Published online by Cambridge University Press: 16 February 2011
For 15 years, the chemistry of the intercalation of donors species into graphite has beenlargely developed and a great number of new phases were discovered : over 100 if one takes into account the various stages and stacking, which involves different properties of the compounds for a given intercalate. Four new systems and synthesis methods were developed : intercalation of metallic alloys containing an alkali metal, ionic species (alkali metal hydrides, hydroxides and, even chlorides), alkali metals with oxygen (by addition to the metal of a small quantity of its peroxide M2O2), intercalation under high pressure of the alkali metal. Those new syntheses, still in progress, lead to compounds in which the first stages exhibit a fairly high intercalate/carbon ratio : from LiC2 to MC4 (M = Na, K, Rb or Cs) instead of LiC6 or MC8 obtained by classical methods.
The increase of this ratio confers them interesting properties and possibilities of application, especially in the field of new materials for primary or secondary batteries.