Scribner Tutorial EIS for Fuel Cell Research v5

¾¾¾¾¾¾Scribner Associates ‐ Tutorial  Electrochemical Impedance Spectroscopy (EIS): A Powerful and Cost-Effective Tool for Fuel Cell Diagnostics Electrochemical Impedance Spectroscopy (EIS) is a powerful diagnostic tool that you can use to characterize limitations and improve the performance of fuel cells. There are three fundamental sources of voltage loss in fuel cells: charge transfer activation or “kinetic” losses, ion and electron transport or “ohmic” losses, and concentration or “mass transfer” losses. Among other factors, EIS is an experimental technique that can be used to separate and quantify these sources of polarization. By applying physically-sound equivalent circuit models wherein physiochemical processes occurring within the fuel cell are represented by a network of resistors, capacitors and inductors, you can extract meaningful qualitative and quantitative information regarding the sources of impedance within the fuel cell. EIS is useful for research and development of new materials and electrode structures, as well as for product verification and quality assurance in manufacturing operations. This article provides a quick primer on EIS with an introduction to its application in fuel cell testing and research. Instrumentation and measurement basics During an impedance measurement, a frequency response analyzer (FRA) is used to impose a small amplitude AC signal to the fuel cell via the load (Figure 1). The AC voltage and ...