Correlating the Ionic Drift under Pt/Pt Electrodes for Ionic Liquids Measured by Low-Voltage Electrophoretic NMR with Chronoamperometry

Abstract

The current density under an electric field is usually measured by chronoamperometry. After the application of an electric field, electric double layers are immediately formed on the electrodes and the current spike decays quickly. The thickness of the electrical double layers is thin and composed of several ion layers. Ions in the bulk electrolyte remote from the electrodes are supposed to scarcely migrate. In this study, ion migration in the bulk for ionic liquids was measured by using a modified electrophoretic NMR (ENMR) or low-voltage ENMR sequence in which a delay time is introduced after the application of the static electric field to induce the ion migration prior to the commencement of the pulsed gradient spin−echo NMR measurements. This is the first attempt to measure the ion migration in the bulk under the influence of small electric fields similar to those used in electric devices.