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Overscreening and crowding in electrochemical ionic liquid systems
journal contribution
posted on 2023-11-13, 05:01 authored by S Begić, F Chen, E Jónsson, M ForsythIt is known that ionic liquids (ILs) assemble differently at an electrode surface compared to traditional electrolytes; however, the impact of this on electrochemical processes is not yet clear. In this work, we investigate interfacial behavior of two ILs, 1-ethyl-3-methylimidazolium dicyanamide ([C2mim][dca]) and N-butyl-N-methylpyrrolidinium dicyanamide ([C4mpyr][dca]) in the context of a rechargeable zinc battery. In previous experiments, [C2mim][dca] outperformed [C4mpyr][dca] in several ways (e.g., lower overpotential required to initiate electrodeposition of zinc, higher zinc deposition peak current density, and greater number of supported charge-discharge cycles). Here, using molecular-dynamics simulations, we investigate a set of mixtures containing zinc in those ILs, confined by graphene electrodes. Our results reveal the presence of layers and show how the two systems differ with respect to those layers: [C4mpyr][dca] exhibits a tendency for high overscreening and undergoes a transition into the crowding regime, whereas [C2mim][dca] exhibits low overscreening and shows no signs of crowding. As a result, the interfacial concentration of zinc and anions is higher in [C2mim][dca], strongly suggesting a large impact on the electrochemical performance of a battery.
History
Journal
Physical Review MaterialsVolume
3Article number
ARTN 095801Pagination
1 - 8Location
College Park, Md.Publisher DOI
ISSN
2475-9953eISSN
2475-9953Language
EnglishPublication classification
C1 Refereed article in a scholarly journalCopyright notice
2019, American Physical SocietyIssue
9Publisher
AMER PHYSICAL SOCUsage metrics
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No categories selectedKeywords
Science & TechnologyTechnologyMaterials Science, MultidisciplinaryMaterials ScienceMOLECULAR-DYNAMICS SIMULATIONSFORCE-FIELDDOUBLE-LAYERIMIDAZOLIUMCAPACITANCEMIXTURESNANOSTRUCTUREPYRROLIDINIUMINTERFACESINSIGHTSChemical Physics & Physical ChemistryElectrical propertiesElectrochemical propertiesElectrochemistryElectrostatic interactionsGrapheneIonic fluidsLiquid-solid interfacesSurfacesMolecular dynamics030304 Physical Chemistry of Materials030604 Electrochemistry850602 Energy Storage (excl. Hydrogen)Institute for Frontier MaterialsCE1401000123406 Physical chemistry3401 Analytical chemistry
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