Open AccessA Platinum Micro-Reference Electrode for Impedance Measurements in a PEM Water Electrolysis Cell
Author(s) -
Alexandra HartigWeiß,
Maximilian Bernt,
Armin Siebel,
Hubert A. Gasteiger
Publication year - 2021
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/ac3717
Subject(s) - anode , electrode , proton exchange membrane fuel cell , cathode , materials science , dielectric spectroscopy , platinum , nafion , analytical chemistry (journal) , composite material , electrolysis , reference electrode , membrane electrode assembly , current collector , chemistry , electrochemistry , electrolyte , membrane , chromatography , catalysis , biochemistry
We present a platinum wire micro-reference electrode (Pt-WRE) suitable for recording individual electrochemical impedance spectra of both the anode and the cathode in a proton exchange membrane water electrolyzer (PEM-WE). For this purpose, a thin, insulated Pt-wire reference electrode (Pt-WRE) was laminated centrally between two 50 μ m Nafion® membranes, whereby the potential of the Pt-WRE is determined by the ratio of the local H 2 and O 2 permeation fluxes at the tip of the Pt-WRE. Impedance analysis with the Pt-WRE allows determination of the proton sheet resistance of the anode, the anode catalyst layer capacitance, and the high-frequency resistance (HFR) of both electrodes individually, using a simple transmission-line model. This new diagnostic tool was used to analyze performance degradation during an accelerated stress test (AST), where low and high current densities were alternated with idle periods without current (i.e., at open circuit voltage (OCV)), mimicking the fluctuating operation of a PEM-WE with renewable energy. Our analysis revealed that the increasing HFR that was observed over the course of the OCV-AST, which is the main cause for the observed performance decrease, can unequivocally be assigned to an increasing contact resistance between the anode electrode and the porous transport layer.