Concentration dependent electrochemical properties and structural analysis of a simple magnesium electrolyte: magnesium bis(trifluoromethane sulfonyl)imide in diglyme

Sa, Niya; Rajput, Nav Nidhi; Wang, Hao; Key, Baris; Ferrandon, Magali; Srinivasan, Venkat; Persson, Kristin A.; Burrell, Anthony K.; Vaughey, John T.

doi:10.1039/c6ra22816j

Cited by 74 publications

(95 citation statements)

References 39 publications

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“…The potential of Mg during Mg stripping/deposition cycling is shown in Figure 1a. Consistent with previous studies, [24,25] a large stripping overpotential (≈1.87 V) and deposition overpotential (≈−0.8 V) can be observed in the blank electrolyte (no iodine). After the addition of a small amount of iodine, the overpotentials for both Mg stripping and deposition decline, and decrease more with increasing concentration of iodine additives.…”

supporting

confidence: 91%

Reducing Mg Anode Overpotential via Ion Conductive Surface Layer Formation by Iodine Additive

Gao

Han

et al. 2017

Advanced Energy Materials

119

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Another challenge is the development of electrolytes that can effectively utilize an Mg metal anode. Extensive effort has been put in to develop electrolytes capable of reversibly depositing/stripping Mg. Most work has focused on complex electrolytes that allow fast and reversible Mg deposition/stripping. Such electrolytes were first proposed by Aurbach's group in 2000, [8] and subsequently they developed the all phenyl complex showing high anodic stability. [9] Later, a non-nucleophilic electrolyte, Mg-HMDS, was developed by Muldoon and co-workers, and Fichtner and co-workers for Mg/S batteries. [10,11] To eliminate the organic Grignard species in the electrolyte, an all inorganic electrolyte, magnesium aluminum chloride complex, was reported. [12][13][14][15] These complex electrolytes have enabled the usage of Mg-cathode half-cells to evaluate various cathode materials due to their capability of facile Mg deposition/stripping; [8,10,[16][17][18] however, their complicated synthesis procedure, incompatibility with oxide cathodes, sensitivity to air and moisture, low ionic conductivity, and high cost have rendered them less attractive for practical applications than conventional organic electrolytes based on simple salts (salts containing anions of PF 6 − , BF 4 − , TFSI − , etc.). Unfortunately, most of these simple salt electrolytes are not compatible with Mg metal because poorly or nonconductive surface layers are normally formed on the Mg surface. In the electrolytes based on common aprotic organic solvents (such as AN, PC, etc.), the surface film is dominated by the decomposition of solvent due to their weak reduction stability, and the formed layer can block the deposition/stripping of Mg. [19] Even for solvents that are stable with Mg metal (such as glyme), the decomposition of salts or the reaction of trace moisture with Mg can still form a surface film covering the Mg surface, leading to a large overpotential for Mg deposition/stripping. [20][21][22][23] Therefore, the formation of a poorly or even nonconductive surface layer on Mg metal in common simple salt organic electrolytes is inevitable due to Mg's strong reducing ability, which remains a challenge for the application of a Mg metal anode in these simple salt electrolytes. Herein, we propose for the first time a facile approach to solve this problem by tuning the composition of the surface layer and forming an Mg ion conductive layer. By adding a small concentration of iodine (<50 × 10 −3 m) into the electrolyte, an insoluble magnesium iodide layer is formed on the surface of the Mg metal, which acts as a solid electrolyte Electrolytes that are able to reversibly deposit/strip Mg are crucial for rechargeable Mg batteries. The most studied complex electrolytes based on Lewis acid-base chemistry are expensive, difficult to be synthesized, and show limited anodic stability. Conventional electrolytes using simple salts such as Mg(TFSI) 2 can be readily synthesized, but Mg deposition/stripping in these simple salt electrolytes is accompanied by a large...

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supporting

confidence: 91%

Reducing Mg Anode Overpotential via Ion Conductive Surface Layer Formation by Iodine Additive

Gao

Han

et al. 2017

Advanced Energy Materials

119

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“…Also, the charge‐delocalized framework makes this conjugated [NTf 2 ] − anion highly resistant to positive potential polarization, and thus high anodic stability can be expected in such electrolytes. There have been a number of studies using Mg[NTf 2 ] 2 in different solvents for reversible Mg electrochemistry, particularly in polyether(s) ,. Electrolytes using 0.5 M Mg[NTf 2 ] 2 in a glyme/diglyme mixture showed a high conductivity of 5.2 mS cm −1 , and the anodic stability on stainless steel (SS) substrate was up to 4.2 V vs Mg …”

Section: Rechargeable Mg Batteriesmentioning

confidence: 99%

“…There have been a number of studies using Mg[NTf 2 ] 2 in different solvents for reversible Mg electrochemistry, particularly in polyether(s). [43,[46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] Electrolytes using 0.5 M Mg[NTf 2 ] 2 in a glyme/diglyme mixture showed a high conductivity of 5.2 mS cm À1 , and the anodic stability on stainless steel (SS) substrate was up to 4.2 V vs Mg. [46] Glymes with higher oligomer degree exhibit stronger ability to solvate Mg[NTf 2 ] 2 . [43,51] For example, a higher solubility of Mg has been reported in tetraglyme (G4) than in diglyme (G2).…”

Section: Mg[ntf 2 ] 2 Electrolytesmentioning

confidence: 99%

Mg Cathode Materials and Electrolytes for Rechargeable Mg Batteries: A Review

MacFarlane

Kar

2019

Batteries & Supercaps

117

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The development of energy storage devices has been motivated by the growing availability of sustainable energy sources, as well as the wider application of portable devices and a variety of electric vehicles including bicycles, scooters, cars and buses. Concerns regarding the safety of lithium batteries in certain applications, and limited lithium and cobalt resources required for conventional cathode materials, have driven researchers to develop alternatives that are safer and cheaper, thereby using more abundant metals such as sodium, magnesium, aluminium, and calcium. Among them, rechargeable magnesium batteries have drawn special interest, since Mg does not plate in a dendritic form, which opens up the possibility of the safe use of a simple metal anode. In this review, we summarize typical Mg electrolyte systems that are compatible with reversible Mg deposition and stripping, focusing on the active Mg complexes. To fabricate a rechargeable device, an appropriate cathode is necessary, which must also be abundant and compatible with the electrolytes to suitable cathode materials are also briefly discussed.

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Section: Recent Mg‐ion Electrolyte Advancesmentioning

confidence: 99%

Rechargeable Magnesium Batteries using Conversion‐Type Cathodes: A Perspective and Minireview

et al. 2018

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would impose restrictions on the penetration of LIBs into these large-volume markets. [3,4] In addition, after 25 years of continuous improvements, the mature LIBs technology is approaching a fundamental limit in terms of energy density (slightly above 300 W h kg −1 ) and costs at the materials level. [4][5][6] With the aforementioned concerns, alternative battery concepts have significantly stimulated research interests to further drive battery technologies to increase both the gravimetric and volumetric energy densities, reduce the cost, and expand the cycling life. [3,6,7] The "beyond Li-ion" technologies such as lithium-air, lithium-sulfur (Li-S), multivalent batteries, and solid-state batteries show the unique feature of using metal anodes that can store more energy via a reversible metal plating/stripping process. Unfortunately, these emerging or reviving technologies involving lithium metal inevitably meet the critical challenges of resource shortage. Furthermore, the high reactivity of lithium metal leads to electrolyte consumption and nonuniform lithium distribution (even dendritic growth) during cycling. These issues still hamper the mainstream commercialization of the lithium-metal-based batteries. [8,9] Rechargeable magnesium (Mg) batteries may offer considerable advantages (see Table 1) over Li-metal batteries because the metallic Mg anode shows double the volumetric capacity, safer and easier processing features, more uniform and nondendritic electroplating during cell charging, and cheaper costs due to its greater abundance in the earth crust. [4,[10][11][12][13] Based on these advantages, intensive attention has been garnered toward the development of new electrolytes, cathodes, and their corresponding mechanistic understandings for the rechargeable Mg batteries. Additionally, several industries including Pellion Technologies (a spin-off company from Massachusetts Institute of Technology), the Toyota Research Institute of North America, and recently Sony Corporation have initiated R&D projects for the rechargeable Mg batteries and tried to find practical application pathways. Nonetheless, developing a high-energy-density Mg battery with long cycle life and high rate capability is still a huge challenge due to the lack of high-performance cathodes and suitable Mg-ion electrolytes. [9,12] It is fair to state that the Chevrel phases, reported by Aurbach et al. in 2000, are still the most attractive Mg-ion Rechargeable magnesium (Mg) batteries are one of the potential contenders to replace current Li-ion batteries to power future electric vehicles with lower cost, higher safety, and extended mileage. To achieve this goal, both high-voltage intercalation-type cathodes and high-capacity conversion-type cathodes are considered. However, there are still no reports to compare rechargeable Mg batteries with the state-of-the art Li-ion batteries in terms of their overall performance. Also, potential cathode materials to deliver higher energy density in rechargeable Mg batteries are rarely summarized. Here, t...

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Concentration dependent electrochemical properties and structural analysis of a simple magnesium electrolyte: magnesium bis(trifluoromethane sulfonyl)imide in diglyme

Abstract: Development of Mg electrolytes that can plate/strip Mg is not trivial and remains one of the major roadblocks to advance Mg battery research.

Cited by 74 publications

References 39 publications

Reducing Mg Anode Overpotential via Ion Conductive Surface Layer Formation by Iodine Additive

Reducing Mg Anode Overpotential via Ion Conductive Surface Layer Formation by Iodine Additive

Mg Cathode Materials and Electrolytes for Rechargeable Mg Batteries: A Review

Rechargeable Magnesium Batteries using Conversion‐Type Cathodes: A Perspective and Minireview

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