Prediction of degradation in lithium−ion batteries is critical to ensure battery safety. In this study, we report for the first time that electrochemical impedance spectroscopy (EIS) predicts serious capacity fade in lithium−ion batteries, which results from charge−discharge cycling under overcharge conditions. A nickel cobalt aluminum oxide (NCA) lithium-ion cell shows a two-stage capacity fade in the overcharge condition with an upper cutoff voltage (UCV) of 4.4 V. The capacity gradually decreases as cycling progresses (first stage), and then decreases steeply in the later cycles (second stage). Such a two-stage capacity fade is not observed when cell cycling in the appropriate voltage range (UCV ≤ 4.2 V). In the first stage, the cell capacities cycled at UCVs of 4.2 V and 4.4 V are approximately identical, with an inductively coupled plasma atomic emission spectrometry analysis confirming overcharge-induced deposition of Ni and Co on the anode surface. EIS analysis is used to model these deposited metals as enhanced impedance signals that represent the charge transfer resistance and interfacial capacitance of the anode in the first stage. This allows the advance prediction of overcharge-induced serious capacity decay in lithium-ion batteries to prevent cell destruction.
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