Disclosed are an aluminum-coated precursor and a preparation method therefor. The aluminum coated precursor has a chemical formula of xMCO.sub.3(1-x).Al(OH).sub.3, wherein M is at least one of nickel, cobalt and manganese, and x is 0.995-0.999. The aluminum-coated precursor has the advantages of a controllable particle size and uniform particle size distribution, a high degree of sphericity, a smooth particle surface, a high tap density, not easily breaking, and an excellent electrochemical performance and energy density.

A positive-electrode active material for nonaqueous-electrolyte secondary batteries which comprises a given lithium-transition metal composite oxide haying a lamellar structure and a compound A containing Ca and/or Sr, the compound A being present on the surface of or at the boundaries of primary particles of the lithium-transition metal composite oxide. The lamellar structure includes an Li layer where Li reversibly goes in and out, and the proportion of non-lithium metallic element(s) present in the Li layer is 0.7-3.0 mol % with respect to the total amount of the non-lithium metallic elements contained in the lithium-transition metal composite oxide. In analysis by X-ray diffraction, the positive-electrode active material gives an X-ray diffraction pattern in which the ratio of the half-band width in of a diffraction peak for the (003) plane to the half-band width n of a diffraction peak for the (104) plane, m/n, is 0.7.5≤m/n≤1.0.

A method for preparing high nickel lithiated metal oxides that includes selecting one or more nickel precursors; at least one non-corrosive lithium salt; and a plurality of metal oxide or hydroxide precursors. The metal precursors and lithium salts are mixed together to form a mixture comprising:

##STR00001##

wherein x = 1.0 - 1.1, 0.80 ≤ y ≤ 0.90, 0.03 < z ≤ 0.15, and 0 ≤ a ≤ 0.05; M is Co or Fe; and N is Al, Mn, Fe, Ca, Mg, Ti, Cr, Nb, Mo, W, B, or a mixture thereof provided N may be Fe when M is Co. The mixture is subjected to sintering (1.sup.st step) in air at ≥ 750° C. to form a powder. The powder is subjected to a 2.sup.nd sintering step in O.sub.2 at ≤ 750° C. to form the high nickel lithiated metal oxides.

The present application discloses a positive electrode active material including a lithium nickel cobalt manganese oxide, the molar content of nickel in the lithium nickel cobalt manganese oxide accounts for 60%-90% of the total molar content of nickel, cobalt and manganese, and the lithium nickel cobalt manganese oxide has a layered crystal structure of a space group R 3m; a transition metal layer of the lithium nickel cobalt manganese oxide includes a doping element, and the local mass concentration of the doping element in particles of the positive electrode active material has a relative deviation of 20% or less; and in a differential scanning calorimetry spectrum of the positive electrode active material in a 78% delithiation state, an initial exothermic temperature of a main exothermic peak is 200° C. or more, and an integral area of the main exothermic peak is 100 J/g or less.

A positive electrode active material includes a lithium transition metal oxide represented by Formula 1, and a lithium-containing inorganic compound layer formed on a surface of the lithium transition metal oxide,
Li.sub.1+a(Ni.sub.bCo.sub.cX.sub.dM.sup.1.sub.eM.sup.2.sub.f).sub.1−aO.sub.2  [Formula 1] in Formula 1, X is at least one selected from the group consisting of manganese (Mn) and aluminum (Al), M.sup.1 is at least one selected from the group consisting of sulfur (S), fluorine (F), phosphorus (P), and nitrogen (N), M.sup.2 is at least one selected from the group consisting of zirconium (Zr), boron (B), cobalt (Co), tungsten (W), magnesium (Mg), cerium (Ce), tantalum (Ta), titanium (Ti), strontium (Sr), barium (Ba), hafnium (Hf), F, P, S, lanthanum (La), and yttrium (Y), 0≤a≤0.1, 0.6≤b≤0.99, 0≤c≤0.2, 0≤d≤0.2, 0<e≤0.1, and 0<f≤0.1. A method of preparing the positive electrode active material, a positive electrode and a lithium secondary battery are also provided.

A process for producing a lithium nickel metal oxide material is provided together with a particulate lithium nickel metal oxide material with a defined crystallite size. Such materials find utility as cathode materials for secondary lithium-ion batteries. The process comprises a first calcination step which comprises heating at a temperature of between about 460° C. and about 540° C. for a period of between three and ten hours, and a subsequent second calcination step which comprises heating to a temperature greater than about 600° C. for a period of between 30 mins and 4 hours.

A process for producing a surface-modified particulate lithium nickel metal oxide material is provided. The process comprises the addition of a controlled quantity of a coating liquid comprising a metal-containing compound and a lithium-containing compound to nickel metal precursor particles using an incipient wetness process followed by a calcination step.

The present invention provides the compound LiMn.sub.2--x-yNa.sub.xM.sub.yO.sub.4/Na.sub.1-zMnLi.sub.zM.sub.tO.sub.2/Na.sub.2CO.sub.3, to be used as a positive electrode for rechargeable lithium ion battery, where M is a metal or metalloid, 0.0≤x≤0.5; 0.0≤y≤0.5; 0.1≤z≤0.5; 0.0≤t≤0.3; as well as the method for producing it. The synthesis process includes disolving or mixing the precursor metals and then calcining them in air or controlled atmosphere in a temperature range between 250° C. and 1000° C., and for a time range of 0.5 h to 72 h to obtain the composite proposed with the interaction of its three present phases, presenting a high retention capacity during repeated loading/unloading cycles and excellent discharge capacity both at room temperature and up to 55° C.

What is provided is 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 hexagonal layered crystal structure belonging to the space group R-3m and contain at least Li and a transition metal, and in powder x-ray diffraction measurement using CuKα rays, the crystallite size L.sub.003 of a diffraction peak in a range of 2θ=18.7±1° is 1,300 Å or less, and wherein the BET specific surface area is 0.2 m.sup.2/g or more and 2.0 m.sup.2/g or less.

A method for preparing a positive electrode active material and a positive electrode active material prepared by the method are provided. The method includes preparing a lithium composite transition metal oxide represented by Formula 1, and washing the lithium composite transition metal oxide with a cleaning liquid containing cleaning water and a surfactant. The cleaning liquid contains cleaning water in an amount of no less than 50 parts by weight and less than 400 parts by weight based on 100 parts by weight of the lithium composite transition metal oxide.