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 method of producing a positive electrode active material for a nonaqueous electrolyte secondary battery, the method includes preparing nickel-containing composite oxide particles having a ratio .sup.1D.sub.90/.sup.1D.sub.10 of a 90% particle size .sup.1D.sub.90 to a 10% particle size .sup.1D.sub.10 in volume-based cumulative particle size distribution of 3 or less; obtaining a raw material mixture containing the composite oxide particles and a lithium compound and having a ratio of a total number of moles of lithium to a total number of moles of metal elements contained in the composite oxide in a range of 1 to 1.3; subjecting the raw material mixture to a heat treatment to obtain a heat-treated material; subjecting the heat-treated material to a dry-dispersion treatment to obtain a first dispersion; and bringing the first dispersion into contact with a liquid medium to obtain a second dispersion.

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.

Provided is a chlorine-containing positive electrode active material that can impart excellent high-temperature storage characteristic to a lithium ion secondary battery. The positive electrode active material disclosed herein includes 0.1% by mass or more and 3% by mass or less of Cl. Further, in the positive electrode active material disclosed herein, the ratio of a peak intensity of a (003) plane to a peak intensity of a (104) plane in Miller indexes hlk that is determined by powder X-ray diffraction is 0.8 or more and 1.5 or less.

A method for preparing nickel-cobalt-manganese hydroxide. The method comprises the following steps: (1) dissolving microcrystalline cellulose into water to obtain a suspension; and adding a nickel source, a cobalt source, and a manganese source into the suspension to obtain a solution containing nickel, cobalt, and manganese; (2) adding hexamethylenetetramine into the solution containing nickel, cobalt, and manganese, heating the reaction solution to 80-90° C., and reacting for 5-10 min, then heating with a microwave hydrothermal synthesis instrument at a frequency of 2450 MHz for 10-60 min; and (3) filtering the reaction solution obtained in step (2), and taking the filter residue, washing the filter residue with pure water and ethanol respectively, then drying, crushing, and screening the filter residue to obtain nickel-cobalt-manganese hydroxide. Nickel-cobalt-manganese hydroxide prepared from the abovementioned method has a uniform particle size and consistent morphology and structure; thus solving the problems of the uncontrollable appearance and structure and the inconsistent performances of the product caused by the vigorous reaction in the existing method for preparing nickel-cobalt-manganese hydroxide.

With an aim to provide a method for producing an oxide particle with controlled color characteristics and also provide an oxide particle with controlled color characteristics, the present invention provides a method for producing an oxide particle, wherein the color characteristics of the oxide particle are controlled by controlling a ratio of an M-OH bond between an element (M) and a hydroxide group (OH) or an M-OH bond/M-O bond ratio, where the element (M) is one element or plural different elements other than oxygen or hydrogen included in the oxide particle selected from metal oxide particles and semi-metal oxide particles. According to the present invention, by controlling the M-OH bond or the M-OH bond/M-O bond ratio of the metal oxide particle or the semi-metal oxide particle, the oxide particle with controlled color characteristics of any of reflectance, transmittance, molar absorption coefficient, hue, and saturation can be provided.

Provided are nickel manganese composite hydroxide particles that are a precursor for forming cathode active material comprising lithium nickel manganese composite oxide having hollow structure of particles having a small and uniform particle size for obtaining a non-aqueous electrolyte secondary battery having high capacity, high output and good cyclability. When obtaining the nickel manganese composite hydroxide particles from a crystallization reaction, an aqueous solution for nucleation, which includes at least a metallic compound that contains nickel and a metallic compound that contains manganese, and does not include a complex ion formation agent that forms complex ions with nickel, manganese and cobalt, is controlled so that the temperature of the solution is 60° C. or greater, and so that the pH value that is measured at a standard solution temperature of 25° C. is 11.5 to 13.5, and after nucleation is performed, an aqueous solution for particle growth, which includes the nuclei that were formed in the nucleation step and does not substantially include a complex ion formation agent that forms complex ions with nickel, manganese and cobalt, is controlled so that the temperature of the solution is 60° C. or greater, and so that the pH value that is measured at a standard solution temperature of 25° C. is 9.5 to 11.5, and is less than the pH value in the nucleation step.

Provided is a nickel-containing composite hydroxide that is a precursor of a positive-electrode active material with which a nonaqueous-electrolyte secondary battery having a low irreversible capacity and a high energy density can be configured. An aqueous alkaline aqueous solution and a complexing agent are added to an mixed aqueous solution including at least nickel and cobalt to regulate the pH (measured at a reference liquid temperature of 25° C.) of this mixed aqueous solution to 11.0 to 13.0, the ammonium concentration to 4 to 15 g/L, and the reaction temperature to 20° C. to 45° C. Using stirring blades having an inclination angle of 20° to 60° with respect to a horizontal plane, the mixture is stirred to conduct a crystallization reaction under such conditions that when the nickel-containing composite hydroxide to be obtained is roasted in air at 800° C. for 2 hours, the roasted composite hydroxide has a BET value of 12 to 50 m.sup.2/g. Thus a nickel-containing composite hydroxide expressed by Ni.sub.1−x−yCo.sub.xAl.sub.yM.sub.t(OH).sub.2+α (where, 0<x≦0.20, 0<y≦0.15, 0≦t≦0.10, 0≦α 0.50, and M is one or more kind of element selected from among Mg, Ca, Ba, Nb, Mo, V, Ti, Zr and Y), or the general formula: Ni.sub.1−x−zCo.sub.xMn.sub.zM.sub.t(OH).sub.2+α (where 0<x≦0.50, 0<z≦0.50, x+z≦0.70, 0≦t≦0.10, 0≦α≦0.50, and M is one or more kind of element selected from among Mg, Ca, Ba, Nb, Mo, V, Ti, Zr and Y) is obtained.

The disclosure relates to a precursor manufacturing a lithium rich cathode active material and a Lithium rich cathode active material using the same, more specifically relates to a novel precursor for manufacturing a lithium rich cathode active material of which capacity properties and cycle life characteristics are considerably improved by solving a problem of conventional lithium rich cathode active material, and a Lithium rich cathode active material using the same.

A cathode active material with high durability and a lithium ion secondary battery. The cathode active material is a cathode active material represented by a general formula Li.sub.(1+a)Ni.sub.xCo.sub.yMn.sub.zW.sub.tO.sub.2 (−0.05≦a≦0.2, x=1−y−z−t, 0≦y<1, 0≦t<1, 0<t≦0.03), wherein the cathode active material satisfies the following formula (1):

σ1/t1≦0.92  (1)

where t1 is an element concentration average of insides and grain boundaries of primary particles of a W element, and σ1 is an element concentration standard deviation of the insides and grain boundaries of the primary particles of the W element.