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Title: Diffusional motion of redox centers in carbonate electrolytes

Abstract

Ferrocene (Fc) and N-(ferrocenylmethyl)-N,N-dimethyl-N-ethylammonium bistrifluoromethyl-sulfonimide (Fc1N112-TFSI) were dissolved in carbonate solvents and self-diffusion coefficients ( D) of solutes and solvents were measured by 1H and 19F pulsed field gradient nuclear magnetic resonance (NMR) spectroscopy. The organic solvents were propylene carbonate (PC), ethyl methyl carbonate (EMC), and a ternary mixture that also includes ethylene carbonate (EC). Results from NMR studies over the temperature range of 0-50 °C and for various concentrations (0.25-1.7 M) of Fc1N112-TFSI are compared to values of D simulated with classical molecular dynamics (MD). The measured self-diffusion coefficients gradually decreased as the Fc1N112-TFSI concentration increased in all solvents. Since TFSI - has fluoromethyl groups (CF 3), D TFSI could be measured separately and the values found are larger than those for D Fc1N112 in all samples measured. The EC, PC, and EMC have the same D in the neat solvent mixture and when Fc is dissolved in EC/PC/EMC at a concentration of 0.2 M, probably due to the interactions between common carbonyl structures within EC, PC, and EMC. A difference in D ( D PC < D EC < D EMC), and both a higher E a for translational motion and higher effective viscosity for PC in themore » mixture containing Fc1N112-TFSI reflect the interaction between PC and Fc1N112 +, which is a relatively stronger interaction than that between Fc1N112 + and other solvent species. In the EC/PC/EMC solution that is saturated with Fc1N112-TFSI, we find that D PC = D EC = D EMC and Fc1N112 + and all components of the EC/PC/EMC solution have the same E a for translational motion, while the ratio D EC/PC/EMC/ D Fc1N112 is approximately 3. These results reflect the lack of available free volume for independent diffusion in the saturated solution. The Fc1N112 + transference numbers lie around 0.4 and increase slightly as the temperature is increased in the PC and EMC solvents. The trends observed for D from simulations are in good agreement with experimental results and provide molecular level understanding of the solvation structure of Fc1N112-TFSI dissolved in EC/PC/EMC.« less

Authors:
 [1];  [2];  [1];  [1];  [1];  [2];  [3]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pennsylvania State Univ., University Park, PA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Electricity Delivery and Energy Reliability (OE)
OSTI Identifier:
1511407
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 141; Journal Issue: 10; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Han, Kee Sung, Rajput, Nav Nidhi, Wei, Xiaoliang, Wang, Wei, Hu, Jian Zhi, Persson, Kristin A., and Mueller, Karl T. Diffusional motion of redox centers in carbonate electrolytes. United States: N. p., 2014. Web. doi:10.1063/1.4894481.
Han, Kee Sung, Rajput, Nav Nidhi, Wei, Xiaoliang, Wang, Wei, Hu, Jian Zhi, Persson, Kristin A., & Mueller, Karl T. Diffusional motion of redox centers in carbonate electrolytes. United States. doi:10.1063/1.4894481.
Han, Kee Sung, Rajput, Nav Nidhi, Wei, Xiaoliang, Wang, Wei, Hu, Jian Zhi, Persson, Kristin A., and Mueller, Karl T. Thu . "Diffusional motion of redox centers in carbonate electrolytes". United States. doi:10.1063/1.4894481. https://www.osti.gov/servlets/purl/1511407.
@article{osti_1511407,
title = {Diffusional motion of redox centers in carbonate electrolytes},
author = {Han, Kee Sung and Rajput, Nav Nidhi and Wei, Xiaoliang and Wang, Wei and Hu, Jian Zhi and Persson, Kristin A. and Mueller, Karl T.},
abstractNote = {Ferrocene (Fc) and N-(ferrocenylmethyl)-N,N-dimethyl-N-ethylammonium bistrifluoromethyl-sulfonimide (Fc1N112-TFSI) were dissolved in carbonate solvents and self-diffusion coefficients (D) of solutes and solvents were measured by 1H and 19F pulsed field gradient nuclear magnetic resonance (NMR) spectroscopy. The organic solvents were propylene carbonate (PC), ethyl methyl carbonate (EMC), and a ternary mixture that also includes ethylene carbonate (EC). Results from NMR studies over the temperature range of 0-50 °C and for various concentrations (0.25-1.7 M) of Fc1N112-TFSI are compared to values of D simulated with classical molecular dynamics (MD). The measured self-diffusion coefficients gradually decreased as the Fc1N112-TFSI concentration increased in all solvents. Since TFSI- has fluoromethyl groups (CF3), DTFSI could be measured separately and the values found are larger than those for DFc1N112 in all samples measured. The EC, PC, and EMC have the same D in the neat solvent mixture and when Fc is dissolved in EC/PC/EMC at a concentration of 0.2 M, probably due to the interactions between common carbonyl structures within EC, PC, and EMC. A difference in D (DPC < DEC < DEMC), and both a higher Ea for translational motion and higher effective viscosity for PC in the mixture containing Fc1N112-TFSI reflect the interaction between PC and Fc1N112+, which is a relatively stronger interaction than that between Fc1N112+ and other solvent species. In the EC/PC/EMC solution that is saturated with Fc1N112-TFSI, we find that DPC = DEC = DEMC and Fc1N112+ and all components of the EC/PC/EMC solution have the same Ea for translational motion, while the ratio DEC/PC/EMC/DFc1N112 is approximately 3. These results reflect the lack of available free volume for independent diffusion in the saturated solution. The Fc1N112+ transference numbers lie around 0.4 and increase slightly as the temperature is increased in the PC and EMC solvents. The trends observed for D from simulations are in good agreement with experimental results and provide molecular level understanding of the solvation structure of Fc1N112-TFSI dissolved in EC/PC/EMC.},
doi = {10.1063/1.4894481},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 10,
volume = 141,
place = {United States},
year = {2014},
month = {9}
}

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Works referenced in this record:

Recent Progress in Redox Flow Battery Research and Development
journal, September 2012

  • Wang, Wei; Luo, Qingtao; Li, Bin
  • Advanced Functional Materials, Vol. 23, Issue 8, p. 970-986
  • DOI: 10.1002/adfm.201200694