Electrochemical impedance spectroscopy (EIS) is a powerful technique used to characterize the behavior of the electrochemical systems for design and diagnostic purposes. However, it is not easy to interpret EIS data. Particular attention has been paid to porous electrodes, because they can enhance power and energy density of the electrochemical systems but is difficult to characterize their microstructure. In the last decades, several models have been developed, based on “equivalent circuits,” Poisson-Nernst-Planck (PNP) equations, distribution of relaxation of times (DRT) and recently, distribution of diffusion times (DDT). These models, however, can be applied only to thin film electrodes. In this work, a generalized framework is presented, based on DDT method, adopting Tikhon...[ Read more ]

Electrochemical impedance spectroscopy (EIS) is a powerful technique used to characterize the behavior of the electrochemical systems for design and diagnostic purposes. However, it is not easy to interpret EIS data. Particular attention has been paid to porous electrodes, because they can enhance power and energy density of the electrochemical systems but is difficult to characterize their microstructure. In the last decades, several models have been developed, based on “equivalent circuits,” Poisson-Nernst-Planck (PNP) equations, distribution of relaxation of times (DRT) and recently, distribution of diffusion times (DDT). These models, however, can be applied only to thin film electrodes. In this work, a generalized framework is presented, based on DDT method, adopting Tikhonov regularization, which extends the existing theories, analyzing EIS data for thick electrodes. We apply our model to two cases of batteries i) a Si nanowire Li-ion battery and ii) a Li-ion battery with plastic crystal electrolyte, and show the capability to recover the physical properties of the electrochemical systems such as chemical diffusivity D̃ and ionic conductivities of the phases. Furthermore, we highlight that this framework can be used for other classes of electrochemical systems such as semiconductors, fuel cells, and supercapacitors.