Aging-Optimized Fast Charging of Lithium Ion Cells Based on Three-Electrode Cell Measurements

Fast charging is thought to be the key to enable long-distance battery electric mobility and widespread adoption of battery electric vehicles. Herein, optimized 28 mAh three-electrode cells with lithium titanium oxide coated aluminum meshes as reference electrodes are used to analyze their charging performance potential. Lithium plating only occurs if the anode potential falls below 0 V versus Li/Li+, which has to be avoided during charging. Thus, current multistep protocols are derived to allow fast charging of the three-electrode cells without significantly increased aging for 300 cycles when compared to 1 C constant current-constant voltage charging. In contrast, it is shown that charging with an average current to the same state of charge in the same time is much more harmful. This average current exceeds the current limits at high states of charge as determined by the three-electrode measurements. Consequently, postmortem scanning electron microscopy images indicate the occurrence of lithium plating. After 300 aging cycles using the multistep or 1 C reference charging, the three-electrode cells show a surprising charging performance increase which is linked to reduced overpotentials at the anode. The results demonstrate the suitability of this three-electrode cell design to determine aging-optimized fast charging current profiles.