TRANSITION METAL PRECURSOR HAVING LOW TAP DENSITY AND LITHIUM TRANSITION METAL OXIDE HAVING HIGH PARTICLE STRENGTH 5 [TECHNICAL FIELD] The present invention relates to a repeatedly chargeable and dischargeable lithium secondary battery. More palticularly, the present in\~entionr elates to a lithiu~n transition metal oxide used as a positive electrode active material of lithiu~ns econdary batteries and a transition rnetal precursor for preparation of a lithium transition metal 10 oxide. 111 line with develop~nent of inforlnation technology (IT), various pol-table infornlation and communication devices have entered widespread use and thus the 21'' century is developing into a "ubiquitous society" where high quality information 15 services are available regardless of time and place. Lithium secondary batteries play a key role in such development towards the ubiquitous society. Lithium secondary batteries have higher operating voltage and energy density, are used for a longer period of time than other secondary batteries and, thus, can satisfy sopl~isticated requirelllents according to diversification and increasing complexity of devices. Recently, much effort globally has been put into expanding applications to 5 eco-friendly transportation systems such as electric veliicles and the like, power storage, and the like through further advancelllent of conventional litl~iums econdary batteries. As use of lithium secondary batteries is expanding to niiddle and large-scale devices, demand for litliiuni secondary batteries having larger capacity, higher output and liiglier safety characteristics than conr~entional lithiun~ secondary batteries is 10 increasing. First, to obtain larger capacity, capacity per unit weight or unit volume of an active material must be high. Secondly, tap density of an active material IIILIS~b e high. Packing density of an electrode may increase with increasing tap density. In particular, to manufacture an 15 electrode, an active material is mixed with a binder or a conductive material and then coated on a c u ~ ~ ecnotl lector to form a thin film, and the electrode is hardencd by applying pressure thereto. In this regard, \vlic~i the active material is not satisfactorily filled, the electrode cannot be thinly manufactured and the volume thereof is large and, tht~sl,a rger capacity cannot be realized under given volume conditions of batteries. Thirdly, a specific surface area of an active material Intist be small. When the specific surface area of the active material is large, a liquid phase is present on a surface of the active material. Accordingl~~w,h en tlie active material is coated on a cui~ent collector, a ratio of the liquid phase to the active material is high and, even after 5 manufacturing an electrode, many surfaces exist between particles. Accordingly, electric flow is hindered and a large amount of binder for adhesion is required. Therefore, to reduce resistance of an electrode and enhance adhesion, a larger amount of a conductive material and a binder must be added and, as such, the amount of an active nlaterial decreases. Accordingly, larger capacity may not be obtained under limited 10 volume conditions. There is a tendency that the tap density of an active material increases with increasing precursor tap density. Therefore, tecl~nologies of tlie art are generally developed towards increase in tap density of the precursor. Tap density of a precursor is proportional to an average particle diamctcr of particles constituting the precursor. [TECHNICAL PROBLEM] However, apart fsom teclinologies for increasing tap density of an active material, pasticles constituting an active nlaterial are broken or crushed in a slurry preparation process and a rolling process \&en manufacturing an electrode. Surfaces, which are not stabilized through heat treatment, of the broken or crushcd particles side react with an electrolyte and, as such, forms films having high resistance. In addition, by-products formed by continuous reaction with the electrolyte are deposited at a negative electrode and, as such, perfomlance of the negative electrode 5 is dcteriorated . In addition, the elcctrol~.tei s continuously consumed and, thus, swelling occurs due to generation of gases. The inventors of the present illvention aim to address the aforcmetltioned proble~ns of the related art by using a transition metal precursor in wliich a ratio of tap 10 density to average particle diameter D50 of the precursor satisfies the condition represented by Eq~ration 1 below. In accordance \vitl~ one aspect of the present invention, provided is a tralisition lnetal precursor for preparation of a lithium trausition nletal oxide, in which the ratio of tap density to average particle diameter D50 of the precursor satisfies the 15 condition represented by Equation I below: Tap density O < Average particle diameter D50 of transition metal precursor < 3500 (g/cc. cm) (1). 111 Equation 1 above, the tap density indicates a bulk dc~lsity of a powder obtained by vibrating a container under a constant conditions when filled with the powder, aud the average particle dia~ncter D50 of the transitio~i tnetal precursor indicates a particle diameter corresponding to 50% of passed mass perceritage in a grain size accutn~~latioctuir ve. The ratio of tap density to average particle diameter D50 of the transition metal precursor may be 500:l to 3500:1, 1000:l to 3500:1, 1500:l to 3500:1, or 2000:l 5 to 3500: 1. The transition nletal precursor is a powder of an aggregate of particles (hereinafter, referred to as precursor particles) constituting the transition metal precursor. Similarly, a lithium composite transition metal oxide described below is a powder of an aggregate of particles (hereinafter, referred to as oxide particles) corlstitutit~gth e lithium 10 composition transition ~netaol xide. The transition lnetal precursor may be co~nposed of one kind of transition nletal or include hvo or lnore kinds of transition metals. The two or more kinds of transition metals may be at least two selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), aluminum (Al), copper (Cu), iron (Fe), niagnesium (Mg), 15 boron (B), chomi~ui(iC r), and period 2 transition metals. The transition nletal precursor particles may be transition tnetal oxide particles, transition metal sulfide particles, tra~isition metal nitride particles, transition metal pliosphide particles, transition metal liydroxide particles, or the like. In particular, the transition metal precursor particles niay be transition metal hydroxide particles, more particularly a co~npouudre presented by Fortnnla 2 below: wherein M represents at least two selected fro~nth e group consisting of Ni, Co, Mn, Al, Cu, Fe, Mg, B, Cr, and period 2 transition nletals; and 05~50.5.In this 5 regard, M may include two transition metals selected fiotii the g r o ~ ~cop~ lsistingo f Ni, Co, and Mn or all thereof. The average particle diameter D50 of the transition metal precursor tilay be 1 Llm to 30 pm. The present invention provides a litliiutn transition nletal oxide prepared by 10 mixing the transition metal precursor and a lithium precursor atid sintering the mixture. A lithium transition metal oside including at least two kinds of transition metals may be defined as a litliium composite transition metal oxide. In this regard, a ratio of an average pai-ticle diameter D50 of lithium transition tnetal oside to an average particle diatneter D50 of transition rnetal precursor 15 for preparation of the lithium transition tnetal oxide may satisfy the condition rcpresented by Equation 3 below: The oxide particles cotlstituting the lithium composite transition nletal oxide may be a cotnpour~dr epresented by For~nula4 below: M is at least one metal cation selected froni the group consisting of Al, Cu, 5 Fe, Mg, B, Cr, and period 2 tratlsitioti metals; and A is at least one tnonovalelit or divalent anion. In addition, the litltium coniposite tratlsitioli metal oxide particles may be tlie co~~ipoutoidf Forlliula 4 \vllelere x>y and x>z. Tlie litliiu~ltlr ansition liietal oxide may be composed of one kitid of transition 10 metal or include t\vo or more kinds of transition metals. The two or more kitids of transition tlietals may be at least two selected fro111 the group coltsisting of Ni, Co, Mn, Al, Cu, Fe, Mg, B, Cr, and period 2 transition metals. The present invention also provides a litllium secondary battery in \vliich a unit cell including a positive electrode iticluding the lithium transition ~ttetal oxide 15 described above, a negative electrode, and a polytller membrane disposed between the positivc elcctrodc and tlie negative electrode is accommodated in a battery case. Tlte litltium secotidary battery may be a lithium ion battery, a lithium ion polyttler battery, or a lithium polyner battery. A positive electrode active tnaterial according to the present invention may further include other lithium-containing transition metal oxides in addition to the litliiuln transition metal oxide described above. Exa~l~ploefs other lithium-containing transitioi~n letal oxides include, but are 5 not linlited to, layered co~npoundss uch as lithium cobalt oxide (LiCo02) and lithiunl nickel oxide (LiNiOz), or conlpounds substituted \vith one or Inore transition metals; lithium manganese oxides such as compounds of For~llulaL il+,.Mn2,,04 wliere 011r0.33, T'iMn03, LiMn203, and T,iMtiOz; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV308, LiV304, V205, and Cu12V207; Ni-site type lithium nickel oxides having 10 the foilllula LiNi,,.M,.02 where M=Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and 0.015y50.3; lithiun~ln anganese comnposite oxides having the forli~ulaL iMn2.,.My02w here M=Co, Ni, Fe, Cr, Zn, or ?'a, and 0.015~~50o.1r the formula Li2Mn3MOs where M=Fe, Co, Ni, Cu, or Zn; LiMn2Ol where sorile of the Li atoms are substituted xvitlith alkaline earth metal ions; disulfide compounds; and Fe2(M004)~. 15 T11c positive electrode may be available from coating, on a positive electrode current collector, a slurry prepared by nlixing a positive electrode mixture including the positive electrode active material and a solvent such as NMP or the like and drying and rolling the coated positive electrode current collector. The positive electrode mixture nlay sclcctivcly include a conductive material, a binder, a filler, and the like, in addition to the positive electrode active material. The positive electrode current collector is generally manufactured to a thickness of 3 to 500 kum. The positive electrode curpent collector is not particularly limited so long as it does not cause chemical changes in the manufactured battery and 5 has high conductivity. For example, the positive electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper, or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, aluminum-cadmium alloys, or the like. The positive electrode current collector may have fine irregularities at a surface thereof to increase adhesion between the positive 10 electrode active material and the positive electrode current collector. In addition, the positive electrode cul~enct ollector may be used in any of various forn~isn cluding films, sheets, foils, nets, porous structures, foatns, and non-woven fabrics. The conductive material is typically added in an amount of 1 to 30 wt% based on the total weight of a mixture including a positive electrode active material. 15 'rllcre is no particular limit as to the conductive inaterial, so long as it does not cause chcnlical changes in the nmarlufactured battery and bas conductivity. Examples of conductive materials include graphite such as natural or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furllace black, lamp black, and thermal black; conductive fibers such as carbon fibers and nletallic fibers; tuetallic powders such as carbon fluoride powder, alumin~utnp owder, and nickel powder; conductive \vliiskers such as zinc oxide and potassi~unti tanatc; conductive metal oxides such as titanium oxide; and polyplienylene derivatives. The binder is a co~llponent assisting in binding between an active material 5 and a conductive material and in binding of the active material to a current collector. The binder may be added in an atno~unot f 1 wt% to 30 wt% based on the total weight of a ~nixturein cluding a positive electrode active material. Non-limiting exan~pleso f the binder include polyvinylidene fluoride, polyvitlyl alcohols, carboxymetl~ylcellulose (CMC), starcli, l~ydroxypropylcellulose, regenerated cellulose, polyvinyl pyrrolidone, 10 tetrafluoroetl~ylene,p olyctl~~~lepnoel,y propylene, etl~ylene-propylene-dienet erpolymer (EPDM), sulfonated EPDM, styrene butadienc rubber, fluorine rubber, and various The filler is used as a co~nponento inhibit positive electrode expansion. The filler is not particularly limited so long as it is a fibrous material that does not cause 15 chemical changes in the manufactured battery. Examples of the filler includc olefinbased polynlers such as polyetliylene and polypropylene; and fibrous nlaterials such as glass fiber and carbon fiber. As a dispersion solution, isopropyl alcohol, N-~netl~ylpyrrolido~(lNeM P), acetone, or the like tnay be used. A method of ~unifornllyc oating a metal inaterial xvith a paste of an electrode material may be selected fi.0111 aniong lu101\711 methods or an appropriate new method in consideration of properties and the like of materials. For example, a paste may be applied to a current collector and then unifornlly dispersed thereon using a doctor blade 5 or the like. In sonie cases, the application and dispersing processes nlap be simultaneously perforlned as a single process. In addition, die casting, colunla coating, screen-printing, or tlie like nlay be used. In another embodiment, a paste of an electrode matcrial may be ~noldedo n a separate substrate and the adhered to a current collector by pressing or lamination. 10 The paste coated on the nletal plate is preferably dried in a vacuum oven at 50°C to 200°C for one day. Tile negative electrode lilay be available from, for exa~llple, coating a negative electrode active inaterial on a negative electrode current collector and drying the coated negative clcctrode current collector. As desired, as described above, 15 components such as a conductive inaterial, a binder, a filler, and tlie like may be selectively further added to the negative electrode active nmaterial. Tlie negative electrode current collector is typically manufactured to a thickness of 3 to 500 ym. The negative electrode current collector is not particillarly limited so long as it does not cause che~~~icchaanl ges in tlie inanufactilred battery and has conductivity. For example, the negative electrode current collector may be made of copper, stainless steel, aluminum, nickel, titanium, sintered carbon, copper, or stainless steel surface-treated ~vith carbon, nickel, titanium, silver, or the like, aluminumcadmiuln alloys, or the like. As in the positive electrode current collector, the negative 5 electrode current collector may have fine inegularities at a surface thereof to enhance adhesion between the negative electrode current collector and the negative electrode active material. In addition, the negative electrode current collector may be used in various forms including films, sheets, foils, nets, porous structures, foams, and nonwoven fabrics. 10 Exanlples of the negative electrode active material include, but are not limited to, carbon such as hard carbon and graphite-based carbon; metal composite oxides such as LisFc203 where 05x51, Li,W02 where 0x51, Sn,Mel,R4e',,0, where Me: Mn, Fe, Pb, or Ge; Me': Al, B, P, Si, Group 1, Group I1 and Gronp 111 elements, or halogens; O A transition metal precursor was prepared in thc satne manner as in Comnparative Exanlple 1, except that, during reaction, the atnnlonia solution as an 15 additive was not continuously supplied. 50 g of each of the transition nletal precursor prepared according to xvach of Exa~nplcs 1 to 3 and Co~nparativeE xamples 1 and 2 \vas added to a 100 cc cylinder for tapping using a KYT-4000 lncasuri~lgd evice (available from SEISHIN) and thcn was tapped 3000 times. In addition, powder distribution bascd on volume was obtained using S-3500 (available from Microtrac), D50 values were measured, and tap density 5 wit11 respect to D50 was calculated. Results are sl~o\\ln in Table 1 below. [Table 11 As shown in Table 1 above, it can be confir~tled that the transition inetal precursors according to the present invention (Examples 1 to 3) have a low ratio of tap density to D50, namely, 3500 or less, while the transition nletal precursors of 10 Conlparative Exa~nples1 and 2 have a liigli ratio of tap density to D50, na~nely3, 500 or 111orc. Exa~ilple 1 Exanlplc 2 Exa~nple3 Co~nparative Example 1 Comparative Example 2 Each of the transition metal precursors ol Examples 1 to 3 and Comparative Tap density (glcc) 1.42 1.52 1.60 1.99 1.81 D50 (p~n) 5.62 5.66 5.70 5.48 5.13 Tap densityID50 (g/cc.cm) 2527 2686 2807 363 1 3528 Examples 1 and 2 was mixed with Li2C03 SO that a molar ratio of Li to Ni+Co+Mn was 1 .I 0 and the nlixtt~rew as heated at a heating rate of 5 "C/nlin and calcined at 950°C for 10 hours, to prepare a lithium transition metal oxide powder as a positive electrode active material. 5 D50 corresponding to powder distribution based on volume of each of the prepared positive electrode active material powders was meastired using S-3500 (available from Microtrac) and each positive elcctrode active inaterial powder was subjected to ultraso~lic dispersion for 60 seconds. Subsequently, D50 corresponding to powder distribution based on volume thereof was measured again. Subsequently, 10 changes in particle sizes before and after pulverization follo~vingth e two processes were calculated. and results are summarized in Table 2 below. As shown in Table 2 above, it can be confit.med that, in the same transition D50 of active material/ D5O of precursor (changes in particle sizes before and after calcination 0.996 1.005 1.032 1.204 1.230 Exanlple 1 Example 2 Example 3 Comparative Exarllple 1 Comparative Example 2 D50 (pn) of precursor 5.62 5.66 5.70 5.48 5.13 D50 (pm) of active n~aterial 5.65 5.64 5.68 6.60 6.31 nletal composition, the lithium transition metal oxides prepared fro111 the transition metal precursors according to the present invention (Examples 1 to 3) have s~llall changes in particle sizes before and after calcination, nameljr, 1.2 or less, while the lithium transition metal oxides prepared fiom the transition tnetal precursors of 5 Conlparative Examples 1 and 2 have large changes in particle sizes before and after calcination, namely, 1.2 or more. 10 g of the positive electrode active material powder using each of the 10 transition tnetal precursors of Examples 1 to 3 and Conlparative Examples 1 and 2 was added to a PDM-300 paste mixer, alumina beads with a dia~netero f 5 mnl u7cre added thereto, and each positive electrode active material powder was pulverized using a ball ~rtill under a condition of 600 x 600 based on revolutions (rpm) per minute (rpnl) x revolutions per nlinute (rpm). The pulverized active material powder was subjected to 15 ultrasonic dispersion for 60 seconds using S-3500 available from Microtrac and then 050 corresponding to powder distribution based on volume thereof was measured again. Subsequently, changes in particle sizes before and after pulverization following the two processes were calculated, and results are summarized in Table 3 below. [Table 31 D50 (pin) before pulverization I I I D50 (~unl)a fter pulverization Example 1 I 5.65 I I I D50 after pulverization/D50 before pulverization Exarnple 2 Comparative Example 1 As shown in Table 3 above, it can be confirmed that, in the same transition 5.05 Comparative Exarnple 2 metal conlposition, the lithium transition metal oxides prepared from the transition 0.895 5.64 6.60 metal precursors according to the present invention (Examples 1 to 3) exhibit small 6.3 1 5 changes in particle sizes during pulverization and, thus, the positive electrode active 5.00 4.04 nlaterials exhibit high strengtl~. On the contrary, the lithium transition ~netal oxides 0.885 0.612 4.20 prepared from the transition metal precursol.~o f Comparative Examples 1 and 2 exhibit 0.666 lo\v strength. Although the preferred embodiments of the present invention havc bccri 10 disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, \vithoout departing from the scope and spirit of the invention as disclosed in the acco~npanyingc laims. [INDUSTRIAL APPLICABILITI'] A transition lnetal precursor according to the present invention has a lower tap density than conve~ltio~~traaln sition metal precursors consisting of conventional transition nletal precursor particles, when average particle diameter D50 of the transition ~uetalp recursor of the present invention is s~tbstantiallyt he same as tl~oseo f 5 conventional transition nletal precursors. In this regard, the expression "substantially the same as" means average particle diameter D50 within a measurement error range of 0.2 pm or less. As a result, a lithium transition ~netal oxide prepared using the transition metal precursor according to the present itlvention exhibits a smaller cha~lgein average 10 particle diameter D50 during sintering, when compared with conventional lithium transition nletal oxides, and has a higher strength, when compared with lithium transition metal oxides prepared using conventional transition metal precursors. Therefore, by using a lithium secondary battery using the lithium transition metal oxide as a positive electrode active material, breaking or crushing of lithiurn 15 transition rnetal oxide particles during rolling may be nlininlized and, as such, the lithium secondary battery exhibits improved high temperature characteristics, lifespan characteristics, and safety. In addition, reduction in capacity may be mitii~nized and output characteristics inay be improved. [CLAIMS] [Claim 1 I A transition metal precursor for preparation of a litllium tra~isitiontn etal oxide, in which a ratio of tap density to average particle diameter D50 of the precursor satisfies 5 a cor~ditiotrle presented by Equation 1 below: Tap density < Average particle diarnctcr D50 of transition metal precursor < 3500 (g/cc. cm) (1). [Claim 21 The transition metal precursor according to claim 1, wherein the transition metal precursor comnl~risesa t least two transition metals. 10 [Claim 31 The transition metal precursor according to claiin 2, wherein the at least two transition tnetals arc at least two selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), alutniin~m (At), copper (Cu), iron (Fc), lnagtlesium (Mg), boron (B), chron~iutn(C r), and period 2 transition metals. 15 [Claim 41 The tra~lsitionm etal precursor according to claim 3, \vherein the at least two transition metals cotnprisc two transition nletals selected from the gmup consisting of Ni, Co, atid Mn, or all thereof. [Claim 5 1 The transition lnetal precursor according to clai~n 1, wherein precursor particles constit~~tintgh e trallsitio~l lnetal precursor are transition ~netalh ydroxide particles. 5 [Claim 61 The transition metal precursor according to claim 5, wherein the transition nletal hydroxide particles are a conlpound represented by Fonnula 2 below: w\lllcrcin M is at least two selected fro111 Ni, Co, Mn, A1, Cu, Fe, Mg, B, Cr, and 10 period 2 transition metals; and 05~50.5. [Claim 71 'lie transitioll nletal precursor according to claim 6, \vherein M co~nprisestw o transition metals selected from the group consisti~lgo f Ni, Co, and Mn, or all thereof. [Claim 81 15 The transition metal precursor according to claitn 1, wherein the tra~lsition ~netapl recursor has an average particle dianleter D50 of 1 to 30 pm. [Claim 91 A lithium transition metal oxide in which a ratio of average particle diameter D50 of the lithium transition nietal oxide to average particle diameter D50 of a transition ~iietapl recursor for preparation of tlie litliiu~ntr ansition metal oxide satisfies the condition represented by Equation 3 below: 5 0 < Average particle diameter D50 oflithiulii transition metal oxide Average particle diameter D50 of transition metal precursor < 1.2 (3). [Claim 101 The lithium transition metal oxide according to clailn 9, mlierein tlie litliium transition metal oxide co~nprisesa t least two transition metals. [Claim 1 1 I 10 The lithium transition metal oxide according to clai~n 10, \\herein the lithium transition metal oxide is a colnpound represented by Forliiula 4 below: and 05t<0.2: 15 M is at least one metal cation selected from tlie group consisting of Al, Cu, Fe, Mg, B, Cr, and period 2 transition metals; and A is at least one monovalent or divalent anion. IClaini 121 Tlie lithiunl transition metal oxide according to clainl 11, wherein, in For~nula 4, x>y and x>z. [Claim 131 The lithiunl transition metal oxide according to clainl 11, wherein the lithiurn 5 transition metal oxide co~nprisesa t least two trailsition metals. [Claim 141 A lithium secondary battery in which a unit cell conlprising a positive electrode comprising the lithium transition metal oxide according to any one of claims 9 to 13, a negative electrode, and a polymer membrane disposed bettveen the positive electrode 10 and the negative electrode is accommodated in a battery case. The litl~iutn secondary battery according to clainl 14, wherein the lithium secondary battery is a lithium ion battery. [Claim 161 15 The lithium secondary battery according to claim 14, wherein the lithiunl secondary battery is a lithium ion polymer battery. [Claim 171 The lithium secolldary battery according to claim 14, wherein the lithium ' secoildary battery is a lithium polynler battery.