The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material including a lithium composite oxide containing at least nickel and cobalt, wherein since the cobalt in the lithium composite oxide has a concentration gradient having at least different slopes from a surface portion toward a central portion, it is possible to improve the stability of particles not only in a surface portion of the lithium composite oxide but also in a central portion thereof, a positive electrode including the positive electrode active material, and a lithium secondary battery using the negative electrode.

The present invention pertains to: a positive electrode active material precursor containing first secondary particle composed of an aggregate of a plurality of first primary particles, the positive electrode active material precursor including a first center portion represented by chemical formula 1 and a first surface portion represented by chemical formula 2, wherein the thickness of the first surface portion is 2-20% of the average radius of the positive electrode active material precursor; and a positive electrode active material containing the positive electrode active material precursor.

The disclosure provides a modified positive electrode material, a preparation method therefor, and a lithium ion battery. The modified positive electrode material includes a core and a coating layer. The core contains Mn and Ni, the coating layer includes a first oxide coating layer coating on a surface of the core. A first element forming the first oxide coating layer is selected from one or more of a group of Si, Ti, V, Zr, Mo, W, Bi, Nb, and Au. The first element with a high-valent state can partially enter the surface core structure of the positive electrode material to occupy the sites of manganese ions, and form a chemical bond stronger than a Mn—O. Thus, 0 and Mn in the core structure are difficult to precipitate, and the coating layer is difficult to fall off in cycle process. Moreover, structural stability of the modified positive electrode material is improved.

A sol of inorganic oxide particles is stably dispersed in a hydrophilic organic solvent containing a hydrocarbon such as a paraffinic hydrocarbon or a naphthenic hydrocarbon. The sol contains a dispersion medium containing an organic solvent containing a C.sub.6-18 paraffinic hydrocarbon, a C.sub.6-18 naphthenic hydrocarbon, or a mixture of these, a C.sub.4-8 alcohol having a carbon chain with a carbon-carbon bond in the molecule in an amount of 0.1 to 5% by mass in the entire dispersion medium, and inorganic oxide particles having an average particle diameter of 5 to 200 nm as measured by dynamic light scattering as a dispersoid, wherein the inorganic oxide particles contain a C.sub.1-3 alkyl group bonded to a silicon atom and a C.sub.4-18 alkyl group. The paraffinic hydrocarbon is a normal paraffinic hydrocarbon or an isoparaffinic hydrocarbon. The naphthenic hydrocarbon is a saturated aliphatic cyclic hydrocarbon substitutable with a C.sub.1-10 alkyl group.

This positive electrode active material for nonaqueous electrolyte secondary batteries contains: a lithium transition metal composite oxide having secondary particles, each of which is formed of aggregated primary particles; and a surface modification layer which is formed on the surface of each primary particle of the lithium transition metal composite oxide. The lithium transition metal composite oxide contains at least Al and 80% by mole or more of Ni relative to the total number of moles of the metal elements excluding Li; and the surface modification layer contains at least Ba, and at least one of Sr and Ca.

By a method including at least a spraying/mixing step of: mixing a precursor compound of a positive electrode active material with a lithium compound to prepare a mixture; and simultaneously spraying a spraying agent containing at least one element onto the mixture, there can be produced a positive electrode active material for non-aqueous electrolyte secondary batteries, which does not adversely affect battery properties of non-aqueous electrolyte secondary batteries, without reducing production efficiency.

Supplemental lithium can be used to stabilize lithium ion batteries with lithium rich metal oxides as the positive electrode active material. Dramatic improvements in the specific capacity at long cycling have been obtained. The supplemental lithium can be provided with the negative electrode, or alternatively as a sacrificial material that is subsequently driven into the negative electrode active material. The supplemental lithium can be provided to the negative electrode active material prior to assembly of the battery using electrochemical deposition. The positive electrode active materials can comprise a layered-layered structure comprising manganese as well as nickel and/or cobalt.

A dispersion liquid contains fine particles of core-shell type inorganic oxide that have high dispersion stability and transparency and allow for excellent light resistance and weather resistance by being mixed in a coating film. The fine particles are produced by treating the surfaces of (a) fine particles of titanium-containing metal oxide serving as core particles with a hydrate and/or an oxide of a metal element such as zirconium to provide surface-treated particles or fine particles of titanium-containing metal oxide having (b) an intermediate layer and by covering the surfaces of the surface-treated particles to form (c) a shell layer with a composite oxide of silicon and at least one metal element selected from aluminum, zirconium, and antimony.

A lithium secondary battery is produced by employing a charging method where a positive electrode upon charging has a maximum achieved potential of 4.3 V (vs. Li/Li.sup.+) or lower. The lithium secondary battery contains an active material including a solid solution of a lithium transition metal composite oxide having an α-NaFeO.sub.2-type crystal structure. The solid solution has a diffraction peak observed near 20 to 30° in X-ray diffractometry using CuKα radiation for a monoclinic Li[Li.sub.1/3Mn.sub.2/3]O.sub.2-type before charge-discharge. The lithium secondary battery is charged to reach at least a region with substantially flat fluctuation of potential appearing in a positive electrode potential region exceeding 4.3 V (vs. Li/Li.sup.+) and 4.8 V (vs. Li/Li.sup.+) or lower. A dischargeable electric quantity in a potential region of 4.3 V (vs. Li/Li.sup.+) or lower is 177 mAh/g or higher.

A calcium carbonate-containing material and a process for preparing the inventive calcium carbonate-containing material, wherein a paint includes the inventive calcium carbonate-containing material, and to the use of the inventive calcium carbonate-containing material. The calcium carbonate-containing material is prepared from an avian eggshell, wherein the calcium carbonate-containing material has a weight-median particle size d50 of from 0.5 to 10 μm, and/or a weight top cut particle size d98 of from 2.0 to 40 μm, and wherein the calcium carbonate-containing material includes organic matter in an amount of below 1.5 wt. %, based on the total dry weight of the calcium carbonate-containing material, and wherein the calcium carbonate-containing material has i) a brightness from 90 to 100%, according to R457, and/or ii) L* from 95 to 100, according to DIN 6174.