Drift Correction in Operando Electrochemical Impedance Spectroscopy for Batteries Research

Operando Electrochemical Impedance Spectroscopy on a cycling battery involves several challenges. As the battery state is continuously changing during discharge/charge cycling, the fundamental stability criterion is not fulfilled, and certain drift of the impedance data is emerged. In the present study, an algorithm for the drift correction was developed for different sets of synthetic data. Various computational steps were followed once created a given set of impedance data: single-frequency-point hysteresis correction, time-state drift correction, regularization of the Distribution of Relaxation Times using the Levenberg-Marquardt algorithm with a penalty contribution, and validation of the resulting data by two-pole Hilbert Transform. An evaluation of the influence of hysteresis noise proved a robust algorithm for the drift corrections of operando impedance.