Year

2004

Degree Name

Doctor of Philosophy

Department

Institute for Superconducting and Electronic Materials - Faculty of Engineering

Abstract

In order to improve the capacity of lithium ion batteries higher capacity anode materials are required to replace the existing carbonaceous materials. The higher capacity materials must however also have a good cycle life. Many materials have been investigated to try and find a material offering such a desirable combination of properties. A number of materials are investigated as possible anode materials for lithium ion batteries including intermetallics with compositions based on FeAl3, Al47Fe15Si38, Al20Fe5Si2, Al9FeSi3, FeSi and FeSi2 along with other materials such as Bi2Sr2CaCu2O8, Bi2Sr2Ca0.3Y0.7Cu2O8, and nanometre SiC. The intermetallic materials for the investigation were prepared through the arc melting of the constituent elements together followed by ball milling. The Bi2Sr2CaCu2O8 and Bi2Sr2Ca0.3Y0.7Cu2O8 materials were also ball milled but were initially prepared through the spray drying of nitrate solutions with subsequent sintering operations. The SiC materials were obtained through commercial suppliers. Although many of the materials offered a high initial discharge capacity the capacity was not maintained over the following cycles. All the materials did however demonstrate the dramatic influence that the microstructure can have on the electrochemical properties of the material. Given the variability of the electrochemical performance with the alteration of the microstructure, improvement of the cycle life through exploration of microstructural variation may be possible. Although a range of intermetallic compositions were examined and there were differences in the experimental methods used to examine them the results do suggest that for intermetallic materials compositions with under 60 weight percent of active material and a specific surface area less than 180 m2/g should be examined.

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.