Porous silicon-based anode active material, method for preparing the same, and lithium secondary battery comprising the same
Provided are a porous silicon-based anode active material including porous SiO x particles (0≤x<2) having surfaces coated with an oxide layer, a method of preparing the same, and a lithium secondary battery including the porous silicon-based anode active material. Since the anode active material includes an oxide layer formed on the porous SiO x particles (0≤x<2), a reactivity between the anode active material and an electrolyte solution may be reduced and, as a result, an electrical short circuit in an electrode may be minimized. Also, since a plurality of pores is included in surfaces or the surfaces and inside of the SiO x particles, a thickness change rate of the electrode generated during charge and discharge of a secondary battery may be reduced and lifetime characteristics may be improved.
1. An anode, comprising:
an anode active material; and
a binder,
wherein the anode active material comprises:
porous SiO x particles (0≤x<2), wherein the porous SiO x particles comprise an oxide layer coated on surfaces thereof; and
carbon-based anode active material particles,
wherein the oxide layer comprises SiO y (0<y≤2), and x<y,
wherein the porous SiO x particles include pores on surfaces and inside of SiO x particles, and
wherein the oxide layer is formed by heat treating the porous SiO x particles in air or an oxygen atmosphere.
2. The anode of claim 1 , wherein x and y respectively satisfy 0≤x<1 and 1<y≤2.
3. The anode of claim 2 , wherein x and y respectively satisfy 0≤x<0.5 and 1.2≤y≤2.
4. The anode of claim 1 , wherein a thickness of the oxide layer is greater than 0 and equal to or less than 200 nm.
5. The anode of claim 4 , wherein the thickness of the oxide layer is greater than 0 and equal to or less than 100 nm.
6. The anode of claim 1 , wherein an average particle diameter (D 50 ) of the porous SiO x , particles is in a range of 1μ 0 m 20μ m.
7. The anode of claim 1 , wherein an average pore diameter of the porous SiO x particles is in a range of 30 nm to 500 nm as measured on the surface thereof.
8. The anode of claim 1 , wherein a specific surface area of the porous SiO x particles is in a range of 5 m 2 /g to 50 m 2 /g.
9. The anode of claim 1 , wherein the porous SiO x particles are porous silicon (Si) particles.
10. The anode of claim 1 , wherein the carbon-based anode active material particles comprises any one selected from the group consisting of natural graphite, artificial graphite, meso-carbon microbeads, amorphous hard carbon, and low crystalline soft carbon, or a mixture of two or more thereof.
11. A method of preparing the anode active material of claim 1 , the method comprising:
preparing porous SiO x particles (0≤x<2 ) by forming pores on the surfaces and inside of SiO x , particles;
heat treating the porous SiO x particles in air or an oxygen atmosphere to prepare porous SiO x particles having surfaces coated with an oxide layer; and
mixing the heated treated porous SiO x particles with the carbon-based anode active material particles to form the anode active material.
12. The method of claim 11 , wherein the forming of the pores comprises:
mixing a fluorinated solution with a metal precursor solution and introducing SiO x particles (0≤x<2) into the mixed solution to electrodeposit metal particles on surfaces of the SiO x particles;
etching by contacting the SiO x particles having metal particles electrodeposited thereon with an etching solution; and
removing the metal particles by contacting the etched SiO x particles with a metal removal solution.
13. The method of claim 11 , wherein the SiO x particles (0≤x≤2) comprise Si particles or one prepared by mechanical alloying after mixing Si particles and SiO 2 particles.
14. The method of claim 11 , wherein the oxide layer comprises SiO y (0<y≤2), and x<y.
15. The method of claim 11 , wherein the heat treatment is performed in a temperature range of 600° C. to 900° C. for 1 minute to 12 hours.
16. The method of claim 11 , wherein a thickness of the oxide layer is greater than 0 and equal to or less than 200 nm.
17. The method of claim 11 , wherein the carbon-based anode active material comprises any one selected from the group consisting of natural graphite, artificial graphite, meso-carbon microbeads, amorphous hard carbon, and low crystalline soft carbon, or a mixture of two or more thereof.
18. A lithium secondary battery comprising the anode of claim 1 .
19. The anode of claim 1 , further comprising:
a conductive material.
20. The anode of claim 1 , wherein an average particle diameter (D 50 ) of the carbon-based anode active material particles is in a range of 2 μm to 20 μm.
21. An anode comprising:
an anode active material; and
a binder,
wherein the anode active material comprises:
porous SiO x particles (0≤x<2) comprising an oxide layer coated on surfaces thereof; and
carbon-based anode active material particles,
wherein the oxide layer comprises SiO y (0<y≤2), and x<y,
wherein the porous SiO x particles include pores on surfaces and inside of SiO x particles,
wherein the anode active material is prepared by a method comprising:
heat treating the porous SiO x particles in air or an oxygen atmosphere to form the oxide layer; and
mixing the heated treated porous SiO x particles with the carbon-based anode active material particles to form the anode active material.