Ionic Liquid Electrodeposition Research Articles

Synthesis of Te-Bi core-shell nanowires by two-step electrodeposition in ionic liquids

Te-Bi core-shell nanowires were synthesized by electrochemical deposition in ionic liquids without using a template. The nanowires were synthesized in two steps: self-standing single crystal Te nanowires with a diameter of 76.2±28.4nm and a length of a few microns were electrodeposited first, taking advantage of the templating properties of the mixture of ionic liquids EOPipTFSI:EOPipBr 95:5 mole%. The Bi shell was then deposited on the Te core in EOPipTFSI. The influence of various experimental parameters on Bi shell deposition was studied. Thanks to the higher viscosity of the electrolyte compared to an aqueous medium, a lower growth rate is observed, leading to a thin layer of bismuth. In addition, High Resolution Transmission Electronic Microscopy shows that under optimal conditions the Te nanowires are entirely covered by a homogeneous, compact and polycrystalline Bi shell and that the core/shell interface is smooth.

Effect of Magnetic Field on Al Electrodeposition in Ionic Liquid

1.Introduction Aluminum is a very important material because of its distinctive features of a bright silvery appearance, light weight and high corrosion resistance. Also, it is used as a base in light-emitting diodes owing to its high reflectance of more than 90% in the visible light region. We have previously carried out Al electrodeposition with additives and reported a shiny coating under the control of a stirred flow [1]. In that work, the surface roughness and glossiness was drastically improved by increasing the stirring rate. To pursue a novel convection method, we consider that the superimposition of a magnetic field, B, is a possible solution. Lorentz force occurs when a magnetic field is applied perpendicular to current, and a convection caused by the power is called MHD convection [2]. Therefore in an ionic liquid which consists of only ion species, the MHD convection can expect to act more effectively as compared with an aqueous solution system. In this report, Al films were electrodeposited in EMIC-AlCl3 ionic liquid under a uniform magnetic field, whereupon their morphology and crystal orientation were analyzed by scanning electron microscopy and X-ray diffractometry. 2.Experimental Electrodeposition was carried out with a three-electrode system. The electrolyte used was EMIC-AlCl3 (1:2). The cathode was a Cu plate and the anode was an Al plate. All experiments were conducted in a glove box purged using by Ar gas at 60°C. The Al electrodeposition was conducted galvanostatically until the amount of electrical charge reached 29 C cm−2, which corresponds to a deposition 10 µm thick. A static and uniform magnetic field of 0.3 T was applied parallel to the electrode surface. The surface morphology of the electrodeposited Al films was observed using SEM, while the crystal orientation was measured by XRD using the Cu-Kα line. 3.Results and discussion In the galvanostatic electrolysis experiment, potential shifted to the noble direction by applying a magnetic field, and when current density was enlarged, the difference appeared more notably. The magnetic field also affected the orientation of deposition, and a (200) plane orientated priority. These are considered that the stirring effect by a MHD convection is involving. The SEM images show that the crystal grains change remarkably in the presence of a magnetic field, where a typical morphological variation is shown in Fig. 1. Fig. 1(a) shows angular deposits around 1.0 µm in size, and a surface covered with fine irregular grains. The application of magnetic field, however, created large grains with tabular-facet planes 2–4 µm in size (Fig. 1 (b)), although no additives were used in the present experiments. [1] H. Takahashi, C. Namekata, T. Kikuchi, H. Matsushima and M. Ueda, Journal of the Surface Finishing Society of Japan, 68, 208 (2017). [2] A. Bund, S. Koehler, H. H. Kuehnlein and W. Plieth, Electrochimica Acta, 49, 147 (2003). Figure 1

Aluminizing via Ionic Liquid Electrodeposition and Pack Cementation: A Comparative Study with Inconel 738 and a CoNiCrAlY

A novel aluminizing process based upon room temperature Al-electrodeposition from Ionic Liquids followed by diffusion heat treatment was applied on bare- and CoNiCrAlY-coated Inconel 738 (IN738). The aluminized samples were tested by isothermal oxidation at 1000 °C in air. The microstructural and chemical evolution of the samples were determined as function of oxidation time and compared with the currently applied coatings obtained via pack cementation. The newly proposed method is suitable for the CoNiCrAlY coating, but not for the bare IN738. In the latter, the formed Al-enriched layer is much thinner and the anticorrosion properties resulted in being reduced. This is probably due to the presence of precipitates, which slow down the aluminum inward diffusion impairing the formation of a well-developed interdiffusion zone (IDZ). Traces of the electrolyte, embedded during the Al-electrodeposition process, can be seen as the origin of these precipitates.

Analysis of Cathodic Reaction Process of SiCl4 in Ionic Liquids

Electrodeposition of semiconductor materials such as Si with very negative reduction potentials has been attempted in various non-aqueous solvents [1-3]. In particular, since ionic liquids exhibit relatively large electrochemical windows and are applicable under low temperature condition, they are expected to be one of the promising solvents for Si electrodeposition. Several studies have suggested the capability of ionic liquids to electrodeposit Si [4-6]. We also applied trimethylhexylammonium bis(trifluoromethylsulfonyl) imide (TMHATFSI) ionic liquid for the electrodeposition of Si [7-9]. To control this deposition process more precisely, its reaction mechanism should be elucidated further in detail. In the present study, we analyzed the reaction mechanism of SiCl4 during Si electrodeposition in ionic liquids using three approaches; 1) Electrochemical quartz crystal microbalance (EQCM), 2) X-ray reflectivity (XRR), and 3) Density functional theory (DFT) calculation. Electrodeposition of Si was conducted in TMHATFSI at 40 oC, controlled by thermo block. 3 electrodes cell (W.E. : Au, R.E. : Ag/Ag+, C.E. : Pt) was employed for the Si film electrodeposition. During XRR measurement, 2 electrodes cell (W.E. : Au, C.E. : Au) was used at 30 oC, controlled by thin thermo plate. EQCM measurement was carried out in Ar atmosphere, while the mixture of Ar and N2 was introduced into the electrolytic cell during the XRR measurement. The XRR measurement data were analyzed by GenX software. DFT calculation was performed by Gaussian09 package to support the XRR measurements. Results of the EQCM measurements during the cyclic voltammetry indicated a preliminary stage prior to the electrodeposition, in which no mass increase was detected in spite of substantial amount of charge transfer, suggesting the sequential reduction of SiCl4 through Si (III) and Si (II) species over the multiple stages. These were thought to be intermediate state in Si electrodeposition. Such a state was then investigated by using XRR measurement. The intensity of the reflectivity gradually decreased with the progress of the Si electrodeposition. Analyzed results of the XRR measurement indicated that a layer, which is thought to be polymer-like structure of Si containing dimer such as Si2Cl6, would be generated prior to the formation of metallic Si (0) films. This polymer-like structure was also supported by the results of DFT calculation; energy profiles showed that Si-Si bond formation between two SiCl4 molecules was more favorable than that between SiCl4 and Si surface, after SiCl4 received electrons from the surface. These results suggest that the cathodic reaction of SiCl4 proceeds through the formation of intermediate states containing polymer-like structure of Si. We would like to thank Dr. Apurva Mehta (SLAC National Accelerator Laboratory) and Mr. Trevor Petach (Department of Physics, Stanford University) for their kind advices and helps with the experiment. This study was financially supported in part by the Japan Science and Technology Agency (JST) CREST program. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Y. T. acknowledges the Leading Graduate Program in Science and Engineering, Waseda University, from MEXT, Japan.

Analysis of Cathodic Reaction Process of SiCl4 during Si Electrodeposition in Ionic Liquids

Elementary steps in the electrochemical reduction process of SiCl4 in trimethyl-n-hexylammonium bis(trifluoromethylsulfonyl) imide (TMHATFSI) was investigated, focusing on molecular level behavior of the reactants at solid-liquid interface. Electrochemical measurements using an electrochemical quartz crystal microbalance (EQCM) identified a reduction peak corresponding to Si electrodeposition and several elementary steps with stable intermediates forming prior to the deposition. For detailed analysis, X-ray reflectivity (XRR) measurements with synchrotron radiation were applied in situ. The change in reflectivity of the electrode surface during the deposition was found to be due to the formation of a polymer-like Si such as Si2Cl6, which is an intermediate layer during the deposition process. These results were theoretically supported by density functional theory (DFT) calculations: after an electron transfers from the electrode, the Si in SiCl4 forms the bond with another SiCl4, rather than the Si of the substrate, resulting in the formation of the intermediate structure. These data suggest an elementary step in the SiCl4 reduction process which can be described as follows; when SiCl4 is reduced, a polymer-like Si form such as Si2Cl6 is generated. This intermediate species further reacts with other Si reactants after receiving additional electrons, which then finally deposits as Si on the substrate.

Ionic liquid electrodeposition of strain-released Germanium nanowires as stable anodes for lithium ion batteries.

With the growing demand for portable and wearable electronic devices, it is imperative to develop high performance Li-ion batteries with long life times. Germanium-based materials have recently demonstrated excellent lithium-ion storage ability and are being considered as the most promising candidates for the anodes of lithium-ion batteries. Nevertheless, the practical implementation of Ge-based materials to Li-ion batteries is greatly hampered by the poor cycling ability that resulted from the huge volume variation during lithiation/delithiation processes. Herein, we develop a simple and efficient method for the preparation of Ge nanowires without catalyst nanoparticles and templates, using ionic liquid electrodeposition with subsequent annealing treatment. The Ge nanowire anode shows improved electrochemical performance compared with the Ge dense film anode. A capacity of ∼1200 mA h g-1 after 200 cycles at 0.1 C is obtained, with an initial coulombic efficiency of 81.3%. In addition, the Ge nanowire anode demonstrates superior rate capability with excellent capacity retention and stability (producing highly stable discharge capacities of about 620 mA h g-1 at 5 C). The improved electrochemical performance is the result of the enhanced electron migration and electron transport paths of the nanowires, and sufficient elasticity to buffer the volume expansion. This approach encompasses a low energy processing method where all the material is electrochemically active and binder free. The improved cycling stability and rate performance characteristics make these anodes highly attractive for the most demanding lithium-ion applications.

Pd Nanoparticle Formation during Constant Potential Electrodepositions in Ionic Liquids

Electrodepositions in ionic liquids (ILs) allow for opportunities to improve deposited morphologies, access redox potentials that cannot be achieved in aqueous baths, and utilize less hazardous bath compositions. The driver to utilize ILs for Pd electrodeposition is to minimize hydrogen embrittlement challenges commonly associated with Pd electrodeposition in aqueous electrolytes. Generally, the resulting Pd deposits in ILs are thin films, loosely adhered fine powders or dendritic structures, depending upon the IL selected and the electrochemical parameters used(1, 2). Recently, it has also been shown that electroreduction of Pd in ILs can result in nanoparticles being formed in solution, rather than on an substrate electrode when high overpotentials are used(3). Previously, we showed Pd nanosphere formation can be controlled through potentiostatic pulse deposition in 1-butyl, 3-methylimidazolium chloride [Bmim][Cl] onto Ni electrode substrates(4). The nanosphere size was found to be a function of cycle time. In contrast, using 1-buty, 1-methylpyrrolidinum dicyanamide [Bmpyrr][DCA] under constant potential conditions, thin film Pd layers on nickel electrode substrates were obtained(5). We will present how, upon further investigation, these Pd “thin films” formed from constant potential deposition in [Bmpyrr][DCA] are actually agglomerates of nanoparticles that can be scraped off the Ni substrate and dispersed in solution in an unagglomerated state. These nanoparticles have an average size of 6.3 ± 1.6 nm when deposited at -2.3V vs. Fc/Fc+. Further investigation into the conditions for electrodeposition in ILs where it was thought that thin films were formed will also be discussed to better understand if the resulting deposits were truly thin films and not nanoparticle agglomerations.

Non-Equilibrium Ionic Liquid-Electrode Interface at Elevated Temperature and Its Influence on Co2+ Reduction Process

Electrodeposition in Ionic Liquid (IL) media is still at its infancy stage. Recently much attention is devoted to exploration of the IL-electrode interface for better understanding of the electrochemical processes at the electrified surfaces. Herein, we provide a new perspective of the temperature-driven IL-substrate interface structuring. We observed an increase in Co2+ reduction kinetics induced by applying a high temperature gradient. In contrast, keeping the cell at a high constant temperature (100°C) leads to slower Co2+ reduction kinetics, it results in a shift of the reduction onset and evolution of the cyclic voltammogram shape with time. We could ascribe these phenomena to the disturbance of the electrochemical double layer (induced by heating) and its further slow reorganization at constant temperature. We showed that such non-equilibrium behavior can be beneficial for the synthesis of metallic thin films from ILs. Electrochemical quartz crystal microgravimetry, impedance spectroscopy, cyclic voltammetry and chronoamperometry were employed within this work.

Size-Controlled Synthesis of Palladium Nanospheres by Pulse Electrodeposition in 1-Butyl-3-methylimmidazolium Chloride Ionic Liquid

Pd electrodeposition in ionic liquids has been mostly limited to the formation of thin films, which has restricted its potential application to the electronics and decorative industry only. The electrochemical synthesis of nanostructured Pd could broaden its applications to the catalyst industry as well. In 1-butyl-3-methylimmidazolium chloride, the Pd deposits reported so far have had uncontrolled growth without any well-defined morphology. In this study, we report controlled synthesis of Pd nanoparticles with well-defined morphology on pre-etched Ni electrodes. Potentiostatic pulse deposition was used to synthesize these Pd nanoparticles, which had spherical shape and unimodal size distribution. In contrast, thin film-like morphology was deposited during direct electrodeposition. The size of the Pd nanospheres was controlled by controlling the duty cycle; the size of the Pd nanospheres increased from 14.8 ± 3.5 to 30.8 ± 6.6 nm when the duty cycle decreased from 0.5 to 0.2. The size of the Pd nanospheres showed linear dependence on the duty cycle giving excellent control. X-ray diffraction analysis revealed face-centered cubic crystalline microstructure for the Pd particles. The analysis also suggested that the amount of Pd increased by decreasing the duty cycle. The surface of the Pd deposits was dominated by metallic state as revealed by X-ray photoelectron spectroscopy.

Electrodeposition in Ionic Liquids.

Due to their attractive physico-chemical properties, ionic liquids (ILs) are increasingly used as deposition electrolytes. This review summarizes recent advances in electrodeposition in ILs and focuses on its similarities and differences with that in aqueous solutions. The electrodeposition in ILs is divided into direct and template-assisted deposition. We detail the direct deposition of metals, alloys and semiconductors in five types of ILs, including halometallate ILs, air- and water-stable ILs, deep eutectic solvents (DESs), ILs with metal-containing cations, and protic ILs. Template-assisted deposition of nanostructures and macroporous structures in ILs is also presented. The effects of modulating factors such as deposition conditions (current density, current density mode, deposition time, temperature) and electrolyte components (cation, anion, metal salts, additives, water content) on the morphology, compositions, microstructures and properties of the prepared materials are highlighted.

Grain boundary segregation in Al–Mn electrodeposits prepared from ionic liquid

Among the various preparation methods for nanocrystalline alloys, ionic liquid electrodeposition at low temperature is of interest for its scalability and efficiency. To achieve nanostructures with stabilized structures, it is desirable to directly deposit alloys in which the grain boundaries are decorated with a segregated alloying element. Here a combination of atom-probe tomography and aberration-corrected scanning transmission electron microscopy are used to confirm that in Al–Mn nanocrystalline alloys deposited from an ionic liquid, Mn is slightly segregated at grain boundaries in the as-deposited condition. The apparent heat of grain boundary segregation is calculated to lie between 1100 and 1500 J mol−1, which aligns reasonably well with a value calculated using a Miedema-based segregation model, and which is also in line with a more refined CALPHAD-type estimation if it is assumed that the Al–Mn deposits are not fully equilibrated at the deposition temperature.

Effect of 1-Butyl-1-Methylpyrrolidnium Dicyanamide on the Structure of Pd Electrodeposit

One of the most widely investigated applications of ionic liquids (ILs) is electrodeposition (1). Wide electrochemical window, good conductivity, metal complexing ability, and low water content are the advantages of doing electrodeposition in ILs. Electrodeposition of metals from every group of the periodic table has been studied (2). One of such metal is Pd, which has hydrogen embrittlement issues in aqueous-based solutions. In ILs, the embrittlement issue could be avoided (3). Although many ILs have been tried for Pd electrodeposition, the morphology of the electrodeposit has often been often been powdery and prone to cracks (3-5). Understanding the structure of the Pd electrodeposited in ILs could reveal ways to improve its morphology. In this work, structure of the Pd electrodeposited in 1-butyl-methylpyrrolidinium dicyanamide ([Bmpyrr][DCA]) is studied. Due to the metal complexing ability of [DCA]- anions, previous works have shown that [Bmpyrr][DCA] is a suitable room-temperature ILs to electrodeposit Pd (6, 7). After electrodeposition, we found significant presence of nitrogen on the Pd deposits through X-ray photoelectron spectroscopy (Figure 1). Since the source of nitrogen cannot be atmosphere, we hypothesized that the nitrogen was from [Bmpyrr][DCA] tethered to the Pd electrodeposit. This raises interesting questions as to the role of ILs in the structure of the Pd deposits. We will present further characterization of the Pd deposits using X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron microscopy (XPS) to study the role of [Bmpyrr][DCA] on structure of the Pd deposit.

Effects of Organic Additives Containing Carbonyl Group on Electrodeposition of Al from AlCl3-[Emim]Cl Ionic Liquid

Electrodeposition of Al in ionic liquids for preparation of aluminum products had opened up a new research direction, but the previous studies found that aluminum product from pure ionic liquid electrodeposition was unable to meet the requirements in both uniformity and smoothness. Electrodepostion in pure ionic liquid often results in the deposits with rough surface or even dendritic products after long-time deposition. In this study, five kinds of small organic molecules containing carbonyl as additives were investigated, such as acetone, acetic acid amide, acetic acid, methyl acetate and methyl carbamate. Additives were added to [Emim]Cl/AlCl3(33.3/66.7 mol%) with a concentration of 5 mmol/L, 15 mmol/L, 45 mmol/L. Cyclic voltammetry was studied on a glassy carbon electrode at a scan rate of 100 mV.s(-1) and temperature of 323 K. The electrode potential was scanned from the open circuit potential to negative-potential, then retraced to get cyclic voltammetry curve. Among those organic additives, methyl carbamate was proved to be an excellent additive. The brightness of Al can be improved by adding 45 mmol/L methyl carbamate. Smooth, uniform and mirror bright Al deposition would be obtained afterward. Furthermore, the effects of additive for Al deposit on morphology, crystal orientation and Al deposition mechanism by the analysis of galvanostatic deposition, scanning electron microscope (SEM), X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis) and nuclear magnetic resonance (NMR) was conjectured. The results showed that methyl carbamate as an additive would make grain refinement more apparent and present more strong Al(200) crystal plane orientation. As an additive, methyl carbamate did not form new metal complex in the electrolytic liquid and did not affect the structure of active aluminum ion in the electrolyte. The positive center of carbonyl carbon atom in methyl carbamate molecular can be easily adsorbed at the cathode surface. This procedure inhibited the process of Al deposition and obtained the smooth and bright effect. Therefore, Al deposition layer of mirror can be obtained, which has an important guiding significance in the selection of ionic liquid additive in electrodeposition system.

Nanowires of Cu–Zn and Cu–Zn–Al shape memory alloys elaborated via electrodeposition in ionic liquid

The electrosynthesis of Cu–Zn, Al and Cu–Zn–Al nanowires from the 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquid was investigated. The anion of the metallic salts was the same as the solvent, i.e. bis(trifluoromethylsulfonyl)imide. The electrodeposition mechanism of each individual metal is complicated and shows many cathodic stages. The arrangement of these different steps in the current density–potential curves of alloys leads to unexpected composition evolution of deposits versus potential. According to the applied polarisation, a wide range of alloy compositions can be obtained.

Nanostructured tin electrodeposited in ionic liquid for use as an anode for Li-ion batteries

Nanostructured tin (Sn) is fabricated via electrodeposition in an ionic liquid (IL). The advantages of electrodeposition in IL (compared to that in conventional aqueous solution) include increased deposition current efficiency and suppressed corrosion of the Cu current collector. The former is associated with the elimination of hydrogen evolution during the cathodic deposition and the latter is attributed to the chemical benignity of ILs. It is found that the Sn morphologies can be effectively manipulated by adjusting the deposition potential in the IL plating solution. The higher the deposition overpotential, the better is the electrochemical performance of the Sn electrode for Li-ion batteries. The electrode deposited at −2.4 V, consisting of Sn nanospheres, shows a reversible discharge (delithiation) capacity of 980 mA h g−1 (at 0.1 A g−1). When the charge–discharge rate is increased to 15 A g−1, the measured capacity is as high as 588 mA h g−1. These properties are clearly superior to those of the Sn electrode deposited in aqueous solution.

Properties of CuSbS2 thin films electrodeposited from ionic liquids as p-type absorber for photovoltaic solar cells

Electrodeposition of CuSbS2 semiconductor thin films for photovoltaic solar cells is investigated from ionic liquid electrolyte based on choline chloride–urea eutectic. Cyclic voltammetry study shows Cu and Sb deposition potential of −0.54V and −0.48V vs Pt, respectively. Highly crystalline CuSbS2 films in the chalcostibite orthorhombic structure without binary compound phases are electrodeposited at a potential of −0.65V vs Pt with Cu to Sb precursor ratio of 1:1 and Na2S2O3 as sulfur source in ionic liquid medium held at 80°C. Increase in Cu-precursor ratio (1:0.71) led to Cu3SbS3 ternary and that of Sb-precursor ratio (1:1.4) led to binary Sb2S3 phase inclusion in the phase field of the CuSbS2 films. Electrochemical impedance spectroscopy studies show diffusive ionic transport limited growth mechanism. Single phase CuSbS2 films show direct band gap energy of 1.66±0.01eV and films with inclusive secondary phases have band gap energy of 1.73±0.01eV. As-deposited CuSbS2 films are p-type and a hetero-junction in the nZnO–pCuSbS2 structure showed rectifying current–voltage behavior and low reverse current consistent with compact pinhole free CuSbS2 film synthesized by ionic liquid electrodeposition.

Effect of Current Density on Nucleation and Morphology of Lithium during Electrodeposition in Ionic Liquids

Lithium metal is very attractive anode material but the dendrite formation during charging prevents the batteries with lithium metal anode from wide commercialization. Our group has focused on some room-temperature ionic liquids as electrolytes from the viewpoint of high stability at the negative potential of Li/Li+. In the present study, the morphology of electrodeposited lithium in the ionic liquids was investigated by ex situ SEM observations. The effect of current density on lithium dendrite formation was figured out. The electrolytes are prepared by addition of 10 wt.% of Li[Tf2N] to [C3mpip][Tf2N], [C4mpyr][Tf2N], and [N6,1,1,1][Tf2N] (see Figure). Two-electrode cells were fabricated, using nickel foils as working electrodes and lithium foils as counter electrodes. Lithium metal was electrodeposited with the current density from 5 to 200 μA cm-2 for total coulomb amount of 3 C cm-2. The morphology of electrodeposited lithium on each working electrode was observed by ex situ SEM after washing with dimethylcarbonate (see Figure). For the cell with [C3mpip][Tf2N], when the current density was higher than 50 μA cm-2, the needle like deposits were observed and the deposits were apparently thought to have grown from a semisphere-like nuclei.1 When the current density was higher than 50 μA cm-2 for the cell with [N6,1,1,1][Tf2N], and was higher than 100 μA cm-2 with [C4mpyr][Tf2N], the needle like deposits were also observed and the deposits were thought to have grown from a semisphere like nuclei.1 The results for the lithium deposit morphology obtained from each cell with three ionic liquids were discussed with lithium-ion diffusion coefficient of the electrolytes, and we concluded as follows; The deposits were better distributed with decreased size when the current density was increased in the current range where the deposition was charge-transfer controlled. With higher current density where the deposition was diffusion controlled, deposits were more distributed but large and dendritic. The current density dependency of the lithium deposition behavior from ionic liquid are very similar to the case with noble metal deposition from aqueous solution, which is due to the high stability of the ionic liquid used in this study at the negative potential of Li/Li+.[1] H. Sano, et al., ECS Electrochem. Lett., to be submitted.

Importance of the double layer structure in the electrochemical deposition of Co from soluble Co2+ - based precursors in Ionic Liquid media

Electrodeposition in Ionic Liquid (IL) media is being widely used to obtain different metals, alloys and more recently binary compounds. However, the understanding of this process is still slim due to poor knowledge in the chemistry of ILs and also the complex structure of the double layer at the electrode surface. It is then difficult to predict deposition conditions when trying to synthesize a desired deposit. In this work, we provide insight into the processes taking place at the electrode by detailed studies of Co2+ reduction in ionic liquid media at elevated temperature, which have revealed an unusual Cyclic Voltammetry profile. A drastic drop in the reaction rate was observed, together with a well-shaped reduction peak during the oxidation sweep. Using Electrochemical Quartz Crystal Microbalance, Impedance Spectroscopy measurements and varying bath parameters, we ascribed those phenomena to the reconstruction of the double layer structure upon imposed polarization. Similar behaviors were observed for other systems (Mn2+, Ni2+, Zn2+). Finally, this work provides new insight into the electrochemical processes in ILs. We anticipate that it will also result in significant improvement in preparing metal and other deposits in the ionic liquid media.

Ionic liquid electrodeposition of 3D germanium–acetylene black–Ni foam nanocomposite electrodes for lithium-ion batteries

A simple process involving the electrophoretic deposition of acetylene black onto Ni foam and the ionic liquid electrodeposition of Ge has been used to synthesize a 3D Ge–acetylene black–Ni foam electrode material at room temperature.

Electrodeposition in Ionic Liquids: From Nanoscale Processes to Macroporous Materials

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