Provided are a nickel-based active material precursor for a lithium secondary battery including a porous core and a shell on the porous core, the shell having a radial arrangement structure with a higher density than that of the porous core, wherein the nickel-based active material precursor have a size of 9 μm to 14 μm, and the porous core has a volume of about 5% by volume to about 20% by volume based on the total volume of the nickel-based active material precursor; a method of preparing the nickel-based active material precursor; a nickel-based active material produced from the nickel-based active material; and a lithium secondary battery including a cathode containing the nickel-based active material.

A precursor for lithium secondary battery positive electrode active materials containing at least nickel, in which the following formula (1) is satisfied.

0.20≤Dmin/Dmax  (1) (in the formula (1), Dmin is a minimum particle diameter (μm) in a cumulative particle size distribution curve obtained by measuring the precursor for lithium secondary battery positive electrode active materials with a laser diffraction-type particle size distribution measuring instrument, and Dmax is a maximum particle diameter (μm) in the cumulative particle size distribution curve obtained by the measurement with the laser diffraction-type particle size distribution measuring instrument.)

The present invention relates to a lithium-nickel composite oxide, wherein the lithium-nickel composite oxide is represented by a following general formula: Li.sub.1+uNi.sub.xCo.sub.yA.sub.sB.sub.tO.sub.2+α, wherein u, x, y, s, t and α in the formula satisfy 0≤u<0.3, 0.03≤x≤0.93, 0.03≤y≤0.50, 0.04≤s≤0.6, 0≤t<0.1, 0≤α<0.3 and x+y+s+t=1, wherein an element A is at least one selected from Mn and Al, and an element B is at least one selected from Mg, Ca, Ti, V, Zr, Nb, Mo, Sr and W, and wherein a content of Fe is less than 10 ppb, and a content of Cr is less than 10 ppb.

A cathode active material for a lithium secondary battery according to embodiments of the present invention has a high-nickel composition and includes a lithium-nickel composite metal oxide particle in which lithium, nickel and a metal having an oxidation number of +2 are combined in a predetermined range. A cation disorder caused when a nickel ion is present at a lithium-ion site is reduced to improve structural stability of the cathode active material. An initial capacity and a battery efficiency of a lithium secondary battery can be improved using the cathode active material.

Cathode material from exhausted lithium ion batteries are dissolved in a solution for extracting the useful elements Co (cobalt), Ni (nickel), Al (Aluminum) and Mn (manganese) to produce active cathode materials for new batteries. The solution includes compounds of desirable materials such as cobalt, nickel, aluminum and manganese dissolved as compounds from the exhausted cathode material of spent cells. Depending on a desired proportion, or ratio, of the desired materials, raw materials are added to the solution to achieve the desired ratio of the commingled compounds for the recycled cathode material for new cells. The desired materials precipitate out of solution without extensive heating or separation of the desired materials into individual compounds or elements. The resulting active cathode material has the predetermined ratio for use in new cells, and avoids high heat typically required to separate the useful elements because the desired materials remain commingled in solution.

A method for producing a positive electrode active substance for a non-aqueous electrolyte secondary battery is characterized by including: a washing step for washing a lithium-containing transition metal oxide with water and then dehydrating the same so as to obtain a cake-like composition; a tungsten addition step for adding at least a tungsten compound or a tungsten-containing solution to the cake-like composition so as to obtain a tungsten-added product; a first heat treatment step for heat treating the tungsten-added product at a temperature of 180° C. or lower; and a second heat treatment step for heat treating the tungsten-added product in an atmosphere other than a reducing atmosphere at a temperature of higher than 180° C. to 330° C. This method is further characterized by including a boron addition step for adding a boron compound or a boron-containing solution to the cake-like composition.

The present invention relates to a positive electrode active material for a lithium secondary battery, a method for preparing the same and a lithium secondary battery including the same, the positive electrode active material includes a core including a first lithium complex metal oxide, and a shell located surrounding the core and including a second lithium complex metal oxide, and further includes a buffer layer located between the core and the shell, wherein the buffer layer includes a pore, and a three-dimensional network structure of a third lithium complex metal oxide which is connecting the core and the shell, and accordingly, minimizing destruction of the active material caused by a rolling process during the electrode preparation, and maximizing reactivity with an electrolyte liquid.

A cathode active material contains a secondary particle containing or consisting of a group of a plurality of primary particles. At least some of the primary particles disposed on the surface of the secondary particle include first primary particle in the form of flakes having a pair of first crystal faces facing toward each other. The first crystal faces are arranged in a radial direction, ends of the first crystal faces pair are provided with a plurality of crystal faces different from the first crystal faces to connect the ends of the first crystal faces pair. Longitudinal cross-sections of the first primary particle contain a pair of first crystal faces spaced apart from each other. Second and third crystal faces are disposed in the outermost surface of the secondary particle to be connected to each other at an angle.

A mixed conductor represented by Formula 1:
A.sub.1±xM.sub.2±yO.sub.4−δ  Formula 1
wherein, in Formula 1, A is a monovalent cation, and M is at least one of a monovalent cation, a divalent cation, a trivalent cation, a tetravalent cation, a pentavalent cation, or a hexavalent cation, 0≤x≤1, 0≤y≤2, and 0≤δ≤1, with the proviso that when M includes vanadium, 0<δ≤1, and wherein the mixed conductor has an inverse spinel crystal structure.

Provided is a cathode active material including a core including a compound represented by Formula 1; and a coating layer including a phosphorus-containing compound disposed on a surface of the core:
Li.sub.aZr.sub.αW.sub.βM.sub.1−α−βO.sub.2−bS.sub.b  Formula 1 In Formula 1, M, Zr, W, a, α, β, and b are the same as defined in relation to the present specification.