Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

25Mg NMR and computational modeling studies of the solvation structures and molecular dynamics in magnesium based liquid electrolytes

Journal Article · · Nano Energy
 [1];  [2];  [3];  [1];  [4];  [1];  [1];  [1];  [2];  [5];  [6];  [7];  [1];  [1];  [8]
  1. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Joint Center for Energy Storage Research (JCESR)
  2. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
  3. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Joint Center for Energy Storage Research (JCESR); China Agricultural University, Beijing (China)
  4. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Joint Center for Energy Storage Research (JCESR); Xiamen University (China)
  5. NASA Ames Research Center (ARC), Moffett Field, Mountain View, CA (United States)
  6. Xiamen University (China)
  7. China Agricultural University, Beijing (China)
  8. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, Berkeley, CA (United States)
+ Show Author Affiliations
There is increasing evidence that the solvation structure of the active components in a liquid electrolyte solution strongly impacts the performance in electrochemical applications. Here, in this work, the nanoscale solvation structures and dynamics of Mg(BH4)2 and Mg(TFSI)2 dissolved in diglyme (DGM) at various concentrations and ratios of Mg(BH4)2/Mg(TFSI)2 were investigated using a combination of natural abundance 25Mg NMR, quantum chemistry calculations of 25Mg NMR chemical shifts, classical molecular dynamics (MD) calculations, and electrochemical performance tests. By mixing two competing Mg salts, we were able to reduce the strong covalent interactions between Mg2+ and BH$$_4^–$$ anions. A small increase is observed in the coordination number of Mg-TFSI and a significant increase in the interaction of Mg2+ ions with glymes. Through a combination of NMR, DFT and MD simulations, various stable species around 1 nm in size were detected in the mixed salt solution, which play key roles in the enhanced electrochemical performance of the mixed electrolyte. It is established that for the neat Mg(TFSI)2 in DGM electrolyte at dilute concentrations the TFSI- is fully dissociated from Mg2+. At higher concentrations, Mg2+ and TFSI- are only partially dissociated as contact ion pairs are formed. In contrast, at 0.01M Mg(BH4)2 (saturated concentration) in DGM, the first solvation shell of a Mg2+ ion contains two BH$$_4^–$$ anions and one DGM molecule, while the second solvation shell consists of five to six DGM molecules. An exchange mechanism between the solvation structures in the combined electrolyte containing both Mg(BH4)2 and Mg(TFSI)2 in DGM was found to result in the observation of a single 25Mg NMR peak. This exchange is responsible for an increase in uncoordinated anions, as well as improved stability and ionic conductivity as compared to single anion solution. Solvent molecule rearrangement and direct Mg-ion exchange between the basic solvation structures are hypothesized as likely reasons for the exchange. We elucidate that the solvent rearrangement is energetically much more favorable than direct Mg-ion hopping and is thus suggested as the dominant exchange mechanism.
Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER)
Grant/Contract Number:
AC02-05CH11231; AC05-76RL01830
OSTI ID:
1478415
Alternate ID(s):
OSTI ID: 1496456
OSTI ID: 1455272
OSTI ID: 23075389
OSTI ID: 1489681
Journal Information:
Nano Energy, Journal Name: Nano Energy Journal Issue: C Vol. 46; ISSN 2211-2855
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

References (54)

Progress in Rechargeable Magnesium Battery Technology journal December 2007
Magnesium Borohydride: From Hydrogen Storage to Magnesium Battery journal August 2012
Fervent Hype behind Magnesium Batteries: An Open Call to Synthetic Chemists-Electrolytes and Cathodes Needed journal August 2017
Optimized Slater-type basis sets for the elements 1-118 journal May 2003
Development and testing of a general amber force field journal January 2004
Nonaqueous magnesium electrochemistry and its application in secondary batteries journal January 2003
The use of in situ techniques in R&D of Li and Mg rechargeable batteries journal February 2011
On the electrochemical behavior of magnesium electrodes in polar aprotic electrolyte solutions journal May 1999
A comparison between the electrochemical behavior of reversible magnesium and lithium electrodes journal July 2001
Automatic atom type and bond type perception in molecular mechanical calculations journal October 2006
Progress in nonaqueous magnesium electrochemistry journal December 2007
Liquid electrolyte lithium/sulfur battery: Fundamental chemistry, problems, and solutions journal June 2013
Natural abundance 17O nuclear magnetic resonance and computational modeling studies of lithium based liquid electrolytes journal July 2015
Natural abundance 17O, 6Li NMR and molecular modeling studies of the solvation structures of lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane liquid electrolytes journal March 2016
Nanocomposite polymer electrolyte for rechargeable magnesium batteries journal March 2015
Rechargeable magnesium battery: Current status and key challenges for the future journal October 2014
Mixed ionic liquids as electrolyte for reversible deposition and dissolution of magnesium journal December 2006
In Situ Natural Abundance 17 O and 25 Mg NMR Investigation of Aqueous Mg(OH) 2 Dissolution in the Presence of Supercritical CO 2 journal October 2016
Determination of Mg 2+ Speciation in a TFSI – -Based Ionic Liquid With and Without Chelating Ethers Using Raman Spectroscopy journal June 2015
Exploration of the Detailed Conditions for Reductive Stability of Mg(TFSI) 2 in Diglyme: Implications for Multivalent Electrolytes journal February 2016
Unique Behavior of Dimethoxyethane (DME)/Mg(N(SO 2 CF 3 ) 2 ) 2 Solutions journal August 2016
Confession of a Magnesium Battery journal August 2015
Revealing the Solvation Structure and Dynamics of Carbonate Electrolytes in Lithium-Ion Batteries by Two-Dimensional Infrared Spectrum Modeling journal November 2017
The High Performance of Crystal Water Containing Manganese Birnessite Cathodes for Magnesium Batteries journal May 2015
Role of Chloride for a Simple, Non-Grignard Mg Electrolyte in Ether-Based Solvents journal June 2016
Magnesium(II) Bis(trifluoromethane sulfonyl) Imide-Based Electrolytes with Wide Electrochemical Windows for Rechargeable Magnesium Batteries journal March 2014
On the Way to Rechargeable Mg Batteries: The Challenge of New Cathode Materials † journal February 2010
Quest for Nonaqueous Multivalent Secondary Batteries: Magnesium and Beyond journal October 2014
A well-behaved electrostatic potential based method using charge restraints for deriving atomic charges: the RESP model journal October 1993
Structural Analysis of Electrolyte Solutions for Rechargeable Mg Batteries by Stereoscopic Means and DFT Calculations journal April 2011
The Coupling between Stability and Ion Pair Formation in Magnesium Electrolytes from First-Principles Quantum Mechanics and Classical Molecular Dynamics journal February 2015
Designer Ionic Liquids for Reversible Electrochemical Deposition/Dissolution of Magnesium journal January 2016
Density Functional Theory Study on Metal Bis(trifluoromethylsulfonyl)imides:  Electronic Structures, Energies, Catalysis, and Predictions journal August 2003
LiTFSI Structure and Transport in Ethylene Carbonate from Molecular Dynamics Simulations journal March 2006
Ion Transport through Ultrathin Electrolyte under Applied Voltages journal December 2014
Prototype systems for rechargeable magnesium batteries journal October 2000
Structure and compatibility of a magnesium electrolyte with a sulphur cathode journal August 2011
Towards a calcium-based rechargeable battery journal October 2015
Density functional theory with dispersion corrections for supramolecular structures, aggregates, and complexes of (bio)organic molecules journal January 2007
Corrosion of magnesium electrolytes: chlorides – the culprit journal December 2012
Electrochemically stable cathode current collectors for rechargeable magnesium batteries journal January 2014
Solvation structure and energetics of electrolytes for multivalent energy storage journal January 2014
Concentration dependent electrochemical properties and structural analysis of a simple magnesium electrolyte: magnesium bis(trifluoromethane sulfonyl)imide in diglyme journal January 2016
Electrolyte roadblocks to a magnesium rechargeable battery journal January 2012
Boron-based electrolyte solutions with wide electrochemical windows for rechargeable magnesium batteries journal August 2012
Mg rechargeable batteries: an on-going challenge journal January 2013
Molecular dynamics with coupling to an external bath journal October 1984
Density-functional exchange-energy approximation with correct asymptotic behavior journal September 1988
Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density journal January 1988
"Water-in-salt" electrolyte enables high-voltage aqueous lithium-ion chemistries journal November 2015
Improved Electrolyte Solutions for Rechargeable Magnesium Batteries journal January 2006
Electrolyte Solutions with a Wide Electrochemical Window for Rechargeable Magnesium Batteries journal January 2008
Evaluation of (CF 3 SO 2 ) 2 N − (TFSI) Based Electrolyte Solutions for Mg Batteries journal January 2015
The challenge of developing rechargeable magnesium batteries journal May 2014

Similar Records

25Mg NMR and Computational Modeling Studies of the Solvation Structures and Molecular Dynamics in Magnesium Based Liquid Electrolytes
Journal Article · Sun Apr 01 00:00:00 EDT 2018 · Nano Energy · OSTI ID:1489681
25 Mg NMR and computational modeling studies of the solvation structures and molecular dynamics in magnesium based liquid electrolytes
Journal Article · Sun Apr 01 00:00:00 EDT 2018 · Nano Energy · OSTI ID:1455272
Reversible Electrochemical Interface of Mg Metal and Conventional Electrolyte Enabled by Intermediate Adsorption
Journal Article · Tue Dec 03 19:00:00 EST 2019 · ACS Energy Letters · OSTI ID:1638713

Related Subjects

25 ENERGY STORAGE
25Mg NMR
Magnesium battery
Mg(BH4)2
Mg(TFSI)2
classical molecular dynamics calculations
solvation structures