary battery is cylindrical, and since the diameter at the central part of the shaft core in the longitudinal direction is smaller than the diameters at both ends of the shaft core in the longitudinal direction, performance degradation of the secondary battery can be minimized when the electrode expands or contract. <P>COPYRIGHT: (C)2013,JPO&INPIT |
