A positive electrode active material precursor for a lithium secondary battery containing at least Ni, in which S/D.sub.50 that is a ratio of a BET specific surface area S to a 50% cumulative volume particle size D.sub.50 is 2×10 to 20×10.sup.6 m/g, and, in powder X-ray diffraction measurement using a CuKα ray, A/B that is a ratio of an integrated intensity A of a diffraction peak within a range of 2θ=37.5±1° to an integrated intensity B of a diffraction peak within a range of 2θ=62.8±1° is more than 0.80 and 1.33 or less.

A lithium metal composite oxide having a layered structure, containing at least Li, Ni, and an element X, in which the element X is one or more elements selected from the group consisting of Co, Mn, Mg, Ca, Sr, Ba, Zn, B, Al, Ga, Ti, Zr, Ge, Fe, Cu, Cr, V, W, Mo, Sc, Y, Nb, La, Ta, Tc, Ru, Rh, Pd, Ag, Cd, In, and Sn, L/D.sub.50 that is a ratio of an average primary particle diameter L to a 50% cumulative volume particle size D.sub.50 is 0.3 to 1.5, and, in powder X-ray diffraction measurement using a CuKα ray, a crystallite diameter A calculated from a diffraction peak within a range of 2θ=44.5±1° is 700 Å or less.

Provided are a positive electrode active material with which a nonaqueous electrolyte secondary battery having a high energy density can be obtained, a nickel-manganese composite hydroxide suitable as a precursor of the positive electrode active material, and production methods capable of easily producing these in an industrial scale. Provided is a nickel-manganese composite hydroxide represented by General Formula (1): Ni.sub.xMn.sub.yM.sub.z(OH).sub.2+α and containing a secondary particle formed of a plurality of flocculated primary particles. The nickel-manganese composite hydroxide has a half width of a diffraction peak of a (001) plane obtained by X-ray diffraction measurement of at least 0.10° and up to 0.40° and has a degree of sparsity/density represented by [(void area within secondary particle/cross section of secondary particle)×100](%) of at least 0.5% and up to 10%. Also provided is a production method of the nickel-manganese composite hydroxide.

The present invention relates to a surface-modified particulate lithium nickel oxide material. The invention also relates to a process of making a surface-modified particulate lithium nickel oxide material. Further aspects of the invention include a cathode comprising the surface-modified particulate lithium nickel oxide material, a lithium secondary cell or battery comprising such a cathode, and the use of the particulate lithium nickel oxide to improve the capacity retention of a lithium secondary cell or battery.

An object of the present invention is to provide a powder of a CeO.sub.2—ZrO.sub.2-based complex oxide which enables to achieve an improvement in the purification performance at a low to middle temperature of an exhaust gas purification catalyst, and, in order to achieve the above-mentioned object, the present invention provides a powder of a CeO.sub.2—ZrO.sub.2-based complex oxide, wherein a pore volume with from-10-to-100-nm diameters after a heat treatment performed at 1,000° C. for 3 hours in an air atmosphere, is 0.35 mL/g or more, and wherein an amount of carbon dioxide desorbed after the heat treatment, as measured by a temperature programmed desorption method, is 80 μmol/g or more.

The invention concerns the area of ceramics an relates to a method for separating impurities from silicon carbide, said method being applicable to SiC powders from grinding sludges, and to temperature-treated and purified silicon carbide powder. The aim of the invention is to provide a method with which different impurities are substantially completely removed using a simple and economical process. This is achieved by a method in which pulverulent SiC waste products that have a mass percent of SiC of at least 50% and an average grain size d.sub.50 ranging from 0.5 to 1000 μm and have been subjected to a temperature treatment and cooled are mechanically treated and physically separated. The physically separated SiC powder is then divided into two fractions, one of which has a mass of impurities that is greater than the mass of impurities in the other fraction at least by a factor of 2.

The present invention relates to a surface-modified particulate lithium nickel oxide material. The invention also relates to a process of preparing a particulate lithium nickel oxide material. Further aspects of the invention include a cathode comprising the particulate lithium nickel oxide material, a lithium secondary cell or battery comprising such a cathode, and the use of the particulate lithium nickel oxide to improve the capacity retention of a lithium secondary cell or battery.

The invention relates to improved particulate lithium nickel oxide materials which are useful as cathode materials in lithium secondary batteries. The invention also provides processes for preparing such lithium nickel oxide materials, and electrodes and cells comprising the materials.

A positive electrode active material for an all-solid-state lithium-ion battery composed of particles containing crystals of a lithium metal composite oxide, wherein the particles have a layered structure and contain at least Li and a transition metal, and in powder x-ray diffraction measurement using CuKα rays, a ratio I.sub.003/I.sub.004 of an integrated intensity I.sub.104 of a diffraction peak in a range of 2θ=44.4±1° to an integrated intensity I.sub.003 of a diffraction peak in a range of 2θ=18.5±1° exceeds 1.23, and wherein a press density A when the positive electrode active material for an all-solid-state lithium-ion battery is compressed at a pressure of 45 MPa is 2.90 g/cm.sup.3 or more.

Described herein are low or no-cobalt materials useful as electrode active materials in a cathode for lithium or lithium-ion batteries. For example, compositions of matter are described herein, such as electrode active materials that can be incorporated into an electrode, such as a cathode. The disclosed electrode active materials exhibit high specific energy and voltage, and can also exhibit high rate capability and/or long operational lifetime.