Positive-electrode active material for non-aqueous electrolyte secondary cell and process for preparing the same
A positive-electrode active material for non-aqueous electrolyte secondary cells which combine improved discharge property and operational safety, and a process for preparing the same are provided. The positive-electrode active material comprises a base and one or more layers for coating the base, wherein at least one of the layers is a coating layer comprising one or more metallic components and one or more components selected from the group consisting of sulfur, selenium, and tellurium.
1. A process for preparing a positive-electrode active material, comprising:
dispersing a base into water;
using a raw material containing: one or more metallic components; and one or more components selected from the group consisting of sulfur, selenium, and tellurium, as a coating raw material;
adding said coating raw material into dispersion liquid containing the base under the control of pH to form a coating layer on the base by a precipitation method; and
filtering said dispersion liquid followed by drying the coated base.
2. The process for preparing a positive-electrode active material according to claim 1 , wherein a material containing manganese is used as the base.
3. The process for preparing a positive-electrode active material according to claim 1 , wherein a material having a spinel structure is used as the base.
4. The process for preparing a positive-electrode active material according to claim 1 , wherein a material containing one or more of lithium, magnesium, aluminum, silicon, chromium, iron, zirconium, niobium, indium, tungsten, or cerium is used as the metallic component.
5. The process for preparing a positive-electrode active material according to claim 1 , wherein a material containing sulfur is used as the coating raw material.
6. The process for preparing a positive-electrode active material according to claim 1 , wherein a raw material containing one or more metallic components is added simultaneously with or in advance to the addition of the raw material containing one or more of sulfur, selenium, or tellurium.