Technical field [One] [Mutual citation with related application] [2] This application claims the benefit of priority based on Korean Patent Application No. 10-2017-0155469 filed on November 21, 2017, and all contents disclosed in the Korean patent application document are included as part of this specification. [3] [4] [Technical field] [5] The present invention relates to a positive electrode active material precursor and a method of manufacturing the same, and more particularly, to a positive electrode active material precursor for preparing a high-concentration nickel (Ni-rich) positive electrode active material having excellent electrochemical properties and thermal stability, and a method of manufacturing the same. [6] Background [7] As technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, a lithium secondary battery having a high energy density and voltage, a long cycle life, and a low self-discharge rate has been commercialized and widely used. [8] Lithium transition metal composite oxide is used as a positive electrode active material of a lithium secondary battery, and among them , lithium cobalt composite metal oxide of LiCoO 2 having a high working voltage and excellent capacity characteristics is mainly used. However, LiCoO 2 has very poor thermal properties due to destabilization of the crystal structure due to delithiation, and is expensive, so it is limited in mass use as a power source in fields such as electric vehicles. [9] As a material for replacing LiCoO 2 , lithium manganese composite metal oxides (such as LiMnO 2 or LiMn 2 O 4 ), lithium iron phosphate compounds ( such as LiFePO 4 ), or lithium nickel composite metal oxides ( such as LiNiO 2 ) have been developed. Among them, research and development of lithium nickel composite metal oxides, which have a high reversible capacity of about 200 mAh/g and are easy to implement a large-capacity battery, are actively in progress. However, LiNiO 2 has poor thermal stability compared to LiCoO 2, and when an internal short circuit occurs due to pressure from the outside in a charged state, the positive electrode active material itself decomposes, causing a battery burst and ignition. [10] Accordingly , as a method to improve low thermal stability while maintaining excellent reversible capacity of LiNiO 2 , a nickel cobalt manganese-based lithium composite metal oxide in which a part of Ni is replaced with Mn and Co (hereinafter simply referred to as'NCM-based lithium oxide' ) Was developed. However, the conventional NCM-based lithium oxide developed to date has limited application due to insufficient capacity characteristics. [11] In order to improve such a problem, studies have recently been made to increase the content of Ni in NCM-based lithium oxide. However, in the case of a high-concentration nickel positive electrode active material having a high nickel content, there is a problem in that the structural stability and chemical stability of the active material are inferior. In addition, as the nickel content in the active material increases, the residual amount of lithium by-products present in the form of LiOH and Li 2 CO 3 on the surface of the positive electrode active material increases, resulting in gas generation and swelling, thereby reducing the life and stability of the battery. There is also a problem of deterioration. [12] In order to solve the above problems, a positive electrode active material having a concentration gradient in which the nickel content in the positive electrode active material gradually decreases has been proposed. In such a positive electrode active material having a concentration gradient, the first metal solution with a high nickel content and the second metal solution with a low nickel content are adjusted to form a precursor with a high nickel content in the center and a lower nickel content toward the surface. Then, it is prepared by mixing the precursor and a lithium raw material such as lithium hydroxide or lithium carbonate, followed by firing. However, in the case of the positive electrode active material having a concentration gradient as described above, since the nickel content is gradually lowered, there is a limit to increasing the nickel content in the entire positive electrode active material, so there is a limit to the capacity increase. Since it has to be fired, there is a problem that thermal stability is poor. In addition, since it has to be prepared by mixing two types of metal solutions, it is difficult to control the pH in the reactor, so that the quality control of the precursor is difficult, and the process is complicated. [13] Accordingly, development of a new technology capable of manufacturing a high-concentration nickel (Ni-rich) positive electrode active material having excellent thermal stability while meeting high capacity is required. [14] [15] Korean Patent Publication No. 10-2016-0063982 (Publication date: 2016.06.07) [16] Detailed description of the invention Technical challenge [17] The present invention is to solve the above problems, and to provide a positive electrode active material precursor and a manufacturing method capable of forming a high concentration nickel positive electrode active material excellent in thermal stability. [18] In addition, the present invention is to provide a positive electrode active material prepared by using the positive electrode active material precursor, and a positive electrode for a secondary battery and a secondary battery including the same. Means of solving the task [19] In one aspect, the present invention is a transition metal hydroxide particles represented by the following formula (1); And it provides a positive electrode active material precursor comprising cobalt oxide particles and manganese oxide particles attached to the surface of the transition metal hydroxide particles. [20] [Formula 1] [21] [Ni a Co b M 1 c M 2 d ](OH) 2 [22] In Formula 1, 0.8≤a<1, 0