| 摘要 |
A lithium ion secondary battery includes an electrode assembly having a first electrode plate, a second electrode plate, and a separator interposed therebetween; a case in which the electrode assembly is received; a cap plate formed with a terminal hole and an electrolyte injection hole; and a washer installed at an upper portion of the cap plate, the washer having at least one transparent part formed thereon or having a transparent part formed on an entire surface thereof. |
