Equivalent Circuit Model for Electrochemical Impedance Spectroscopy of Commercial 18650 Lithium‐ion Cell Under Over‐discharge and Overcharge Conditions

This study endeavors to assess the impedance responses exhibited by 18650 Graphite||LiCoO ₂ (C ₆||LCO) cells under conditions of over‐discharge and overcharge. The impedance measurements are conducted at a potential of 4.20 V, followed by subjecting the cells to over‐discharge and overcharge scenarios. It is observed that the impedance magnitude experiences augmentation in both instances. Upon reaching a potential of 2.70 V, the electrochemical attributes of the cells revert to their normal state post over‐discharge. However, the impedance characteristics persist even upon exceeding a potential of 4.70 V. These observations imply that overcharge induces enduring alterations in impedance behavior,