On the correlation between free volume, phase diagram and ionic conductivity of aqueous and non-aqueous lithium battery electrolyte solutions over a wide concentration range

From National Research Council Canada

DOI	Resolve DOI: https://doi.org/10.1149/2.1601704jes
Author	Search for: Yim, Chae-Ho¹ ; Search for: Tam, Jasper¹ ; Search for: Soboleski, Hayden¹ ; Search for: Abu-lebdeh, Yaser¹
Name affiliation	National Research Council Canada. Energy, Mining and Environment
Format	Text
Type	Article
Proceedings title	Journal of The Electrochemical Society
Conference	Meeting of the IMLB, June 19-24, 2016, Chicago IL, USA
ISSN	0013-4651 1945-7111
Volume	164
Issue	6
Pages	A1002–A1011
Subject	conductivity; electrolytes; free volume; Li-ion battery
Abstract	There is little known about the transport behavior of ions in electrolyte solutions at very high concentrations and there is currently no one widely-accepted theory or equation to describe it over the whole concentration range. In this work, the ionic conductivity (κ) of lithium salts in aqueous and non-aqueous electrolyte solutions have been measured as a function of concentration (C) and have been fitted to known theoretical and empirical equations. A new, isothermal, semi-empirical equation based on free volume theory: κ=AC exp[−γVo/Vf C] where Vo and Vf are the occupied and unoccupied “free” volume, respectively, gives better fit over the whole concentration range than the known equations. Vf and V02, ϕ, the apparent molar volume of the salt, were calculated from density measurements and it is found that free volume decreases with concentration in both the aqueous and non-aqueous solutions over the whole range. We hypothesize that the changes to transport properties in solution with concentration are caused by structural changes that switches the conductivity mechanism from vehicular to a Grotthuss-type or a mixture of both. We, for the first time, correlate the origin of Cmax, the concentration of highest conductivity, to the eutectic composition in the salt-solvent phase diagram.
Publication date	2017-03-15
Publisher	Electrochemical Society
Terms of use	Permission is granted to temporarily download one copy of the materials for personal, noncommercial transitory viewing only. NRC Publications Archive - Copyright and terms of use
Language	English
Peer reviewed	Yes
NPARC number	23001721
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Record identifier	268ff755-09b0-4985-8621-c95638ca1743
Record created	2017-03-21
Record modified	2017-03-21

Date modified:: 2019-03-19

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