DESIGN,PREPARATION,PROPERTIES AND MANIFESTATION OF FUNCTIONALITY OF FLUORIDE-GRAPHITE INTERCALATION COMPOUNDS.

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1.The Intercalation Mechanism in AHF solution of Metal Fluorides.The reaction of tin tetrafluoride with graphite in liquid AHF in the presence of fluorine yields a stage-2 graphite intercalation compound with an identity period I_C=11.53 A,whereas no intercalation reaction occurs without fluorine. With lead tetrafluoride, however, the reaction proceeds without fluorine yielding a stage-2 compound. From the results, it is concluded that reaction in this system proceeds in the absence of fluorine and the following reaction mechanism can be proposed :xC+PbF_4+2HF*Cx (HF_2) _2+PbF_2PbF_4+4HF <double half arrows> PbF_6^<2->+2H_2F^+Cx (HF_2) _2+PbF_6^<2-> <double half arrows> CxPbF_6+2HF_2^-In this system part of PbF_4 acts as an oxidizing agent for the formation of a GIC.2.Fluoride Ion Conduction of Fluorine Intercalated CxF.Impedance analysis of CxF with ionic or semi-ionic C-F bonding has indicated that the fluoride ions in the graphite gallery have some mobility, and that CxF are fluoride ion conducting solid state electrolytes.3. Fluorine Intercalation Reaction and the Nature of C-F Bonding.The longer time (ca.8 hours) oxidation of graphite by elemental fluorine in liquid HF usually give fluorine rich CxF (x<4) with semi-ionic C-F bond, whereas direct interaction of elemental fluorine with graphite at room temperature yields CxF (6<x) with ionic C-F bond. It has become possible to control the chemical composition, physical properties and C-F bond character by controling the intercalation reaction.4.Electrochemical Characteristics of CxF.The discharge reaction of semi-ionic CxF cathode for a lithium cell is a heterogeneous electrodereaction, While that of ionic CxF Cathode is a homogeneous reaction. This difference leads to discharge performances of semi-ionic CxF cathode which is extremely superior to those of ionic CxF.