The present invention provides a positive active material for use in a secondary lithium battery, a method for preparing the positive active material and a secondary lithium battery containing the positive active material. The positive active material includes a core of lithium transition metal oxide represented by Formula Li.sub.xM.sub.yN.sub.1-yO.sub.2-A.sub. and a coating layer of lithium transition metal silicate represented by Formula xLi.sub.2O.yNO.sub.a.SiO.sub.2-B.sub.which in-situ formed on the core, wherein 0.8x1.3, 0.6y1.0, 0.01x2.1, 0.2y1.5, 0.1a3.0, 00.2, 00.4, 00.5, 00.5. The positive active material according to the present invention has high capacity, desirable cycling performance and safety performance, as well as desirable thermal stability.

A lithium complex oxide and method of manufacturing the same, more particularly, a lithium complex oxide effective in improving the characteristics of capacity, resistance, and lifetime with reduced residual lithium and with different interplanar distances of crystalline structure between a primary particle locating in an internal part of secondary particle and a primary particle locating on the surface part of the secondary particle, and a method of preparing the same.

To improve cycling characteristics of a non-aqueous electrolyte secondary battery by obtaining a nickel-cobalt composite hydroxide having a sharp particle size distribution as a precursor, a slurry including a nickel-cobalt composite hydroxide obtained by continuously supplying an aqueous solution that includes at least nickel and cobalt, an ammonium ion donor aqueous solution and a caustic alkali aqueous solution to a reaction vessel and reacting, is continuously extracted and separated into a large particle size portion and s small particle size portion by classification, and the small particle size portion is continuously returned to the reaction vessel. As a result, a nickel-cobalt composite hydroxide is obtained that is expressed by the general formula: Ni.sub.1-x-yCo.sub.xM.sub.y(OH).sub.2 (where, 0.05x0.50, 0y0.10, 0.05x+y0.50, and M is at least one kind of metal element selected from among Al, Mg, Mn, Ti, Fe, Cu, Zn and Ga, and that satisfies the relationships (D50D10)/D500.30, and (D90D50)/D500.30 among D10, D50 and D90 of this composite hydroxide.

The invention is directed towards an electrochemically active cathode material for a battery. The electrochemically active cathode material includes a non-stoichiometric beta-delithiated layered nickel oxide. The non-stoichiometric beta-delithiated layered nickel oxide has a chemical formula. The chemical formula is L.sub.ixA.sub.yNi.sub.1+a-zM.sub.zO.sub.2nH.sub.2O where x is from about 0.02 to about 0.20; y is from about 0.03 to about 0.20; a is from about 0.02 to about 0.2; z is from about 0 to about 0.2; and n is from about 0 to about 1. Within the chemical formula, A is an alkali metal. The alkali metal includes potassium, rubidium, cesium, and any combination thereof. Within the chemical formula, M comprises an alkaline earth metal, a transition metal, a non-transition metal, and any combination thereof.

To improve cycling characteristics of a non-aqueous electrolyte secondary battery by obtaining a nickel-cobalt composite hydroxide having a sharp particle size distribution as a precursor, a slurry including a nickel-cobalt composite hydroxide obtained by continuously supplying an aqueous solution that includes at least nickel and cobalt, an ammonium ion donor aqueous solution and a caustic alkali aqueous solution to a reaction vessel and reacting, is continuously extracted and separated into a large particle size portion and s small particle size portion by classification, and the small particle size portion is continuously returned to the reaction vessel. As a result, a nickel-cobalt composite hydroxide is obtained that is expressed by the general formula: Ni.sub.1xyCo.sub.xM.sub.y(OH).sub.2 (where, 0.05x0.50, 0y0.10, 0.05x+y0.50, and M is at least one kind of metal element selected from among Al, Mg, Mn, Ti, Fe, Cu, Zn and Ga, and that satisfies the relationships (D50D10)/D500.30, and (D90D50)/D500.30 among D10, D50 and D90 of this composite hydroxide.

A positive electrode active material includes secondary particles. The secondary particles include a plurality of primary particles. The primary particles include a lithium-containing composite metal oxide. Inside the secondary particles, an electron conducting oxide is disposed at at least a part of a grain boundary between the primary particles. The electron conducting oxide has a perovskite structure.

A positive electrode active material is provided that has a high capacity, a low irreversible capacity, an excellent initial charge/discharge efficiency, and excellent rate characteristics. This positive electrode active material comprises a hexagonal lithium nickel complex oxide having a layer structure and represented by the general formula Li.sub.xNi.sub.1yzCo.sub.yM.sub.zO.sub.2 (0.98x1.04, 0.25y0.40, 0z0.07, and M is at least one element selected from Al, Ti, Mn, Ga, Mg, and Nb), wherein a lithium occupancy rate in a lithium main layer as obtained by Rietveld analysis from the x-ray diffraction pattern is at least 98.7%, and a crystallite diameter as calculated from the peak for the (003) plane in x-ray diffraction is 50 to 300 nm.

The present invention provides a positive electrode active material for a secondary battery, the positive electrode active material being a primary particle having a monolithic structure that includes a lithium composite metal oxide of Formula 1 below, wherein the primary particle has an average particle size (D.sub.50) of 2 m to 20 m and a Brunauer-Emmett-Teller (BET) specific surface area of 0.15 m.sup.2/g to 1.9 m.sup.2/g, and a secondary battery including the same.

The present invention provides a spinel-structured cathode active material, comprising lithium-containing compound particles having a chemical formula of LiNi.sub.0.5xMn.sub.1.5y{A}.sub.uO.sub.z and a first metal oxide and a second metal oxide coated on the surface of the lithium-containing compound particles, wherein the first metal oxide is an oxide of a metal having a valence of four or higher than four, and partially covers on the surface of the lithium-containing compound particles as a coating material; the second metal oxide is an oxide of a metal having a valence of lower than four, and the other areas on the surface of the lithium-containing compound particles that are not covered by the first metal oxide are coated with the second metal oxide in a thickness of 1-20 nm or forms a shallow gradient solid solution with a depth of less than 200 nm. When the cathode active material is applied to a lithium ion secondary battery, it has better cycling stability than an uncoated lithium transition metal oxide.

The present invention provides a positive electrode active material for a secondary battery, the positive electrode active material including a lithium composite metal oxide particle represented by Formula 1 below, and a secondary battery including the same.

Li.sub.aNi.sub.1?x?yCo.sub.xM1.sub.yM2.sub.zM3.sub.wO.sub.2[Formula 1]

In Formula 1,

M1 is a metal element whose surface energy (?E.sub.surf) calculated by Equation 1 below is ?0.5 eV or higher, M2 is a metal element whose surface energy (?E.sub.surf) calculated by Equation 1 below is ?1.5 eV or higher and less than ?0.5 eV, M3 is a metal element whose surface energy (?E.sub.surf) calculated by Equation 1 below is less than ?1.5 eV, and 1.0?a?1.5, 0<x?0.5, 0<z?0.05, 0.002?w?0.1, 0<x+y?0.7.

[00001]$\begin{array}{cc}\begin{array}{c}?.Math..Math.E_{\mathrm{surf}}=.Math.E_{\mathrm{surf}.Math..Math.2}-E_{\mathrm{surf}.Math..Math.1}\\ =.Math.\left(E_{\mathrm{slab}.Math..Math.2}-E_{\mathrm{bulk}}\right)-\left(E_{\mathrm{slab}.Math..Math.1}-E_{\mathrm{bulk}}\right)\end{array}& \left[\mathrm{Equation}.Math..Math.1\right]\end{array}$

In Equation 1 above, E.sub.surf2 represents an extent to which a metal element is oriented toward the outermost surface of the lithium composite metal oxide particle, E.sub.surf1 represents an extent to which the metal element is oriented toward a central portion of the lithium co