Fast Fourier Transform-Based Distribution of Relaxation Times Analysis for Efficient and Flexible Time-Domain Electrochemical Impedance Characterization

Electrochemical impedance spectroscopy (EIS) is a powerful analytical technique for studying electrochemical systems, offering broad frequency range coverage and straightforward implementation. However, EIS measurements at low frequencies are limited by both lengthy acquisition times and the risk of disrupting steady-state conditions, which is a particular challenge for battery systems. While the distribution of relaxation times (DRT) method has emerged as an effective tool for interpreting EIS data and accelerating impedance acquisition, existing acquisition approaches are limited to pulse-based input signals and their linear combinations. Here, we present a novel fast Fourier transform-based DRT formulation that enables rapid EIS acquisition using arbitrary current signals. Our approach demonstrates improved DRT and impedance recovery while ensuring computational efficiency. This advancement in DRT analysis and time-based measurements opens new possibilities for fast and efficient EIS characterization.