CHARGE HOLDING METHOD FOR LITHIUM-ION SECONDARY BATTERY, BATTERY SYSTEM, VEHICLE, AND BATTERY-MOUNTED DEVICE

摘要

An object is to provide a method of charging and maintaining a lithium ion secondary battery which method is capable of preventing a decrease in the capacity of the battery. Another object is to provide a battery system capable of preventing a decrease in battery capacity, and a vehicle and a battery-mounted device which have such a battery system mounted therein. A method of charging and maintaining lithium ion secondary batteries 101 using positive active material particles 135 made from a two-phase coexistence type positive active material PM in a positive electrode plate 130 includes an overcharge step S7 for charging the lithium ion secondary batteries to bring their SOC (State of Charge) SC into an overcharge SOC not higher than 100% but higher than a target SOC, a return discharge step S8 for discharging, after the overcharge step, the lithium ion secondary batteries to make their SOC equal to the target SOC, and a maintaining step S10.