Negative active material, method of preparing the same, and lithium battery including the same
Provided are a negative active material, a method of preparing the same, and a lithium battery including the negative active material. The negative active material includes a carbonaceous core that has a sulfur content of about 10 ppm to 900 ppm; and an amorphous carbon layer continuously formed on a surface of the carbonaceous core, wherein the carbonaceous core has a crystalloid plate structure, and a crystallite size measured from a full width at half maximum of the peak with respect to the surface (002) of about 10 nm to about 45 nm in an X-ray diffraction spectrum of the carbonaceous core. The lithium battery including a negative electrode including the negative active material has improved capacity characteristics and ring lifetime characteristics.
1. A negative active material comprising:
a carbonaceous core comprising a sulfur content of from about 10 ppm to 900 ppm; and
an amorphous carbon layer continuously formed on a surface of the carbonaceous core,
wherein the carbonaceous core has a crystalloid plate structure, and a crystallite size measured from a full width at half maximum of the peak with respect to the surface (002) of from about 10 nm to about 45 nm in an X-ray diffraction spectrum of the carbonaceous core.
2. The negative active material of claim 1 , wherein the carbonaceous core has a peak with respect to a surface (002) at a Bragg angle 2θ of 26.4°±0.1° in the X-ray diffraction spectrum of the carbonaceous core.
3. The negative active material of claim 1 , wherein the carbonaceous core has a full width at half maximum of the peak with respect to the surface (002) of from about 0.2° to about 0.6 in the X-ray diffraction spectrum of the carbonaceous core.
4. The negative active material of claim 1 , wherein the carbonaceous core has an interlayer spacing (d 002 ) of the surface (002) measured by X-ray diffraction of about 3.36 Å to about 3.37 Å.
5. The negative active material of claim 1 , wherein the amorphous carbon layer is a pitch coating.
6. The negative active material of claim 1 , wherein the negative active material is spherical or oval, and a longer direction particle size thereof d 50 is from about 1 μm to about 40 μm.
7. The negative active material of claim 1 , wherein the negative active material has voids therein.
8. The negative active material of claim 1 , wherein a BET specific surface area of the negative active material is from about 1 m 2 /g to about 30 m 2 /g.
9. The negative active material of claim 1 , wherein a tap density of the negative active material is from about 0.2 g/cc to 2.0 g/cc.
10. The negative active material of claim 1 , wherein the negative active material additionally comprises metal nanoparticles.
11. The negative active material of claim 10 , wherein the metal nanoparticles is selected from the group consisting of silicon (Si), tin (Sn), nickel (Ni), and a mixture thereof.
12. The negative active material of claim 10 , wherein a size of the metal nanoparticles is from about 1 nm to about 500 nm.
13. A lithium battery comprising:
a positive electrode comprising a positive active material;
a negative electrode comprising a negative active material comprising:
a carbonaceous core comprising a sulfur content of from about 10 ppm to 900 ppm; and
an amorphous carbon layer continuously formed on a surface of the carbonaceous core,
wherein the carbonaceous core has a crystalloid plate structure, and a crystallite size measured from a full width at half maximum of the peak with respect to the surface (002) of from about 10 nm to about 45 nm in an X-ray diffraction spectrum of the carbonaceous core; and
an electrolytic solution interposed between the positive and negative electrodes.