Direct Measurement of iR-Free Individual-Electrode Overpotentials in Polymer Electrolyte Fuel Cells

Abstract

A method of measuring error-free potentials of individual electrodes directly in the polymer electrolyte fuel cell and under a full range of load is introduced. Successful measurement is accomplished by placing a reference electrode in ionic contact with the active layer of a fuel cell electrode of interest, that is, away from the electrolyte membrane. Half-cell measurements with the proposed reference electrode configuration are compared with measurements in two other fuel-cell reference electrode arrangements to illustrate the conditions necessary for directly achieving correct measurement of potentials (overpotentials). Functioning of the fuel cell reference electrodes is explained through modeling of electrical potential and reactant distribution in the working fuel cell.

Proton exchange membrane fuel cell contamination model: Competitive adsorption followed by a surface segregated electrochemical reaction leading to an irreversibly adsorbed product

“…Constant current operation is less desirable as potential changes of more than 0.4-0.5 V for H 2 S [29,[33][34][35] and 0.3 V for SO 2 [30] were observed. Preferably, a reference electrode should be considered but implementation is not necessarily trivial [44] especially if the additional requirement of contaminant insensitivity is added. The ionomer is permeable to contaminants such as H 2 S [16,45] and SO 2 [46].…”

An impedance study for the anode micro-porous layer in an operating direct methanol fuel cell

“…The amplitude of the sinusoidal modulation voltage did not exceed 10 mV. To resolve the anode and cathode impedance, an Ag/AgCl electrode (MF-2052, BAS Inc.) was placed at the region of constant potential (RCP) [32][33][34][35][36] of the membrane as a reference electrode. The detailed description of the setup of reference electrode was proposed and demonstrated in our previous work [32].…”

Reference and counter electrode positions affect electrochemical characterization of bioanodes in different bioelectrochemical systems

“…The electrochemical characterization of thin solid electrolyte fuel cells, for example, showed that results were RE position dependent and prone to errors (Fiaud et al, 1987;Hsieh et al, 1997;Piela et al, 2007;Winkler et al, 1998;Zeng et al, 2010). When the RE is placed in a region of nonuniform current density, the RE can possibly sample a range of equipotential surfaces, resulting in the discrepancies in the measurements (Hsieh et al, 1997).…”