| 摘要 |
<P>PROBLEM TO BE SOLVED: To improve the safety of an electric storage device by limiting the movement of ions to the end face of a negative electrode from the surface of a positive electrode. <P>SOLUTION: The electric storage device 10 has a positive electrode 13 and a negative electrode 14 opposite thereto. A separator 15 is provided between the positive electrode 13 and the negative electrode 14. The surface 14b of the negative electrode is formed to be larger than the surface 13b of the positive electrode in such a manner that a positive electrode outer edge 13c and a negative electrode outer edge 14c are apart from each other by 2 mm or more. By this configuration, an ion restricting section 15b is formed at the outer peripheral portion of the separator 15. As shown by an arrow A, a lithium ion is necessary to pass through the lithium restricting section 15b so that it can reach the end face 14a of the negative electrode from the surface 13b of the positive electrode. However, the wider ion restricting section 15b results in higher resistance of the moving path of lithium ions. Accordingly, the movement of lithium ions toward the end face 14a of the negative electrode can be restricted, when the device is charged with a large current, whereby the deposition of metal lithium on the end face 14a of the negative electrode can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT |
