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AuthorEifert, Lászlódc.contributor.author
Date of accession2021-02-10T16:11:39Zdc.date.accessioned
Available in OPARU since2021-02-10T16:11:39Zdc.date.available
Year of creation2020dc.date.created
Date of first publication2021-02-10dc.date.issued
AbstractThis thesis aims to provide an extended insight into the carbon felt electrodes of vanadium redox flow batteries and suitable characterization techniques. The carbon felt electrodes are a crucial component of the battery since they facilitate the redox reactions of the electroactive species in the electrolyte. They provide a large surface area, due to their porous structure, and a sufficient number of active sites, which is affected by the chemical composition and pretreatment procedures. Additionally, each characterization technique itself unveils various aspects of the carbon felt and only the combination of several methods leads to a comprehensive insight. Moreover, the utilization of sophisticated methods, such as differential electrochemical mass spectrometry and synchrotron X-ray radiography and tomography, enabled an unprecedented view inside the vanadium redox flow battery. The first objective of this thesis was to develop an accelerated aging procedure to establish a systematic benchmark for carbon felt electrodes. The procedures include thermal treatment, which is widely utilized to increase the wettability and electrochemical performance of the carbon felt, as well as a chemical and an electrochemical aging to distinguish the influence of the acidic electrolyte and a long term application in a full-cell of a vanadium redox flow battery, respectively. In the first publication (A1), the procedures were applied on three different carbon felt electrodes, which subsequently were characterized by a wide range of state-of-the-art methods to outline the effects of the accelerated aging, and to single out the differences in the carbon felt types. In a complementing study (A2), a pore network model was applied to investigate the transport properties of carbon felt electrodes for the first time in the context of vanadium redox flow batteries. The comprehensive characterization introduced in the first publication was also applied to carbon-carbon composite materials synthesized by a novel method. This provided extensive insight into the properties and performance of the composite materials and led to the publication reprinted in A3. Beyond that, the artificial aging procedures were also adopted in the context of the investigation on the carbon-based gas diffusion electrodes of fuel cell systems, as shown in publication A4. Here, the stability of a novel hydrophobic coating applied on electrospun gas diffusion electrodes was studied via previously introduced degradation protocols and characterization methods. Based on the findings of Part A, Part B of this thesis applied the differential electrochemical mass spectrometry via a modification that enabled the mounting of a carbon felt electrode for the first time. This method provided an unprecedented insight into the influence of the electrolyte on the side reactions taking place on a carbon felt electrode by the comparison of vanadium-containing electrolyte and the solely sulfuric acid-based electrolyte (B1). Additional experiments in B2 focused on how the above-mentioned accelerated aging procedures affect the side reactions and reveal how the stability of the carbon felt electrodes and their affinity to side reactions changes throughout the operational life of a vanadium redox flow battery. The third pillar of this thesis (Part C) comprises the comprehensive characterization of carbon felt electrodes via synchrotron X-ray radiography and tomography. In publication C1, a detailed study is presented that provides an experimental approach to the pore network model applied in Part A of this thesis. It investigated the influence of the electrode compression ratio and the vanadium species on the saturation – and thus utilization – of the carbon felt electrode. Here, a small sample size allowed a high resolution of the obtained images and an accurate measurement of the pressure drop during electrolyte injection experiments. This approach was previously applied to investigate fuel-cell materials and successfully adopted in the context of the vanadium redox flow battery for the first time. Based on these results, a consequential step was the development and design of a novel vanadium redox flow full-cell that enables a comprehensive investigation via synchrotron X-ray radiography and tomography. In the final publication (C2), a set of viable experiments were presented that investigate the electrolyte flow through the porous electrode in an operating vanadium redox flow battery.dc.description.abstract
Languageen_USdc.language.iso
PublisherUniversität Ulmdc.publisher
Has partL. Eifert, R. Banerjee, Z. Jusys, R. Zeis, Characterization of Carbon Felt Electrodes for Vanadium Redox Flow Batteries: Impact of Treatment Methods, J. Electrochem. Soc.165 (2018) A2577–A2586. doi:10.1149/2.0531811jesdc.relation.haspart
Has partR. Banerjee, N. Bevilacqua, L. Eifert, R. Zeis, Characterization of carbon felt electrodes for vanadium redox flow batteries –A pore network modeling approach, J. Energy Storage 21(2019) 163–171. doi:10.1016/j.est.2018.11.014dc.relation.haspart
Has partM. Schnucklake, L. Eifert, J. Schneider, R. Zeis, C. Roth, Porous N-and S-doped carbon–carbon composite electrodes by soft-templating for redox flow batteries, Beilstein J. Nanotechnol.10 (2019) 1131–1139. doi:10.3762/bjnano.10.113dc.relation.haspart
Has partM. Balakrishnan, P. Shrestha, CH. Lee, N. Ge, K. F. Fahy, M. Messerschmidt, J. Scholta, L. Eifert, J. Maibach, R. Zeis, B.D. Hatton, A. Bazylak,Degradation Characteristics of Electrospun Gas Diffusion Layers with Custom Pore Structures for Polymer Electrolyte Membrane Fuel Cells, ACS Appl. Mater. Interfaces. (2021). doi: 10.1021/acsami.0c15324dc.relation.haspart
Has partL. Eifert, Z. Jusys, R. Banerjee, R.J. Behm, R. Zeis, Differential Electrochemical Mass Spectrometry of Carbon Felt Electrodes for Vanadium Redox Flow Batteries, ACS Appl. Energy Mater.(2018) acsaem.8b01550. doi:10.1021/acsaem.8b01550dc.relation.haspart
Has partL. Eifert, Z. Jusys, R.J. Behm, R. Zeis, Side reactions and stability of pre-treated carbon felt electrodes for vanadium redox flow batteries: A DEMS study, Carbon N. Y.(2019), 158, 580–587.doi:10.1016/j.carbon.2019.11.029dc.relation.haspart
Has partN. Bevilacqua, L. Eifert, R. Banerjee, K. Köble, T. Faragó, M. Zuber, A. Bazylak, R. Zeis, Visualization of electrolyte flow in vanadium redox flow batteries using synchrotron X-ray radiography and tomography –Impact of electrolyte species and electrode compression, Journal of Power Sources(2019), 439, 227071. doi:10.1016/j.jpowsour.2019.227071dc.relation.haspart
Has partL. Eifert, N. Bevilacqua, K. Köble, K. Fahy, L. Xiao, M. Li, K. Duan, A. Bazylak, P.-C. Sui, R. Zeis, Synchrotron X‐ray Radiography and Tomography of Vanadium Redox Flow Batteries –Cell Design, Electrolyte Flow Geometry,and Gas Bubble Formation, ChemSusChem (2020), doi:10.1002/cssc.202000541dc.relation.haspart
LicenseStandarddc.rights
Link to license texthttps://oparu.uni-ulm.de/xmlui/license_v3dc.rights.uri
KeywordVanadium redox flow batterydc.subject
KeywordCarbon materialsdc.subject
KeywordRedox flowdc.subject
Dewey Decimal GroupDDC 540 / Chemistry & allied sciencesdc.subject.ddc
LCSHCarbondc.subject.lcsh
LCSHElectrochemistrydc.subject.lcsh
LCSHOxidation-reduction reactiondc.subject.lcsh
LCSHElectrodes, Carbondc.subject.lcsh
TitleCharacterization and modification of carbon electrodes for vanadium redox flow batteriesdc.title
Resource typeDissertationdc.type
Date of acceptance2020-10-27dcterms.dateAccepted
RefereeZeis, Roswithadc.contributor.referee
RefereeStreb, Carstendc.contributor.referee
DOIhttp://dx.doi.org/10.18725/OPARU-34975dc.identifier.doi
PPN1748113666dc.identifier.ppn
URNhttp://nbn-resolving.de/urn:nbn:de:bsz:289-oparu-35037-0dc.identifier.urn
GNDKohlenstoffdc.subject.gnd
GNDElektrochemiedc.subject.gnd
GNDRedox-Akkumulatordc.subject.gnd
FacultyFakultät für Naturwissenschaftenuulm.affiliationGeneral
InstitutionInstitut für Anorganische Chemie I (Materialien und Katalyse)uulm.affiliationSpecific
Grantor of degreeFakultät für Naturwissenschaftenuulm.thesisGrantor
DCMI TypeTextuulm.typeDCMI
CategoryPublikationenuulm.category
In cooperation withHelmholtz-Institut Ulmuulm.cooperation
Bibliographyuulmuulm.bibliographie


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