New graphite fluorides as electrode materials in lithium batteries

Abstract

Graphite fluorination at room temperature can be achieved with the use of a volatile fluoride such as BF 3, BrF 5, ClF 3 and IF 5 in a F 2 + HF atmosphere. The compounds obtained by this new method have a ternary composition and a layered structure in which the carbon hexagons remain planar and the CF bonds are slightly ionic. This enhances their properties as cathode materials in lithium batteries utilizing liquid or solid polymer electrolytes. Energy densities higher than 2 kW h kg −1 have been achieved in both these media particularly with IF 5 derived compounds.