Residual Capacity Estimation of Stationary Lithium-Ion Secondary Battery Based on Its Discharge Voltage Characteristics

摘要

The relationship between the residual capacity and the discharge voltage of a lithium-ion secondary battery having sufficient capacity to be used as a backup power supply in telecommunication applications is described. From results of high-temperature accelerated deterioration tests conducted on lithium-ion secondary cells, a drop in not only the capacity but also the discharge duration and the discharge voltage was observed, and a fixed relationship was found between the drop in discharge voltage and the residual capacity. This relationship was confirmed not only for single cells, but also for a multicell battery composed of 14 cells which was periodically discharged while being maintained at a floating charge. The possibility of estimating the residual capacity of lithium-ion secondary cells and batteries from a voltage measurement obtained in constant-current discharging was confirmed.