6533b7d0fe1ef96bd125af7f
RESEARCH PRODUCT
Molecular scale structure and dynamics at an ionic liquid/electrode interface.
Peter ReichertPeter ReichertMartin NielsenDiego PontoniKasper S. KjærTim Brandt Van DrielJannis W. OchsmannMoshe DeutschMarkus MezgerMarkus MezgerJulian MarsJulian Marssubject
ChemistryRelaxation (NMR)Analytical chemistryCharge density02 engineering and technologyElectrolyte010402 general chemistry021001 nanoscience & nanotechnology01 natural sciences0104 chemical sciencesDielectric spectroscopyIonAnodechemistry.chemical_compoundChemical physicsIonic liquidElectrodePhysical and Theoretical Chemistry0210 nano-technologydescription
After a century of research, the potential-dependent ion distribution at electrode/electrolyte interfaces is still under debate. In particular for solvent-free electrolytes such as room-temperature ionic liquids, classical theories for the electrical double layer are not applicable. Using a combination of in situ high-energy X-ray reflectivity and impedance spectroscopy measurements, we determined this distribution with sub-molecular resolution. We find oscillatory charge density profiles consisting of alternating anion- and cation-enriched layers at both cathodic and anodic potentials. This structure is shown to arise from the same ion-ion correlations dominating the liquid bulk structure. The relaxation dynamics of the interfacial structure upon charging/discharging were studied by impedance spectroscopy and time resolved X-ray reflectivity experiments with sub-millisecond resolution. The analysis revealed three relaxation processes of vastly different characteristic time scales: a 2 ms scale interface-normal ion transport, a 100 ms scale molecular reorientation, and a minute scale lateral ordering within the first layer.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2017-09-30 | Faraday discussions |