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Development of analytical techniques for lithium-sulfur batteries

Development of analytical techniques for lithium-sulfur batteries
Development of analytical techniques for lithium-sulfur batteries
The first technique involves the determination of the total atomic sulfur content and the average polysulfide chain length of a polysulfide solution. These experiments elucidated the 2-phase boundaries and eutonic point, giving an accurate representation of the ternary (lithium sulfide-sulfur-electrolyte) phase diagram. The 2-phase boundary describes the maximum solubility of a polysulfide solution in contact with either solid lithium sulfide or solid sulfur. On the other hand, the eutonic point describes the maximum solubility of a polysulfide solution in contact with both solid lithium sulfide and solid sulfur, thus the concentration of polysulfide species at the eutonic point is the maximum that can be achieved. The saturation concentration of polysulfide species will depend on the nature of the solvent and the lithium salt, and these variables can be tuned to improve the Li-S battery performance. This was observed when increasing the electrolyte salt concentration which limited the polysulfide solubility and in turn improved the cyclability of the Li-S battery. Therefore, the composition of the ternary phase diagram can be implemented to explain changes in Li-S battery galvanostatic cycling performance.

The second technique, electrochemical impedance spectroscopy, will give further insight to the Li-S battery system. This technique, initially developed from Lasia et al. to determine the electroactive surface area of catalysts, has been applied to the cathode formulations for Li-S batteries in this study.1 Starting with the impedance of the basic components in a Li-S battery to understand features on the Nyquist plot. The complexity of cell setup was increased until the impedance of a full Li-S battery was achieved. This method allows determination of the specific surface area of different Li-S battery cathode formulations whilst also studying how the specific surface area of an electrode changes during galvanostatic cycling.
University of Southampton
Furness, Liam Michael
2c50e6af-80f2-40d4-8aca-59843b79b6c1
Furness, Liam Michael
2c50e6af-80f2-40d4-8aca-59843b79b6c1
Garcia-Araez, Nuria
9358a0f9-309c-495e-b6bf-da985ad81c37

Furness, Liam Michael (2020) Development of analytical techniques for lithium-sulfur batteries. Doctoral Thesis, 197pp.

Record type: Thesis (Doctoral)

Abstract

The first technique involves the determination of the total atomic sulfur content and the average polysulfide chain length of a polysulfide solution. These experiments elucidated the 2-phase boundaries and eutonic point, giving an accurate representation of the ternary (lithium sulfide-sulfur-electrolyte) phase diagram. The 2-phase boundary describes the maximum solubility of a polysulfide solution in contact with either solid lithium sulfide or solid sulfur. On the other hand, the eutonic point describes the maximum solubility of a polysulfide solution in contact with both solid lithium sulfide and solid sulfur, thus the concentration of polysulfide species at the eutonic point is the maximum that can be achieved. The saturation concentration of polysulfide species will depend on the nature of the solvent and the lithium salt, and these variables can be tuned to improve the Li-S battery performance. This was observed when increasing the electrolyte salt concentration which limited the polysulfide solubility and in turn improved the cyclability of the Li-S battery. Therefore, the composition of the ternary phase diagram can be implemented to explain changes in Li-S battery galvanostatic cycling performance.

The second technique, electrochemical impedance spectroscopy, will give further insight to the Li-S battery system. This technique, initially developed from Lasia et al. to determine the electroactive surface area of catalysts, has been applied to the cathode formulations for Li-S batteries in this study.1 Starting with the impedance of the basic components in a Li-S battery to understand features on the Nyquist plot. The complexity of cell setup was increased until the impedance of a full Li-S battery was achieved. This method allows determination of the specific surface area of different Li-S battery cathode formulations whilst also studying how the specific surface area of an electrode changes during galvanostatic cycling.

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Liam Michael Furness - Thesis Final Version
Restricted to Repository staff only until 12 November 2021.
Available under License University of Southampton Thesis Licence.
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More information

Published date: June 2020

Identifiers

Local EPrints ID: 446974
URI: http://eprints.soton.ac.uk/id/eprint/446974
PURE UUID: 5f5b145e-c9af-456b-a64c-349fc0046a97
ORCID for Nuria Garcia-Araez: ORCID iD orcid.org/0000-0001-9095-2379

Catalogue record

Date deposited: 01 Mar 2021 17:31
Last modified: 02 Mar 2021 02:43

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Contributors

Author: Liam Michael Furness
Thesis advisor: Nuria Garcia-Araez ORCID iD

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