| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a secondary battery capable of improving charge/discharge cycle characteristics by preventing micro short circuit at a center side of a winding, in case an alloy material is used as an anode active material. <P>SOLUTION: A cathode 21 has an insulating protection member 30 at an outer peripheral face exposed region 21D and an inner peripheral face exposed region 21E at the center side of the winding. A width of the protection member 30 is formed larger than that of a cathode collector 21A within the range of 0.54 mm or more and 5 mm or less. The outer peripheral face exposed region 21D and the inner peripheral face exposed region 21E at the center side of the winding easily deformed by the expansion and contraction at charging and discharging, and a width direction end part 21F easily contacting with an anode 22 when the width of the cathode 21 is expanded by the charging or discharging are protected and micro short circuit is restrained. It is preferable that the protection member 30 is arranged at a part of the outer peripheral face exposed region 21D and the inner peripheral face exposed region 21E in longitudinal direction thereof. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
