Carbon Fluoride Cathode Modified by Electroconducting Polymers

Abstract

Carbon fluoride with a general formula (CFx)n represents an attractive cathode material for primary lithium cells operating in aprotic medium. (CFx)n compound was obtained by the gaseous fluorination of carbon tissue at 450°C. The degree of fluorination, i.e. the value x for the final product, was equal to 0.95. During the electrochemical reduction of carbon fluoride, a ternary intercalated compound CLixF is formed which is chemically decomposed to carbon and lithium fluoride. Reduction process of (CFx)n is irreversible due to covalent C-F bonding with sp3 hybridization. This discharge process was strictly controlled by diffusion of Li+ into the layered host of carbon fluoride. X-ray method was applied for elucidation of reduction process. Modification of carbon fluoride was realized by using a composite material with different percentages of conducting organic polymer, i.e. polyaniline (PANI) in the form of emeraldine base (EB). PANI was introduced into the fluoride cathode material by a careful powder mixing or by the solution casting method using N-methylpyrrolidone (NMP) as a solvent. Electrochemical properties and kinetic parameters of composite (CFx)n- PANI cathode were evaluated.