| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium secondary battery with high safety, without being broken even by a dendrite deposition. SOLUTION: The mixture of granular MgO of about 2 μm in diameter and granular polyethylene of about 1 μm in diameter are kneaded by adding N- methylpyrolidone(NMP) solution in which polyamide to be binding agent is dissolved and a sheet of proper thickness is formed. This sheet is immersed in the water, NMP is eluted in the water and a through hole is opened at the trace. After this sheet is pulled up from the water and is dried, the sheet is pressed. At this point, thickness of the sheet is adjusted so that thickness of separators 9, 9 after the sheet is pressed may be 10 μm to 100 μm, preferably, 10 μm or more and less than 17 μm. |
