| 摘要 |
PROBLEM TO BE SOLVED: To provide a moisture removal method of a lithium ion secondary battery which allows for manufacturing cost reduction while contributing to enhancement of battery performance.SOLUTION: A method for removing moisture contained in a lithium ion secondary battery constituted of a positive electrode, a negative electrode, a separator, and an electrolyte includes a moisture removal step for removing moisture in a lithium ion secondary battery by applying a voltage thereto. The moisture removal step has a charge step including a region where charging is performed with a charging voltage higher than the electrolysis voltage of water and lower than a voltage causing negative electrode film formation reaction, and a discharge step including a region where discharge is performed with a discharge voltage lower than the electrolysis voltage of water. In the moisture removal step, the charge step and discharge step are performed alternately, the voltage being applied to the lithium ion secondary battery is changed periodically, and the charging voltage is raised as the time elapsed after start of charging increases. |
