Anode active material for lithium secondary battery and lithium secondary battery including the same
An anode active material for a lithium secondary battery according to embodiments of the present invention includes a carbon-based active material and a silicon-based active material including silicon-based active material particles having a particle size distribution in a range from 1 μm to 19 μm. A lithium secondary battery having improved life-span and rapid charge/discharge properties at room temperature is provided.
1 . An anode active material for a lithium secondary battery, comprising:
a carbon-based active material; and
a silicon-based active material including silicon-based active material particles having a particle size distribution in a range from 1 μm to 19 μm,
wherein silicon included in the silicon-based active material has a peak intensity ratio defined by Equation 2 of 1.2 or less in a Raman spectrum,
Peak intensity ratio= I (515)/ I (480), [Equation 2]
Wherein I(515) is a peak intensity of silicon included in the silicon-based active material in a region corresponding to a wave number of 515 cm −1 in the Raman spectrum, and I(480) is a peak intensity of silicon included in the silicon-based active material in a region corresponding to a wave number of 480 cm −1 in the Raman spectrum.
2 . The anode active material for a lithium secondary battery according to claim 1 , wherein the silicon-based active material particles have a particle size distribution within a range from 2 μm to 16 μm.
3 . The anode active material for a lithium secondary battery according to claim 1 , wherein the silicon-based active material particles do not include particles having a particle size less than 1 μm or greater than 19 μm.
4 . The anode active material for a lithium secondary battery according to claim 1 , wherein a D50 of the silicon-based active material particles is in a range from 5 μm to 8 μm,
wherein the D50 is defined as a particle diameter when a cumulative volume percentage corresponds to 50% in a particle size distribution based on a particle volume.
5 . The anode active material for a lithium secondary battery according to claim 1 , wherein a D10 of the silicon-based active material particles is in a range from 1 μm to 4 μm, and a D90 of the silicon-based active material particles is in a range from 8 μm to 16 μm,
wherein the D10 and the D90 are defined as particle diameters when the volume cumulative percentages correspond to 10% and 90%, respectively, in a particle size distribution based on a particle volume.
6 . The anode active material for a lithium secondary battery according to claim 1 , wherein the carbon-based active material includes at least one selected from the group consisting of artificial graphite, natural graphite, activated carbon, a carbon nanotube, a carbon nanowire, graphene, a carbon fiber, carbon black, graphite, a porous carbon, and a material obtained by a thermal decomposition of cryogel, xerogel or aerogel.
7 . The anode active material for a lithium secondary battery according to claim 1 , wherein the carbon-based active material includes carbon-based active material particles having an amorphous structure.
8 . The anode active material for a lithium secondary battery according to claim 1 , wherein the silicon-based active material includes at least one of a SiOx (0≤x<2) and a silicon carbide.
9 . The anode active material for a lithium secondary battery according to 8 , wherein the silicon carbide includes a porous carbon, and silicon coated at an inside of pores in the porous carbon or on a surface of the porous carbon.
10 . The anode active material for a lithium secondary battery according to claim 8 , wherein the SiOx has a specific surface area ranging from 1 m 2 /g to 6 m 2 /g.
11 . The anode active material for a lithium secondary battery according to claim 8 , wherein a specific surface area of the silicon carbide is in a range from 5 m 2 /g to 12 m 2 /g.
12 . The anode active material for a lithium secondary battery according to claim 1 , wherein a content of the silicon-based active material is in a range from 1 wt % to 15 wt % based on a total weight of the carbon-based active material and the silicon-based active material.
13 . The anode active material for a lithium secondary battery according to claim 1 , wherein silicon included in the silicon-based active material has an amorphous structure or has a crystallite size of 7 nm or less measured by an XRD (X-ray diffraction) analysis.
14 . The anode active material for a lithium secondary battery according to claim 13 , wherein the crystallite size of silicon contained in the silicon-based active material is measured based on Equation 1:
L
=
0
.
9
λ
β
cos
θ
[
Equation
1
]
wherein, in Equation 1, L is the crystallite size (nm), λ is an X-ray wavelength (nm), β is a full width at half maximum (rad) of a peak of a (111) plane of silicon included in the silicon-based active material, and θ is a diffraction angle (rad).
15 . A lithium secondary battery, comprising
an anode comprising an anode active material layer that includes the anode active material for a lithium secondary battery of claim 1 ; and
a cathode facing the anode.