Crystal and molecular structure of magnesium borohydride diglymate

Lobkovskii, B.; Titov, L. V.; Levicheva, M. D.; Chekhlov, A. N.

doi:10.1007/bf00743602

Cited by 14 publications

(30 citation statements)

References 2 publications

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“…In comparison, electrolytes comprising Mg(BH 4 ) 2 in DME and THF show lower coulombic efficiencies. The solution structures of Mg(BH 4 ) 2 in different solvents are investigated and identified using NMR, which are consistent with the solid structures from single crystal X-ray diffraction in the literature5051. Mg(BH 4 ) 2 forms coordination structures of Mg(BH 4 ) 2 DGM, Mg 2 (BH 4 ) 4 (DME) 3 , Mg(BH 4 ) 2 (THF) 3 in DGM, DME and THF respectively.…”

Section: Discussionsupporting

confidence: 71%

Coordination Chemistry in magnesium battery electrolytes: how ligands affect their performance

Shao

Liu

et al. 2013

Sci Rep

170

241

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Magnesium battery is potentially a safe, cost-effective, and high energy density technology for large scale energy storage. However, the development of magnesium battery has been hindered by the limited performance and the lack of fundamental understandings of electrolytes. Here, we present a study in understanding coordination chemistry of Mg(BH4)2 in ethereal solvents. The O donor denticity, i.e. ligand strength of the ethereal solvents which act as ligands to form solvated Mg complexes, plays a significant role in enhancing coulombic efficiency of the corresponding solvated Mg complex electrolytes. A new electrolyte is developed based on Mg(BH4)2, diglyme and LiBH4. The preliminary electrochemical test results show that the new electrolyte demonstrates a close to 100% coulombic efficiency, no dendrite formation, and stable cycling performance for Mg plating/stripping and Mg insertion/de-insertion in a model cathode material Mo6S8 Chevrel phase.

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Section: Discussionsupporting

confidence: 71%

Coordination Chemistry in magnesium battery electrolytes: how ligands affect their performance

Shao

Liu

et al. 2013

Sci Rep

170

241

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“…All the Ca ± O(polyether) bond lengths of 2 and 4 lie within the range found for other diglyme or polyether carboxylate adducts of calcium (2.430(2) ± 2.625(4) ), and so do the O-Ca-O angles (62.5(3) ± 65.99 (14)). [22,23] The Ca ± O(H 2 O) bond lengths in 2 and 4 are 0.1 longer than those found in the literature for complexes that have the same coordination number at the metal atom, [24] (8) . [26] The O(H) ± I hydrogen bond lengths become longer in average when going from 1 to 4, while those in 3 and 4 are the same, within standard deviations.…”

Section: Discussionmentioning

confidence: 70%

A Logical Concept of Structure Prediction Derived from Supramolecular Polymers of Alkaline Earth Metal Halides Formed by Hydrogen Bonding and Complexation of the Metal Ion

Fromm

2001

Chem. Eur. J.

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Several different dimensional polymers derived from alkaline earth metal iodides are obtained as a result of supramolecular noncovalent bonding modes of the metal ion, namely complexation and hydrogen bonding. These polymers consist of complex cations linked to the halide ions by hydrogen bonds of the water ligands coordinated to the metal. They are built up in a logical way, depending on the ratio of complexing ligands to complexing and hydrogen-bonding ligands so that their dimensionality and, to a certain extent, their structure can be predicted.

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“…Geometry optimization and calculation of free energy.-In crystals formed by precipitation from solutions of magnesium borohydride dissolved in THF 29 or diglyme, 30 each magnesium atom is chelated directly by BH 4 − and solvent oxygens. In this study, clusters of magnesium cations, borohydride anions, and solvent molecules (G1 and THF depicted in Fig.…”

Section: Methodsmentioning

confidence: 99%

Exploring the Liquid Structure and Ion Formation in Magnesium Borohydride Electrolyte Using Density Functional Theory

Deetz¹,

Cao²,

Wang³

et al. 2018

J. Electrochem. Soc.

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Rechargeable magnesium batteries have attracted much interest due their high volumetric capacity, potential for safe operation, and the natural abundance of magnesium. However, the development of magnesium batteries for practical applications has been obstructed by the lack of understanding of the liquid structure of electrolytes. Herein, we use quantum density functional theory coupled with a continuum solvation model to investigate the structure of Mg(BH 4 ) 2 in two ethereal solvents: tetrahydrofuran (THF), and monoglyme (G1). The most energetically favorable clusters of Mg(BH 4 ) 2 , MgBH 4 + , and Mg 2+ , with associated solvent molecule ligands, are determined. The free energy required to generate monovalent ions in the electrolyte is positive and the formation of divalent complexes is prohibitive. Singly and doubly charged complexes are more stable in G1 than THF, which is consistent with experimental findings. From the standpoint of free energy, clusters containing multiple magnesium atoms are not favored. Theoretical 25 Mg-NMR, 11 B-NMR spectra, and infrared vibrational modes of borohydride were calculated for each cluster. The relationships between cluster charge and the signals of each spectrum are determined. These analytical descriptors could be useful to characterize the degree of ion dissociation in the electrolyte. For rechargeable batteries to become widespread in electric vehicle and grid energy storage applications, it is imperative that they are safe and low cost.1,2 These challenges have motivated researchers in recent years to consider alternatives to lithium-ion batteries, such as sodium 3,4 and multivalent 5,6 battery chemistries. Ever since the first prototypes were developed, 7,8 magnesium batteries have attracted much interest from the research community. Compared with lithiumion batteries, magnesium batteries have several advantages, such as their high volumetric capacity (3832 mAh/cm 3 ), which is a result of the divalency of magnesium. Additionally, the cycling of plating/stripping of Mg 2+ onto the magnesium metal anode does not produce dendrites, which alleviates one of safety concerns of lithium batteries. 9,10 However, magnesium batteries face crucial challenges before they can succeed in practical applications.11 In particular, the choice of the electrolyte is critical to their performance. 12,13 There are only a handful of electrolytes known to be stable 14 during battery cycling, due to the reactivity of the Mg anode. that an electrolyte consisting of magnesium borohydride in an ethereal solvent, such as tetrahydrofuran or monoglyme, could reversibly plate/strip Mg 2+ onto a magnesium metal anode. X-ray photoelectron spectroscopy 13 has shown that a Mg anode using this electrolyte did not yield signals for boron or carbon, implying that the electrolyte is electrochemically stable during charge and discharge cycles. This marked the discovery of the first stable, halide-free electrolyte for magnesium batteries. Since then, there have been a number of experimental 13,[20][21][22...

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Crystal and molecular structure of magnesium borohydride diglymate

Cited by 14 publications

References 2 publications

Coordination Chemistry in magnesium battery electrolytes: how ligands affect their performance

Coordination Chemistry in magnesium battery electrolytes: how ligands affect their performance

A Logical Concept of Structure Prediction Derived from Supramolecular Polymers of Alkaline Earth Metal Halides Formed by Hydrogen Bonding and Complexation of the Metal Ion

Exploring the Liquid Structure and Ion Formation in Magnesium Borohydride Electrolyte Using Density Functional Theory

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