Kær, Søren Knudsen

Li, Na

Simon Araya, Samuel

English

A water purification system is typically used in PEM water electrolysis systems, but over time the quality of the circulating water may deteriorate due to metallic impurities originating from the piping system, catalyst layers andother components degradation. These impurities lead to a progressive increase of the cell voltage [1].In this work, the influence of 5 ppm Fe3+ contamination on cell performance of PEM water electrolysis has been investigated, and the temperature and current density effects on cell performance in the presence of Fe3+ were also studied

    Aalborg UniversitetThe influence of ferric ion impurities on a proton exchange membrane electrolyzeroperated at varying temperature and current density conditionsLi, Na; Simon Araya, Samuel; Kær, Søren KnudsenPublication date:2019Link to publication from Aalborg UniversityCitation for published version (APA):Li, N., Simon Araya, S., & Kær, S. K. (2019). The influence of ferric ion impurities on a proton exchangemembrane electrolyzer operated at varying temperature and current density conditions. Poster presented at 2ndInternational Conference on Electrolysis 2019, Loen, Norway.General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            ? Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            ? You may not further distribute the material or use it for any profit-making activity or commercial gain            ? You may freely distribute the URL identifying the publication in the public portal ?Take down policyIf you believe that this document breaches copyright please contact us at vbn@aub.aau.dk providing details, and we will remove access tothe work immediately and investigate your claim.Downloaded from vbn.aau.dk on: November 24, 2020The influence of ferric ion impurities on a proton exchange membraneelectrolyzer operated at varying temperature and current densityconditionsNa Li, Samuel Simon Araya, Søren Knudsen KærDept. of Energy Technology, Aalborg University, Denmarknal@et.aau.dkIntroductionA water purification system is typically usedin PEM water electrolysis systems, but overtime the quality of the circulating water maydeteriorate due to metallic impurities originat-ing from the piping system, catalyst layers andother components degradation. These impuri-ties lead to a progressive increase of the cellvoltage [1].In this work, the influence of 5 ppm Fe3+ con-tamination on cell performance of PEM waterelectrolysis has been investigated, and the tem-perature and current density effects on cell per-formance in the presence of Fe3+ were alsostudied.Experimental setupFig. 1: Schematic of the experimental setupResults and discussionThe Electrochemical impedance spectroscopy(EIS) and polarization results showed thatcell performance decreased severely when 5ppm of Fe3+ solution in water was tested in anelectrolyzer cell.Fig. 2: voltage profile of the entire test periodIn Fig. 2, where the voltage profile of the entiretest period is given, it can be seen that the volt-age of the cell increases significantly comparedto DI water operation, after introducing Fe3+ ionsfrom the 4th hour of the testing on-wards. Con-sequently, the The IV curve slopes became sig-nificantly steeper after Fe3+ ions are introduced,showing the increase in the overall resistance,as can be seen in Fig. 3.Fig. 3: polarization curves at different test conditionsAs shown in Fig. 4 for DI water operation, bothhigh temperature and low current density canimprove the cell performance, where the ohmicresistance decreased clearly.In the case of contaminated feed solution, thecell performance decreases progressively, evenat higher temperature and lower current density.as can be seen in Fig. 5.Fig. 4: EIS spectra at different operating conditionswith DI water feedHigher temperature (80 ◦C) reduces the ohmicresistance, both for DI water and contaminatedsolution operation. Whereas, higher currentdensity (2 A/cm2) seems detrimental at lowertemperatures in the presence of Fe3+ ions, butcan contribute to reduced mass transfer resis-tance at higher temperature.Fig. 5: EIS spectra at different operating conditionswith contaminated solutionA strong effect of ionic contamination is seenthroughout the tested frequency spectrum. Thiscan be explained by the higher affinity of Fe3+ions than protons for the sulfonic acid groupsites, which could substitute protons in normalion exchange processes [2] and by membranedegradation through radical attack promoted bythe metallic ions [3].ConclusionsIt has been shown that the cell perfomance de-grades severely with Fe3+ in feed water. TheFe3+ ions adsorbed on Nafion membrane andcatalyst layers, resulting in the increase ofmembrane ohmic resistance and charge trans-fer resistance on both electrodes. Further-more, some metallic impurities may promotethe generation of hydroxide radicals from hy-drogen peroxide and hence degrade the mem-brane severely by the caused Fenton mecha-nism [3, 4]. High temperature operation cancontribute to improve cell performance at thetested Fe3+ concentration.References[1] Shucheng Sun, Zhigang Shao, HongmeiYu, Guangfu Li, and Baolian Yi. Investiga-tions on degradation of the long-term pro-ton exchange membrane water electrolysisstack. Journal of Power Sources, 267:515–520, dec 2014.[2] Michael J. Kelly, Günter Fafilek, Jürgen O.Besenhard, Hermann Kronberger, and Ger-hard E. Nauer. Contaminant absorp-tion and conductivity in polymer electrolytemembranes. Journal of Power Sources,145(2):249–252, aug 2005.[3] Christoph Rakousky, Uwe Reimer, KlausWippermann, Marcelo Carmo, WiebkeLueke, and Detlef Stolten. An analysis ofdegradation phenomena in polymer elec-trolyte membrane water electrolysis. Jour-nal of Power Sources, 326:120–128, sep2016.[4] Na Li, Samuel Simon Araya, andSøren Knudsen Kær. The effect ofFe3+ contamination in feed water on protonexchange membrane electrolyzer perfor-mance. International Journal of HydrogenEnergy, apr 2019.AcknowledgementThe authors would like to acknowledge the fi-nancial support from Innovation Fund Denmarkthrough the e-STORE project, Grant No. 4106-00025B. Na Li appreciates China ScholarshipCouncil for the financial support.

The influence of ferric ion impurities on a proton exchange membrane electrolyzer operated at varying temperature and current density conditions

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The influence of ferric ion impurities on a proton exchange membrane electrolyzer operated at varying temperature and current density conditions

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