Evaluation of Mg[N(SO2CF3)2]2/Acetonitrile Electrolyte for Use in Mg-Ion Cells

Tran, Tuan T.; Lamanna, W. M.; Obrovac, M. N.

doi:10.1149/2.012301jes

Cited by 64 publications

(78 citation statements)

References 9 publications

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“…61,62 In contrast to the relatively large shifts on Mg, renormalization of the LUMO levels on MgO are much smaller, with a maximum reduction of 0.5 eV occurring for ACN. The smaller shift on the oxide is expected due to the much smaller contribution of image charge interactions in insulating surfaces such as MgO.…”

Section: Ionization Energy (Ie)mentioning

confidence: 97%

Interface-Induced Renormalization of Electrolyte Energy Levels in Magnesium Batteries

Kumar¹,

Siegel

2016

J. Phys. Chem. Lett.

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A promising strategy for increasing the energy density of Li-ion batteries is to substitute a multivalent (MV) metal for the commonly used lithiated carbon anode. Magnesium is a prime candidate for such a MV battery due to its high volumetric capacity, abundance, and limited tendency to form dendrites. One challenge that is slowing the implementation of Mg-based batteries, however, is the development of efficient and stable electrolytes. Computational screening for molecular species having sufficiently wide electrochemical windows is a starting point for the identification of optimal electrolytes. Nevertheless, this window can be altered via interfacial interactions with electrodes. These interactions are typically omitted in screening studies, yet they have the potential to generate large shifts to the HOMO and LUMO of the electrolyte components. The present study quantifies the stability of several common electrolyte solvents on model electrodes of relevance for Mg batteries. Many-body perturbation theory calculations based on the G 0 W 0 method were used to predict shifts in a solvent's electronic levels arising from interfacial interactions. In molecules exhibiting large dipole moments, our calculations indicate that these interactions reduce the HOMO− LUMO gap by ∼25% (compared to isolated molecules). We conclude that electrode interactions can narrow an electrolyte's electrochemical window significantly, thereby accelerating redox decomposition reactions. Accounting for these interactions in screening studies presents an opportunity to refine predictions of electrolyte stability.

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Section: Ionization Energy (Ie)mentioning

confidence: 97%

Interface-Induced Renormalization of Electrolyte Energy Levels in Magnesium Batteries

Kumar¹,

Siegel

2016

J. Phys. Chem. Lett.

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“…For example, while excellent cycling performance is observed for Chevrel phase materials in Mg(AlCl 2 BuEt) 2 /THF, fundamentally poorer REVIEW behavior is observed for the same cathode in Mg(ClO 4 ) 2 / AN, and no insertion at all occurs when the solvent is PC [120]. At the anode, AN does not appear to support reversible magnesium electrochemistry, as it decomposes at −0.2 V rather than plate magnesium [281]. Further, water in the electrolyte has been long known as crucial to improving electrode capacity [116,229], while other additives like LiCl boost ionic conductivity [287].…”

Section: Electrolytementioning

confidence: 99%

“…However, a more critical view reveals a large number of discrepancies in magnesium battery literature. A number of studies on the MIB electrolytes [98,280] and their compatibility with Mg [109,281] and current collectors [111,[282][283][284][285][286] conflict with the experimental protocol reported in a significant fraction of publications on MIB cathodes. Presumably, these experimental protocols have been designed on the implicit assumption that the setups used in LIB research carries over to MIB studies.…”

Section: Experimental Design For Mib Cathode Researchmentioning

confidence: 99%

Beyond Li-ion: electrode materials for sodium- and magnesium-ion batteries

2015

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to develop and install renewable energy harvesting technologies [3]. However, their successful implementation will be dependent on reliable and robust storage devices since harvesting solar and wind energy is inherently intermittent and the majority of consumption targets cannot be readily tethered to the grid.As energy storage devices, batteries possess high portability, high energy density, high Coulombic efficiency, and long cycle life. They are ideal power sources for portable devices, automobiles, and backup power supplies; accordingly, batteries power nearly all of our mobile electronics and are used to improve the efficiency of hybrid electric vehicles [4,5]. Unfortunately, considerable improvements in performance are still required in order to meet the demands of advanced portable devices and achieve energy sustainability (e.g., through smart grid and electric vehicle technologies) [6]. These enduring needs have driven intensive research investments. While efforts have been successful, there is still significant room for improvement regarding the development and understanding of electrode materials [7]. The overall capacity and potential cycling window of many electrode materials are limited to prevent degradation over long term cycling. In addition to exploring new electrode materials, there have been strong efforts to improve those that are already utilized. Expense reduction is a priority as approximately 23% and 8% of the overall battery pack costs stem from the respective cathode and anode active materials alone [8].An alkali-ion battery consists of several electrochemical cells connected in parallel and/or in series to provide a designated current or voltage. Each electrochemical cell has two electrodes separated by an electrolyte that is electrically insulating but ionically conductive. During discharge, when the alkali-ion battery operates as a galvanic cell, alkali ions exit the negative electrode (typically carbon) and insert themselves into the positive electrode while electronsThe need for economical and sustainable energy storage drives battery research today. While Li-ion batteries are the most mature technology, scalable electrochemical energy storage applications benefit from reductions in cost and improved safety. Sodium-and magnesium-ion batteries are two technologies that may prove to be viable alternatives. Both metals are cheaper and more abundant than Li, and have better safety characteristics, while divalent magnesium has the added bonus of passing twice as much charge per atom. On the other hand, both are still emerging fields of research with challenges to overcome. For example, electrodes incorporating Na + are often pulverized under the repeated strain of shuttling the relatively large ion, while insertion and transport of Mg 2+ is often kinetically slow, which stems from larger electrostatic forces. This review provides an overview of cathode and anode materials for sodium-ion batteries, and a comprehensive summary of research on cathodes for magnesium-ion batteries. In additi...

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“…50 Another peculiarity of the Mg(TFSI) 2 /G2 electrolyte is the debated instability of plating/stripping overpotentials at different salt concentrations and current densities. 28,50,51 In pursuit of understanding the Mg(TFSI) 2 electrolyte behavior and its potential improvement, extensive computational studies were carried out. 5,6,27,31 Using a combination of classical MD simulations and quantum chemistry calculations hybridized with implicit solvent models, 52 it was shown that the solvent donor strength and its chelating ability largely determine the solubility of Mg(TFSI) 2 and the ion-pair solvation structure.…”

Section: ■ Introductionmentioning

confidence: 99%

Exploration of the Detailed Conditions for Reductive Stability of Mg(TFSI)₂ in Diglyme: Implications for Multivalent Electrolytes

2016

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We reveal the general mechanisms of partial reduction of multivalent complex cations in conditions specific for the bulk solvent and in the vicinity of the electrified metal electrode surface and disclose the factors affecting the reductive stability of electrolytes for multivalent electrochemistry. Using a combination of ab initio techniques, we clarify the relation between the reductive stability of contact-ion pairs comprising a multivalent cation and a complex anion, their solvation structures, solvent dynamics, and the electrode overpotential. We found that for ion pairs with multiple configurations of the complex anion and the Mg cation whose available orbitals are partially delocalized over the molecular complex and have antibonding character, the primary factor of the reductive stability is the shape factor of the solvation sphere of the metal cation center and the degree of the convexity of a polyhedron formed by the metal cation and its coordinating atoms. We focused specifically on the details of Mg (II) bis(trifluoromethanesulfonyl)imide in diethylene glycol dimethyl ether (Mg(TFSI)2)/diglyme) and its singly charged ion pair, MgTFSI+. In particular, we found that both stable (MgTFSI)+ and (MgTFSI)0 ion pairs have the same TFSI configuration but drastically different solvation structures in the bulk solution. This implies that the MgTFSI/dyglyme reductive stability is ultimately determined by the relative time scale of the solvent dynamics and electron transfer at the Mg–anode interface. In the vicinity of the anode surface, steric factors and hindered solvent dynamics may increase the reductive stability of (MgTFSI)+ ion pairs at lower overpotential by reducing the metal cation coordination, in stark contrast to the reduction at high overpotential accompanied by TFSI decomposition. By examining other solute/solvent combinations, we conclude that the electrolytes with highly coordinated Mg cation centers are more prone to reductive instability due to the chemical decomposition of the anion or solvent molecules. The obtained findings disclose critical factors for stable electrolyte design and show the role of interfacial phenomena in reduction of multivalent ions.

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Evaluation of Mg[N(SO₂CF₃)₂]₂/Acetonitrile Electrolyte for Use in Mg-Ion Cells

Cited by 64 publications

References 9 publications

Interface-Induced Renormalization of Electrolyte Energy Levels in Magnesium Batteries

Interface-Induced Renormalization of Electrolyte Energy Levels in Magnesium Batteries

Beyond Li-ion: electrode materials for sodium- and magnesium-ion batteries

Exploration of the Detailed Conditions for Reductive Stability of Mg(TFSI)₂ in Diglyme: Implications for Multivalent Electrolytes

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Evaluation of Mg[N(SO2CF3)2]2/Acetonitrile Electrolyte for Use in Mg-Ion Cells

Cited by 64 publications

References 9 publications

Interface-Induced Renormalization of Electrolyte Energy Levels in Magnesium Batteries

Interface-Induced Renormalization of Electrolyte Energy Levels in Magnesium Batteries

Beyond Li-ion: electrode materials for sodium- and magnesium-ion batteries

Exploration of the Detailed Conditions for Reductive Stability of Mg(TFSI)2 in Diglyme: Implications for Multivalent Electrolytes

Contact Info

Product

Resources

About

Evaluation of Mg[N(SO₂CF₃)₂]₂/Acetonitrile Electrolyte for Use in Mg-Ion Cells

Exploration of the Detailed Conditions for Reductive Stability of Mg(TFSI)₂ in Diglyme: Implications for Multivalent Electrolytes