INSPECTION EQUIPMENT OF LITHIUM ION SECONDARY BATTERY, INSPECTION METHOD AND SECONDARY BATTERY MODULE

PROBLEM TO BE SOLVED: To provide a short-time and highly accurate inspection method, and inspection equipment by using a signal, except an electric signal such as current, voltage by a charge/discharge test as a method for inspecting an internal state of a lithium ion secondary battery in details.SOLUTION: In an inspection method of a lithium ion secondary battery in which an electrode group consisting of electrolyte, a positive pole, a negative pole, and a separator is arranged in one container, when a sensor which detects acoustic emission (ultrasonic waves) is adhered to the outside of the container, and charged or discharged current is applied and stopped between the positive pole and the negative pole, the acoustic emission to be generated in a battery container is detected. Especially, amplitude intensity of the acoustic emission to be generated when a plurality of charged and discharged currents with different values are added and stopped to the battery is measured, linear approximation is performed to charged and discharged current values and acoustic emission amplitude intensity, and cycle frequencies with which the battery charges and discharges so far are estimated with an inclination of the linear approximation and a numerical value of an intercept.