Impedance Evolution Characteristics in Lithium-Ion Batteries

A three-electrode cell can be a useful tool for measuring electrode-level and cell-level electrochemical characteristics, such as the impedance response and potential variations in lithium-ion cells. In this paper, a reliable three-electrode coin cell setup is introduced, which improves the stability and accuracy of electrochemical measurements by modifying the electrode alignment and employing Li 4 Ti 5 O 12 as a reference electrode. An important highlight is the ability to obtain impedance evolution characteristics at different depth of discharge (DOD) for an individual electrode and the full cell based on both the frequency response analysis and the carrier function Laplace transform characteristics. The reliability of the proposed modified three-electrode coin cell setup has been validated by analyzing the impedance response of symmetric and full cells, and the voltage profiles of the full cell along with the positive/negative electrode contributions. The importance of the resistance contributions from the negative and positive electrodes to the full cell impedance evolution at different DOD is highlighted.