Electrochemical Impedance Spectroscopy (EIS) is a powerful and sensitive technique used to investigate the properties of electrochemical systems, including batteries, fuel cells, and corrosion on metal surfaces. It operates by applying a small amplitude alternating current (AC) voltage to an electrochemical cell and measuring the resulting current to assess the cell's impedance over a range of frequencies. This technique is highly valued in various fields of research and industry due to its ability to provide detailed information about the internal processes and mechanisms within electrochemical systems.