Magnesium(II) Bis(trifluoromethane sulfonyl) Imide-Based Electrolytes with Wide Electrochemical Windows for Rechargeable Magnesium Batteries

Ha, Se-Young; Lee, Yong-Won; Woo, Sang Won; Koo, Bonjae; Kim, Jeom-Soo; Cho, Jaephil; Lee, Kyu‐Tae; Choi, Nam‐Soon

doi:10.1021/am405619v

Cited by 418 publications

(498 citation statements)

References 30 publications

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“…These systems provide a relatively facile delivery of Mg 2+ ions in a chloride-free electrolyte and an 28,30,48,49 in cells with a working Mg electrode. However, these electrolytes suffer from low (≤87%) CE, significant overpotential, destructive incompatibilities with Mg metal resulting in passivation of the anode surface, and parasitic loss of electrolyte due to the electrochemical decomposition of solvent (e.g., AN) mimicking Mg-plating/insertion.…”

Section: ■ Introductionmentioning

confidence: 99%

“…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%

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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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Section: ■ Introductionmentioning

confidence: 99%

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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“…[70] The Mg/ CMK3-S cell exhibited a very low-discharge plateau of 0.2 V with a capacity of 500 mAh/g in the first discharge and the cell could be cycled only for several cycles. Itaoka et al prepared sulfur composites with S and bis(alkenyl) compound with a crown or linear ether unit.…”

Section: Conductive Salt-based Electrolytesmentioning

confidence: 96%

“…[70] However, this electrolyte shows a high overpotential (about 2 V) and a low cycling efficiency. Recently, Ma et al reported the enhancement of electrochemical properties of Mg(TFSI) 2 tetraglyme solution by adding some quantities of Mg(BH 4 ) 2 to scavenge water and suggested that removal of water from the electrolytes is vital to achieve reversible Mg cycling.…”

Section: Electrolytes From Chloride-free Magnesium Saltsmentioning

confidence: 99%

Magnesium-sulfur battery: its beginning and recent progress

Zhao‐Karger

Fichtner

2017

MRS Communications

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Rechargeable magnesium (Mg) battery has been considered as a promising candidate for future battery generations because of its potential high-energy density, its safety features and low cost. The challenges lying ahead for the realization of Mg battery in general are to develop proper electrolytes fulfilling a multitude of requirements and to discover cathode materials enabling high-energy Mg batteries. The combination of Mg anode with a sulfur cathode is one of the promising electrochemical couples due to its advantages of safety, low costs, and a high theoretical energy density of over 3200 Wh/L. However, the research on magnesium-sulfur (Mg-S) battery is just at its beginning and the development of suitable electrolytes has been the key challenge for further improvement, and, thus, in the focus of recent research. In this review, we highlight the recent progress achieved in Mg electrolytes and Mg-S batteries and discuss the major technical issues, which must be resolved for the improvement of Mg-S batteries.

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“…7,8 The observed cycling performance of a novel HMNB configuration, NaTi 2 (PO 4 ) 3 /C vs Mg (NaTi 2 (PO 4 ) 3 /C//Mg), indicates that 0.3 M Mg(TFSI) 2 + 0.5 M NaBF 4 in diglyme may be a promising electrolyte candidate for future HMNBs.…”

mentioning

confidence: 99%

Communication—Mg(TFSI)₂-Based Hybrid Magnesium-Sodium Electrolyte: Case Study with NaTi₂(PO₄)₃//Mg Cell

Rudola¹,

Azmansah²,

Balaya³

2018

J. Electrochem. Soc.

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Currently, only two types of hybrid Mg-Na electrolytes are known. Herein, we report a new hybrid Mg-Na electrolyte, based on Mg(TFSI) 2 and NaBF 4 salts in diglyme solvent, which engenders non-dendritic cycling of Mg metal when used in hybrid Mg-Na cells. Using NaTi 2 (PO 4 ) 3 as sodium intercalation-type cathode, NaTi 2 (PO 4 ) 3 /C vs Mg cell delivered discharge capacity approaching 120 mAh/g with flat plateau at 1.25 V vs Mg/Mg 2+ , along with relatively good rate performance and cycling stability. © 2018 The Electrochemical Society. [DOI: 10.1149/2.1091805jes] Manuscript submitted December 18, 2017; revised manuscript received March 30, 2018. Published April 7, 2018 Recently, different 'hybrid batteries' have gained attention as they combine benefits of different battery chemistries such as Mg//LiFePO 4 , Zn//LiMn 2 O 4 etc.1,2 Hybrid batteries based on Mg and Na chemistries may be particularly attractive from cost perspective as both Mg and Na resources are earth-abundant while Li resources are scarcer and current Li-ion cathodes production expensive. Such hybrid magnesium-sodium batteries (HMNBs) offer the benefits of high volumetric/gravimetric specific capacity associated with Mg metal as anode (3833 mAh/cm 3 /2234 mAh/g), while also enjoying the kinetically facile Na-ion cathodes.1 This is because such HMNBs operate by reversible Mg plating/stripping at Mg anode and Na + extraction/insertion at the cathode during each charge/discharge cycle.1 Due to higher reduction potential of Mg/Mg 2+ vs Na/Na + redox couple (−2.37 V for Mg/Mg 2+ and −2.71 V for Na/Na + vs S.H.E), Mg 2+ (and not Na + ) will reduce first at the anode thus getting plated during charging and correspondingly getting stripped during discharging upon oxidation. HMNBs also ensures much higher specific energy density vs that of Na metal batteries (for same cathode) on account of the higher volumetric/gravimetric specific capacity of Mg metal as anode vs that of Na metal as anode (1128 mAh/cm 3 /1166 mAh/g). The lynchpin for the HMNB concept is the dual-salt electrolyte which enables simultaneous transport of Na + and Mg 2+ ions. HMNBs were first reported by Walter et al. using FeS 2 as Na-ion cathode, Mg metal as anode and borohydride salts (Mg(BH 4 ) 2 and NaBH 4 ) in diethylene glycol dimethyl ether (diglyme) as dual-salt electrolyte.3 Afterwards, there have been three other reports of HMNBs using either borohydrides-based electrolyte and TiS 2 cathode, 4 or [Mg 2 Cl 2 ][AlCl 4 ] 2 and NaAlCl 4 in dimethoxyethane (monoglyme) electrolyte and either Na 3 V 2 (PO 4 ) 3 or FeFe(CN) 6 cathode. 5,6 These reports demonstrated good cycling performance of HMNBs.In this contribution, we investigated dual-salt HMNB electrolytes based on magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI) 2 ) as Mg(TFSI) 2 -based electrolytes have been reported to be good candidates for rechargeable Mg batteries with good cycle life till 100 cycles. 7,8 The observed cycling performance of a novel HMNB configuration, NaTi 2 (PO 4 ) 3 /C vs Mg (NaTi 2 (PO 4 ) 3 /C//...

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Magnesium(II) Bis(trifluoromethane sulfonyl) Imide-Based Electrolytes with Wide Electrochemical Windows for Rechargeable Magnesium Batteries

Cited by 418 publications

References 30 publications

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

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

Magnesium-sulfur battery: its beginning and recent progress

Communication—Mg(TFSI)₂-Based Hybrid Magnesium-Sodium Electrolyte: Case Study with NaTi₂(PO₄)₃//Mg Cell

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Magnesium(II) Bis(trifluoromethane sulfonyl) Imide-Based Electrolytes with Wide Electrochemical Windows for Rechargeable Magnesium Batteries

Cited by 418 publications

References 30 publications

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

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

Magnesium-sulfur battery: its beginning and recent progress

Communication—Mg(TFSI)2-Based Hybrid Magnesium-Sodium Electrolyte: Case Study with NaTi2(PO4)3//Mg Cell

Contact Info

Product

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About

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

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

Communication—Mg(TFSI)₂-Based Hybrid Magnesium-Sodium Electrolyte: Case Study with NaTi₂(PO₄)₃//Mg Cell