The present invention relates to a precursor for preparation of a lithium composite transition metal oxide, a method for preparing the same and a lithium composite transition metal oxide obtained fi·om the same. More patticularly, the present 10 invention relates to a transition metal precursor which has a specific composition and is prepared in an aqueous transition metal solution, mixed with a transition metalcontaining salt, including an alkaline material, a method for preparing the same and a lithium composite transition metal oxide obtained fi·om the same. 15 [BACKGROUND ART] As mobile device technology continues to develop and demand therefor continues to increase, demand for secondary batteries as energy sources is rapidly increasing. Among these secondary batteries, much research has focused on lithium -1- secondary batteries having high energy density and discharge voltage. Such batteries are commercially available and widely used. Generally, as cathode active materials for lithium secondary batteries, lithiumcontaining cobalt oxides such as LiCo02 are mainly used. In addition thereto, use of 5 lithium-containing manganese oxides such as LiMn02 having a layered crystal structure, LiMn204 having a spinel crystal structure, and the like and lithium-containing nickel oxides such as LiNi02 is also under consideration. Among cathode active materials, LiCo02 is widely used due to excellent overall physical properties such as excellent cycle properties, and the like. However, 10 LiCo02 is low in safety and expensive due to resource limitations of cobalt as a raw 15 material. Lithium nickel based oxides such as LiNi02 are cheaper than LiCo02 and exhibit high discharge capacity when charged to a voltage of 4.25 V. However, the lithium nickel based oxides have problems such as high production costs, swelling due to gas generation in batteries, low chemical stability, high pH and the like. In addition, lithium manganese oxides, such as LiMn02, LiMn204, and the like, are advantageous in that they contain Mn, which is an abundant and environmentally friendly raw material, and thus are drawing much attention as a cathode active material that can replace LiCo02. In particular, among the lithium manganese oxides, LiMn20 4 has advantages such as a relatively cheap price, high output and the like. On the other -2- hand, LiMn204 has lower energy density, when compared with LiCo02 and three component-based active materials. To overcome these drawbacks, a variety of materials have been developed. Especially, layered structure transition metal oxides such as LiNil/3Mnl/3Col/302, S LiNio.sMno.3Coo.202 and the like including two or more materials of Ni, Mn and Co have been highlighted. However, these materials do not satisfY requirements of medium and large batteries such as those used in electric vehicles, systems for storing power and the like. Accordingly, study into Mn-enriched (l-x)LiMOrxLhM03 based materials 10 stable under high voltage is being conducted. However, the Mn-emiched (l-x)LiM02- xLhM03 based materials include a large amount of Mn and thereby are easily oxidized 15 by dissolved oxygen inside an aqueous transition metal solution during synthesis of a transition metal precursor through a co-precipitation method, and, accordingly, synthesis is not easy. To compensate for this problem, methods such as surface treatment, formation of a core-shell structure and substitution with hetero elements and the like have been tried. However, the methods also are not suitable for easy synthesis. In addition, there are still problems such as additional costs during processes, deterioration of precursor tap density and the like. -3- As described above, a precursor for preparation of a lithium composite transition metal oxide having satisfactory performance and a lithium composite transition metal oxide obtained from the same has yet to be developed. [DISCLOSURE] 5 [TECHNICAL PROBLEM] The present invention aims to address the aforementioned problems of the related art and to achieve teclmical goals that have long been sought. As a result of a variety of extensive and intensive studies and experiments, the inventors of the present invention developed a transition metal precursor having a 10 specific composition resulting in improvements in crystallizability, spheroidization degree of a pulvemlent body and tap density, and confirmed that, when a lithium composite transition metal oxide prepared using the transition metal precursor was used as a cathode active material, an electrode preparation process is easy and electrochemical characteristics of a secondary batte1y based on the lithium composite 15 transition metal oxide are improved, thus completing the present invention. [TECHNICAL SOLUTION] In accordance with one aspect of the present invention, provided is a transition metal precursor, having a composition represented by Formula I below, prepared in an -4- aqueous transition metal solution mixed with a transition metal-containing salt and including an alkaline material: wherein M is at least one selected form the group consisting of Ni, Ti, Co, AI, 5 Cu, Fe, Mg, B, Cr, Zr, Zn and Period 0 transition metals; A is at least one selected form the group consisting of anions of P04, B03, 0.5:SU:Sl.O; 0:Sb:S0.5; a+ b =I; O After filling a 4 L wet reactor tank with 3 L of distilled water, nitrogen gas was continuously added to the tank at a rate of 2 Llmin to remove dissolved oxygen. Here, the temperature of distilled water in the tank was maintained ·at SOD using a temperature -20- maintenance device. In addition, the distilled water in the tank was stirred at 1000 to 1500 rpm using an impeller connected to a motor installed outside the tank. Manganese sulfate, nickel sulfate, and cobalt sulfate were mixed in a molar ratio of 0.50: 0.45: 0.05 to prepare a 1.5 M aqueous transition metal solution. 5 Subsequently, to substitute anion sites, 0.5 mol% of phosphate and 4.0 mol% of sucrose which provide P04 anions were mixed therewith. Separately, a 3 M aqueous sodium hydroxide solution was prepared. The aqueous transition metal solution was continuously pumped into the wet reactor tank, using a metering pump, at a rate of 0.18 L!lu·. The aqueous sodium hydroxide solution was pumped in a rate-variable manner by 10 a control unit for adjusting a pH of the distilled water in the tank such that the distilled water in the wet reactor tank was maintained at a pH of 11.5. In this regard, a 14% ammonia solution as an additive was continuously co-pumped to the reactor at a rate of 0.04 L!lu·. Flow rates of the aqueous transition metal solution, the aqueous sodium 15 hydroxide solution and the aqueous all11l1onia solution were adjusted such that an average residence time of the solutions in the wet reactor tank was approximately 6 hours. After the reaction in the tank reached a steady state, a certain duration of time was given to synthesize a composite transition metal precursor with a higher density. -21- After reaching the steady state, the manganese-nickel composite transition metal precursor, which was prepared by 20-hour continuous reaction of transition metal ions of the aqueous transition metal solution, hydroxide ions of the sodium hydroxide and anm10nia ions of the ammonia solution, was continuously obtained through an 5 overflow pipe installed on the top side of the tank. 10 15 The resulting composite transition metal precursor was washed several times with distilled water and dried in a 120 oc constant-temperature drying oven for 24 hours to obtain a manganese-nickel composite transition metal precursor. A transition metal precursor was prepared in the same manner as in Example 1, except that sucrose was not mixed with the aqueous transition metal solution. A transition metal precursor was prepared in the same manner as in Example 1, except that phosphate was not mixed with the aqueous transition metal solution. A transition metal precursor was prepared in the same manner as in Example 1, except that sucrose and phosphate were not mixed with the aqueous transition metal solution. -22- 5 SEM images of the transition metal precursors prepared according to Examples 1 and 2, and Comparative Examples 1 and 2, respectively, captured using FE-SEM (model S-4800 available from Hitachi), are illustrated in FIGS. 1 to 4. Referring to FIGS. 1 to 4, it can be confirmed that the transition metal precursor of Example 1 using 2mol% of sucrose exhibited stronger cohesive strength of primary patiicles than that of the precursor of Comparative Example 1 and thus pmiicles of the precursor of Example I had a more spherical shape Referring to FIG. I to FIG. 4, it was confirmed that the precursor prepared 10 according to Example I, which uses sucrose and anion sites of which were substituted with P04, has many pores, a wide specific surface area and a uniform diameter, when compared with the precursors prepared according to Comparative Examples I and 2. In addition, it was confirmed that, in the precursor prepared according to Example 1, pnmary pmiicles exhibited improved cohesive force and thereby particle 15 crystallizability and pmiicle spheroidization degree were improved. Furthermore, it was confirmed that, although sucrose was not used, the precursor prepared according to Example 2, anion sites of which were substituted with P04, exhibited improved particle crystallizability and pmiicle spheroidization degree, when compared with the precursors prepared according to Comparative Examples 1 and 2. -23- The tap densities of the precursors prepared according to Examples I and 2, and Comparative Examples I and 2, respectively, were measured and summarized in Table 1 below. 5 [Table 1] Tap density (glee) Example 1 1.54 Example2 0.95 Comparative 0.55 Example 1 Comparative 0.80 Example2 As shown in Table 1, it can be confirmed that the precursors prepared according to Examples 1 and 2, anion sites of which were substituted, exhibit improved tap densities, when compared with the precursorsprepared according to Comparative Examples 1 and 2, anion sites of which were not substituted. Such a result is caused by 10 easy precipitation of the transition metal hydroxide due to anion sites substituted with P04 and thereby improved crystallizability and cohesive force of the primary particles. Manufacture of coin cell -24- Each of the manganese-nickel-cobalt composite transition metal precursors prepared according to Examples I and 2, and Comparative Examples I and 2 was mixed with LhC03 in accordance with the molar ratio of each composition and then sintered at 900 to 950 oc for 5 to I 0 hours by heating at a heating rate of 3 to 5 °C/min to prepare a 5 cathode active material powder. The prepared cathode active material powder, Denka as a conductive material, and KF! I 00 as a binder were mixed in a weight ratio of 95:2.5:2.5 to prepare a slurry. The slurry was uniformly coated on AI foil having a thickness of20 f.!m. The coated AI foil was dried at 130 °C, thereby completing fabrication of a cathode for a lithium 10 secondary battery. The fabricated cathode for a lithium secondary battery, lithium metal foil as a counter electrode (i.e., an anode), a polyethylene membrane as a separator (Celgard, thickness: 20 f.!m), and a liquid electrolyte containing I M LiPF6 dissolved in a mixed solvent of ethylene carbonate, dimethylene carbonate, and diethyl carbonate in a volume 15 ratio of I :2:1 were used to manufacture a 2016 coin cell. Initial charge and discharge characteristics Electrical characteristics of the cathode active material of each of coin cells manufactured according to Examples 3 and 4, and Comparative Examples 3 and 4 were -25- evaluated at 3.0 to 4.4 V using an electrochemical analyzer (Toscat 3100U available from Toyo Systems). To evaluate performance of each coin cell, charge and discharge capacity of each coin cell was measured at a current of 1 C and at a voltage range of 3.0 to 4.4 V. 5 Results of discharge capacities and charge and discharge efficiencies of the coin cells are summarized in Table 2 below. [Table 2] Initial discharge Initial charge and Initial charge Samples capacity discharge efficiency capacity (mAh/g) (%) (mAhlg) Example 3 185 172 93 Example4 183 169 92 Comparative Example3 169 153 90 Comparative 162 90 180 Example4 As shown in Table 2, it can be confirmed that the precursors prepared according to Examples 1 and 2, anion sites of which were substituted, have superior 10 initial charge and discharge capacity and efficiency, when compared with the precursors prepared according to Comparative Examples 1 and 2, anion sites of which were not substituted. -26- Lifespan characteristics Each of com cells manufactured according to Examples 3 and 4, and Comparative Examples 3 and 4 was charged and discharged thirty times at a current of 5 0.5 C to evaluate lifespan characteristics. Results are summarized in Table 3 below. [Table 3] Lifespan characteristics 301hll st discharge capacity (%) Example} 97.0 Example4 92.0 Comparative 92.2 Example 3 Comparative 96.0 Example4 As shown in Table 3, it can be confirmed that the precursor prepared according to Example 1, which uses sucrose and anion sites of which were substituted with P04, exhibits lifespan characteristics of 97%, which is the highest value. 10 Output characteristics -27- To evaluate output characteristics, each of coin cells manufactured according to Examples 3 and 4, and Comparative Examples 3 and 4 was charged and discharged at a current of 0.5 C and then discharged at a current of 1.0 C and 2.0 C. Results are summarized in Table4 below. 5 [Table 4] 0.1 c discharge 2 c discharge Output characteristics capacity capacity 0.1 C/2.0 C (%) (mAhlg) (mAh/g) Example 3 172 146 85 Example4 172 136 79 Comparative 155 121 78 Example} Comparative 166 112 67 Example4 As shown in Table 4, it can be confirmed that the precursors prepared according to Examples 1 and 2, anion sites of which were substituted, exhibit improved output characteristics when compared with the precursors prepared according to Comparative Examples 1 and 2, anion sites of which were not substituted. 10 Those skilled in the mt will appreciate that various modifications, additions and substitutions are possible, wit)10ut departing from the scope and spirit of the invention as disclosed in the accompanying claims. -28- [INDUSTRIAL APPLICABILITY] As described above, a transition metal precursor for preparing a lithium composite transition metal oxide according to the present invention is prepared in a state including a reducing agent to prevent oxidation of Mn and, as such, a precursor having a 5 larger specific surface area and a uniform diameter may be synthesized. At the same time, by substituting anion sites, precipitation suppression due to addition of a reducing agent may be solved and, as such, the crystallizability, spheroidization degree and tap density of the precursor may be improved. In addition, when a lithium composite transition metal oxide prepared using the 1 0 precursor is used as a cathode active material, an electrode process becomes easy and a secondary battery based on the lithium composite transition metal oxide may exhibit 15 excellent initial discharge capacity and efficiency, and improved output characteristics and lifespan characteristics. [CLAIMS] [Claim 1] A transition metal precursor having a composition represented by Formula I below and parepared in an aqueous transition metal solution, mixed with a transition metal-containing salt, comprising an alkaline material: (I) wherein M is at least one selected form the group consisting of Ni, Ti, Co, AI, Cu, Fe, Mg, B, Cr, Zr, Zn and Period II transition metals; A is at least one selected form the group consisting of anions of P04, B03, O.S:sa:Sl.O; O:Sb:SO.S; a+b=I; O