BEST MODE FOR CARRYING OUT THE INVENTION [0027] Hereinafter, the present invention will be described in more detail. [0028] It will be understood that words or terms used in the 25 specification and claims of the present invention shall not 10 be construed as being limited to having the meaning defined in commonly used dictionaries. It will be further understood that the words or terms should be interpreted as having meanings that are consistent with their meanings in the 5 context of the relevant art and the technical idea of the invention, based on the principle that an inventor may properly define the meaning of the words or terms to best explain the invention. [0029] A positive electrode active material according to the 10 present invention is a lithium cobalt-based positive electrode active material including a core portion including a lithium cobalt-based oxide represented by Formula 1 below and a shell portion including a lithium cobalt-based oxide represented by Formula 2 below, wherein the lithium cobalt15 based positive electrode active material includes 2500 ppm or more, preferably 3000 ppm or more of a doping element M based on the total weight of the positive electrode active material. [0030] [Formula 1] LiaCo1-bMbO2 20 [0031] In Formula 1, M is one or more selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Fe, V, Cr, Ba, Ca, Sr, and Nb, and 1≤a≤1.2 and 0.005≤b≤0.05. [0032] [Formula 2] LixCo1-yMyO2 25 [0033] In Formula 2, M is one or more selected from the 11 group consisting of Al, Mg, W, Mo, Zr, Ti, Fe, V, Cr, Ba, Ca, Sr, and Nb, and 0.5≤ x<1 and 0≤ y≤ 0.01. [0034] In a voltage profile measured by charging/discharging a secondary battery at room temperature under conditions of 5 0.1 C/0.1 C, the secondary battery including the above lithium cobalt-based positive electrode active material according to the present invention, an inflection point indicating a phase transition to a monoclinic system does not appear. At this time, the secondary battery may be a coin 10 cell including a positive electrode having the positive electrode active material of the present invention and a lithium metal negative electrode. [0035] The lithium cobalt-based positive electrode active 15 material according to the present invention has a shell portion with a lithium defect having a three-dimensional structure on the surface thereof, thereby having excellent intercalation and de-intercalation of lithium, and has a core portion including an excessive amount of doping element, 20 thereby having improved structural stability, so that a phase transition to a monoclinic system does not appear during charging/discharging. Accordingly, even during a highvoltage driving of 4.45 V or greater, the generation of gas and cobalt elution are suppressed, so that excellent lifespan 25 properties and high-temperature storage properties are 12 exhibited. [0036] Hereinafter, a lithium cobalt-based positive electrode active material according to the present invention 5 will be described in more detail. [0037] Lithium cobalt-based positive electrode active material 10 [0038] The positive electrode active material according to the present invention has a core-shell structure including a core portion and a shell portion. At this time, the shell portion refers to a region adjacent to the surface of a positive electrode active material particle, and the core 15 portion refers to the remaining regions in the positive electrode active material particle except for the shell portion. The core portion includes a lithium cobalt-based oxide doped with a doping element M, and specifically, includes a lithium cobalt-based oxide represented by Formula 20 1 below. [0039] [Formula 1] LiaCo1-bMbO2 [0040] In Formula 1, M is one or more selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Fe, V, Cr, Ba, Ca, 25 Sr, and Nb, preferably one or more selected from the group 13 consisting of Al, Mg, Ca, Sr, Ba, Ti, and Zr, more preferably one or more selected from Al and Mg. [0041] Meanwhile, the doping element M may include two or more elements different from each other. For example, the 5 doping element M may include a first doping element selected from the group consisting of Al, Mg, Ca, Sr, and Ba, and a combination thereof, and a second doping element selected from the group consisting of Ti and Zr, and a combination thereof. When the first doping element and the second doping 10 element are included, the structural stability may be further improved. [0042] The a represents the atomic ratio of lithium in the lithium cobalt-based oxide of Formula 1, and may be 1≤ a≤ 1.2, preferably 1≤ a≤ 1.1. 15 [0043] The b represents the atomic ratio of the doping element M in the lithium cobalt-based oxide of Formula 1, and may be 0.001≤ b≤ 0.05, preferably 0.001≤ b≤ 0.0 2 . When the atomic ratio of the doping element in the lithium cobaltbased oxide satisfies the above range, the structural 20 stability of the positive electrode active material is improved, so that a phase transition to a monoclinic system does not appear during charging/discharging, and even during a high-voltage driving of 4.45 V or greater, the generation of gas and cobalt elution are suppressed. 25 14 [0044] Meanwhile, the shell portion includes a lithium cobalt-based oxide with a lithium defect having a ratio of the atomic number of lithium to the sum of the atomic numbers of Co and the doping element M, that is the atomic ratio of 5 Li/(Co+M), of less than 1. Specifically, the shell portion include a lithium cobalt-based oxide represented by Formula 2. [0045] [Formula 2] LixCo1-yMyO2 [0046] In Formula 2, M is one or more selected from the 10 group consisting of Al, Mg, W, Mo, Zr, Ti, Fe, V, Cr, Ba, Ca, Sr, and Nb, preferably one or more selected from the group consisting of Al, Mg, Ca, Sr, Ba, Ti, and Zr, more preferably one or more selected from Al and Mg. [0047] Meanwhile, the doping element M may include two or 15 more elements different from each other. For example, the doping element M may include a first doping element selected from the group consisting of Al, Mg, Ca, Sr, and Ba, and a combination thereof, and a second doping element selected from the group consisting of Ti and Zr, and a combination 20 thereof. When the first doping element and the second doping element are included, the structural stability may be further improved. [0048] The x represents the atomic ratio of lithium in the lithium cobalt-based oxide of Formula 2, and may be 0.5≤ x<1, 25 preferably 0.55≤ x<1, more preferably 0.9≤ x≤ 0.99. When the 15 atomic ratio of lithium in the lithium cobalt-based oxide of the shell portion satisfies the above range, the lithium cobalt-based oxide of the shell portion has a threedimensional crystal structure such as a spinel-like crystal 5 structure, and thus, the moving speed of lithium ions in the shell portion increases, thereby improving output properties and rate properties. [0049] The y represents the atomic ratio of the doping element in the lithium cobalt-based oxide of Formula 2, and 10 may be 0≤ y≤ 0.01, preferably 0≤ y≤ 0.001. It is preferable that the lithium cobalt-based oxide forming the shell portion has fewer doping elements than the lithium cobalt-based oxide forming the core portion, or no doping element. When the atomic ratio of the doping element included in the shell 15 portion is out of the above range, a phase transition to a monoclinic system appears during charging/discharging, and the effect of suppressing the generation of gas and cobalt elution during a high-voltage driving of 4.45 V is insignificant. 20 [0050] The lithium cobalt-based positive electrode active material according to the present invention includes the doping element M in an amount of 2500 ppm or more, preferably 3000 ppm or more, more preferably 3000 ppm to 5000 ppm. When 25 the content of the doping element in the positive electrode 16 active material is less than 2500 ppm, a phase transition to a monoclinic system appears during charging/discharging, and the effect of suppressing the generation of gas and cobalt elution during a high-voltage driving of 4.45 V is 5 insignificant. [0051] In a voltage profile measured by charging/discharging a secondary battery including the lithium cobalt-based positive electrode active material according to the present 10 invention including a lithium cobalt oxide containing a doping element at a specific atomic ratio or higher and including a lithium-cobalt-based oxide with a lithium defect having a Li/(Co+M) atomic ratio of less than 1, an inflection point does not appear. In general, in the case of a battery 15 applied with a lithium cobalt-based oxide having a lithium defect portion, an inflection point at which a voltage profile is bent appears in the range of 4.1 V-4.2 V during an initial charging/discharging, which indicates that a phase transition to a monoclinic system has appeared in the lithium 20 cobalt-based oxide during the charging/discharging. However, in the case of the positive electrode active material according to the present invention, such inflection point does not appear in a charge/discharging voltage profile, which indicates there has been no phase transition to a 25 monoclinic system. 17 [0052] Meanwhile, in the positive electrode active material according to the present invention, the ratio of the half diameter of the core portion to the thickness of the shell 5 portion may be, for example, 1:0.01 to 1:0.1. When the shell portion is too thin, the effect of increasing the mobility of lithium ions is insignificant, and when the shell portion is too thick, the structural stability of an active material particle may be reduced. More specifically, under the 10 condition of the above-mentioned ratio of the half diameter of the core portion to the thickness of the shell portion, the thickness of the shell portion may be 1-500 μm, or 10-450 μm. 15 [0053] Also, in the positive electrode active material according to the present invention, the lithium cobalt-based oxide represented by Formula 1 may have a layered crystal structure, and the lithium cobalt-based oxide represented by Formula 2 may have a spinel-like structure. When the core 20 portion and the shell portion have a structure as described above, a positive electrode active material having excellent electrical properties as well as excellent structural stability may be implemented. The crystal structure of the lithium cobalt-based positive electrode active material may 25 be determined by a typical crystal structure determination 18 method, for example, a transmission electron microscopy, Xray diffraction, and the like. [0054] Meanwhile, in the positive electrode active material 5 according to the present invention, the lithium cobalt-based oxide of the core portion and of the shell portion may each independently include lithium in a constant concentration regardless of the position, or may have a concentration gradient in which the concentration of lithium gradually 10 increases from the surface of the active material particle to the center thereof. When lithium is distributed in the core portion and the shell portion so as to have a concentration gradient, the concentration gradient slope of the lithium of the core portion and the shell portion may be the same or 15 different from each other, or may be in the form of a primary function or a secondary function which varies depending on the thickness of the particle from the center of the active material particle. [0055] The concentration of lithium in the core portion and 20 the shell portion of the positive electrode active material may be measured by various component analysis methods known in the art, for example X-ray photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Energy Disperive x-ray spectroscopy (EDS), Inductively Coupled 25 Plasma-Atomic Emission Spectrometer (ICP-AES), Time of Flight 19 Secondary Ion Mass Spectrometry (ToF-SIMS), and the like. [0056] The positive electrode active material according to the present invention may have an average particle diameter (D50) of 3 μm to 50 μm, preferably 10 μm to 50 μm. When the 5 average particle diameter (D50) of the positive electrode active material satisfies the above range, an appropriate specific surface area and an appropriate positive electrode mixture density may be implemented. At this time, the average particle diameter (D50) of the positive electrode 10 active material refers to a particle diameter at 50% in a particle diameter distribution, and may be, for example, measured by a laser diffraction method. Specifically, the positive electrode active material particles are dispersed in a dispersion medium, and then introduced to a commercially 15 available laser diffraction particle size measurement device (for example, Microtrac MT 3000) to be irradiated with an ultrasonic wave of about 28 kHz to an output of 60W. Thereafter, the particle diameter may be measured at 50% in particle diameter distribution. 20 [0057] The positive electrode active material according to the present invention has excellent electrical properties due to the shell portion with a lithium defect, and has excellent stability even during a high-voltage driving of 4.45 V due to 25 the core portion including a doping element in a high 20 concentration. Therefore, the positive electrode active material according to the present invention may be usefully applied to a secondary battery driven at a high voltage of 4.45 V or greater. 5 [0058] Method for preparing lithium cobalt-based positive electrode active material [0059] Next, a method for preparing a lithium cobalt-based positive electrode active material according to the present 10 invention will be described. [0060] The method for preparing a lithium cobalt-based positive electrode active material according to the present invention includes (1) a first step in which a core portion including a lithium cobalt-based oxide represented by Formula 15 1 below is formed by mixing a first cobalt raw material, a first lithium raw material, and a doping element raw material, and then subjecting the mixture to a first heat treatment, and (2) a second step in which a shell portion including a lithium cobalt-based oxide represented by Formula 2 below is 20 formed by mixing the lithium cobalt-based oxide represented by Formula 1 above and a second cobalt raw material, and then subjecting the mixture to a second heat treatment. [0061] [0062] Hereinafter, each step will be described in detail. 25 21 [0063] (1) First step: Forming core portion [0064] First, a core portion is formed by mixing a first cobalt raw material, a first lithium raw material, and a doping element raw material, and then subjecting the mixture 5 to a first heat treatment. [0065] The first cobalt raw material may be, for example, an oxide, a hydroxide, an oxyhydroxide, a halide, a nitrate, a carbonate, an acetate, an oxalate, a citrate, or a sulfate, and the like, all containing cobalt, more specifically 10 Co(OH)2, Co3O4, CoOOH, Co(OCOCH3)2·4H2O, Co(NO3)2·6H2O, or CoSO4·7H2O, and the like, and any one thereof or a mixture of two or more thereof may be used. [0066] The first lithium raw material may be, for example, an oxide, a hydroxide, an oxyhydroxide, a halide, a nitrate, 15 a carbonate, an acetate, an oxalate, a citrate, or a sulfate, and the like, all containing lithium, more specifically Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, Li2O, Li2SO4, CH3COOLi, or Li3C6H6O7, and the like, all containing lithium, and any one thereof or a mixture of two 20 or more thereof may be used. [0067] The doping element raw material may be one or more metals selected from the group consisting of Al, Mg, W, Mo, Zr, Ti, Fe, V, Cr, Ba, Ca, Sr, and Nb, or an oxide, a hydroxide, an oxyhydroxide, a halide, a nitrate, a carbonate 25 an acetate, an oxalate, a citrate, or a sulfate, and the like, 22 all containing the same. Any one thereof or a mixture of two or more thereof may be used. Among these, one or more metals selected from Al and Mg, or an oxide, a hydroxide, an oxyhydroxide, a halide, a nitrate, a carbonate, an acetate, 5 an oxalate, a citrate, or a sulfate, all including the one or more metals are specifically preferable. [0068] Meanwhile in the first step, the first cobalt raw material, the first lithium raw material, and the doping 10 element M raw material may be mixed in an amount such that the atomic ratio of Li/(Co+M) of the core portion is 1 to 1.2, preferably 1 to 1.1. When the mixing ratio of the first cobalt raw material and the first lithium raw material satisfies the above range, a core portion including a lithium 15 cobalt-based oxide having a layered structure may be formed. [0069] Meanwhile, the first cobalt raw material and the first lithium raw material may be introduced together at once, or may be introduced separately such that the Li/(Co+M) ratio is decreased over time. In the latter case, a core portion 20 having a concentration gradient in which the concentration of lithium decreases from the center of the core portion to the surface thereof may be formed. [0070] Meanwhile, the doping element raw material is mixed in an amount of 2500 ppm or more, preferably 3000 ppm or more, 25 more preferably 3000 ppm to 5000 ppm, of a doping element M 23 based on the total weight with a lithium cobalt-based positive electrode active material to be finally formed. When an excessive amount of doping element raw material is introduced when forming the core portion as described above, 5 the structural stability of the positive electrode active material is improved, so that a phase transition to a monoclinic system may be prevented during charging/discharging. Accordingly, even during a highvoltage driving of 4.45 V or greater, a battery having 10 excellent lifespan properties may be implemented. [0071] Meanwhile, the first heat treatment for the mixture of the raw materials may be performed in a temperature range of at 950°C to 1100°C, preferably 1000°C to 1060°C. When the temperature of the first heat treatment satisfies the above 15 range, the generation of unreacted raw material residues and side reactants is minimized, so that the deterioration of discharge capacity, cycle properties, and driving voltage may be prevented. [0072] The first heat treatment may be performed in the 20 atmosphere or in an oxygen atmosphere, and the first heat treatment may be performed for 8-25 hours, preferably 12-18 hours. When the duration of the first heat treatment satisfies the above range, the diffusion reaction between raw materials may be sufficiently achieved. 25 [0073] Through the process as described above, the core 24 portion including the lithium cobalt-based oxide represented by Formula 1 is formed. The detailed description of the lithium cobalt-based oxide represented by Formula 1 is the same as described above, and thus, a detailed description 5 thereof will be omitted. [0074] (2) Second step: Forming shell portion [0075] Next, a shell portion is formed by mixing the lithium cobalt-based oxide represented by Formula 1 which is formed 10 through the first step and a second cobalt raw material, and then subjecting the mixture to a second heat treatment. [0076] When the second heat treatment is performed by mixing the lithium cobalt-based oxide represented by Formula 1 and the second cobalt raw material, lithium present on the 15 surface of the lithium cobalt-based oxide represented by Formula 1 reacts with the second cobalt raw material during the heat treatment process to form a lithium cobalt-based oxide with a lithium defect having the Li/(Co+M) atomic ratio of less than 1. 20 [0077] At this time, the second cobalt raw material may be, for example, an oxide, a hydroxide, an oxyhydroxide, a halide, a nitrate, a carbonate, an acetate, an oxalate, a citrate, or a sulfate, and the like, all containing cobalt, more specifically Co(OH)2, Co3O4, CoOOH, Co(OCOCH3)2·4H2O, 25 Co(NO3)2·6H2O, or CoSO4·7H2O, and the like, and any one 25 thereof or a mixture of two or more thereof may be used. The second cobalt raw material may be the same as the first cobalt raw material, or may be different therefrom. [0078] Meanwhile, in the present step, a second lithium raw 5 material may be further mixed, if necessary. When the second cobalt raw material and the second lithium raw material are used together, the second cobalt raw material and the second lithium raw material may be mixed in an amount such that the atomic ratio of Li/(Co+M) of the shell portion is 0.5 0 to 10 less than 1, preferably 0.55 to less than 1, more preferably 0.90 to 0.99. [0079] The second lithium raw material may be, for example, an oxide, a hydroxide, an oxyhydroxide, a halide, a nitrate, a carbonate, an acetate, an oxalate, a citrate, or a sulfate, 15 and the like, all containing lithium, more specifically Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, Li2O, Li2SO4, CH3COOLi, or Li3C6H6O7, and the like, all containing lithium, and any one thereof or a mixture of two or more thereof may be used. The second lithium raw material 20 may be the same as the first lithium raw material, or may be different therefrom. [0080] Meanwhile, the second cobalt raw material and the second lithium raw material may be introduced together at once, or may be introduced separately such that the Li/(Co+M) 25 ratio is decreased over time. In the latter case, a shell 26 portion having a concentration gradient in which the concentration of lithium decreases from the center of the shell portion to the surface thereof may be formed. [0081] Meanwhile, the second heat treatment may be performed 5 in a temperature range of at 500℃ to 1050℃, preferably 750°C to 1000°C. When the second heat treatment temperature satisfies the above range, the lithium cobalt-based oxide of the shell portion may be formed to have a spinel-like structure. Specifically, when the second heat treatment 10 temperature is less than 500℃, crystallization is not sufficiently achieved, so that the effect of improving the mobility of lithium ions may be insignificant. When the second heat treatment temperature is greater than 1050℃, crystallization may be excessively achieved or Li is 15 evaporated to formed an unstable structure. [0082] The second heat treatment may be performed in the atmosphere or in an oxygen atmosphere, and the second heat treatment may be performed for 5-25 hours, preferably 8-18 hours, preferably 8-12 hours. When the duration of the 20 second heat treatment satisfies the above range, a stable spinel-like crystal structure may be formed in the shell portion. [0083] Through the process as described above, the shell portion including the lithium cobalt-based oxide represented 25 by Formula 2 is formed. The detailed description of the 27 lithium cobalt-based oxide represented by Formula 2 is the same as described above, and thus, a detailed description thereof will be omitted. 5 [0084] A positive electrode active material according to the present invention prepared as described above has a core portion including a doping element in a high concentration, thereby having excellent structural stability. Accordingly, even though a shell portion with a lithium defect is present, 10 a phase transition to a monoclinic system does not appear during charging/discharging, and even during a high-voltage driving of 4.45 V or greater, the generation of gas and cobalt elution are suppressed. Also, since the shell portion of the lithium defect having a three-dimensional structure is 15 included, the lithium ion moving speed is fast, so that excellent electrical properties may be exhibited. [0085] Positive electrode and lithium secondary battery [0086] Next, a positive electrode according to the present 20 invention will be described. [0087] The positive electrode active material according to the present invention may be usefully used for manufacturing a positive electrode for a secondary battery. [0088] Specifically, a positive electrode for a secondary 25 battery according to the present invention includes a 28 positive electrode current collector, and a positive electrode active material layer formed on the positive electrode current collector. At this time, the positive electrode active material layer includes the positive 5 electrode active material according to the present invention. [0089] The positive electrode may be manufactured according to a typical manufacturing method of a positive electrode except that the positive electrode active material according 10 to the present invention is used. For example, the positive electrode may be manufactured by manufacturing a positive electrode mixture by dissolving or dispersing components constituting a positive electrode active material layer, which are a positive electrode active material, a conductive 15 material and/or a binder, in a solvent, applying the mixture on at least one surface of a positive electrode current collector, followed by drying and then roll-pressing. Alternatively, the positive electrode may be manufactured by casting the positive electrode mixture on a separate support, 20 and then laminating a film peeled off from the support on the positive electrode current collector. [0090] At this time, the positive electrode current collector is not particularly limited as long as it has conductivity without causing a chemical change in a battery. 25 For example, stainless steel, aluminum, nickel, titanium, 29 fired carbon, or aluminum or stainless steel that is surfacetreated with one of carbon, nickel, titanium, silver, and the like may be used. Also, the positive electrode current collector may typically have a thickness of 3 μm to 500 μm, 5 and microscopic irregularities may be formed on the surface of the positive electrode current collector to improve the adhesion of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a 10 porous body, a foamed body, a non-woven body, and the like. [0091] On at least one surface of the current collector, a positive electrode active material layer including the positive electrode active material according to the present invention, and when necessary, further including at least one 15 of a conductive material or a binder optionally is disposed. [0092] At this time, the positive electrode active material is the positive electrode active material according to the present invention, and may be included in an amount of 80-99 wt%, more specifically 85-98 wt% based on the total weight of 20 the positive electrode active material layer. When included in the above content range, excellent capacity properties may be exhibited. [0093] The conductive material is used to impart conductivity to an electrode, and any conductive material may 25 be used without particular limitation as long as it has 30 electronic conductivity without causing a chemical change in a battery to be constituted. Specific examples of the conductive material may include graphite such as natural graphite or artificial graphite; a carbon-based material such 5 as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; a conductive whisker such as a zinc oxide whisker and a potassium titanate whisker; a conductive metal oxide 10 such as titanium oxide; or a conductive polymer such as a polyphenylene derivative, and any one thereof or a mixture of two or more thereof may be used. The conductive material may be included in an amount of 1 wt% to 30 wt% based on the total weight of the positive electrode active material layer. 15 [0094] Also, the binder serves to improve the bonding between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples of the binder may include polyvinylidene fluoride (PVDF), a polyvinylidene 20 fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, an ethylene-propylene-diene monomer (EPDM), a 25 sulfonated EPDM, styrene-butadiene rubber (SBR), fluorine 31 rubber, or various copolymers thereof, and any one thereof or a mixture of two or more thereof may be used. The binder may be included in an amount of 1 wt% to 30 wt% based on the total weight of the positive electrode active material layer. 5 [0095] Meanwhile, the solvent used for preparing the positive electrode mixture may be a solvent commonly used in the art. For example, dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, and the like may be used alone, or a mixture thereof may be used. The 10 amount of the solvent to be used may be appropriately adjusted in consideration of the applying thickness, preparation yield, viscosity, and the like of a slurry. [0096] Next, a secondary battery according to the present 15 invention will be described. [0097] The secondary battery according to the present invention includes a positive electrode, a negative electrode disposed to face the positive electrode, a separator interposed between the positive electrode and the negative 20 electrode, and an electrolyte. At this time, the positive electrode is the positive electrode according to the present invention described above. [0098] Meanwhile, the secondary battery may further include a battery case for accommodating an electrode assembly 25 composed of the positive electrode, the negative electrode, 32 and the separator, and a sealing member for sealing the battery case, optionally. [0099] In the secondary battery, the negative electrode includes a negative electrode current collector and a 5 negative electrode active material layer disposed on at least one surface of the negative electrode current collector. [00100] The negative electrode may be manufactured according to a typical manufacturing method of a negative electrode known in the art. For example, the negative electrode may be 10 manufactured by manufacturing a negative electrode mixture by dissolving or dispersing components constituting a negative electrode active material layer, which are a negative electrode active material, a conductive material and/or a binder, in a solvent, applying the mixture on at least one 15 surface of a negative electrode current collector, followed by drying and then roll-pressing. [00101] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing a chemical change in a battery. For example, 20 copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel that is surface-treated with one of carbon, nickel, titanium, silver, and the like, an aluminum-cadmium alloy, and the like may be used. Also, the negative electrode collector may typically have a 25 thickness of 3 μm to 500 μm, and as in the case of the 33 positive electrode current collector, microscopic irregularities may be formed on a surface of the negative electrode current collector to improve the adhesion of a negative electrode active material. For example, the negative 5 electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foamed body, a non-woven body, and the like. [00102] As the negative electrode active material, a compound capable of reversible intercalation and de-intercalation of 10 lithium may be used. Specific examples thereof may include a carbonaceous material such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; a (semi)metal-based material alloyable with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, a Si alloy, a Sn alloy, 15 or an Al alloy; a metal oxide which may be doped and undoped with lithium such as SiOv(0