Anomalous relaxation and electrical impedance: A diffusion approach with adsorption–desorption at the interfaces

This paper investigates several strategies for modeling electrochemical impedance, in particular, exploring the effects of fractional calculus. It focuses on the theoretical approach for describing systems with anomalous diffusion; as a result, these effects can be analytically expressed as functions of frequency when different boundary conditions are considered. Starting with the normal case as a reference scenario, this study discusses how to increase the complexity of mathematical solutions by generalizing fundamental equations. The second strategy extends the continuity equation to include a fractional contribution. Subsequently, Fick's law is also extended, considering a case that incorporates a fractal derivative. Finally, we utilize electrochemical impedance to determine electric conductivity, analyze mean-square displacement, and connect it to the diffusion process.