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Electrochemical Characteristics of Graphite Intercalation Compounds With Fluorine-Lithium Cells

Published online by Cambridge University Press:  15 February 2011

Nobuatsu Watanabe
Affiliation:
Department of Industrial Chemistry, Faculty of Engineering, Kyoto University, Kyoto 606, Japan
Hidekazu Touhara
Affiliation:
Department of Industrial Chemistry, Faculty of Engineering, Kyoto University, Kyoto 606, Japan
Tsuyoshi Nakajima
Affiliation:
Department of Industrial Chemistry, Faculty of Engineering, Kyoto University, Kyoto 606, Japan
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Abstract

The discharge reaction mechanism for two types of graphite fluorides, (CF)n and (C2F)n cathodes of lithium cells utilizing a 1 M LiClO4-propylene carbonate (PC) system were studied by means of x-ray diffraction, ESCA, NMR and transmission electron microscopy. It has been revealed that the discharge reaction proceeds through the formation of an intermediate solvated ternary compound of (C·F·Li)·PC or (C2· F·Li)·PC, and then they decompose to graphite with low crystallinity and LiF. The decomposition process is not involved in the electrochemical reaction and this discharge reaction infers the open-circuit voltage of cells. New graphite intercalation compounds, CxF(MFn)y(MFn=AIF3, MgF2) were prepared under a fluorine atmosphere of 1 atm in the temperature range between 20 and 400°C. These compounds are highly stable even in moist air and have high electrical conductivity. The discharge potentials of CxF(MFn)y-lithium cells are 2.5–2.8 V at current densities 40–400μA, which are higher than those of (CF)n or (C2F)n-lithium cells below 300μA.

Type
Research Article
Copyright
Copyright © Materials Research Society 1983

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References

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