Synthesis method for carbon material based on LixM1-yM'(XO4)n

A method of synthesis of a material made of particles,

• wherein the particles comprise a core and a coating and/or are connected to each other by cross-linking, wherein the core comprises at least one compound of the formula LixM1−yM′y(XO4)n, wherein x, y and n are numbers such that 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 line of the periodic table, M′ is an element with fixed valency selected from the group consisting of Mg2+, Ca2+, Al3+, Zn2+ and combinations thereof and X is 5, P or Si, wherein the coating comprises carbon connecting at least two particles to each other, and wherein the cross-linking comprises carbon connecting at least two particles to each other, the method comprising bringing into equilibrium in a reaction medium, in the proportions required, a mixture comprising the following precursors;
• a) a source of M, wherein at least part of the transition metal or metals that constitute M are in an oxidation state greater than that of the metal in the final compound LixM1−yM′y(XO4)n;
• b) a source of an element M′;
• c) a compound that is a source of lithium;
• and optionally,
• d) a compound that is a source of X;
• wherein the sources of the elements M, M′, Li and X are introduced, in whole or in part, in the form of compounds having more than one source element, and
• wherein the synthesis is carried out by reaction and bringing into equilibrium, in the absence of carbon or in the presence of an amount of carbon insufficient or too inert kinetically to realize the reduction of a metal salt that constitutes M, in the proportions required, the mixture of precursors a) to d) with a gaseous reducing atmosphere, in such a way as to bring the transition metal or metals to the desired degree of valency,
• wherein the synthesis is carried out in the presence of an organic substance as a source of carbon conductor, and
• wherein the synthesis leads to the material by a pyrolysis step for the carbon conductor after or simultaneously with preparing the mixture of the precursors and reduction of the mixture obtained.