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Address: Chattanooga, Tennessee, United States
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In this thesis, lithium insertion in hard carbon prepared from sucrose is studied. Sucrose is par... more In this thesis, lithium insertion in hard carbon prepared from sucrose is studied. Sucrose is particularly promising from a commercial stand point because it has a large reversible capacity (600mAh/g) and is very cheap. However, these materials suffer from two problems: large irreversible capacity and hysteresis in the voltage profile, which are the focus of this thesis. Reducing the hysteresis in the voltage profile requires reducing the hydrogen content which can be achieved by heating hard carbon to higher temperatures. However, above a critical temperature, a loss in the reversible capacity occurs. In this thesis, this loss in capacity is correlated to micropore closure or what we call the formation of "embedded fullerenes." This correlation required a prototype CO2 gas adsorption analyser to be built and the design of this system is explained. Furthermore, a model of the low voltage plateau based on lithium adsorption is explored and a model of micropore closure with heat treatment temperature and exposure time is also developed. The irreversible capacity is correlated to the adsorption of air in the micropores of the hard carbon. Two techniques based on improved dewatering procedures and a novel surface treatment are described that effectively reduce the irreversible capacity in hard carbon. These techniques will prove instrumental in the development of better hard carbon anode materials in the future. This thesis leads to a better understanding of the large reversible capacity, the loss in reversible capacity with increased heat treatment temperatures and the irreversible capacity in hard carbon.
Electrochimica Acta, 1999
... that the problem of low density can be solved using composite anode materials consisting of .... more ... that the problem of low density can be solved using composite anode materials consisting of ... a study of the electrochemistry and structure of promising hard carbon materials is presented ... Author Keywords: Lithium-ion battery; Mesocarbon micro-beads; MCMB; Lithium insertion. ...
Journal of The Electrochemical Society, 1998
Journal of The Electrochemical Society, 1998
In this thesis, lithium insertion in hard carbon prepared from sucrose is studied. Sucrose is par... more In this thesis, lithium insertion in hard carbon prepared from sucrose is studied. Sucrose is particularly promising from a commercial stand point because it has a large reversible capacity (600mAh/g) and is very cheap. However, these materials suffer from two problems: large irreversible capacity and hysteresis in the voltage profile, which are the focus of this thesis. Reducing the hysteresis in the voltage profile requires reducing the hydrogen content which can be achieved by heating hard carbon to higher temperatures. However, above a critical temperature, a loss in the reversible capacity occurs. In this thesis, this loss in capacity is correlated to micropore closure or what we call the formation of "embedded fullerenes." This correlation required a prototype CO2 gas adsorption analyser to be built and the design of this system is explained. Furthermore, a model of the low voltage plateau based on lithium adsorption is explored and a model of micropore closure with heat treatment temperature and exposure time is also developed. The irreversible capacity is correlated to the adsorption of air in the micropores of the hard carbon. Two techniques based on improved dewatering procedures and a novel surface treatment are described that effectively reduce the irreversible capacity in hard carbon. These techniques will prove instrumental in the development of better hard carbon anode materials in the future. This thesis leads to a better understanding of the large reversible capacity, the loss in reversible capacity with increased heat treatment temperatures and the irreversible capacity in hard carbon.
Electrochimica Acta, 1999
... that the problem of low density can be solved using composite anode materials consisting of .... more ... that the problem of low density can be solved using composite anode materials consisting of ... a study of the electrochemistry and structure of promising hard carbon materials is presented ... Author Keywords: Lithium-ion battery; Mesocarbon micro-beads; MCMB; Lithium insertion. ...
Journal of The Electrochemical Society, 1998
Journal of The Electrochemical Society, 1998