Electrochemical impedance preprocessing with distribution of relaxation time transform

Electrochemical impedance spectroscopy (EIS) oriented methods are increasingly discussed and attempted in the analysis and diagnosis of the Lithium-ion battery (LIB). Yet, the parasitic, nonlinear and time-variant features of LIB pose challenges for their proper employment. To fill in the gap between the acquisition of EIS and its following utilization, it is essential to validate, calibrate and modify the raw EIS measurements. In this paper, theoretical background of such EIS preprocessing techniques based on the distribution of relaxation time (DRT) transform are closely discussed. An EIS validation approach alternative to the Kramers-Krönig relations is presented with mathematical rigor. To fix the high-frequency distortion, inductive correction for EIS is investigated. For the isolation or modification of particular kinetics, EIS data manipulation measures are proposed. Diagnosis of the low-frequency EIS is performed to reflect the extend of the induced nonlinearity and time-variance. The practicality and the benefits of these treatments are validated with commercial batteries, and they can well serve as routine checks for EIS. As the applications of EIS are going on-vehicle, online and dynamic, this paper seeks to supplement some valuable references for the effective preprocessing of EIS data prior to their critical usage.