Carbon surface conditioning produces an anode suitable for heavy-duty discharge in Li secondary batteries
Book
·
OSTI ID:162937
- Rikkyo Univ., Tokyo (Japan). Dept. of Chemistry
Carbon fibers prepared at 1,000 C from mesophase pitch were treated with trimethyl silazane for modifying surface -OH group into trimethyl silyl group. The irreversible reduction current on the first cathodic sweep was diminished. Low-temperature carbon fibers prepared at 700 C and active carbon fibers were evaluated for electrochemical lithium doping and undoping reaction in propylene carbonate (PC)/ethylene carbonate or PC/dimethyl carbonate mixtures (1:1) containing 1 M LiClO{sub 4} at room temperature. Pristine samples prepared at 700 C gave very poor reversibility and capacity on cyclic voltammograms(cv), but a constant current charge/discharge with a very low current gave a capacity over 400 mAh/g. After prolonged heating at 700 C, the cv characteristics were gradually improved. Partial oxidation in a mild oxidizing atmosphere at 700 C for a few minutes was found to be quite effective in improving the cv characteristics remarkably. The charge/discharge capacity, however, was very similar to that obtained for the pristine sample at a very low constant current. Active carbon fibers were found to have considerable capacity after repeated oxidation/reduction cycles in solution. Partial oxidation treatment was also effective in increasing the charge/discharge current. The improvement due to the heat treatment is elucidated based on the removal of a surface inhibiting layer through the treatment.
- OSTI ID:
- 162937
- Report Number(s):
- CONF-950412--; ISBN 1-55899-296-0
- Country of Publication:
- United States
- Language:
- English
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