Investigation on Effect of Charging/Discharging Range on Capacity Degradation of Lithium Iron Phosphate Batteries

摘要

This paper investigates the effect of the utilization region on capacity degrading of lithium-ion batteries. The selected batteries of the approximately same initial full capacity are deliberately discharged by a constant current and charged by the constant current-constant voltage (CC-CV) scheme cyclically in three different ranges, low, middle, and high state-of-charge (SOC), with an equal amount of charge. After a great number of charging/discharging cycles, the batteries' full capacities are measured. Experimental results indicate that the least full capacity degradation happens to the battery operated in the high SOC range. In addition, the full capacity degradation of the battery operated in the low SOC range increases rather than decreases in the first 300 cycles. After 2860 charging/discharging cycles, the full capacities have been deteriorated to 94.01 %, 86.20 % and 88.70 % for batteries with high, middle and low operating ranges, respectively.