Experimental Analysis on the Influence of Operating Profiles on High Temperature Polymer Electrolyte Membrane Fuel Cells

Tancredi Chinese,Rodolfo Taccani,Benedetta Marmiroli,Federico Ustolin,Heinz Amenitsch

doi:10.3390/en14206737

Tancredi Chinese, Rodolfo Taccani + Show 3 more

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https://doi.org/10.3390/en14206737

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Journal: Energies	Publication Date: Oct 16, 2021
Citations: 4	License type: CC BY 4.0

Affiliation: University of Trieste, Institute of Inorganic Chemistry

Abstract

The Energy System lab at the University of Trieste has carried out a study to investigate the reduction in performance of high temperature polymer electrolyte membrane (HTPEM) fuel cell membrane electrode assemblies (MEAs) when subjected to different ageing tests. In this study, start and stop cycles, load cycles, open circuit voltage (OCV) permanence and constant load profile were considered. Polarization curves (PC) together with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) data were recorded during the ageing tests to assess the fuel cell performance. In this paper, experimental data are presented to confirm the test methodology previously proposed by the authors and to quantitatively correlate the performance degradation to the operational profiles. It was demonstrated that OCV condition, start and stop and load cycling increase degradation of the MEAs with respect to constant load operation. As expected, the OCV is the operational condition that influences performance degradation the most. Finally, the MEAs were analyzed with synchrotron small angle X-ray scattering (SAXS) technique at the Austrian SAXS beamline at Elettra-Sincrotrone Trieste to analyze the nano-morphological catalyst evolution. As for the catalyst morphology evolution, the ex situ SAXS methodology proposed by the authors is confirmed in its ability to assess the catalyst nanoparticles aggregation.

Highlights

Polybenzimidazole (PBI)-based high temperature polymer electrolyte membrane (HTPEM) fuel cells are a suitable alternative to Nafion-based low temperature PEM (LTPEM), especially for micro–combined heat and power applications
For membrane electrode assemblies (MEAs) CL_2 operated at constant load a degradation value of 29 μV/h was found as already reported by the authors in [11]
The effects of open circuit voltage (OCV) and start-stop cycles were studied with electrochemical diagnostic tools such as polarization curves, electrochemical impedance spectroscopy (EIS)

Summary

Introduction

Polybenzimidazole (PBI)-based high temperature polymer electrolyte membrane (HTPEM) fuel cells are a suitable alternative to Nafion-based low temperature PEM (LTPEM), especially for micro–combined heat and power (mCHP) applications. High costs and degradation are still two major issues to be overcame to achieve commercialization [1,2]. The high cost is greatly influenced by the platinum-based electrocatalysts needed to facilitate the kinetics of the electrode reactions. Degradation of the catalyst layer may induce processes which are responsible for the performance losses of the membrane electrode assembly (MEA) when subjected to fuel cell operational conditions [3,4]. The modification of the phosphoric acid position and content in the PBI membrane and thinning of this latter can deteriorate the MEA performance [5,6].

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