Charging control method for lithium-ion battery, charging control apparatus for lithium-ion battery and lithium-ion battery system

A charging control method for controlling charging of a lithium-ion battery, which is provided with a positive electrode and a negative electrode, the charging control method comprising:

• charging processing for charging the lithium-ion battery to a target voltage by a constant-current and constant-voltage charging method, the lithium-ion battery including a cathode active material having Olivine-type crystal structure;
• negative-electrode potential evaluation processing for evaluating a potential change quantity of the negative electrode;
• and
• voltage setting processing for setting the target voltage to decrease based on the potential change quantity of the negative-electrode evaluated by the negative-electrode potential evaluation processing;
• wherein
• the negative-electrode potential evaluation processing evaluates the potential change quantity of the negative-electrode based on one of or both of a charging voltage, which is measured as a voltage charged to the lithium-ion battery, and a discharging voltage, which is measured as a voltage discharged from the lithium-ion battery;
• and
• the negative-electrode potential evaluation processing specifies a stepwise change point, at which a quantity of change in one of or both of the charging voltage and the discharging voltage relative to the charging rate changes in excess of a threshold value, and evaluates the potential change quantity of the negative electrode based on a shift quantity of the stepwise change point in increasing and decreasing directions.