A method for the synthesis of compounds of the formula C-LixM1-yM'y(XO4)n, where C represents carbon cross-linked with the compound LixM1-yM'y(XO4)n, in which x, y and n are numbers such as 0<=x<=2, 0<=y<=0.6, and 1<=n<=1.5, M is a
transition metal or a mixture of transition metals from the first period of the
periodic table, M' is an element with fixed valency selected among Mg<2+>, Ca<2+>, Al<3+>, Zn<2+> or a combination of these same elements and X is chosen among S, P and Si, by bringing into equilibrium, in the required proportions, the mixture of precursors, with a
gaseous atmosphere, the synthesis taking place by reaction and bringing into equilibrium, in the required proportions, the mixture of the precursors, the procedure comprising at least one
pyrolysis step of the
carbon source compound in such a way as to obtain a compound in which the
electronic conductivity measured on a sample of
powder compressed at a pressure of 3750 Kg.cm<-2 >is greater than 10<-8 >S.cm<-1>. The materials obtained have excellent electrical
conductivity, as well a very improved
chemical activity.