Characterisation and Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

Abstract

In designing and controlling fuel cell systems, it is advantageous to have models which predict fuel cell behaviour in steady‐state as well as in dynamic operation. This work examines the use of electro‐chemical impedance spectroscopy (EIS) for characterising and developing an impedance model for a high temperature PEM (HT‐PEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell is a Nyquist plot, which shows the imaginary and real parts of the impedance of the measured system. The full stack impedance depends on the impedance of each of the single cells of the stack. Equivalent circuit models for each single cell can be used to predict the stack impedance at different temperature profiles of the stack. The information available in such models can be used to predict the fuel cell stack performance, e.g. in systems where different electronic components introduce current harmonics.

In-Situ Dynamic Characterization of Energy Storage and Conversion Systems

“…However, Zhang [79] also expected a constant level of RΩ at a current density larger than 1.0 A cm -2 because of a constant water uptake of the membrane balanced between produced and purged water. This constant level was observed in Andreasen's experiments both on a 1 kW cell stack [78] and a single cell MEA [83] even at a current density lower than 1.0 A cm -2 .…”

“…And generally it is quite a small semi-circle comparing to the following impedance arcs. It dominates the region of frequency from above 100 Hz up to 1000 Hz [68,78,79,[81][82][83][84], or even higher. The effects of temperature [79,82] and current density [81,82] on this impedance arc are observable but not as significant as on other impedance arcs dominating lower frequency regions.…”

“…The processes involved in data interpretation mainly include charge transfer process, mass transfer process, and gas diffusion process. However, some groups observing two impedance arcs in Nyquist plot preferred to classify the impedance arcs into anodic and cathodic processes [73][74][75][76][77][78].…”

“…In some cases, the double layer capacitor may be substituted by a CPE to reflect the non-ideal characteristics of the interface. Many researchers preferred to ascribe this HF arc to the charge transfer process occurring on the anode, that was the charge transfer process involved in hydrogen oxidation reaction (HOR) [73,77,78,80]. Some other groups stated that the charge transfer processes of both HOR and ORR contributed to this HF impedance arc; however, the contribution of HOR was negligible at low current density [79,82].…”

A New Algorithm Design for the Real-time Electrochemical Impedance Monitoring System

“…Then, processing units do not interfere with each other, impedance spectra and their final results are possible to monitor. This new design is expected to provide development guides for monitoring systems of electric vehicle batteries, 15) fuel cell power plants, 16,17) and so on.…”