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 nickel-hydrogen secondary battery includes an electrode group comprising a separator, a positive electrode, and a negative electrode, and the positive electrode contains a positive electrode active material including a base particle comprising a nickel hydroxide particle containing Mn in solid solution and a conductive layer comprising a Co compound and covering the surface of the base particle, wherein the X-ray absorption edge energy of Mn detected within 6500 to 6600 eV by measurement with an XAFS method is 6548 eV or higher.

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.)

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.

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 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.

The present application discloses a method for preparing metal oxide nanoparticles, including the following steps: providing an organic reagent with a molecular formula of X—(SO.sub.2)—Y and a metal oxide nanoparticle sample, in which the metal oxide nanoparticle sample is an aqueous metal oxide nanoparticle; in X—(SO.sub.2)—Y, X contains polar functional groups; mixing the organic reagent and the metal oxide nanoparticle sample in a liquid medium and adding an alkaline reagent to a mixed solution of the organic reagent and the metal oxide nanoparticle sample to prepare the metal oxide nanoparticles. The method provided in the present application can reduce the surface defect state of metal oxide nanoparticles, thereby improving the stability of metal oxide nanoparticles.

The present application discloses a method for preparing metal oxide nanoparticles, including the following steps: providing an organic reagent with a molecular formula of X—(SO.sub.2)—Y and a metal oxide nanoparticle sample, in which the metal oxide nanoparticle sample is an aqueous metal oxide nanoparticle; in X—(SO.sub.2)—Y, X contains polar functional groups; mixing the organic reagent and the metal oxide nanoparticle sample in a liquid medium and adding an alkaline reagent to a mixed solution of the organic reagent and the metal oxide nanoparticle sample to prepare the metal oxide nanoparticles. The method provided in the present application can reduce the surface defect state of metal oxide nanoparticles, thereby improving the stability of metal oxide nanoparticles.

A method for preparing a transition-metal adamantane carboxylate salt is presented. The method includes mixing a transition-metal hydroxide and a diamondoid compound having at least one carboxylic acid moiety to form a reactant mixture, where M is a transition metal. Further, the method includes hydrothermally treating the reactant mixture at a reaction temperature for a reaction time to form the transition-metal adamantane carboxylate salt.