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Title: Rate theory of solvent exchange and kinetics of Li+ − BF4−/PF6− ion pairs in acetonitrile

Authors:
 [1]; ORCiD logo [2]
  1. Physical Science Division, Pacific Northwest National Laboratory, Richland, Washington 93352, USA
  2. Department of Chemistry, University of Wisconsin - Parkside, Kenosha, Wisconsin 53141, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1318756
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
The Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 145; Journal Issue: 9; Related Information: CHORUS Timestamp: 2017-09-11 21:32:50; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Dang, Liem X., and Chang, Tsun-Mei. Rate theory of solvent exchange and kinetics of Li+ − BF4−/PF6− ion pairs in acetonitrile. United States: N. p., 2016. Web. doi:10.1063/1.4961904.
Dang, Liem X., & Chang, Tsun-Mei. Rate theory of solvent exchange and kinetics of Li+ − BF4−/PF6− ion pairs in acetonitrile. United States. doi:10.1063/1.4961904.
Dang, Liem X., and Chang, Tsun-Mei. 2016. "Rate theory of solvent exchange and kinetics of Li+ − BF4−/PF6− ion pairs in acetonitrile". United States. doi:10.1063/1.4961904.
@article{osti_1318756,
title = {Rate theory of solvent exchange and kinetics of Li+ − BF4−/PF6− ion pairs in acetonitrile},
author = {Dang, Liem X. and Chang, Tsun-Mei},
abstractNote = {},
doi = {10.1063/1.4961904},
journal = {The Journal of Chemical Physics},
number = 9,
volume = 145,
place = {United States},
year = 2016,
month = 9
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4961904

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  • In this paper, we describe our efforts to apply rate theories in studies of solvent exchange around Li +(aq) and the kinetics of ion pairings in lithium-ion batteries (LIB). We report one of the first computer simulations of the exchange dynamics around hydrated Li + in acetonitrile (ACN), which is common solvent used in LIBs. We also provide details of the ion-pairing kinetics of Li +-[BF 4] and Li +-[PF 6] in ACN. Using our polarizable force-field models and employing classical rate theories of chemical reactions, we examine the ACN exchange process between the first and second solvation shells aroundmore » Li +(aq). We calculate exchange rates using transition state theory and weighted them with transmission coefficients determined by the reactive flux and Impey, Madden, and McDonald approaches and Grote-Hynes theory. We found the relaxation times changed from 180 ps to 4600 ps and from 30 ps to 280 ps for Li +-[BF 4] and Li +-[PF 6] ion pairs, respectively. These results confirm that the solvent response to the kinetics of ion pairing is significant. Our results also show that, in addition to affecting the free energy of solvation into ACN, the anion type also should significantly influence the kinetics of ion pairing. These results will increase our understanding of the thermodynamic and kinetic properties of LIB systems.« less
  • The kinetics of the reaction of 2,4-dinitrohalogenobenzenes (chlorine, bromine, and iodine derivatives) with tetraethylammonium azide in acetonitrile and in a mixed acetonitrile-dioxane solvent (80 vol. % dioxane) were studied. It was established that there is a marked increase (by more than three orders of magnitude) in the azidization rate constant in the transition from protic solvents to aprotic media, due to the decrease in the activation energy barrier of the reaction. The nucleophilicity parameters N/sup +/ for the azide ion in the investigated solvents were determined in terms of Ritchie's relationship. It was established that the effect of the naturemore » of the leaving group on the rate constant of the reactions is complex in character, and it was shown that treatment of the relative reactivity series for the investigated substrates must be based on an analysis of the activation parameters and not restricted to data obtained at only one temperature.« less
  • To enhance our understanding of the solvent exchange mechanism in liquid methanol, we report a systematic study of this process using molecular dynamics simulations. We use transition state theory, the Impey-Madden-McDonald method, the reactive flux method, and Grote-Hynes theory to compute the rate constants for this process. Solvent coupling was found to dominate, resulting in a significantly small transmission coefficient. We predict a positive activation volume for the methanol exchange process. The essential features of the dynamics of the system as well as the pressure dependence are recovered from a Generalized Langevin Equation description of the dynamics. We find thatmore » the dynamics and response to anharmonicity can be decomposed into two time regimes, one corresponding to short time response (< 0.1 ps) and long time response (> 5 ps). An effective characterization of the process results from launching dynamics from the planar hypersurface corresponding to Grote-Hynes theory. This results in improved numerical convergence of correlation functions. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.« less
  • Despite extensive studies of proton-transfer thermodynamics and kinetics in acetonitrile solution, proton exchange between solute and solvent has rarely been encountered. Here, rapid (20-min t[sub 1/2] at room temperature) proton exchange between the N-H groups of a cobalt(I) macrocycle and CD[sub 3]CN solvent is reported. The reaction is anomalously rapid for a simple proton-transfer process and may signal reactivity of the metal center toward C-H activation.