2 Method for evaluating their capacities by calculating mathematically specific elements among resistance elements of equivalent circuit model fitted from impedance spectrum of secondary batteries

摘要

PURPOSE: A method for selecting (sorting) the initial capacity of a secondary battery by using the specific resistance factor calculation of the equivalent circuit model simulated from impedance spectrum is provided, to separate effectively the batteries having different initial discharge characteristics. CONSTITUTION: The method comprises the steps of partially charging secondary batteries below the full charge voltage or preparing secondary batteries partially discharged below the full charge voltage; measuring the impedance spectrum of the prepared batteries; obtaining the specific internal resistance factors from the equivalent circuit model simulated from the measured impedance spectrum and calculating mathematically; and comparing the obtained value of the resistance factor with the initial discharge capacity graph of batteries to select (sort) the initial discharge capacity of batteries of equal group.