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dc.contributor.authorWang, Evelyna
dc.contributor.authorZhao, Evan Wenbo Wenbo
dc.contributor.authorGrey, Clare
dc.date.accessioned2021-12-18T00:30:10Z
dc.date.available2021-12-18T00:30:10Z
dc.date.issued2021-10-19
dc.identifier.issn0013-4651
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/331597
dc.description.abstractRedox-active molecules or ions are important in a variety of electrochemical energy storage systems. In lithium-air batteries (LABs), redox active mediators are added as soluble catalysts that mitigate (dis)charge overpotentials as well as promote solution-phase reactions that improve the capacity and cycle life of a cell. Redox flow batteries (RFBs) are dependent on the dissolved species to carry and store charge. In both of these systems, crossover phenomena, whereby the redox-active species in solution diffuse from one side of the cell to the other, result in capacity loss. Here, we report a technique to monitor crossover reactions in lithium-air batteries and redox-flow batteries, exploiting methodology previously developed to monitor radical formation in redox flow batteries. In this technique, radical concentrations are directly quantified operando by flowing an electrolyte solution containing 2,2,6,6-tetramethylpiperidinyloxyl (TEMPO) through nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectrometers. We apply this to Li-TEMPO flow batteries and find the coulombic efficiency is only 50%; 50% of the oxidized TEMPO radical, TEMPO+, formed at the cathode, crosses over to the anode where it is reduced, regenerating TEMPO. Numerical modelling simulations of static systems cannot capture the extent of redox shuttling seen experimentally unless extremely fast diffusion of TEMPO and TEMPO+ is assumed in 1D models or convection is included in 2D models, confirming that redox shuttling is enhanced significantly by flow. Finally, we tested Nafion membranes in both flow cells and static LABs and found that the membrane limited crossover of TEMPO and TEMPO+ by factors of ~15x and ~7x respectively.
dc.publisherThe Electrochemical Society
dc.rightsAll Rights Reserved
dc.rights.urihttp://www.rioxx.net/licenses/all-rights-reserved
dc.titleMagnetic Resonance and Computational Studies on Crossover Reactions in Li-Air Batteries and Redox-Flow Batteries Using TEMPO
dc.typeArticle
dc.publisher.departmentDepartment of Chemistry Student
dc.publisher.departmentDepartment of Chemistry
dc.date.updated2021-12-06T10:54:08Z
prism.endingPage76
prism.issueIdentifier1
prism.publicationDate2021
prism.publicationNameECS Meeting Abstracts
prism.startingPage76
prism.volumeMA2021-02
dc.identifier.doi10.17863/CAM.79049
rioxxterms.versionofrecord10.1149/ma2021-02176mtgabs
rioxxterms.versionAM
dc.contributor.orcidWang, Evelyna [0000-0002-5697-474X]
dc.contributor.orcidZhao, Evan Wenbo Wenbo [0000-0003-2233-8603]
dc.contributor.orcidGrey, Clare [0000-0001-5572-192X]
dc.identifier.eissn2151-2043
rioxxterms.typeJournal Article/Review
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/M009521/1)
pubs.funder-project-idEngineering and Physical Sciences Research Council (EP/P007767/1)
cam.orpheus.successTue Feb 01 19:02:24 GMT 2022 - Embargo updated*
cam.depositDate2021-12-06
pubs.licence-identifierapollo-deposit-licence-2-1
pubs.licence-display-nameApollo Repository Deposit Licence Agreement
rioxxterms.freetoread.startdate2021-10-19


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