Magnesium Anode Research Articles

Modeling Degradation Mechanisms in Magnesium Batteries with Electronic Structure Calculations

With ever-increasing global energy demands, emphasis on the development of renewable sources of energy continues to increase. Of particular interest are energy storage technologies that include multi-valent systems based on magnesium, rather than monovalent lithium. These systems promise energy densities which could surpass state-of-the art Li-ion batteries. One potential drawback of this technology, however, is the degradation of the electrolyte due to reactions with battery electrodes. To investigate this issue, electronic structure calculations are employed to map-out degradation mechanisms for a range of common electrolytic solutions with a magnesium anode. Classical Monte Carlo techniques coupled with density functional theory were used to identify and classify the most likely sites for adsorption of electrolyte components on low-energy magnesium surfaces. Further, energy landscapes for the various degradation mechanisms were determined. From these results, we postulate the most likely degradation pathways, identify the factors that control electrolyte stability, and ultimately pinpoint promising electrolyte compositions.

High Capacity Magnesium Metal Rechargeable Battery Enabled By Dual Ion Chemistry

Electrochemical energy storage is the core technology for the success of green transportation and renewable energy. Among existing energy storage chemistries, magnesium metal rechargeable batteries (MRB) are receiving growing attention due to the abundance of magnesium and its highly reversible and dendrite-free deposition/dissolution in Grignard–based complex electrolyte, which enables the exploit of the high capacity magnesium anode(2233 mAh/g).These merits have made MRB a promising candidate system to store electrochemical energy. However, the strong coulombic interaction between an intercalation host and the bivalent Mg2+ makes the solid state diffusion of the latter rather sluggish, resulting in low Mg2+intercalation level, large polarization during charge/discharge and/or rapid capacity decay for common cathode materials. To solve the problem, we developed a high capacity MRB by coupling TiS2 with magnesium foil in a dual-ion chemistry(Mg2+/Li+). The battery operates by Li+ insertion/extraction at cathode and Mg deposition/dissolution at anode. The battery simultaneously combines high-capacity/high-voltage, fast Li+ intercalation of TiS2 and the high-capacity/dendrite-free deposition of Mg anode. Compared to other MRBs, the theoretical specific capacity and specific energy of the dual-ion battery is 161.0 mAh/g and 209.3 Wh/kg even when the weight of lithium salt was taken into account, which are 32.2% and 56.2% higher than 121.8 mAh/g and 134 Wh/kg of the state-of-the-art MRB(with Mo6X8 cathode). Noteworthily, there is still a huge potential to be exploited for this dual-ion battery concept. If a high voltage/capacity cathode compatible to electrolyte can be found, the specific energy could be increased largely. This could make it an alternative even competitive to the mainstream LIB technology, not mentioning the advantages of a dendrite-free Mg anode that is free of inert masses (current collector, binder, and conductive additives) and first cycle irreversible reaction associated with SEI formation. Figure 1

Method of sacrificial anode dual transistor-driving in stray current field

In order to control a magnesium anode in a stray current interference field, a dual transistor driving system has been proposed. It consisted of a combination of PNP and NPN transistors. Dual transistor driven system and direct anode to cathode connection were electrochemically tested in 3% NaCl solution. The dual transistor driven system increased the anode efficiency and reduced hydrogen evolution and the risk of embrittlement. Anode susceptibility to the cathodic and anodic stray current interference was reduced.

A New Iodoaluminate Ionic Liquid for Secondary Magnesium Batteries

Recent advances in technological fields such as portable electronic devices, automotive, load levelling and peak shaving for the power grid applications, as well as other specific low and high temperature applications, have resulted in an urgent need to develop new and improved energy conversion and storage systems.1 Magnesium secondary batteries, first proposed in the late 1990s,2,3 demonstrate intrinsic fundamental advantages over other competing technologies i.e., Li secondary batteries, and are therefore promising candidates for energy conversion and storage. Early Mg secondary batteries comprised of a metallic magnesium anode, a composite cathode and a polymer electrolyte based on polyethylene glycol incorporating an innovative δ-MgCl2 salt.4,5 Subsequent electrolytes based on Grignard and other organo-Mg compounds have also been explored,6 and were shown to exhibit good Mg deposition/stripping. Nevertheless, these electrolytes suffer from several drawbacks associated with their chemical stability in ethereal-based solvents, which are characterized by high vapour pressure and flammability. In order to overcome these drawbacks, the use of ionic liquids (ILs) as a solvent for stable Mg-ion source precursors is appealing in order to obtain electrolytes with a high chemical inertia, a wide electrochemical stability window, a low volatility and negligible flammability.7 Here we present a new room temperature ionic liquid synthesized by reacting 1-ethyl-3 methylimidazolium iodide with aluminium iodide. δ-MgI2 8 is used as the magnesium source to obtain a family of Mg2+ conducting electrolytes with the general formula [EMImI/(AlI3)m]/(δ-MgI2)n. δ-MgI2 which is a highly disordered form of MgI2 and synthesized by reacting metallic Mg with n-iodobutane. Similar to the previously described δ-MgCl2,9 δ-MgI2 forms concatenated polymer chain complexes with aluminium through iodine bridging atoms. The chemical composition of the samples was determined by ICP-AES and microanalysis. Their thermal stability and transitions were studied by differential scanning calorimetry (DSC). The applicability of the [EMImI/(AlI3)m]/(δ-MgI2)n electrolytes in prototype cells was evaluated by studying the conductivity of the materials as well as the electrochemical performance in terms of Mg deposition/stripping, coulombic efficiency, and exchange current density. Results of the deposition/stripping performance for a selected concentration are shown in Figure 1. References (1) Armand, M.; Tarascon, J.-M. Nature 2008, 451, 652. (2) Di Noto, V.; Fauri, M. Batterie primarie (non ricaricabili) e secondarie (ricaricabili) a base di elettroliti polimerici basati su ioni magnesio. PD99A000179, 1999. (3) Di Noto, V.; Fauri, M. Magnesium-based Primary (Non Rechargeable) and Secondary (Rechargeable) Batteries. PCT/EP00/07221, 2000. (4) Di Noto, V.; Lavina, S.; Longo, D.; Vidali, M. Electrochim. Acta 1998, 43, 1225. (5) Di Noto, V.; Marigo, A.; Viviani, M.; Marega, C.; Bresadola, S.; Zannetti, R. Makromol. Chem. 1992, 193, 123. (6) Liebenow, C.; Yang, Z.; Lobitz, P. Electrochem. Commun. 2000, 2, 641. (7) Armand, M.; Endres, F.; MacFarlane, D. R.; Ohno, H.; Scrosati, B. Nat. Mater. 2009, 8, 621. (8) Vittadello, M.; Waxman, D. I.; Sideris, P. J.; Gan, Z.; Vezzù K.; Negro, E.; Safari, A.; Greenbaum, S. G.; Di Noto, V. Electrochim. Acta 2011, 57, 112. (9) Vittadello, M.; Stallworth, P. E.; Alamgir, F. M.; Suarez, S.; Abbrent, S.; Drain, C. M.; Di Noto, V.; Greenbaum, S. G. Inorg. Chim. Acta 2006, 359, 2513. Figure 1

Electrochemically generated base-promoted synthesis and biological activities of 2,4-disubstituted carbonotrithioates

The electrosynthesis of new 2,4-dialkylcarbonotrithioates, in satisfactory yields, starting from arylthiols and carbon disulfide using an electrogenerated base (EGB) that is reported to promote the reaction is reported. The EGB was prepared by pro-base-free electrolysis of acetonitrile under galvanostatic conditions using a sacrificial magnesium anode. The as-prepared compounds were fully characterized by 1H, 13C, 19F NMR spectroscopy and mass spectrometry. The antimicrobial and cytotoxic activities of some representative compounds were investigated against human pathogenic bacteria, colon and lung cancer cell lines. Promising results were found against gram-positive and gram-negative bacteria and DLD-1 and A-549 cancer cell lines.

Parametric investigation of room-temperature fluoride-ion batteries: assessment of electrolytes, Mg-based anodes, and BiF3-cathodes

Multiparametric investigations for RT fluoride ion batteries.

A novel rechargeable battery with a magnesium anode, a titanium dioxide cathode, and a magnesium borohydride/tetraglyme electrolyte.

The strong push for electric vehicles and large-scale power storage systems has generated intense interest in rechargeable magnesium batteries due to the innate merits associated with the magnesium metal anode in terms of volumetric capacity, abundance, and operational safety. Herein, we report a novel pathway toward the development of an advanced battery containing a magnesium anode, a titanium dioxide cathode, and a magnesium borohydride/tetraglyme electrolyte, which delivers high specific capacity, as well as exceptional cycle life and rate capability. This work demonstrates the importance of compatibility of the electrochemical activities of the cathode materials and electrolytes in rechargeable Mg batteries.

Behavior of Alloying Elements during Anodizing of Mg-Cu and Mg-W Alloys in a Fluoride/Glycerol Electrolyte

Anodizing of sputtering-deposited magnesium and Mg-0.75at.%Cu and Mg-1.23at.%W alloys has been carried out in a fluoride/glycerol electrolyte. The aims of the study were to investigate the enrichment of alloying elements in the alloy immediately beneath the anodic film and the migration of alloying element species in the film. The specimens were examined by electron microscopy and ion beam analysis. An enrichment of copper is revealed in the Mg-Cu alloy that increases with the anodizing time up to ∼6×1015 Cu atoms cm−2. Copper species are then incorporated into the anodic film and migrate outwards. In contrast, no enrichment of tungsten occurs in the Mg-W alloy, and tungsten species are immobile in the film.

A New Rechargeable Battery Design Based on Magnesium and Persulfate

A battery concept based on the chemical system of magnesium (anode) and persulfate (cathode) is presented. A complete procedure is given to prepare the battery for testing, although no experimental data is presented herein. The similarities of this system to a well-tested Li||LiFePO4 system lend strong credibility to the concept, and the estimated performance characteristics presented. The advantages of this design include the following many areas. First, inexpensive, and available, battery reagents exist. Second, by analogy to the lithium ion battery for which comparisons are made, the full fabrication process for battery separator design is known and efficient; and both the kJ/kg and Amps/kg values are estimated to be substantially larger than the lithium ion battery (e.g., Li||LiFePO4) experimental design. Finally, flammability of the Mg||MgS2O8 system can be expected to provide less of a potential flammability concern, compared to comparable lithium ion batteries. This is because lithium metal, as with any alkali metal, is aggressively flammable even under reduced moisture environments. The proposed magnesium persulfate battery calculated metrics yield an improvement of 194% greater output power (W/cm2&middotkg), and 154% greater stored energy (MJ/kg) than state-of-the-art lithium iron phosphate batteries.

Hybrid Mg2+/Li+ Battery with Long Cycle Life and High Rate Capability

A rechargeable hybrid Mg2+/Li+ battery is designed by coupling a dendrite-free magnesium anode with an electrolyte-compatible cathode in a mixed Mg2+/Li+ electrolyte. Due to the highly reversible lithiation/delithiation of the cathode and Mg deposition/dissolution in the electrolyte, the battery demonstrates the best overall performance among reported magnesium-ion batteries and mixed-ion batteries in terms of cycling stability, specific capacity, specific energy, and rate capability. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Performance Improvement of Magnesium Sulfur Batteries with Modified Non‐Nucleophilic Electrolytes

The combination of a magnesium anode with a sulfur cathode is one of the most promising electrochemical couples because of its advantages of good safety, low cost, and a high theoretical energy density. However, magnesium sulfur batteries are still in a very early stage of research and development, and the discovery of suitable electrolytes is the key challenge for further improvement. Here, a new preparation method for non‐nucleophilic electrolyte solutions using a two‐step reaction in one‐pot is presented, which provides a feasible way to optimize the physiochemical properties of the electrolyte for the application in magnesium sulfur batteries. The first use of modified electrolytes in glymes and binary solvents of glyme and ionic liquid shows beneficial effects on the performance of magnesium sulfur batteries. New insights into the reaction mechanism of electrochemical conversion between magnesium and sulfur are also investigated.

Metal | polypyrrole battery with the air regenerated positive electrode

Recharge characteristics of the battery based on the electrochemically synthesized polypyrrole cathode and aluminum, zinc, or magnesium anode in 2 M NH4Cl are investigated. It is shown that polypyrrole electrode can be regenerated by the reoxidation with the dissolved oxygen from the air. Using the polypyrrole synthesized on high surface graphite-felt electrode under modest discharge conditions, stable discharge voltage of 1.1 V is obtained. Such behavior is explained by the complex interaction of polypyrrole and hydrogen peroxide produced by the oxygen reduction reaction. The electrochemical characteristics are compared with the zinc–manganese dioxide and zinc-air systems.

High performance magnesium anode in paper-based microfluidic battery, powering on-chip fluorescence assay.

A high power density and long-lasting stable/disposable magnesium battery anode was explored for a paper-based fluidic battery to power on-chip functions of various Point of Care (POC) devices. The single galvanic cell with magnesium foil anode and silver foil cathode in Origami cellulose chip provided open circuit potential, 2.2 V, and power density, 3.0 mW/cm(2). A paper-based fluidic galvanic cell was operated with one drop of water (80 μl) and continued to run until it was dry. To prove the concept about powering on-chip POC devices, two-serial galvanic cells are developed and incorporated with a UV-light emitting diode (λ = 365 nm) and fluorescence assay for alkaline phosphatase reaction. Further, detection using smart phones was performed for quantitative measurement of fluorescent density. To conclude, a magnesium-based fluidic battery paper chip was extremely low-cost, required minute sample volumes, was easy to dispose of, light weight, easy to stack, store and transport, easy to fabricate, scalable, and has faster analysis times.

Interface Engineering of Lithium Metal Anodes Using Atomic Layer Deposition

Passivation of lithium metal is of significant interest to the battery community: as the lightest and most electropositive alkali metal, lithium has a low density, resulting in an extremely high specific capacity value of 3.86Ah/g and energy density of 11,701Wh/kg, making it the holy grail of battery anodes. However, due to the extreme reactivity of lithium metal surfaces, controlled passivation and characterization is extremely difficult.We have developed a bespoke integrated deposition, transfer, and characterization system capable of coating lithium metal anodes using Atomic layer deposition (ALD), characterizing the surface chemistry using XPS/SEM/UPS/Auger spectroscopy, and transfer directly from UHV into an Ar glovebox for battery assembly, disassembly, and electrochemical testing. After testing, the metal anodes can be transferred directly back to the XPS/SEM/UPS/Auger system for characterization. Passivation coatings for lithium metal require the coatings be conformal, easily deposited at low temperature, and stable against organic electrolytes. Preventing direct contact of the lithium metal surface with the electrolyte and any dissolved species that would ordinarily react will ensure that the lithium atoms are oxidized in a reversible manner, rather than losing ions/electrons to highly stable, low ionic conductivity surface species such as Li2CO3. Lithium metal passivation may allow the relaxation of purity requirements for both electrolytes and, in the case of Li-O2batteries, cathode gas purity.To date, Li metal passivation has been demonstrated with coatings of chlorosilanes[1] and other polymeric[2], organic[3], and inorganic coatings, but ALD has not been applied directly to lithium metal anodes for the purposes of passivation. Known for conformality, low temperature deposition, excellent thickness control, and pinhole free films, ALD is a promising technique for this application.We have developed ALD processes suitable for the passivation of Li metal, and we assess the behavior of these functional ALD coatings electrochemically using CV and EIS electrochemical techniques. Surface characterization by in-situ XPS, FTIR, and Raman spectroscopy of passivated and pristine lithium metal subjected to both gaseous environments and electrolytes with controlled/measured H2O content will be discussed, where the surface characterization is accomplished without ambient air exposure.We show that passivation of lithium metal is not only possible with ALD, but that it is effective at preventing the tarnishing of the lithium metal surface due to reaction with atmospheric H2O and CO2. Using our unique capabilities, we are able to probe the chemistry of both passivated and unpassivated lithium metal, while using in-situgas dosing we can decouple and characterize the interface chemistry and reactions.This work has implications beyond the passivation of lithium metal besides its focus and greatest impact on the metallic lithium anode battery systems Li-O2 and Li-S. The methodology can greatly impact other promising metal anode battery systems such as magnesium and sodium anode batteries, where similar deleterious surface reactions may apply. Fundamental understanding of the controlled surface passivation of lithium by ALD coatings could be extended to these other next-generation metal anode battery systems, and indeed could have a beneficial impact on the cyclability and storage lifetimes of lithium metal anode primary batteries.

Is There Room for Ionic Liquids in the Development of Mg Batteries?

Magnesium anode batteries: Batteries with pure Mg metal anodes have been noted as being potential post Li-ion technologies for the following reasons: -Mg holds almost 6 times the specific energy of LiC6 -Mg is cheaper than Li -Mg is a safer material than Li Despite the clear motivation for assembling Mg batteries, their shortfall to date has been in large part due to the fact that conventional Mg electrolytes are simply not compatible with reversible Mg electrodeposition and dissolution. Electrolytes providing a reversible Mg2+/Mg0 couple: Families of Mg electrolytes known to give reversible deposition and dissolution of Mg include RMgX, Mg(BR4)2, Rm,,(RO)mMgX2-m + AX3-nR’n (A=Al,B; X=F,Cl,Br; R=alkyl or aryl group). Unfortunately, these materials have not found commercial success primarily due to issues with one or more of the following: low anodic stability, low conductivity, low cycling efficiency, corrosiveness, difficulty with production on a large scale, high nucleophilicity, and or lack of compatible cathode materials. The reader is referred to the literature to understand specific drawbacks for each species.1,2 The Case for Room Temperature Ionic Liquids (RTILs): In recent years, ionic liquids have generated a lot of excitement in several branches of science, one of them being energy storage. To date, use of ionic liquid media for Mg electrochemistry has been met with very limited success. There have been claims of reversible Mg deposition and dissolution using conventional Mg salts in RTILs but not without considerable subsequent criticism.3,4It may be that RTILs simply cannot provide an appropriate environment, however, we feel as though they may be overlooked and are more compatible than previously suggested. The obvious benefits from using RTILs in batteries are the following general physical properties: Non-volatileHigh Thermal stability and liquid rangeIntrinsically conductiveWide electrochemical windows The first two characteristics allow us to create extremely dry and inert environments by performing electrochemistry under vacuum as well as high temperatures. In such conditions (0.4mTorr, 100°C) we show moderate stripping behavior, not observed under normal inert gas atmospheres (fig 1 black curve). Furthermore, we believe there are interesting lessons to be learned from work being done with Li and Zn batteries using RTIL solvents. Specifically, double layer structures and solvation environments behave much differently in RTILs than in conventional solvents and have been shown to drastically alter the electrochemical response. For instance, the voltammograms in figure 1 with Zn and Mg salts show unusual cathodic current dips possibly due to a compact ion double layer changing as the potential is swept. See Figure 1:Comparison of Mg, Zn, & Li-TFSI electrolyte solutions in BMPTFSI (~0.1M). We will here present the challenges faced with using Mg electrolytes in RTILs and the possible strategies for using them to create an environment capable of providing facile, reversible Mg/Mg2+electrochemistry. Acknowledgment We acknowledge support from the Army Research Office grant number W911NF-11-1-0432.

Alternative Synthesis Pathways of Electrolytes for Magnesium-Ion Batteries

Battery chemistries based on multivalent ions are beginning to receive considerable attention from both researchers and industry because it is possible to transfer more than one electron per metal atom. Magnesium-ion systems in particular have been the subject of a great deal of research because of the ability to use metallic magnesium anodes for high energy density, and as such the capacity of the cell is limited only by the cathode material. One of the biggest hurdles that is limiting progress in this area is the development of electrolytes that facilitate the reversible deposition of magnesium metal. The current state of the art electrolytes are based on of Grignard-derived Lewis bases paired with Lewis acids such as aluminum chloride.[1] The presence of chloride ions in these solutions has proven to be problematic because they cause pitting and corrode parts commonly used in coin cells, namely stainless steel.[2] In recent years, other researchers have explored various alkoxide-based electrolytes, but these solutions also employ Grignard reagents.[3–5] As such, it is imperative that researchers identify pathways that can result in halide-free electrolyte solutions.We have identified a synthesis pathway to produce viable Mg electrolytes that does not require Grignard reagents. The Mg source is derived from various alcohols in a simple one-step reaction. The electrolyte is composed of the alcohol-based magnesium compound and a Lewis acid (AlCl3) in an ethereal solvent. Figure 1a shows the cyclic voltammetric behavior of the electrolyte solution as a function of the amount of AlCl3 in the system, and that the optimal molar ratio of the two components is in the range of a 1:1 or 1:2 mixture. The oxidation limit of the 1:1 mixture is as high as 2.9 V vs. Mg, which is comparable to other alcohol-based electrolytes in the literature. Additionally, Figure 1b and 1c show EDX and SEM data indicating that the resulting magnesium deposits are of good purity. We will discuss the effects of different Lewis acids on these magnesium sources, using NMR and Raman spectroscopies to determine speciation in a range ethereal solvents. Deposition behavior and conductivity as a function of solution composition will be discussed.REFERENCES[1] Aurbach, D.; Suresh, G. S.; Levi, E.; Mitelman, a.; Mizrahi, O.; Chusid, O.; Brunelli, M. Adv. Mater. 2007, 19, 4260–4267.[2] Muldoon, J.; Bucur, C. B.; Oliver, A. G.; Zajicek, J.; Allred, G. D.; Boggess, W. C. Energy Environ. Sci. 2013, 6, 482–487.[3] Liao, C.; Guo, B.; Jiang, D.; Custelcean, R.; Mahurin, S. M.; Sun, X.-G.; Dai, S. J. Mater. Chem. A 2014, 2, 581–584.[4] Nelson, E. G.; Kampf, J. W.; Bartlett, B. M. Chem. Commun. 2013, 2, 3–5.[5] Wang, F.; Guo, Y.; Yang, J.; Nuli, Y.; Hirano, S. Chem. Commun. 2012, 48, 10763–10765.ACKNOWLEDGEMENTSSupport was provided by the National Science Foundation through the Graduate Research Fellowship Program. Additional support was provided by the ISN North American Low Carbon Emission Self-Sufficiency Fund from the Andlinger Center for Energy and the Environment at Princeton University.

Method of sacrificial anode transistor-driving in cathodic protection system

A magnesium anode driving system has been proposed. A PNP driving transistor has been used. Electrochemical testing in 3%NaCl, results and comparison of the driving system and classic direct anode to cathode connection are presented. The driving system reduced the protection current and stabilized the working conditions of the anode. Higher anode efficiency was achieved. Overprotection and hydrogen embrittlement threats were prevented and the potential of the cathode met the protection criterion. The expected anode operating time has been prolonged.

Electrical Energy Storage By a Mg/Cus Accumulator: An Alternative to Lithium Batteries

Rechargeable magnesium batteries are considered to be very promising candidates for next generation non-lithium batteries.[1-5] They use divalent Mg2+ cations instead of monovalent Li+ leading to high theoretical capacities. In addition, magnesium (used as anode) has the lowest standard electrode potential compared to other multivalent metals like aluminum or zinc which will be reflected in high cell voltages. The higher safety, environmental compatibility of the electrode materials, and the low costs of magnesium due to its high abundance compared to lithium are further advantages. Numerous research activities focus on the investigation of new cathode materials.[6-9] In addition, a high electrochemical stability of the electrolyte, especially towards the magnesium anode, is absolutely essential. To develop new electrolytes with improved physical and electrochemical properties therefore is another challenging task in this field.[10-11] In our presentation a different concept of a magnesium battery will be shown. The general idea is to use a CuS cathode which dissolves upon discharge when Cu2+ is reduced to Cu. At the anode Mg is oxidized to Mg2+ forming MgS as a solid discharge product. Here, in contrast to already known magnesium batteries, the divalent S2- anions will be used for the charge transfer instead of the Mg2+ cations. In consequence, a suitable sulfide containing electrolyte is required. It should be noted that, provided that the proposed electrode reactions are fully reversible, the suggested Mg/CuS accumulator can theoretically also be set up in the “discharged” state, i.e. MgS vs. Cu instead of Mg vs. CuS.Besides the processing of the Mg, Cu, MgS, and CuS electrodes the preparation, simulation and electrochemical testing of potential electrolyte candidates is the main focus of this project. Alkali metal sulfides solved in mixtures of organic solvents are chosen as reference electrolytes to be compared with new electrolytes based on ionic liquids. The electrochemical properties are characterized by cyclic voltammetry and impedance spectroscopy. The electrochemical stability of the system and the reversibility of the proposed electrode reactions have to be analyzed by half-cell cycling and full-cell charge/discharge tests. At this, Raman spectroscopy will be a valuable analytical tool to investigate the individual electrode reactions, i.e. the formation and dissolution of MgS and CuS. Experiments are accompanied by MD simulations and physical properties like diffusion coefficients, ion conductivity, etc. can be understood at a molecular level.

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.

Research progress of voltage delay in magnesium battery

Research on magnesium battery has three primary fields as follows: changing the metallurgical factors of the magnesium electrode material to improve discharge performance, identifying inhibitors to form a protective film to reduce self-corrosion of magnesium alloys, and improving the electrochemical properties of the electrolyte to improve discharge continuity. During the research and development of the magnesium battery, the voltage delay that occurs in the discharge process is a critical issue because it limits the application of Mg/MnO2 cells. This paper provides an overview of the relationship between the voltage delay of magnesium primary battery and magnesium anode corrosion. Furthermore, the factors affecting the voltage delay were analyzed, and the existing problems in the study of the voltage delay of magnesium battery were identified.