Alkali metal oxyanion electrode material having a carbon deposited by pyrolysis and process for making same

A process for making an alkali metal oxyanion cathode material comprising particles, where the particles carry, on at least a portion of the particle surface, a carbon coating deposited by pyrolysis, and wherein the particles have the general formula:

• A1M(0.95 to 0.98)M′(0.02 to <0.05)(PO4)p(SiO4)s
• wherein
• A is at least one alkali metal selected from the group consisting of Li, Na and K;
• M is at least Fe and/or Mn, wherein the average valence of M is +2 or greater, and wherein M can be substituted by at most 15% at. of one or more metal at oxidation levels between +1 and +5;
• M′ is a metal of valence of 2+ or more;
• and
• wherein s is equal to the stoichiometric index of M′ and p is equal to (1−s);
• said process comprising:
• performing a high-energy milling step of precursors of the alkali metal oxyanion cathode material, wherein an organic source of carbon is also present during the high-energy milling step, and wherein no further high-energy milling step is performed after the thermal step;
• and
• performing a thermal step of the high-energy milled precursors of the alkali metal oxyanion cathode material, wherein at least a part of the thermal step is performed under an atmosphere comprising a carbonaceous chemical and/or an organic chemical comprising carbon.