Metal-Ion Diffusion in Ionic Liquid Studied by Electrochemical Scanning Electron Microscopy with X-ray Fluorescence Spectrometry

Abstract

Investigating metal-ion transport in ionic liquid media is important to realize batteries and electrodeposition, which utilize intriguing properties of the media. An in situ electrochemical scanning electron microscopy together with X-ray fluorescence spectrometry is developed by a simple modification of an instrument as a tool for the investigation. Diffusion of silver ions (Ag + ) in an ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonylamide (BMI-TFSA) is monitored as the time variation of Ag + concentration during the anodic dissolution of a silver electrode. The results are analyzed by a digital simulation of the diffusion layer based on Fick's law. The diffusion coefficient of Ag + is unexpectedly varied according to the concentration, and the tendency of variation is discussed in terms of viscosity change.

Polymerization of Room-Temperature Ionic Liquid Monomers by Electron Beam Irradiation with the Aim of Fabricating Three-Dimensional Micropolymer/Nanopolymer Structures

“…Room-temperature ionic liquids (RTILs), which are liquid salts consisting only of cations and anions, have fascinated many researchers in various fields because of their unique physicochemical properties such as incombustibility, high ionic conductivity, high thermal stability, and wide electrochemical window. − Among these properties, the negligible vapor pressure of RTILs is one of the most important features in recent research using RTILs under vacuum conditions. , Our research group developed several new technologies that can be categorized as RTIL-vacuum technology. , For example, we have developed an in situ scanning electron microscopy (SEM) technique to investigate electrochemical reactions in RTIL concurrently with the polarization of electrodes. , In a series of investigations, we further noticed that certain types of chemical reactions, i.e., the reduction of metal ions, are induced by electron beam irradiation. , The first finding was that gold particles were produced in an RTIL that contained gold ions during the observation of the RTIL by SEM. On the basis of these perceptions, we have established a completely new method to fabricate micro/nanosized polymer structures by drawing arbitrary patterns on a polymerizable RTIL, 1-allyl-3-ethylimidazolium bis­((trifluoromethane)­sulfonyl)­amide ([AllylEtIm]­[Tf 2 N], Scheme ), with a focused ion beam (FIB) instrument .…”

Three-dimensional micro/nano-scale structure fabricated by combination of non-volatile polymerizable RTIL and FIB irradiation

“…We found that magnetron sputtering onto RTIL yields a wide variety of metal and alloy nanoparticles without any stabilizing agent 23 24 and that RTIL itself can be observed by a scanning electron microscope without accumulation of electrostatic charge at the surface of RTIL 25 . The latter is applicable to scanning electron microscope (SEM) and transmission electron microscope (TEM) observations of hydrated specimens pretreated with RTIL and to in situ SEM observation of chemical reactions in RTIL 26 27 28 29 .…”

Electrochemical quartz crystal microbalance measurement of a Li4Ti5O12 composite electrode in a carbonate electrolyte

“…The local concentration of Li þ has been estimated indirectly by the Raman spectra and the optical absorption of a counter anion [26,27], and directly by 7 Li NMR spectra [25]. Li þ is not detectable by the fluorescent X-ray method, although the direct observation of the concentration distribution of silver species in an ionic liquid has been also reported using a scanning electron microscope with an energy dispersive X-ray analysis [28]. While the concentration distribution can be visualized by these methods, the time required for these measurements is generally longer than that for EQCM.…”