LITHIUM ION SECONDARY BATTERY SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery system that can suppress variation of potential of a reference electrode when the reference electrode is inserted in a secondary battery.SOLUTION: A lithium ion secondary battery system has a lithium ion secondary battery and a switching site. The lithium ion secondary battery has a reference electrode, a positive electrode and a negative electrode. The reference electrode is connected to the positive electrode or the negative electrode by the switching site. The connection between the reference electrode and the positive electrode and the connection between the reference electrode and the negative electrode are switched to each other by the switching site. The absolute value of the differential value obtained by subtracting a current integration value flowing in the reference electrode under the measurement of the negative electrode potential from a current integration value flowing in the reference electrode under the measurement of the positive electrode potential is controlled to be in the range from 10% to 90% of the charging/discharging capacity of the reference electrode.