Ionic Transport and Speciation of Lithium Salts in Glymes: Experimental and Theoretical Results for Electrolytes of Interest for Lithium-Air Batteries

Glycol ethers, or glymes, have been recognized as good candidates as solvents for lithium-air batteries because they exhibit relatively good stability in the presence of superoxide radicals. Diglyme (bis(2-methoxy-ethyl)ether), in spite of its low donor number, has been found to promote the solution...

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Autores principales: Horwitz, G., Factorovich, M., Rodriguez, J., Laria, D., Corti, H.R.
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Acceso en línea:http://hdl.handle.net/20.500.12110/paper_24701343_v3_n9_p11205_Horwitz
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spelling todo:paper_24701343_v3_n9_p11205_Horwitz2023-10-03T16:42:25Z Ionic Transport and Speciation of Lithium Salts in Glymes: Experimental and Theoretical Results for Electrolytes of Interest for Lithium-Air Batteries Horwitz, G. Factorovich, M. Rodriguez, J. Laria, D. Corti, H.R. Glycol ethers, or glymes, have been recognized as good candidates as solvents for lithium-air batteries because they exhibit relatively good stability in the presence of superoxide radicals. Diglyme (bis(2-methoxy-ethyl)ether), in spite of its low donor number, has been found to promote the solution mechanism for the formation of Li2O2 during the discharge reaction, leading to large deposits, that is, high capacities. It has been suggested that lithium salt association in these types of solvents could be responsible for this behavior. Thus, the knowledge of the speciation and transport behavior of lithium salts in these types of solvents is relevant for the optimization of the lithium-air battery performance. In this work, a comprehensive study of lithium trifluoromethanesulfonate (LiTf) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1,2-di-methoxyethane (DME) and diglyme, over a wide range of concentrations, have been performed. Consistent ion pairs and triplet ions formation constants have been obtained by resorting to well-known equations that describe the concentration dependence of the molar conductivities in highly associated electrolytes, and we found that the system LiTf/DME would be the best to promote bulky Li2O2 deposits. Unexpected differences are observed for the association constants of LiTf and, to a lesser extent, for LiTFSI, in DME and diglyme, whose dielectric constants are similar. Molecular dynamics (MD) simulations allowed us to rationalize these differences in terms of the competing interactions of the O-sites of the ethers and the SOx groups of the corresponding anions with Li+ ion. The limiting Li+ diffusivity derived from the fractional Walden rule agrees quite well with those obtained from MD simulations, when solvent viscosity is conveniently rescaled. © 2018 American Chemical Society. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_24701343_v3_n9_p11205_Horwitz
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description Glycol ethers, or glymes, have been recognized as good candidates as solvents for lithium-air batteries because they exhibit relatively good stability in the presence of superoxide radicals. Diglyme (bis(2-methoxy-ethyl)ether), in spite of its low donor number, has been found to promote the solution mechanism for the formation of Li2O2 during the discharge reaction, leading to large deposits, that is, high capacities. It has been suggested that lithium salt association in these types of solvents could be responsible for this behavior. Thus, the knowledge of the speciation and transport behavior of lithium salts in these types of solvents is relevant for the optimization of the lithium-air battery performance. In this work, a comprehensive study of lithium trifluoromethanesulfonate (LiTf) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in 1,2-di-methoxyethane (DME) and diglyme, over a wide range of concentrations, have been performed. Consistent ion pairs and triplet ions formation constants have been obtained by resorting to well-known equations that describe the concentration dependence of the molar conductivities in highly associated electrolytes, and we found that the system LiTf/DME would be the best to promote bulky Li2O2 deposits. Unexpected differences are observed for the association constants of LiTf and, to a lesser extent, for LiTFSI, in DME and diglyme, whose dielectric constants are similar. Molecular dynamics (MD) simulations allowed us to rationalize these differences in terms of the competing interactions of the O-sites of the ethers and the SOx groups of the corresponding anions with Li+ ion. The limiting Li+ diffusivity derived from the fractional Walden rule agrees quite well with those obtained from MD simulations, when solvent viscosity is conveniently rescaled. © 2018 American Chemical Society.
format JOUR
author Horwitz, G.
Factorovich, M.
Rodriguez, J.
Laria, D.
Corti, H.R.
spellingShingle Horwitz, G.
Factorovich, M.
Rodriguez, J.
Laria, D.
Corti, H.R.
Ionic Transport and Speciation of Lithium Salts in Glymes: Experimental and Theoretical Results for Electrolytes of Interest for Lithium-Air Batteries
author_facet Horwitz, G.
Factorovich, M.
Rodriguez, J.
Laria, D.
Corti, H.R.
author_sort Horwitz, G.
title Ionic Transport and Speciation of Lithium Salts in Glymes: Experimental and Theoretical Results for Electrolytes of Interest for Lithium-Air Batteries
title_short Ionic Transport and Speciation of Lithium Salts in Glymes: Experimental and Theoretical Results for Electrolytes of Interest for Lithium-Air Batteries
title_full Ionic Transport and Speciation of Lithium Salts in Glymes: Experimental and Theoretical Results for Electrolytes of Interest for Lithium-Air Batteries
title_fullStr Ionic Transport and Speciation of Lithium Salts in Glymes: Experimental and Theoretical Results for Electrolytes of Interest for Lithium-Air Batteries
title_full_unstemmed Ionic Transport and Speciation of Lithium Salts in Glymes: Experimental and Theoretical Results for Electrolytes of Interest for Lithium-Air Batteries
title_sort ionic transport and speciation of lithium salts in glymes: experimental and theoretical results for electrolytes of interest for lithium-air batteries
url http://hdl.handle.net/20.500.12110/paper_24701343_v3_n9_p11205_Horwitz
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