Electrochemical behavior of graphite highly fluorinated by high oxidation state complex fluorides and elemental fluorine

Highly fluorinated graphites have been synthesized by using elemental fluor ine under pressure and high oxidation state complex fluoride, K2NiF6 or KAg F4 in anhydrous hydrogen fluoride. Their electrochemical discharge as a cat hode of primary lithium battery has been investigated in organic electrolyt e solution. Main products were stage 1 compounds or the stage 1 involving s tage 2 and 3 phases as minor components with approximate compositions of C1 .6F. X-ray photoelectron spectra indicated the existence of nearly semi-ion ic C-F bonds. Electrochemical studies demonstrated that the CxF samples pre pared using KAgF4 and elemental fluorine exhibited high and flat discharge potentials of 3.2 V versus Li/Li+ and discharge capacities of similar to 50 0 mA h g(-1) at cut-off potential 1.5 V. (C) 2000 Elsevier Science Ltd. All rights reserved.