Experimental and numerical methods to investigate the overcharge caused lithium plating for lithium ion battery

Lithium plating can threaten the lithium-ion battery safety, which can be caused by overcharging. Detection on lithium plating is of vital importance in battery management system (BMS). Both experimental and numerical methods are involved in detecting overcharge caused lithium plating for a commercial 26650 type LiNi1/3Co1/3Mn1/3 (NCM)/Graphite cell within this work. Differential analyses are conducted to monitor the lithium stripping capacity and voltage, topography observation also provides a strong basis for lithium plating detection. A deeper detection on lithium plating is conducted by numerical model, which is validated by experiment at several cases. Lithium plating first occurs at the anode-separator interface, if it continues to proceed until the current collector-anode interface, complete lithium plating is appeared. While if lithium plating cannot proceed to the current collector-anode interface, but somewhere before the negative current collector, incomplete lithium plating is considered. The depth of lithium plating (DLP) is defined to quantify the degree of incomplete lithium plating, indicating that incomplete lithium plating can be occurred at the overcharge voltage range of 4.5-4.586 V. Besides, good linear relationships between lithium plating time and capacity with overcharge voltage are observed at 0.2 C and 0.5 C. Further consideration results in alleviating lithium plating by increasing the anode thickness with the reasonable N/P ratio. It is discovered that 6.57% anode thickness excess with slight overcharge before 4.6 V can effectively shorten plating time and achieve complete non-lithium plating.