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Ion Diffusion and Electrochemically ...

Timachova, Ksenia.

Ion Diffusion and Electrochemically Driven Transport in Homogenous and Nanostructured Polymer Electrolytes.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Ion Diffusion and Electrochemically Driven Transport in Homogenous and Nanostructured Polymer Electrolytes.
Author:	Timachova, Ksenia.
Published:	Ann Arbor : ProQuest Dissertations & Theses, 2018
Description:	137 p.
Notes:	Source: Dissertation Abstracts International, Volume: 80-03(E), Section: B.
Notes:	Adviser: Nitash P. Balsara.
Contained By:	Dissertation Abstracts International80-03B(E).
Subject:	Chemical engineering.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10930667
ISBN:	9780438643628

Ion Diffusion and Electrochemically Driven Transport in Homogenous and Nanostructured Polymer Electrolytes.
Timachova, Ksenia.

Ion Diffusion and Electrochemically Driven Transport in Homogenous and Nanostructured Polymer Electrolytes. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 137 p.

Source: Dissertation Abstracts International, Volume: 80-03(E), Section: B.

Thesis (Ph.D.)--University of California, Berkeley, 2018.

There is a growing need for safe, reliable, economical, and energy dense electrical energy storage devices. Polymer electrolytes are of great interest due to their potential use in high specific energy solid-state batteries. Polymer electrolytes are mixtures containing dissociated ions in a polymer matrix. The transport of ions in polymer electrolytes is of significant practical interest in order to enable their use and commercialization in next generation energy storage devices. Most experimental work on the field has focused on studying bulk electrochemical transport properties such as ionic conductivity. In this work, ion transport is primarily studied using a spectroscopic technique called pulsed-field gradient NMR (PFG-NMR). Using this technique, we investigate the molecular mechanisms that dictate ion transport through polymer materials.

ISBN: 9780438643628Subjects--Topical Terms:

206267
Chemical engineering.

Ion Diffusion and Electrochemically Driven Transport in Homogenous and Nanostructured Polymer Electrolytes.
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100 1 $a Timachova, Ksenia. $3 826990
245 1 0 $a Ion Diffusion and Electrochemically Driven Transport in Homogenous and Nanostructured Polymer Electrolytes.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2018
300 $a 137 p.
500 $a Source: Dissertation Abstracts International, Volume: 80-03(E), Section: B.
500 $a Adviser: Nitash P. Balsara.
502 $a Thesis (Ph.D.)--University of California, Berkeley, 2018.
520 $a There is a growing need for safe, reliable, economical, and energy dense electrical energy storage devices. Polymer electrolytes are of great interest due to their potential use in high specific energy solid-state batteries. Polymer electrolytes are mixtures containing dissociated ions in a polymer matrix. The transport of ions in polymer electrolytes is of significant practical interest in order to enable their use and commercialization in next generation energy storage devices. Most experimental work on the field has focused on studying bulk electrochemical transport properties such as ionic conductivity. In this work, ion transport is primarily studied using a spectroscopic technique called pulsed-field gradient NMR (PFG-NMR). Using this technique, we investigate the molecular mechanisms that dictate ion transport through polymer materials.
520 $a Polyethylene oxide (PEO) provides a useful model system to study the effects of molecular weight and salt concentration on ion transport. We present measurements of the electrochemical transport properties of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in PEO over a wide range of PEO molecular weights and salt concentrations. Individual self-diffusion coefficients of the Li and TFSI ions, D + and D-, were measured using PFG-NMR both in the dilute limit and at high salt concentrations. Conductivities calculated from the measured D+ and D- values based on the Nernst-Einstein equation were in agreement with experimental measurements reported in the literature. We determined the molecular weight dependence of the cation transference number in these solutions. We introduce a new parameter, s, the number of lithium ions per polymer chain, that allows us to account for both the effect of salt concentration and molecular weight on cation and anion diffusion. Expressing cation and anion diffusion coefficients as functions of s results in a collapse of D+ and D - onto a single master curve.
520 $a We extend our analysis of ion transport to perfluoropolyether-based polymer electrolytes. Perfluoropolyethers (PFPEs) are polymer electrolytes with fluorinated carbon backbones that have high flash points and have been shown to exhibit moderate conductivities and high cation transference numbers when mixed with lithium salts. Ion transport in four PFPE electrolytes with different endgroups was characterized by differential scanning calorimetry (DSC), ac impedance, and PFG-NMR as a function of salt concentration and temperature. In spite of the chemical similarity of the electrolytes, salt diffusion coefficients measured by PFG-NMR and the glass transition temperature measured by DSC appear to be uncorrelated to ionic conductivity measured by ac impedance. We calculate a non-dimensional parameter, beta, that depends on the salt diffusion coefficients and ionic conductivity. We also use the Vogel-Tammann-Fulcher relationship to fit the temperature dependence of conductivity. We present a linear relationship between the prefactor in the VTF fit and beta; both parameters vary by four orders of magnitude in our experimental window. Our analysis suggests that transport in electrolytes with low dielectric constants (low beta) is dictated by ion hopping between clusters.
520 $a A set of polyether polymers with varying density of ether groups were synthesized to study the effects of polymer mobility and solvation site density on ion transport. The mobility of the polymer backbones dictated by the glass transition temperature were measured using DSC, the diffusion and conductivity of the ions were measured using PFG-NMR and ac impedance, and the steady-state current responses of the electrolytes were calculated from the measurements. The results indicate that the steady-state current response of a polyether-based polymer electrolytes is proportional to the density of lithium solvation sites and inversely proportional to the mobility of the polymer backbone. This set of polyether polymers was used to predict a polymer structure that could have a better steady-state current response than PEO.
590 $a School code: 0028.
650 4 $a Chemical engineering. $3 206267
650 4 $a Polymer chemistry. $3 708579
690 $a 0542
690 $a 0495
710 2 $a University of California, Berkeley. $b Chemical Engineering. $3 826984
773 0 $t Dissertation Abstracts International $g 80-03B(E).
790 $a 0028
791 $a Ph.D.
792 $a 2018
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10930667