On the Interpretation of Impedance Spectra of Large‐Format Lithium‐Ion Batteries and Its Application in Aging Studies

This study presents a new approach for the interpretation of impedance spectra of large‐format lithium‐ion batteries. By application of the method of the distribution of relaxation times (DRT), all time constants contributing to the overall kinetics of a battery can be identified. By a comprehensive impedance spectroscopic investigation of the lithium‐ion cell as a function of temperature and cell potential, it can be described in a recognizable manner, which can be traced back in measurements with three electrode cells. Thereby, an unambiguous assignment of time constants to the underlying type of an electrochemical process and to the electrode of origin can be achieved. The application of these findings in aging studies can significantly increase their gain of knowledge.