Electrochemical Deposition Of Magnesium Research Articles

Formation of needle-like and honeycomb-like magnesium oxide/hydroxide structures by electrodeposition from magnesium nitrate melts

The processes of electrochemical deposition of magnesium oxide/hydroxide on glassy carbon (GC) electrode from magnesium nitrate hexahydrate melt have been investigated. A novel procedure predicting a possibility of direct formation of magnesium oxide during electrodeposition from the nitrate melt used is reported. XRD analysis of the obtained deposits showed the formation of magnesium oxide along with magnesium hydroxide. The electrodeposition of magnesium oxide/hydroxide commences in magnesium underpotential (UPD) and continues through the magnesium overpotential (OPD) region. Network of individual or intertwined very thin needles as well as those grouped in flower-like aggregates or honeycomb-like structures were formed in both magnesium UPD and OPD regions. Formation of the long needles was explained through theories of mechanisms of dendrite formation. Hydrogen evolution commences in the magnesium OPD region and increases with the applied overpotential. Holes observed in the deposit originated from the detached hydrogen bubbles. The number, shape and size of the hole strongly depended on both the applied cathodic potential and the hold time of electrodeposition. Magnesium oxides/hydroxides syntheses taking part simultaneously at various applied potentials are a result of reactions between magnesium cations and products of water and nitrate anions reduction processes. Chemical reactions responsible for direct formation of magnesium oxide observed are those of magnesium ions and oxygen ions, formed by nitrate reduction taking part in the close vicinity of the working electrode.

High-Performing Electrolytes for Secondary Magnesium Batteries Based on Emimcl, AlCl3, and δ-MgCl2

After several studies demonstrating the reversibility of Mg deposition and stripping processes from Grignard solutions [1,2] early Mg secondary batteries, which comprised a metallic magnesium anode, a composite cathode and a polymer electrolyte based on polyethylene glycol and an innovative δ‐MgCl2 salt [3,4] were first proposed in 1998 [5]. Subsequently, electrolytes based on Grignard [6,7] and other organo‐Mg [8]compounds were explored. Nevertheless, ethereal solutions of Grignard compounds are hazardous, due to the volatility and flammability of the solvents. Here, we report about a class of high-performing electrolytes based on 1-ethyl-3-methylimidazolium chloride (EMImCl) doped with AlCl3 and a highly amorphous form of MgCl2 [4]. The measurements of the phase diagrams of these materials allowed us to identify four thermal transitions, which are strongly dependent on salt concentration. Vibrational studies indicated the presence of two different types of concatenated Mg-chloroaluminate complexes. Electrochemical measurements at 25°C revealed a promising redox reversibility in non-blocking conditions with: 1) an exchange current of 0.54-1.68 mA/cm2; 2) a Coulombic efficiency as high as 98.4%; 3) a deposition overpotential <100 mV; and 4) an anodic stability of ca. 2.2 V. Broadband electrical spectroscopy studies provided information about the conduction mechanism of the electrolyte materials in terms of dielectric and polarization phenomena. A relatively uniform Mg chemical environment is revealed by 25Mg NMR spectroscopy. Finally, a structural 3D-model, which explains all the revealed experimental evidences is proposed. Mg-anode cells assembled with the electrolytes and a vanadium oxide cathode were cycled at least 50 times at a high rate (35 mA/g) revealing an initial capacity of 80 mAh/g and an open-circuit voltage of 2.7 V.[1] C. Liebenow, Reversibility of electrochemical magnesium deposition from Grignard solutions, 27 (1997) 221–225.[2] T.D. Gregory, Nonaqueous Electrochemistry of Magnesium, J. Electrochem. Soc. 137 (1990) 775.[3] V.D. Noto, S. Lavina, D. Longo, M. Vidali, A novel electrolytic complex based on δ-MgCl2 and poly(ethylene glycol) 400, Electrochim. Acta. 43 (1998) 1225–1237.[4] M. Vittadello, P.E. Stallworth, F.M. Alamgir, S. Suarez, S. Abbrent, C.M. Drain, et al., Polymeric δ-MgCl2 nanoribbons, Inorganica Chim. Acta. 359 (2006) 2513–2518.[5] V. Di Noto, M. Fauri, G. De Luca, M. Vidali, A new magnesium ion polymer battery (Poster), in: 9th Int. Meet. Lithium Batter., Edinburgh, Scotland, United Kingdom, 1998.[6] D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, et al., Prototype systems for rechargeable magnesium batteries, Nature. 407 (2000) 724–7.[7] Z. Lu, A. Schechter, M. Moshkovich, D. Aurbach, On the electrochemical behavior of magnesium electrodes in polar aprotic electrolyte solutions, J. Electroanal. Chem. 466 (1999) 203–217.[8] Z. Yang, C. Liebenow, P. Lobitz, The electrodeposition of magnesium using solutions of organomagnesium halides, amidomagnesium halides and magnesium organoborates, Electrochem. Commun. 2 (2000) 641–645.

Effect of Electrolytic Properties of a Magnesium Organohaloaluminate Electrolyte on Magnesium Deposition

Complex magnesium organohaloaluminate electrolytes were studied by electrochemical transport measurements and in-situ electrochemical/X-ray absorption spectroscopy. Cyclic voltammetry was employed to examine the reversibility of electrochemical magnesium deposition. To better understand the role of this electrolyte system, ionic transport properties such as transference number, ionic conductivity, and diffusion coefficient of Mg-ion species were measured at different concentrations. Transference number was determined by atomic absorption spectroscopy by quantifying the amount of potentiometric Mg deposition on Pt electrode. Despite exhibiting 100% Coulombic efficiency for Mg deposition and dissolution, the electrolyte showed low ionic conductivity and transference number at moderate and higher concentrations. To further investigate the observed transport properties, electrochemical deposition of magnesium from [Mg2(μ-Cl)3·6(OC4H8)]+ was monitored with in-situ/in-operando X-ray absorption spectroscopy of t...

Electrochemical deposition of magnesium from analogous ionic liquid based on dimethylformamide

In this paper, a homogeneous, colorless analogous ionic liquid containing dimethylformamide (DMF) and magnesium chloride hexahydrate is synthesized. The conductivity of analogous ionic liquid is measured as a function of temperature and composition. Irreversible electrochemical behavior was generally observed by cyclic voltammetry (CV) in the analogous ionic liquid based electrolytes containing simple Mg salt. CV also shows that the reducing reaction of Mg2+ is a diffusion control process. Electrochemical impedance spectroscopy (EIS) of analogous ionic liquid was measured at 20°C, 40°C and 60°C. Electrodeposition of magnesium metal from analogous ionic liquid has been studied. The Mg deposits are also systematically characterized by the techniques of powder X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Results showed that magnesium was found in the deposited film.

Mg deposition observed by in situ electrochemical Mg K-edge X-ray absorption spectroscopy

The electrochemical deposition of magnesium from [Mg2(μ-Cl)3·6(OC4H8)]+ has been monitored in situ with X-ray absorption spectroscopy. The viability of the cell design was confirmed by a reversible shift in the X-ray absorption near-edge spectroscopy (XANES) of the Mg K-edge. In situ electrochemical XANES revealed the presence of an interfacial Mg intermediate below the equilibrium Mg/Mg2+ potential. A new method has been established to directly observe the complex electrochemical reduction process from Mg electrolytes.

Reversibility of electrochemical magnesium deposition from tetrahydrofuran solutions containing pyrrolidinyl magnesium halide

In this paper we reported for the first time the electrochemical behavior of pyrrolidinyl magnesium halide (C4H8NMgX, X=Br and Cl) dissolved in tetrahydrofuran (THF) with regard to potential application as electrolytes for rechargeable magnesium batteries. C4H8NMgX/THF solutions were characterized in term of conductivity, anodic stability, and reversibility of magnesium deposition and dissolution. Furthermore, the effect of metal substrates on magnesium deposition process was studied. Simple preparation, high cycling reversibility and moderate anodic stability of C4H8NMgBr/THF solution indicate the feasible application as the electrolyte for rechargeable magnesium batteries.

Electrochemical co-deposition of magnesium with lithium from quaternary ammonium-based ionic liquid

Electrochemical deposition of magnesium (Mg) has been successfully achieved from an ionic liquid (IL) solution based on quaternary ammonium salt containing lithium (Li) salt. Irreversible electrochemical behavior was generally observed in the IL-based electrolytes containing simple Mg salt. In the IL-based electrolyte dissolving both Mg and Li salts, electrochemical reduction and oxidation of magnesium cation (Mg 2+) have become detectable. Such reversible processes correspond respectively to cathodic deposition and anodic dissolution of metallic Mg, which are accompanied by the co-deposition/co-dissolution of Li. Potentiostatic electrolysis of IL dissolving binary Mg and Li salts gave metallic deposit consisting of both elements with total current efficiency of ca. 52%.

ELECTROCHEMICAL DEPOSITION OF MAGNESIUM IN ETHEREAL GRIGNARD SALT SOLUTION WITH IONIC LIQUID ADDITIVE

The electrochemical deposition of magnesium was investigated in ethereal Grignard salt solution with tetraethylammonium bistrifluoro-methanesulfonimidate additive, using cyclic voltammetry, potentiostatic transients, and scanning electron microscope measurements. The voltammograms showed the presence of reduction and oxidation peaks associated with the deposition and dissolution of magnesium. From the analysis of the experimental current transients, it was shown that the magnesium deposition process was characterized as a three-dimensional nucleation. The deposited product obtained from potentiostatic reduction presented a generally uniform and dense film.

Studies on the Electrodeposition of Magnesium in Ionic Liquids

The electrochemical deposition of magnesium was investigated in the ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIm ), 1-butyl-1-methylpyrrolidinium triflate (BMP TfO), and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfo nyl)amide (BMP ). The electrochemical window of the imidazolium ionic liquid was insufficient for reduction of magnesium triflate, whereas the BMP systems can be used for the reduction of several magnesium salts. Studies of the reduction of other magnesium salts were carried out in nonaqueous solvents such as propylene carbonate for comparison with the work in ionic liquids. Stripping peaks for magnesium were observed in solutions of phenylmagnesium chloride in BMP at elevated temperatures .

Electrochemical Studies of Magnesium Deposition in Ionic Liquids

The electrochemical deposition of magnesium has been investigated in the ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIm BF4), 1-butyl-3-methylpyrrolidinium triflate (BMP TfO), and 1-butyl-3-methylpyrrolidinium bis (trifluorosulfonyl)amide (BMP Tf2N). The electrochemical window of the imidazolium ionic liquid was found to be insufficient for reduction of magnesium triflate, whereas the BMP systems can be used for the reduction of several magnesium salts. Studies of the reduction of other magnesium salts were carried out in nonaqueous solvents such as propylene carbonate for comparison with the work in ionic liquids.

Study of Key Factors Influencing Electrochemical Reversibility of Magnesium Deposition and Dissolution

The electrochemical magnesium deposition and dissolution on metal substrates with high cycling efficiency can be realized in both organic electrolyte and ionic liquid . The effect of metal substrates (Ag, Ni, and Cu) on magnesium deposition–dissolution was studied by cyclic voltammograms and charge–discharge tests of coin cells, and better results were obtained using silver as the substrate in both the electrolytes. X-ray diffraction analysis reveals that the deposited magnesium can react with silver substrate to form silver–magnesium alloy, which decreases the overpotential of electrochemical magnesium deposition–dissolution and promotes the cycling efficiency. It was observed that morphology of magnesium deposit and interfacial impedance developed from the above-mentioned electrolytes varied markedly, leading to different electrode performances such as overpotential in the initial cycles and cycle life.

Reversible deposition and dissolution of magnesium from BMIMBF 4 ionic liquid

In this paper, we reported for the first time the highly reversible magnesium deposition and dissolution processes on silver substrate in the ionic liquid of BMIMBF 4 with 1 M Mg(CF 3SO 3) 2. Stable-state cycles with several millivolts against magnesium at 0.1 mA/cm 2 can be obtained during repeated charge-discharge cycling at room temperature. The cyclic voltammograms also demonstrated reversible magnesium deposition–dissolution processes. Impedance measurements during steady-state Mg deposition represented low electrochemical impedance, though this resistance was high during the initial cycling. Scanning electron microscopy (SEM) results showed that porous Mg deposition became compact and crystalline and the deposited magnesium could be completely dissolved electrochemically, leaving clean and film free surface. The high reversibility of the electrochemical magnesium deposition will inspire us to speculate about the feasibility of secondary magnesium batteries with the electrolyte.

Electrochemical Magnesium Deposition and Dissolution with High Efficiency in Ionic Liquid

Electrochemical Magnesium Deposition and Dissolution with High Efficiency in Ionic Liquid

The electrodeposition of magnesium using solutions of organomagnesium halides, amidomagnesium halides and magnesium organoborates

The electrochemical behaviour of three groups of electrolyte systems having the ability of electrochemical magnesium deposition, were investigated against the background of galvanotechnical or battery application. Solutions of organomagnesium halides, amidomagnesium halides and magnesium organoborates dissolved in tetrahydrofuran were characterized in terms of conductivity, reversibility of the magnesium deposition process and stability of the electrolytes versus irreversible oxidation. Furthermore the open circuit potential of a magnesium electrode in contact with these electrolytes was measured versus a Ag/Ag + reference electrode. A high reoxidation efficiency was found for magnesium electrodeposited from solutions of organomagnesium halides and amidomagnesium halides. The solutions of magnesium organoborates were superior in terms of electrical conductivity and oxidation stability, the process of magnesium electrodeposition and reoxidation, however turned out to be poor.

Reversibility of electrochemical magnesium deposition from Grignard solutions

The reversibility of electrochemical magnesium deposition from Grignard reagents was investigated with regard to potential application of magnesium as a negative electrode in rechargeable batteries. The reoxidation rate depends on the morphology of the magnesium deposit which is controlled by the substrate material. Good results were obtained using silver or gold substrates. Magnesium deposits on these materials was found to be of smooth and compact morphology. A nearly complete electrochemical reoxidation and a low self-discharge were observed.