Electrode materials with high surface conductivity

An electrode material that is reversible to alkali ions comprising complex oxide corresponding to the general formula AaMmZzOoNnFi 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;
• and
• the coefficients a, m, o, n, f≧0 and z≧0 and are selected to ensure electroneutrality, wherein said complex oxide comprises a non powdery coating of a conductive carbonaceous material on a surface thereof, said coating being effective to obtain a regular electric field distribution on the surface of particles of said complex oxide and
• wherein said coefficients are selected to avoid oxidation of the conductive carbonaceous material during deposition thereof on said surface.

An electrode material comprising a complex oxide corresponding to the general formula AaMmZzOoNnF wherein:

• A comprises an alkali metal;
• M comprises at least one transition metal, and optionally at least one of a non-transition metal, or mixtures thereof;
• Z comprises at least one non-metal;
• O is oxygen;
• N is nitrogen;
• and
• F is fluorine;
• and
• the coefficients a, m, z, o, n, f≧0 and z≧0 and are selected to ensure electroneutrality, wherein said complex oxide comprises a non powdery, uniform coating of a conductive carbonaceous material on a surface thereof, said coating being effective to obtain a regular electric field distribution on the surface of particles of said complex oxide and
• wherein said coefficients are selected to avoid oxidation of the conductive carbonaceous material during deposition thereof on said surface, prepared by
• a) providing the complex oxide defined above, 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;
• wherein said alkali-based complex oxide stabilizes all or part of the transition metal ion 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.