Anode active material for lithium secondary battery, method of preparing the same, and lithium secondary battery including the anode active material
View Patent ↗Provided are an anode active material including silicon oxide particles (SiOx, where x satisfies 0<x<2), fiber-type carbon grown on the silicon oxide particles, and a carbon coating layer formed on surfaces of the silicon oxide particles and the fiber-type carbon, and a method of preparing the anode active material. Since the anode active material of the present invention is used in an anode of a lithium secondary battery, conductivity may not only be improved but the physical bonding force between the silicon oxide particles and the fiber-type carbon may also be increased. Thus, the performance of the battery may be improved by addressing limitations related to the exfoliation of the fiber-type carbon which may occur due to the volume change of silicon oxide.
1. An anode active material comprising:
silicon oxide particles represented by the following chemical formula:
SiO x , where x satisfies 0<x<2;
fiber-shaped carbon grown on the silicon oxide particles; and
a carbon coating layer formed on surfaces of the silicon oxide particles and the fiber-shaped carbon,
wherein the anode active material comprises the fiber-shaped carbon in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the silicon oxide particles.
2. The anode active material of claim 1 , wherein the fiber-shaped carbon comprises carbon nanotubes, carbon nanofibers, or a mixture thereof.
3. The anode active material of claim 1 , wherein the fiber-shaped carbon has a diameter of 1 nm to 500 nm and a length of 100 nm to 5 μm.
4. The anode active material of claim 1 , wherein an average particle diameter of the silicon oxide particles is in a range of 4 μm to 45 μm.
5. The anode active material of claim 1 , wherein a coating amount of carbon in the carbon coating layer is in a range of 5 parts by weight to 20 parts by weight based on 100 parts by weight of the anode active material.
6. The anode active material of claim 1 , wherein the carbon coating layer covers the entire surfaces of the silicon oxide particles and the fiber-shaped carbon.
7. A method of preparing an anode active material, the method comprising the steps of:
(i) forming a composite by dispersing a catalytic metal on silicon oxide particles and performing a heat treatment in the presence of a carbon source to grow fiber-shaped carbon, wherein the silicon oxide particles are represented by the following chemical formula:
SiO x , where x satisfies 0<x<2; and
(ii) forming a carbon coating layer by coating the composite with carbon and performing a heat treatment,
wherein the anode active material comprises the fiber-shaped carbon in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the silicon oxide particles.
8. The method of claim 7 , wherein the fiber-shaped carbon comprises carbon nanotubes, carbon nanofibers, or a mixture thereof.
9. The method of claim 7 , wherein the fiber type shaped carbon has a diameter of 1 nm to 500 nm and a length of 100 nm to 5 μm.
10. The method of claim 7 , wherein an average particle diameter of the silicon oxide particles is in a range of 4 μm to 45 μm.
11. The method of claim 7 , wherein the heat treatment in the step (i) is performed in a temperature range of 100° C. to 1,000° C.
12. The method of claim 7 , wherein the carbon source comprises any one selected from the group consisting of methane, ethane, ethylene, butane, acetylene, carbon monoxide, propane, and propylene, or a mixture of two or more thereof.
13. The method of claim 7 , wherein the catalytic metal comprises any one selected from the group consisting of iron (Fe), nickel (Ni), cobalt (Co), calcium (Ca), yttrium (Y), and magnesium (Mg), or a mixed metal of two or more thereof.
14. The method of claim 7 , wherein the carbon coating comprises coating by pyrolytic carbon using any one selected from the group consisting of methane, ethane, ethylene, butane, acetylene, carbon monoxide, propane, and propylene, or a gas-phase or liquid-phase carbon source of two or more thereof; or coating by liquid-phase and solid-phase pitch.
15. The method of claim 7 , wherein the heat treatment in the step (ii) is performed in a temperature range of 300° C. to 1,400° C.
16. The method of claim 7 , wherein a coating amount of carbon in the carbon coating layer is in a range of 5 parts by weight to 20 parts by weight based on 100 parts by weight of the anode active material.
17. An anode comprising a current collector and the anode active material of claim 1 formed at least one surface of the current collector.
18. A lithium secondary battery comprising a cathode, the anode of claim 17 , and a separator disposed between the cathode and the anode.