Method for establishing lithium secondary battery charging protocol, battery management system, battery pack, and battery cell charging device

Abstract

Systems and methods for charging protocols for secondary batteries are provided including: measuring an open-circuit voltage (Vref) according to a state-of-charge (SOC) for a two-electrode cell, charged with a reference current; measuring second open-circuit voltages (V) according to the state-of-charge when charging the cell with a plurality of different charging currents; calculating an internal resistance value (R) according to the state-of-charge using an equation (R)=(V−V)/Ic for the different charging currents, wherein Ic is a value for the different charging currents, and computing a charging current-specific internal resistance profile mapping the internal resistance value according to the state-of-charge for the different charging currents; and identifying, for the charging current-specific internal resistance profiles, each inflection point, determining a lowest resistance value among the inflection points as a reference value, and determining, for the computed charging current-specific internal resistance profiles, the state-of-charge having the reference value as a limit state-of-charge.