Completion determination method and discharge end determination method for lithium ion secondary battery, charge control circuit, discharge control circuit, and power supply

摘要

A method for determining completion of charge of a long-duration lithium ion secondary battery is provided. A method for determining completion of charge a lithium ion secondary battery including one lithium compound having an olivine crystal structure as a positive electrode active material, and a graphite material as a negative electrode active material, includes: (S1) charging the battery by an amount of electricity Xc in time Ti1; (S2) stopping the charging for time Yc after completion of (S1), and measuring a battery voltage Vi1 after the time Yc has passed; (S3) charging the amount of electricity Xc in the time Ti1 after completion of (S2); (S4) stopping the charging for the time Yc after completion of (S3), and measuring a battery voltage Vi2 after the time Yc has passed; and comparing Vi2Vi1 with a predetermined voltage difference Vi3 to determine that the charge has been completed when Vi2Vi1Vi3, and determine that the charge has not been completed when Vi2Vi1Vi3.