Anode active material, method of preparing the same, and anode and lithium battery containing the anode active material
An anode active material is provided. The anode active material includes a silicon thin film containing crystalline silicon having a Raman shift in a Raman spectrum ranging from about 490 to about 500 cm −1 and a full width at half maximum (FWHM) ranging from about 10 to about 30 cm −1 . The volume of the anode active material does not change significantly during charging and discharging. Thus, a lithium battery employing the anode active material has an excellent capacity retention rate and a longer cycle lifetime.
1. An anode active material for a lithium battery, the anode active material comprising a silicon thin film comprising crystalline silicon having a crystalline silicon Raman shift in a Raman spectrum ranging from about 490 to about 500 cm −1 and a full width at half maximum (FWHM) of the crystalline silicon Raman shift ranging from about 10 to about 30 cm −1 .
2. The anode active material of claim 1 , wherein the crystal size of the crystalline silicon is less than about 5 nm.
3. The anode active material of claim 1 , wherein the silicon thin film comprises a radio frequency (RF) sputtered silicon thin film.
4. The anode active material of claim 3 , wherein the RF sputtering uses RF-power ranging from about 30 to 90 watts, and an operating pressure ranging from about 5 to about 20 mtorr.
5. The anode active material of claim 1 , wherein the thickness of the crystalline silicon thin film ranges from about 20 to about 500 nm.
6. An anode for a lithium battery, the anode comprising the anode active material of claim 1 .
7. The anode of claim 6 , wherein the crystal size of the crystalline silicon is less than about 5 nm.
8. The anode of claim 6 , wherein the thickness of the crystalline silicon thin film ranges from about 20 to about 500 nm.
9. A lithium battery comprising:
a cathode;
the anode of claim 6 ; and
a separator.
10. The lithium battery of claim 9 , wherein the crystal size of the crystalline silicon is less than about 5 nm.
11. The lithium battery of claim 9 , wherein the thickness of the crystalline silicon thin film ranges from about 20 to about 500 nm.
12. A method of preparing an anode active material for a lithium battery, the method comprising RF-sputtering a crystalline silicon thin film on a substrate, wherein the crystalline silicon thin film comprises crystalline silicon having a crystalline silicon Raman shift in a Raman spectrum ranging from about 490 to about 500 cm −1 and a full width at half maximum (FWHM) of the crystalline silicon Raman shift ranging from about 10 to about 30 cm −1 .
13. The method of claim 12 , wherein the RF-sputtering uses RF-power ranging from about 30 to about 90 watts, and an operating pressure ranging from about 5 to about 20 mtorr.