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

A charge/discharge device electrically connected to a lithium ion battery having a positive electrode and a negative electrode and in which performance is decreased by a residue of lithium ions in the negative electrode,

• the charge/discharge device comprising a controller configured to perform charge/discharge of the lithium ion battery,
• wherein the controller repeats a cycle a plurality of times, the cycle including:
• a first process of setting an SOC of the lithium ion battery to a first value, that is equal to or smaller than a value of the SOC in which a gradient of the SOC-voltage curve is a minimum value and that is equal to or greater than the value of the SOC in which the gradient of the SOC-voltage curve is two times the minimum value, by charging;
• and
• a second process of setting the SOC of the lithium ion battery to a second value, that is smaller than the first value, by discharging.

A non-transitory computer readable storage medium storing a program configured to cause a charge/discharge device, which is electrically connected to a lithium ion battery having a positive electrode and a negative electrode and in which performance is decreased by a residue of lithium ions in the negative electrode, to repeat a cycle a plurality of times,

• the cycle including:
• a first process of setting an SOC of the lithium ion battery to a first value, that is equal to or smaller than a value of the SOC in which a gradient of the SOC-voltage curve is a minimum value and that is equal to or greater than the value of the SOC in which the gradient of the SOC-voltage curve is two times the minimum value, by charging;
• and
• a second process of setting the SOC of the lithium ion battery to a second value, that is smaller than the first value, by discharging.