Positive-electrode materials: methods for their preparation and use in lithium secondary batteries

A method of preparing a positive-electrode material for a lithium secondary battery, comprising:

• (a) providing a complex oxide compound as reactive substance;
• (b) coating a surface of particles of the reactive substance with a carbon material;
• and
• (c) mixing the coated reactive substance with (i) carbon black, (ii) a mixture of at least a first fibrous carbon material and a second fibrous carbon material, the second fibrous carbon material being different in fiber diameter and/or fiber length from the first fibrous carbon material, and (iii) optionally a binder,
• wherein step (c) is performed by compression shear impact particle-compositing technique,
• wherein the complex oxide compound is a complex oxide of general formula AaMmZzOoNnFf, and wherein:
• A represents an alkaline metal;
• M represents a transition metal, and optionally at least one non-transition metal, or a mixture thereof;
• Z represents a non-metallic element;
• N is a nitrogen atom;
• F is a fluorine atom;
• and
• a≥0, m≥0, z≥0, o>0, n≥0 and f≥0, a, m, o, n, f and z being selected to ensure electro neutrality of the complex oxide,
• wherein the first fibrous carbon material has a fiber diameter of about 5 to 15 nm and the second fibrous carbon material has a fiber diameter of about 70 to 150 nm,
• wherein the first fibrous carbon material has a fiber length of about 1 to 3 μm and the second fibrous carbon material has a fiber length of about 5 to 10 μm.