Review - Nonlinear electrochemical impedance spectroscopy

Nonlinear Electrochemical Impedance Spectroscopy (NLEIS) is a method of characterizing an electrochemical systems by applying a large amplitude sinusoidal perturbation signal. This article presents a comprehensive review of existing literature on NLEIS analysis development and applications. Two types of NLEIS reports available in the literature, viz. one in which only the fundamental impedance is studied and the other in which both the fundamental and higher harmonic responses are analyzed, are reviewed. Early reports on the development of NLEIS methodology are compiled. Recent advances in the application of NLEIS, in particular in the area of fuel cells, are summarized. In addition, applications of related techniques such as total harmonic distortion and Volterra kernel are included in the purview of this article. There is a large scope for applying NLEIS to understand electrochemical processes. The roadblocks that need to be overcome to enable wider application of NLEIS are identified, and directions for further research are suggested.