The breakage or cracking of a positive electrode active material due to pressure application, repeated charging and discharging, or the like is likely to cause dissolution of a transition metal, an excessive side reaction, and the like. With a crack, unevenness, a step, roughness, or the like on the surface of a positive electrode active material, stress tends to be concentrated on part, which easily causes breakage. By contrast, with a smooth surface and a nearly spherical shape, stress concentration is alleviated; thus, breakage is unlikely to occur. Therefore, a positive electrode active material with a smooth surface and little unevenness is formed. For example, when the positive electrode active material is subjected to image analysis using a microscope image, the median value of the solidity is larger than or equal to 0.96. Alternatively, the median value of the fractal dimension of the positive electrode active material is smaller than or equal to 1.143. Alternatively, the median value of the circularity of the positive electrode active material is larger than or equal to 0.7.

A composite metal oxide material and a preparation method thereof, a positive electrode plate, a secondary battery, a battery module, a battery pack and an electrical device are provided. The composite metal oxide material includes a central core and a coating layer on the surface of the central core, in which the central core material has a chemical formula of Li.sub.5Fe.sub.xM.sub.1-xO.sub.4, 0.6≤x≤1; the coating layer material has a chemical formula of LiMO2, M is one or more metal elements with +3 valence, and the absolute value of the difference between the +3-valence ion radius of Fe and the +3-valence ion radius of M is ≤0.02 nm. The composite metal oxide material of the present disclosure makes the secondary battery have high charge capacity, high discharge capacity and long cycle life.

A positive electrode active material in which a discharge capacity decrease due to charge and discharge cycles is suppressed and a secondary battery including the positive electrode active material are provided. A positive electrode active material in which a change in a crystal structure, e.g., a shift in CoO.sub.2 layers is small between a discharged state and a high-voltage charged state is provided. For example, a positive electrode active material that has a layered rock-salt crystal structure belonging to the space group R-3m in a discharged state and a crystal structure belonging to the space group P2/m in a charged state where x in Li.sub.xCoO.sub.2 is greater than 0.1 and less than or equal to 0.24 is provided. When the positive electrode active material is analyzed by powder X-ray diffraction, a diffraction pattern has at least diffraction peaks at 2θ of 19.47±0.10° and 2θ of 45.62±0.05°.

A lithium transition metal oxide which is capable of minimizing a side reaction with an electrolyte, thereby suppressing the generation of gas during charging and discharging of a lithium secondary battery is provided. The lithium transition metal oxide is a lithium cobalt oxide which contains a hetero-element, wherein the hetero-element includes a 4th period transition metal; and at least one selected from the group consisting of a group 2 element, a group 13 element, a group 14 element, a 5th period transition metal, and a 6th period transition metal. The lithium transition metal oxide has a cumulative 50% particle diameter (D50) of 10.0 μm to 25.0 μm and a ratio (D.sub.max/D.sub.min) of a maximum particle diameter (D.sub.max) to a minimum particle diameter (D.sub.min) of 10.0 to 60.0 when measured by laser diffraction scattering particle size distribution.

The disclosure discloses a method for preparing a high-voltage cathode material by body modification and regeneration of a waste lithium cobaltate material. The waste lithium cobaltate cathode material is calcined, and then measured; a lithium source, a magnesium source, nano-scale TiO.sub.2 and the waste lithium cobaltate cathode material powder are mixed to obtain a mixture, placed in a ball milling tank containing absolute ethanol, and the resulting mixture is ball milled, and then dried to obtain a mixed powder; the mixed powder is calcined to obtain a magnesium-titanium co-doped regenerated lithium cobaltate cathode material; the magnesium-titanium co-doped regenerated lithium cobaltate cathode material is added into a mixed solution obtained by ultrasonically mixing absolute ethanol with the aluminum source, and then heated and stirred continually until the solvent evaporates to obtain a residue; the residue is calcined to obtain an aluminum-coated magnesium-titanium co-doped regenerated lithium cobaltate cathode material.

A positive electrode active material for a secondary battery is provided. The positive electrode active material being a lithium cobalt-based oxide includes a doping element M. A lithium cobalt-based oxide particle containing the doping element M in an amount of 3,000 ppm or more, wherein in a bulk portion corresponding to 90% of a core side among the radius from a core of the particle to a surface thereof, the doping element M in the lithium cobalt-based oxide particle is contained at a constant concentration, and in a surface portion from the surface of the particle to 100 nm in a core direction, the doping element M is contained at a concentration equal to or higher than that in the bulk portion and has a concentration in which the concentration thereof is gradient gradually decreased in the core direction from the surface of the particle.

The present invention provides a positive electrode active material precursor for a secondary battery which includes primary particles of Co.sub.3O.sub.4 or CoOOH, wherein the primary particle contains a doping element in an amount of 3,000 ppm or more, and has an average particle diameter (D.sub.50) of 15 μm or more, and a positive electrode active material for a secondary battery which includes particles of a lithium cobalt-based oxide, wherein the primary particle contains a doping element in an amount of 2,500 ppm or more, and has an average particle diameter (D.sub.50) of 15 μm or more.

The present application relates to a cathode material and an electrochemical device comprising the same. In particular, the present application relates to a cathode material having a surface heterophasic structure, wherein the cathode material includes a lithium cobalt oxide and an oxide of cobalt, wherein a Raman spectrum of the cathode material has characteristic peaks in the range of about 470 cm.sup.−1 to about 530 cm.sup.−1, about 560 cm.sup.−1 to about 630 cm.sup.−1 and about 650 cm.sup.−1 to about 750 cm.sup.−1, and wherein the surface heterophasic structure of the cathode material includes the lithium cobalt oxide and the oxide of cobalt. The electrochemical device using the cathode material having a surface heterophasic structure of the present application can exhibit excellent cycle performance and thermal stability.

A cobalt oxide for a lithium secondary battery, a method of preparing the cobalt oxide; a lithium cobalt oxide for a lithium secondary battery formed from the cobalt oxide; and a lithium secondary battery having a positive electrode including the lithium cobalt oxide, the cobalt oxide having a tap density of about 2.8 g/cc to about 3.0 g/cc, and an intensity ratio of about 0.8 to about 1.2 of a second peak at 2θ of about 31.3±1° to a first peak at 2θ of about 19±1° in X-ray diffraction spectra, as analyzed by X-ray diffraction.

A method of producing an inorganic material (S10) according to the present invention includes a vitrification step (S12) of applying shearing stress and compressive stress to a mixed powder (MP) of a plurality of kinds of inorganic compound powders by using a ring ball mill mechanism (70) to vitrify at least a part of the mixed powder (MP); and a dispersion step (S13) of dispersing the vitrified mixed powder (MP) after the vitrification step (S12), where a combined step of the vitrification step (S12) and the dispersion step (S13) is performed a plurality of times to obtain a vitrified inorganic material powder from the mixed powder.