| 摘要 |
PROBLEM TO BE SOLVED: To provide an initial charging method of a lithium secondary cell with good efficiency improving the cell property like capacity keeping rate, and to provide a manufacturing method of the lithium secondary cell applying the above initial charging method. SOLUTION: For the initial charging method, at the time of the first cycle charging of conditioning, during the period after initiation of charging and before the stage of inserting lithium into a negative electrode activator (carbonaceous material), or within the range of charging period starting from initiation of charging up to the time that the potential of the negative electrode becomes 0.3 V, a slow charging period within which, the charging current is made 0.2C or less, is set up. By forming a solid SEI film on a negative electrode during the slow charging period, the capacity deterioration of the cell is improved. High production efficiency is obtained because the charging current can be made to exceed 0.2C except the slow charging period. The production efficiency is improved especially when the negative electrode is made of graphite. |
