Effect of the Charge Process on the Performance of Li-ion Cells during Charge-Discharge Cycling at 0°C

Abstract

Commercially available 18650 Li-ion cells were exposed to charge-discharge cycling at 0°C using two different charging protocols: constant current-constant voltage (CC-CV) and constant current (CC). The effect of the charge process protocol on the Li-ion cell performance is shown and analyzed. After exposing the cells to low temperature charging, a high voltage plateau appeared at the beginning of the discharge. This high voltage plateau is related to the occurrence of lithium plating during the charging process. Interestingly, the intensity of the observed high voltage plateau decreased with cycling. In addition, the Li-ion cells that were charged using a CC protocol exhibited a larger capacity fade in comparison to those that were charged using a CC-CV protocol. Furthermore, electrochemical impedance spectroscopy (EIS) measurements were carried out during cycling. It was shown that the internal impedance of the cells increased with charge-discharge cycling, indicating the formation of an interphase layer during low temperature cycling.