CHARGING METHOD, BATTERY DEVICE, CHARGING DEVICE, DEGRADATION DIAGNOSIS METHOD, BATTERY PACK, ELECTRIC VEHICLE, AND ELECTRICITY STORAGE DEVICE

摘要

A charging method includes: in a case of charging a lithium ion secondary battery having a positive electrode, a negative electrode, and an electrolyte housed in an exterior body, calculating a value obtained by second-order differentiation of a charging current in constant-voltage charging with respect to a charging electric quantity or time during charging; and, during charging with an environmental temperature of T1 immediately before start of charging, in a case where a change in a sign of the value calculated by second-order differentiation from positive to negative or from negative to positive is observed, if an ambient temperature immediately before start of next and subsequent charging is T2 or lower, making the whole or a part of a current in a constant-current charging current section lower than an initial setting.