Electrode materials with high surface conductivity

A process for making an alkali-metal ion-reversible electrode material comprising the steps of:

• (a) providing an alkali-based complex oxide of the general formula
• AaMmZzOoNnFf
• wherein:
• A comprises an alkali metal;
• M comprises at least one transition metal, and optionally at least one non-transition metal, or mixtures thereof;
• Z comprises at least one non-metal;
• O is oxygen;
• N is nitrogen;
• and
• F is fluorine,
• where Z and O are such that the complex oxide is selected from the group consisting of sulfates, phosphates, silicates, oxysulfates, oxyphosphates or oxysilicates and mixtures thereof:
• where a ≧0.1;
• m, o, and z>0;
• and n and f≧0 and selected to ensure electroneutrality in said complex oxide;
• where said alkali-based complex oxide stabilizes all or part of the transition metal ion of M in its lower oxidation level (not considering 0) and conducts alkali metal ions;
• and
• (b) contacting said complex oxide with a carbonaceous precursor under conditions of temperature, time and pressure effective to give a conductive carbon coating on said complex oxide, said carbon coating being in a non powdery form, substantially homogeneous and covering all or most of the surface with a thin film of carbon that is optimized to give electronic conductivity in said complex oxide, without blocking alkali ion exchanges at the surface of said material and without reducing the transition metal of said alkali-based complex oxide to a metallic state, the carbon coated alkali-based complex oxide having mixed electron and alkali-ion conductivity and alkali-ion-exchange capability for use in a battery.