Recovery processing method of lithium ion battery, charge/discharge device, and storage medium

A recovery processing method of a lithium ion battery includes repeating a cycle a plurality of times, and the cycle includes a first process of setting an SOC of the lithium ion battery to a first value that is equal to or less than a value of the SOC where a gradient of an SOC-voltage curve is a minimum value through charging, and a second process of setting the SOC of the lithium ion battery to a second value smaller than the first value through discharging.