WO2008100002A1

WO2008100002A1 - Anode active material for rechargeable lithium ion battery, method for preparing the same, and lithium ion battery manufactured using the same

Info

Publication number: WO2008100002A1
Application number: PCT/KR2007/005273
Authority: WO
Inventors: Jeong-Min Han; Jeong-Hun Oh; Jong-Sung Kim; Chul Youm; Kyung-Hee Han
Original assignee: Ls Mtron, Ltd.
Priority date: 2007-02-16
Filing date: 2007-10-25
Publication date: 2008-08-21
Also published as: KR20080076527A; JP2010519682A; KR100853327B1

Abstract

The present invention relates to an anode active material for a rechargeable lithium ion battery, a method for preparing the same and a lithium ion battery manufactured using the same. According to the present invention, an anode active material's surface is coated with a fluorine- based compound. The present invention can stabilize the surface of the anode active material to reduce the influence caused by a decomposition reaction of an organic electrolyte liquid that results in an irreversible capacity. And, the present invention can reduce the influence on an acid generated by oxidation of an electrolyte during charging or discharging, thereby exhibiting excellent cycleability and high rate capability when charging or discharging.

Description

ANODE ACTIVE MATERIAL FOR RECHARGEABLE

LITHIUM ION BATTERY, METHOD FOR PREPARING THE

SAME, AND LITHIUM ION BATTERY MANUFACTURED

USING THE SAME Technical Field

[1] The present invention relates to an anode active material for a rechargeable lithium ion battery, a method for preparing the same and a lithium ion battery manufactured using the same, and in particular, to an anode active material for a rechargeable lithium ion battery, in which the anode active material's surface is stabilized to reduce the influence caused by a decomposition reaction of an organic electrolyte liquid that results in an irreversible capacity and reduce the influence on an acid generated by oxidation of an electrolyte during charging or discharging, thereby exhibiting excellent cycleability and high rate capability when charging or discharging, and to a method for preparing the same and a lithium ion battery manufactured using the same. Background Art

[2] Recently, a lithium ion battery is widely used as a power source of a portable, small-sized electronic equipment, and the lithium ion battery uses an organic electrolyte liquid to exhibit higher discharge voltage twice than a conventional battery using an alkaline electrolyte liquid, and consequently has a high energy density.

[3] The lithium ion battery used mainly an oxide compound as a cathode active material, for example LiCoO , LiMn O or LiNi Co O (0<x<l), which includes r 2 2 4 1-x x 2 lithium and a transition metal, and has a structure capable of lithium intercalation.

[4] The lithium ion battery used carbon-based materials of various shapes as an anode active material, for example an artificial graphite, a natural graphite or a hard carbon, which have a structure capable of insertion/removal of lithium. The carbon-based anode material has a flat voltage at a low electric potential and a good cycleability. However, the carbon-based anode material has disadvantages of high reactivity with an organic electrolyte liquid or low diffusion rate of lithium therein, and thus it requires improvement in power characteristics, an initial irreversible capacity control or an electrode swelling phenomenon during charging or discharging.

[5] For this purpose, the prior art has used methods for controlling graphite powder in its shape, particle and its distribution, density, coating of an amorphous carbon (pitch) or degree of crystallinity by temperature to improve battery characteristics of graphite (or other carbon-based material) used for an anode. [6] As a concrete example, Korean Laid-open Patent Publication No. 2005-0020186 discloses an anode active material, which includes a carbon-based compound capable of insertion and removal of a lithium ion, and an oxide or hydroxide film formed on the surface of the carbon-based compound and having at least one element selected from the group consisting of Al, Ag, B, Cu, Mg, Si, Ti, Zn and Zr, and can improve cycleability and a high rate capability.

[7] However, the above-mentioned prior art has problems of high reactivity with an organic electrolyte liquid that results in an irreversible capacity and high influence on an acid generated by oxidation of an electrolyte during charging or discharging.

[8] Therefore, to solve the above-mentioned problems, attempts have been continuously made in the related industry and the present invention was devised under this technical background. Disclosure of Invention Technical Problem

[9] An object of the present invention is to provide an anode active material for a rechargeable lithium ion battery, which reduces the influence caused by a decomposition reaction of an organic electrolyte liquid that results in an irreversible capacity and reduces the influence on an acid generated by oxidation of an electrolyte during charging or discharging, thereby exhibiting excellent cycleability and high rate capability when charging or discharging, and to a method for preparing the same and a lithium ion battery comprising an anode made of the same.

Technical Solution

[10] In order to achieve the above-mentioned object, an anode active material for a rechargeable lithium ion battery has a surface coated with a fluorine-based compound.

[11] And, in order to achieve the above-mentioned object, a method for preparing an anode active material for a rechargeable lithium ion battery comprises reacting an anode active material with a fluorine-based compound; and as a reaction result, generating the anode active material having a surface coated with the fluorine-based compound.

[12] Also, in order to achieve the above-mentioned object, a lithium ion battery comprises an anode made of the anode active material prepared by the above- mentioned preparing method. Best Mode for Carrying Out the Invention

[13] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.

[14] Preferably, in the present invention, an anode active material is reacted with a fluorine-based compound, so that the anode active material has a surface coated with the fluorine-based compound. The fluorine-based compound used in coating the surfac e of the anode active material is generated by reacting fluorine (F) with a precursor. More preferably, the fluorine-based compound is in the form of complex salts.

[15] The fluorine-based compound may be CsF, KF, LiF, NaF, RbF, TiF, AgF, AgF ,

BaF , CaF , CuF , CdF , FeF , HgF , Hg F , MnF , MgF , NiF , PbF , SnF , SrF , XeF ,

2 2 2 2 2 2 2 2 2 2 2 2 2 2 2

ZnF 2 , AlF3 , BF3 , BiF3 , CeF 3 , CrF3 , DyF3 , EuF 3 , GaF 3 , GdF 3 , FeF3 , HoF 3 , InF3 , LaF 3 ,

LuF₃, MnF₃, NdF₃, VOF₃, PrF₃, SbF₃, ScF₃, SmF₃, TbF₃, TiF₃, TmF₃, YF₃, YbF₃, TlF₃, CeF 4 , GeF 4 , HfF 4 , SiF 4 , SnF 4 , TiF 4 , VF 4 , ZrF 4 , NbF 5 , SbF 5 , TaF 5 , BiF 5 , MoF 6 , ReF 6 , SF 6 or WF₆.

[16] The precursor may be Cs, K, Li, Na, Rb, Ti, Ag(I), Ag(II), Ba, Ca, Cu, Cd, Fe,

Hg(II), Hg(I), Mn(II), Mg, Ni, Pb, Sn, Sr, Xe, Zn, Al, B, Bi(m), Ce(m), Cr, Dy, Du, Ga, Fe, Ho, In, La, Lu, Mn(m), Nd, VO, Pr, Sb(m), Sc, Sm, Tb, Ti(m), Tm, Y, Yb, Tl, Ce(IV), Ge, Hf, Si, Sn, Ti(IV), V, Zr, Nb, Sb(V), Ta, Bi(V), Mo, Re, S or W.

[17] The anode active material for a rechargeable lithium ion battery may be prepared as follows.

[18] First, an anode active material is reacted with a fluorine -based compound generated by mixing fluorine (F) with a precursor (Sl). Next, as a reaction result, the anode active material having a surface coated with the fluorine-based compound is generated (S2). Specifically, the step (Sl) may include adding, agitating and impregnating an anode active material into a precursor-containing solution (SIa), and mixing the impregnated result with a fluorine-containing solution for a coprecipitation reaction and agitating the mixture (SIb).

[19] In the step (SIa), preferably the precursor-containing solution is used with a content of 0.1 to 10 mol% based on the anode active material. In the case that the content of the precursor-containing solution is less than the above-mentioned minimum value, it is not preferable because a coating effect is insufficient, thereby failing to reduce the influence on an acid. And, in the case that the content of the precursor-containing solution is more than the above-mentioned maximum value, it is not preferable because a capacity or energy density of a battery reduces due to the weight of the precursor- containing solution itself. [20] And, in the step (SIb), a content of the fluorine-containing solution is determined depending on the precursor-containing solution. Specifically, the fluorine-containing solution is preferably used with a content of 0.1 to 60 mol% based on the precursor- containing solution. In the case that the content of the fluorine-containing solution is less than the above-mentioned minimum value, it is not preferable because some precursors are not associated with fluorine, and consequently a desired amount of coating is not made, thereby failing to obtain desired characteristics. And, the content of the fluorine-containing solution is more than the above-mentioned maximum value, it is not preferable because an excessive amount of fluorine is added and thus may influence the performance of the anode active material.

[21] In the step (SIb), the fluorine-containing solution is mixed in a flow rate of 1 to 100

D/min at temperature of 50 to 100⁰C for 3 to 48 hours to bring about a coprecipitation reaction and is agitated, so that the surface of the anode active material is coated with the fluorine-based compound.

[22] In the case that the flow rate of the fluorine-containing solution is less than the above-mentioned minimum value, a fluorine-based compound is slowly coated on the surface of the anode active material, but it is not preferable because it takes a long reaction time. And, in the case that the flow rate of the fluorine-containing solution is more than the above-mentioned maximum value, a fluorine-based compound is not uniformly coated on the surface of the anode active surface due to a rapid association rate of fluorine with a precursor. Further, particles of the generated fluorine-based compound are large, so that a layer of uniform thickness is not coated on the surface of the anode active material, thereby reducing an electrochemical performance of the anode active material.

[23] In the case that the reaction time is less than the above-mentioned minimum value, it is not preferable because it is short to generate a fluorine-based compound by association of fluorine with a precursor and coat the fluorine-based compound on the surface of the anode active material uniformly, thereby failing to generate a fluorine- based compound of a desired shape. In the case that the reaction time is more than the above-mentioned maximum value, it is not preferable because the surface of the anode active material may be deteriorated, for example oxidized by a solvent, which may influence the performance of the anode active material.

[24] In the present invention, to coat the anode active material with the fluorine-based compound, a fluorine-based compound of a desired shape should be obtained. In the case that temperature of the coprecipitation reaction is in the above-mentioned range, the coprecipitation reaction is performed at high temperature, and thus a fluorine-based compound of high dispersity can be obtained in the form of complex salts. The fluorine-based compound of high dispersity in the form of complex salts is better in coating the anode active material.

[25] Subsequently, the anode active material coated with the fluorine-based compound as mentioned above may be passed through the steps of: (S3) washing; (S4) drying the washed result; and (S5) heating the washed and dried result.

[26] At this time, in the step (S3), the washing may be performed using distilled water by a typical method.

[27] In the drying step (S4), the temperature range may vary depending on kind of a solvent. In the present invention, the drying step is performed using water or an alcohol-based solvent such as methanol or ethanol at temperature of 50 to 15O⁰C. In the case that the drying temperature is less than the above-mentioned minimum value, it is not preferable because it takes much time to remove the solvent after the coating step, and consequently an overall process time is increased, and in the case that the drying temperature is more than the above-mentioned maximum value, the surface of the anode active material may be deteriorated, for example oxidized. And, it is not preferable because deterioration may influence the performance of the anode active material. Further, the drying step serves to remove the solvent after the coating step, and thus if the anode active material can be sufficiently dried, the drying time is not limited to a specific range.

[28] And, in the heating step (S5), the heating temperature may vary depending on kind of a precursor used to generate the fluorine-based compound. Specifically, the heating is preferably performed at temperature 150 to 900⁰C for 1 or 20 hours under any one condition selected from the group consisting of an acidic atmosphere, a reduced atmosphere and a vacuum atmosphere. And, in the case that the heating temperature is less than the above-mentioned minimum value, it is not preferable because a fluorine- based compound of a desired shape is not generated. And, the heating temperature is more than the above-mentioned maximum value, it is not preferable because a fluorine-based compound of a desired shape is not generated or carbonization may occur to influence the properties or performance of the anode active material. And, in the case that the heating time is less than the above-mentioned minimum value, it is not preferable because a fluorine-based compound of a desired shape is not generated or impurities may remain. And, the heating time is more than the above-mentioned maximum value, it is not preferable because properties or performance of the anode active material may be influenced.

[29] The anode active material used in the present invention is not limited to a specific kind, if it is prepared by a typical method used in the prior art. Specifically, the anode active material may be prepared by coating a core carbon material with a low crys- tallinity carbon.

[30] The core carbon material may be a natural graphite, an artificial graphite or a mixture thereof. In particular, preferably the core carbon material is a spherical natural graphite.

[31] The low crystallinity carbon may be pitch, tar, a phenol resin, a furan resin or a furfurly alcohol.

[32] That is, the present invention coats the core carbon material with the low crystallinity carbon to prepare an anode active material and coats the surface of the anode active material with the above-mentioned fluorine-based compound.

[33] The lithium ion battery of the present invention is manufactured using the anode active material prepared by the above-mentioned method. The lithium ion battery of the present invention may be manufactured as follows.

[34] First, a cathode active material, a conductive material, a binder material and a solvent are mixed to prepare a cathode active material composition. The cathode active material composition is directly coated on a metal collector and dried to prepare a cathode plate. Alternatively, the cathode active material composition may be cast on a separate support. Next, a film separated from the support may be laminated onto a metal collector to manufacture a cathode plate.

[35] The cathode active material is a lithium-containing metal oxide and is not limited to a specific material, if it is a typical material used in the prior art. For example, the cathode active material may be LiCoO 2 , LiMn x O 2x , LiNi 1-x Mn x O 2x (x=l, 2) or Ni 1-x-y Co x

Mn O (0≤x≤0.5, 0<y≤0.5). More specifically, the cathode active material may be a compound having a structure capable of oxidation and reduction of lithium, for example LiMn 2 O4 , LiCoO 2 , LiNiO 2 , LiFeO 2 , V2 O5 , TiS or MoS.

[36] The conductive material is carbon black, and the binder material may be a vinyli- denefluoride/hexafluoropropylene copolymer, polyvinylidenefluoride, poly aery - lonitrile, polymethylmethacrylate, polytetrafluoroethylene and mixtures thereof or a styrene butadiene rubber-based polymer. The solvent may be N-methylpyrrolidone, acetone or water. At this time, the cathode active material, the conductive material, the binder material and the solvent are used with contents of a typical level used in a lithium ion battery.

[37] A separator is not limited to a specific kind, if it is a typical one used in a lithium ion battery. In particular, preferably the separator has a low resistance to ion movement of an electrolyte and an excellent hygroscopicity of an electrolyte liquid. Specifically, the separator is made of a material selected from the group consisting of a glass fiber, polyester, teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) and mixtures thereof, and may be in the form of non- woven fabrics or woven fabrics. More specifically, a lithium ion battery uses a coilable separator made of a material such as polyethylene or polypropylene, and a lithium ion polymer battery uses a separator having an excellent hygroscopicity of an organic electrolyte liquid. The separator may be manufactured by the following method.

[38] That is, a polymer resin, a filler and a solvent are mixed to prepare a separator composition. The separator composition is directly coated on an upper portion of an electrode and dried to form a separator film, alternatively the separator composition may be cast on a support and dried, and a separator film separated from the support may be laminated onto an upper portion of an electrode.

[39] The polymer resin is not limited to a specific material, and may be all materials used for a binder material of an electrode plate. For example, the polymer resin may be a vinylidenefluoride/hexafluoropropylene copolymer, polyvinylidenefluoride, poly- acrylonitrile, polymethylmethacrylate or mixtures thereof.

[40] An electrolyte liquid may be prepared by mixing and dissolving a solvent, for example propylene carbonate, ethylene carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, dimethylcarbonate, methylethylcarbonate, diethylcarbonate, methylpropylcarbonate, methylisopropylcarbonate, ethylpropylcarbonate, dipropylcarbonate, dibutylcarbonate, diethyleneglycol, dimethylether, or mixtures thereof with any one electrolyte having a lithium salt, selected from the group consisting of LiPF , LiBF , LiSbF , LiAsF , LiClO 4 , LiCF 3 SO3 , Li(CF3 SO 2 )2N, LiC 4 F9SO 3 , LiSbF 6 , LiAlO 4 , LiAlCl 4 , LiN(C x F 2x+l

SO )(C F SO )(x,y each is a natural number), LiCl and LiI, or mixtures thereof. [41] The separator may be arranged between the cathode plate and an anode plate to form a battery structure. The battery structure may be wound or folded and put into a cylindrical or angular battery case, and the organic electrolyte liquid may be added to manufacture a lithium ion battery. [42] And, the battery structures may be stacked in a structure of a bicell and impregnated into the organic electrolyte liquid, and a resultant product may be put into a pouch and sealed tightly to manufacture a lithium ion polymer battery.

Mode for the Invention [43] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. [44] Example 1

[45] A carbon material of spherical natural graphite and pitch were prepared.

[46] The pitch dissolved in tetrahydrofuran was added to the spherical natural graphite at a predetermined weight ratio. They were wet-mixed at an atmospheric pressure for 2 hours or more and dried to produce a mixture. The mixture was sintered at 1,100⁰C and 1,500⁰C for 1 hour, respectively, and classified to remove fine powder, thereby preparing an anode active material.

[47] Next, 2 mol% of Al(NO ) -9H O (based on parts by weight of the anode active material) was dissolved in 2000 D of diluted water in a beaker of 2000 D, and the prepared anode active material was added, agitated and completely impregnated. 500 D of a solution containing NH F (6 mol%) was mixed in a flow rate of 1 D/min to bring

4 about a coprecipitation reaction while the temperature of the beaker was maintained at about 80⁰C. The reactant was agitated for more 12 hours. At this time, an average temperature of a reaction tank was maintained at about 80⁰C.

[48] The anode active material coated with a fluorine-based compound, obtained through the reaction was washed by diluted water and dried in a warm- air thermostat of 110⁰C for 12 hours. Next, the dried anode active material was thermally treated at 400⁰C under an inactive atmosphere, so that the anode active material was coated with AlF . 100 g of the anode active material coated with AlF was put into a reactor of 500 D, N- methylpyrrolidone (NMP) and a binder (PVDF) were added with a small amount and mixed using a mixer. Next, the mixture was compression-dried on a copper foil to form an electrode. At this time, the density of the electrode was 1.5 g/D and the thickness of the electrode was 70 D.

[49] And, a coin cell was manufactured and used to evaluate the charge and discharge efficiency.

[50] Example 2

[51] This example 2 was carried out by the same method as the example 1 except that

Al-isopropoxide and an anhydrous ethanol were used instead of Al(NO ) -9H O and diluted water, respectively.

[52] Example 3

[53] This example 3 was carried out by the same method as the example 1 except that

Zr(SO ) -xH O was used instead of Al(NO ) -9H O.

4 2 2 3 3 2

[54] Example 4

[55] This example 4 was carried out by the same method as the example 1 except that

Zr-ethoxide and an anhydrous ethanol were used instead of Al(NO ) -9H O and diluted water, respectively. [56] Comparative example 1

[57] A carbon material of spherical natural graphite and pitch were prepared.

[58] The pitch dissolved in tetrahydrofuran was mixed with the spherical natural graphite at a predetermined weight ratio. They were sintered at 1,100⁰C and 1,500⁰C for 1 hour, respectively, and classified to remove fine powder, thereby preparing an anode active material. [59] Next, 100 g of the prepared anode active material (a mixture of the graphite carbon material with the pitch) was put into a reactor of 500 D, and N-methylpyrrolidone (NMP) and a binder (PVDF) were added with a small amount and mixed using a mixer. Next, the mixture was compression-dried on a copper foil to form an electrode. At this time, the density of the electrode was 1.5 g/D and the thickness of the electrode was 70 D.

[60] And, a coin cell was manufactured and used to evaluate the charge and discharge efficiency. [61] A charge/discharge test was performed on battery characteristics by the following method using the anode active materials prepared in the examples 1 to 4 and the comparative example 1, and test results are shown in the following Table 1.

[62] First, charging was performed with a charge current of 0.5 D/D until a voltage is 0.01 V while limiting an electrical potential to the range of 0 to 1.5 V. The charging was continuously performed until the charge current is 0.02 D/D while maintaining the voltage at 0.01 V. And, discharging was performed with a discharge current of 0.5 D/D until the voltage is 1.5 V.

[63] In the following Table 1, the charge and discharge efficiency is a ratio of a discharged electrical capacity to a charged electrical capacity. [64] Table 1

[65] Through the above Table 1, it is found that in comparison with the anode active material of the comparative example 1 without surface coating, the anode active materials of the examples 1 to 4, each having a surface coated with the fluorine-based compound according to the present invention exhibits excellent cycleability and high rate capacity, and thus electrochemical characteristics of the anode active materials of the examples 1 to 4 were improved.

[66] As such, the preferred embodiments of the present invention were described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Industrial Applicability

[67] The anode active material surface-coated with the fluorine-based compound according to the present invention has a stabilized surface to reduce the influence caused by a decomposition reaction of an organic electrolyte liquid that results in an irreversible capacity. And, the anode active material of the present invention reduces the influence on an acid generated by oxidation of an electrolyte during charging or discharging, thereby exhibiting excellent cycleability and high rate capability when charging or discharging.

Claims

[1] An anode active material for a rechargeable lithium ion battery, in which the anode active material's surface is coated with a fluorine-based compound.

[2] The anode active material for a rechargeable lithium ion battery according to claim 1, wherein the fluorine-based compound is generated by reacting fluorine (F) with a precursor and is any one material selected from the group consisting of CsF, KF, LiF, NaF, RbF, TiF, AgF, AgF 2 , BaF 2 , CaF 2 , CuF 2 , CdF 2 , FeF 2 , HgF2 , Hg 2 F 2 ,

MnF₂, MgF₂, NiF₂, PbF₂, SnF₂, SrF₂, XeF₂, ZnF₂, AlF₃, BF₃, BiF₃, CeF₃, CrF₃, DyF , EuF , GaF , GdF , FeF , HoF , InF , LaF , LuF , MnF , NdF , VOF , PrF ,

SbF , ScF , SmF , TbF , TiF , TmF , YF , YbF , TlF , CeF , GeF , HfF , SiF ,

3 3 3 3 3 3 3 3 3 4 4 4 4

SnF , TiF , VF , ZrF , NbF , SbF , TaF , BiF , MoF , ReF , SF and WF , or

4 4 4 4 5 5 5 5 6 6 6 6 mixtures thereof.

[3] The anode active material for a rechargeable lithium ion battery according to claim 1, wherein the fluorine-based compound is a material in the form of complex salts.

[4] The anode active material for a rechargeable lithium ion battery according to claim 2, wherein the precursor is any one element selected from the group consisting of Cs, K, Li, Na, Rb, Ti, Ag(I), Ag(II), Ba, Ca, Cu, Cd, Fe, Hg(II), Hg(I), Mn(II), Mg, Ni, Pb, Sn, Sr, Xe, Zn, Al, B, Bi(JR), Ce(m), Cr, Dy, Du, Ga, Fe, Ho, In, La, Lu, Mn(m), Nd, VO, Pr, Sb(m), Sc, Sm, Tb, Ti(m), Tm, Y, Yb, Tl, Ce(IV), Ge, Hf, Si, Sn, Ti(IV), V, Zr, Nb, Sb(V), Ta, Bi(V), Mo, Re, S and W, or mixtures thereof.

[5] A method for preparing an anode active material for a rechargeable lithium ion battery, comprising:

(51) reacting an anode active material with a fluorine-based compound; and

(52) as a reaction result, generating the anode active material having a surface coated with the fluorine-based compound.

[6] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 5, wherein, in the step (Sl), the fluorine -based compound is generated by reacting fluorine (F) with a precursor and is any one material selected from the group consisting of CsF, KF, LiF, NaF, RbF, TiF, AgF, AgF , BaF , CaF , CuF , CdF , FeF , HgF , Hg F , MnF , MgF , NiF , PbF , SnF , SrF , XeF , ZnF , AlF , BF ,

2 2 2 2 2 2 2 2 2 2 2 2 3 3

BiF , CeF , CrF , DyF , EuF , GaF , GdF , FeF , HoF , InF , LaF , LuF , MnF ,

NdF , VOF , PrF , SbF , ScF , SmF , TbF , TiF , TmF , YF , YbF , TlF , CeF ,

3 3 3 3 3 3 3 3 3 3 3 3 4 GeF , HfF , SiF , SnF , TiF , VF , ZrF , NbF , SbF , TaF , BiF , MoF , ReF , SF

4 4 4 4 4 4 4 5 5 5 5 6 6 6 and WF , or mixtures thereof.

6

[7] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 6, wherein the fluorine-based compound is a material in the form of complex salts.

[8] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 6, wherein the precursor is any one element selected from the group consisting of Cs, K, Li, Na, Rb, Ti, Ag(I), Ag(II), Ba, Ca, Cu, Cd, Fe, Hg(II), Hg(I), Mn(II), Mg, Ni, Pb, Sn, Sr, Xe, Zn, Al, B, Bi(m), Ce(m), Cr, Dy, Du, Ga, Fe, Ho, In, La, Lu, Mn(m), Nd, VO, Pr, Sb(m), Sc, Sm, Tb, Ti(m), Tm, Y, Yb, Tl, Ce(IV), Ge, Hf, Si, Sn, Ti(IV), V, Zr, Nb, Sb(V), Ta, Bi(V), Mo, Re, S and W, or mixtures thereof.

[9] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 5, wherein the step (Sl) includes (SIa) adding, agitating and impregnating the anode active material into a precursor-containing solution; and (SIb) mixing the impregnated result with a fluorine-containing solution for a co- precipitation reaction and agitating the mixture.

[10] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 9, wherein, in the step (SIa), the precursor-containing solution is used with a content of 0.1 to 10 mol% based on the anode active material.

[11] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 9, wherein, in the step (SIb), the fluorine-containing solution is used with a content of 0.1 to 60 mol% based on the precursor-containing solution.

[12] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 9, wherein, in the step (SIb), the fluorine-containing solution is mixed at temperature of 50 to 100⁰C in a flow rate of 1 to 100 D/min for 3 to 48 hours and is agitated.

[13] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 5, further comprising: after the step (S2), (S3) washing the anode active material coated with the fluorine -based compound; (S4) drying the washed result; and (S 5) thermally treating the washed and dried result. [14] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 13, wherein, in the step (S4), the drying is performed at temperature of 50 to 15O⁰C. [15] The method for preparing an anode active material for a rechargeable lithium ion battery according to claim 13, wherein, in the step (S5), the thermal treatment is performed at temperature 150 to 900⁰C for 1 to 20 hours under any one condition selected from the group consisting of an acidic atmosphere, a reduced atmosphere and a vacuum atmosphere. [16] A lithium ion battery, comprising an anode made of the anode active material prepared by the method according to any one of claims 5 to 15.