Electrochemical impedance spectroscopy (EIS)

The Electrochemical Impedance Spectroscopy (EIS) system at the Chair of Thermodynamics combines a Metrohm DropSens µStat-i 400 impedance analyser, a Metrohm Autolab PGSTAT302N potentiostat/galvanostat, and rhd-instruments TSC battery and TSC 1600 closed test cells. This configuration enables high-precision measurements on both solid and liquid samples, with flexible cell geometries tailored for pellets, polymer membranes, electrolytes, and gels. By applying small sinusoidal voltage signals across a wide frequency range (1 MHz to 1 mHz), the system records the impedance response and provides information on charge transport, ion diffusion, and interfacial processes. These parameters are essential for determining the permittivity of liquids and solids, as well as conductivity, adsorption, and diffusion coefficients. With advanced software tools (Nyquist, Bode, Lissajous plots, equivalent-circuit fitting), the EIS setup allows detailed characterisation of bulk and surface resistances, capacitances, and diffusion coefficients.