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Title: Evaluating Transport Properties and Ionic Dissociation of LiPF 6 in Concentrated Electrolyte

The presence of lithium hexafluorophosphate (LiPF 6) ion pairs in carbonate-based electrolyte solutions is widely accepted in the field of battery electrolyte research and is expected to affect solution transport properties. No existing techniques are capable of directly quantifying salt dissociation in these solutions. Previous publications by others have provided estimates of dissociation degrees using dilute solution theory and pulsed field gradient nuclear magnetic resonance spectroscopy (PFG-NMR) measurements of self-diffusivity. However, the behavior of a concentrated electrolyte solution can deviate significantly from dilute solution theory predictions. This paper, for the first time, instead uses Onsager–Stefan–Maxwell concentrated solution theory and the generalized Darken relation with PFG-NMR measurements to quantify the degrees of dissociation in electrolyte solutions (LiPF 6 in ethylene carbonate/diethyl carbonate, 1:1 by weight). At LiPF 6 concentrations ranging from 0.1 M to 1.5 M, the salt dissociation degree is found to range from 61% to 37%. Finally, transport properties are then calculated through concentrated solution theory with corrections for these significant levels of ion pairing.
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Technologies Area
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab.
Publication Date:
Grant/Contract Number:
AC02-05CH11231; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 164; Journal Issue: 12; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Argonne National Lab. (ANL), Argonne, IL (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; concentrated solution theory; electrolytes; ionic dissociation; lithium ion battery; pulsed field gradient NMR; transport properties
OSTI Identifier:
1436335