US Patent 11056901 Method for charging secondary battery using multiple charging sections

A method of charging a secondary battery, including first, second and third charging sections in which a CC-charging performed as first, second, and third Crate (C1, C2, C3), respectively, is supplied until the voltage of the secondary battery reaches a respective first, second and third charging cutoff voltage (V1), (V2), (V3) and a CV-charging is performed as the respective charging C-rate gradually decreases in response to reaching the respective charging cutoff voltage (V1), (V2), (V3), wherein the charging cutoff voltage satisfies the V1=n−(0.25˜0.15), V2 n−(0.2˜0.1), and V3=n (here, ‘n’ is an electric potential at the full charge of the secondary battery), and V1<V2<V3.