Charging method for lithium ion secondary battery and charging control system therefor, and electronic apparatus and battery pack having charging control system

A battery pack comprising a charging control apparatus for a lithium ion secondary battery,

• the charging control apparatus for a lithium ion secondary battery, executing:
• a first step of charging the lithium ion secondary battery by increasing or decreasing a charging current until a predetermined set voltage is reached, and a second step of charging the lithium ion secondary battery that has reached the set voltage with a constant voltage while decreasing the charging current to maintain the set voltage,
• wherein, in the first step, IA, IB, and IC satisfy a relationship IA>IB and IB<IC, where IA represents an average charging current value in a range where a state of charge (SOC) of the lithium ion secondary battery is 0%≤SOC<40%, IB represents an average charging current value in a range where the state of charge is 40%≤SOC≤60%, and IC represents an average charging current value in a range where the state of charge is 60%<SOC, and
• wherein, in the first step, a ratio of IMAX to IMiN (IMAX/IMIN) is 1.01 to 3.00, where IMAX represents a maximum value of the charging current value and IMINrepresents a minimum value of the charging current value.