In the positive electrode active material according to the inventive concept, A positive active material for lithium secondary battery comprises a particle comprising M1, M2, and Li, wherein the particle comprises a center, a surface, and an intermediate portion between the center and the surface, wherein M1 and M2 are selected from transition metal and are different each other, and wherein concentrations of M1 and M2 have continuous concentration gradients from the center to the intermediate portion.

A method for forming hollow silica spheres by dissolving a hydrolyzable aryl silane in an aqueous solution of water and an acid to form a hydrolyzed silane solution, mixing the hydrolyzed silane solution with a hydroxide base to form a precipitate, and calcining the precipitate in a multi-stage calcination procedure that includes (a) heating to a first temperature of 180 to 240 C. with a first ramp rate of 3 to 10 C./min and holding the first temperature for 2 minutes to 2 hours, then (b) heating to a second temperature of 600 to 740 C. at a second ramp rate of 0.1 to 4 C./min, and holding the second temperature for 2 to 24 hours.

Provided is a production method for core-shell porous silica particles, the production method including: a preparation step of preparing an aqueous solution comprising non-porous silica particles, a cationic surfactant, a basic catalyst, an electrolyte, and an alcohol; a shell precursor formation step at adding a silica source to the aqueous solution to form a shell precursor on a surface of the non-porous silica particles; and a shell formation step of removing the cationic surfactant from the shell precursor to form a porous shell.

A nickel lithium ion battery positive electrode material having a concentration gradient, and a preparation method therefor. The material is a core-shell material having a concentration gradient, the core material is a material having a high content of nickel, and the shell material is a ternary material having a low content of nickel. The method comprises: synthesizing a material precursor having a high content of nickel by means of co-precipitation, co-precipitating a ternary material solution having a low content of nickel outside the material precursor having a high content of nickel, aging, washing, and drying to form a composite precursor in which the low nickel material coats the high nickel material, adding a lithium source, grinding, mixing, calcining, and cooling to prepare a high nickel lithium ion battery positive electrode material. The obtained material has regular morphology, uniform coating, narrow particle size distribution range, gradient distribution of the concentration of the nickel element, high content of the nickel element in the core, and low content of the nickel element in the shell; the nickel element in the core guarantees the specific capacity of the material, and the shell coating material maintains the stability of the structure of the material, so as to improve the safety of the material in the charge and discharge process, and improve the cycle and rate performance of the material.

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.

A method for forming hollow silica spheres by dissolving a hydrolyzable aryl silane in an aqueous solution of water and an acid to form a hydrolyzed silane solution, mixing the hydrolyzed silane solution with a hydroxide base to form a precipitate, and calcining the precipitate in a multi-stage calcination procedure that includes (a) heating to a first temperature of 180 to 240? C. with a first ramp rate of 3 to 10? C./min and holding the first temperature for 2 minutes to 2 hours, then (b) heating to a second temperature of 600 to 740? C. at a second ramp rate of 0.1 to 4? C./min, and holding the second temperature for 2 to 24 hours.

The present invention relates to a cathode active material for a lithium secondary battery, and more particularly, to a cathode active material for a lithium secondary battery, which includes a core portion and a shell portion surrounding the core portion, in which a total content of cobalt in the core portion and the shell portion is 5 to 12 mol %, and the content of cobalt in the core portion and the shell portion is adjusted to be within a predetermined range. In the cathode active material precursor and the cathode active material for a secondary battery prepared using the same according to the present invention, optimal capacity of a lithium secondary battery may be increased by adjusting the cobalt content in the particles of the cathode active material, and life characteristics may be enhanced by improving stability.

Disclosed herein is a nanocrystal comprising a core comprising a first nanocrystal material, the first nanocrystal material including a Group II-VI semiconductor compound or a Group III-V semiconductor compound; a shell being disposed upon a surface of the core and comprising a second nanocrystal material, the second nanocrystal material being different from the first nanocrystal material and including a Group II-VI semiconductor compound or a Group III-V semiconductor compound; and an alloy interlayer disposed between the core and the shell, wherein the emission peak wavelength of the nanocrystal is shifted into a shorter wavelength than the emission peak wavelength of the core.

Provided is a method for producing a positive electrode active material for nonaqueous electrolyte secondary batteries, the method including: a mixing step of obtaining a W-containing mixture of Li metal composite oxide particles represented by the formula: Li.sub.zNi.sub.1-x-yCO.sub.xM.sub.yO.sub.2 and composed of primary particles and secondary particles formed by aggregation of the primary particles, 2 mass % or more of water with respect to the oxide particles, and a W compound or a W compound and a Li compound, the W-containing mixture having a molar ratio of the total amount of Li contained in water and the solid W compound or the W compound and the Li compound of 3 to 5 with respect to the amount of W contained therein; and a heat treatment step of heating the W-containing mixture to form lithium tungstate on the surface of the primary particles of the Li metal composite oxide particles.

A method for forming hollow silica spheres by dissolving a hydrolyzable aryl silane in an aqueous solution of water and an acid to form a hydrolyzed silane solution, mixing the hydrolyzed silane solution with a hydroxide base to form a precipitate, and calcining the precipitate in a multi-stage calcination procedure that includes (a) heating to a first temperature of 180 to 240? C. with a first ramp rate of 3 to 10? C./min and holding the first temperature for 2 minutes to 2 hours, then (b) heating to a second temperature of 600 to 740? C. at a second ramp rate of 0.1 to 4? C./min, and holding the second temperature for 2 to 24 hours.