Negative active material for rechargeable lithium battery, method of preparing the same, and rechargeable lithium battery including the same

A method of preparing a negative active material for a rechargeable lithium battery, comprising:

• preparing a solution comprising a spherically-shaped natural graphite particle where flake-shaped natural graphite fragments build up and assemble into a cabbage or random shape, an amorphous or semi-crystalline carbon precursor, and a solvent;
• performing ultrasonication on the solution, opening between the flake-shaped natural graphite fragments of a surface part and inside the spherically-shaped natural graphite particle to form an open gap while maintaining crystallinity of the spherically-shaped natural graphite particle, and simultaneously coating the surface of the spherically-shaped natural graphite particle with the amorphous or semi-crystalline carbon precursor and impregnating the amorphous or semi-crystalline carbon precursor in the open gap present on the surface part and inside the spherically-shaped natural graphite particle;
• drying the solution subjected to the ultrasonication to obtain a spherically-shaped natural graphite-modified particle;
• and
• heat-treating the spherically-shaped natural graphite-modified particle to prepare a spherically-shaped natural graphite-modified composite particle including amorphous or semi-crystalline carbon that is coated on the surface of the spherically-shaped natural graphite particle and that is present in the open gap present on the surface part and inside the spherically-shaped natural graphite particle.

A method of preparing a negative active material for a rechargeable lithium battery, comprising:

• preparing a solution comprising a spherically-shaped natural graphite particle where flake-shaped natural graphite fragments build up and assemble into a cabbage or random shape, an amorphous or semi-crystalline carbon precursor, lithium acetate, and a solvent;
• performing ultrasonication on the solution, opening between the flake-shaped natural graphite fragments of a surface part and inside the spherically-shaped natural graphite particle to form an open gap while maintaining crystallinity of the spherically-shaped natural graphite particle, and simultaneously coating the surface of the spherically-shaped natural graphite particle with the amorphous or semi-crystalline carbon precursor and the lithium acetate and impregnating the amorphous or semi-crystalline carbon precursor and the lithium acetate in the open gap present on the surface part and inside the spherically-shaped natural graphite particle;
• drying the solution subjected to the ultrasonication to obtain a spherically-shaped natural graphite-modified particle;
• and
• heat-treating the spherically-shaped natural graphite-modified particle to prepare a spherically-shaped natural graphite-modified composite particle including amorphous or semi-crystalline carbon and a lithium compound that are coated on the surface of the spherically-shaped natural graphite particle and that are present in the open gap present on the surface part and inside the spherically-shaped natural graphite particle,
• wherein the lithium compound comprises Li2O, Li2CO3, or a combination thereof.

A method of preparing a negative active material for a rechargeable lithium battery, comprising:

• preparing a solution comprising a spherically-shaped natural graphite particle where flake-shaped natural graphite fragments build up and assemble into a cabbage or random shape, an amorphous or semi-crystalline carbon precursor, and a solvent;
• performing ultrasonication on the solution, opening between the flake-shaped natural graphite fragments of a surface part and inside the spherically-shaped natural graphite particle to form an open gap while maintaining crystallinity of the spherically-shaped natural graphite particle, and simultaneously coating the surface of the spherically-shaped natural graphite particle with the amorphous or semi-crystalline carbon precursor and impregnating the amorphous or semi-crystalline carbon precursor in the open gap present on the surface part and inside the spherically-shaped natural graphite particle;
• drying the solution subjected to the ultrasonication after adding lithium acetate thereto to obtain a spherically-shaped natural graphite-modified particle including the amorphous or semi-crystalline carbon precursor and the lithium acetate that are coated on the surface of the spherically-shaped natural graphite particle and that are impregnated in the open gap present on the surface part and inside the spherically-shaped natural graphite particle;
• and
• heat-treating the spherically-shaped natural graphite-modified particle to prepare a spherically-shaped natural graphite-modified composite particle including amorphous or semi-crystalline carbon and a lithium compound that are coated on the surface of the spherically-shaped natural graphite particle and that are present in the open gap present on the surface part and inside the spherically-shaped natural graphite particle,
• wherein the lithium compound comprises Li2O, Li2CO3, or a combination thereof.