A fundamental investigation of the lithium/organic solvent interface
A fundamental investigation of the lithium/organic solvent interface
Microelectrodes have been employed to investigate the lithium/organic solvent system. Cyclic voltammetry and potential step techniques have primarily been utilized to study the processes that occur at potential positive to bulk lithium deposition in propylene carbonate (PC) and the process of bulk lithium deposition in PC, ethylene carbonate (EC) and mixtures of PC/EC.
It has been found that the decomposition of PC is likely to be due to base/nucleophile chemistry rather than direct electrochemical reduction. The reduction of oxygen has been found to occur in a quasi-reversible manner in PC. In the presence of a lithium salt electrolyte the reduction of oxygen and water results in the formation of surface films a number of monolayers thick. Lithium underpoptential deposition has been proposed as a likely reaction at potentials slightly positive of zero volts versus a lithium reference. The films formed have been shown to vary with time and a decrease in potential.
The deposition and dissolution of lithium from solutions of PC, EC and PC/EC has been shown to occur at high rates at low overpotentials despite the presence of surface films formed at positive potentials. The I-E data fits the Butler-Volmer equation at low overpotential and mass transport control at high overpotential. Hence, there is no need to propose a more complex mechanism for the Li/Li+ couple and the SEI model certainly appears inappropriate. A slight dependence of the transients on the experimental regime has indicated that the film(s) may play a role in determining the deposit morphology.
Cycling efficiencies have, in general, been shown to be low in PC. This has been attributed to the inefficiency of the dissolution reaction. A number of experiments have been performed in which a central characteristic of the efficiencies obtained has been the deposit morphology. Cycling efficiencies did not vary with a change in oxidation potential while large variations were observed upon varying the deposition potential or the deposition charge density. Placing a lithium surface, formed in-situ, on open circuit has been shown to have little effect on the deposition reaction.
University of Southampton
1993
Rohan, James Francis
(1993)
A fundamental investigation of the lithium/organic solvent interface.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Microelectrodes have been employed to investigate the lithium/organic solvent system. Cyclic voltammetry and potential step techniques have primarily been utilized to study the processes that occur at potential positive to bulk lithium deposition in propylene carbonate (PC) and the process of bulk lithium deposition in PC, ethylene carbonate (EC) and mixtures of PC/EC.
It has been found that the decomposition of PC is likely to be due to base/nucleophile chemistry rather than direct electrochemical reduction. The reduction of oxygen has been found to occur in a quasi-reversible manner in PC. In the presence of a lithium salt electrolyte the reduction of oxygen and water results in the formation of surface films a number of monolayers thick. Lithium underpoptential deposition has been proposed as a likely reaction at potentials slightly positive of zero volts versus a lithium reference. The films formed have been shown to vary with time and a decrease in potential.
The deposition and dissolution of lithium from solutions of PC, EC and PC/EC has been shown to occur at high rates at low overpotentials despite the presence of surface films formed at positive potentials. The I-E data fits the Butler-Volmer equation at low overpotential and mass transport control at high overpotential. Hence, there is no need to propose a more complex mechanism for the Li/Li+ couple and the SEI model certainly appears inappropriate. A slight dependence of the transients on the experimental regime has indicated that the film(s) may play a role in determining the deposit morphology.
Cycling efficiencies have, in general, been shown to be low in PC. This has been attributed to the inefficiency of the dissolution reaction. A number of experiments have been performed in which a central characteristic of the efficiencies obtained has been the deposit morphology. Cycling efficiencies did not vary with a change in oxidation potential while large variations were observed upon varying the deposition potential or the deposition charge density. Placing a lithium surface, formed in-situ, on open circuit has been shown to have little effect on the deposition reaction.
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Published date: 1993
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Local EPrints ID: 462486
URI: http://eprints.soton.ac.uk/id/eprint/462486
PURE UUID: 600d6828-492a-40ae-85fc-da6756d3cc11
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Date deposited: 04 Jul 2022 19:09
Last modified: 04 Jul 2022 19:09
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Author:
James Francis Rohan
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