Provided is a positive electrode active material that is capable of simultaneously improving the battery capacity, output characteristics and cycling characteristics of a secondary battery. When obtaining a transition metal-containing composite hydroxide that is a precursor to the positive electrode active material, by adjusting the pH value of a reaction aqueous solution to be within the range 12.0 to 14.0 and performing generation of nuclei (nucleation), and then adjusting the pH value of the reaction aqueous solution to be within the range 10.5 to 12.0 and causing the nuclei to grow (particle growth), atmosphere control is performed at least one time in which the reaction atmosphere during nucleation and in the initial stage of particle growth is adjusted to be a non-oxidizing atmosphere, and during particle growth is switched to be an oxidizing atmosphere having an oxygen concentration that is 5% by volume or more by directly introducing an oxidizing gas into the reaction aqueous solution while continuing the supply of a raw material aqueous solution, and then is further switched to a non-oxidizing atmosphere by directly introducing an inert gas into the reaction aqueous solution while continuing the supply of the raw material aqueous solution.

A positive electrode active material for a magnesium secondary battery, and a positive electrode for a magnesium secondary battery and a magnesium secondary battery in which the positive electrode active material is used are provided. The positive electrode active material consists of a magnesium composite oxide which is represented by Formula (1): Mg.sub.xM1.sub.yM2.sub.zO.sub.2 and which has a rock salt-type crystal structure of space group Fm-3m. In Formula (1), M1 is Ni, Co, or Mn, M2 is different from M1 and is at least one element selected from the group consisting of Ni, Co, Mn, Ti, V, Cr, Fe, Cu, Nb, W, Mo, and Ru, 0<x1, 0<y<2, 0<z<1; and 1.5<x+y+z2.0.

The present invention discloses a high-voltage ternary positive electrode material for lithium-ion battery and preparation method thereof. The chemical formula of the material is LiNi.sub.0.6-xMg.sub.xCo.sub.0.2-yAl.sub.yMn.sub.0.2-zTi.sub.zO.sub.2-dF.sub.d, wherein 0<x,y,z,d0.05. The precursor of the positive electrode material is synthesized by gradient co-precipitation method and the positive electrode material is prepared by solid phase method. The content of nickel in the synthesized precursor particles has a gradient distribution from the inside to the outside. The obtained precursor is mixed and grinded evenly with the lithium source and the fluorine source at a certain ratio and put into the tube furnace. The obtained precursor is then pre-sintered in the oxygen-enriched air atmosphere and then heated up to be sintered, to obtain the target product. The positive electrode material for lithium-ion battery prepared by the method is free from impurity phase and has a good crystallinity, which is a high energy density positive electrode material.

A nickel-based active material for a lithium secondary battery includes a porous inner portion having closed pores and an outer portion, wherein the porous inner portion has a density less than that of the outer portion, and the nickel-based active material has a net density of 4.7 g/cc or less. A method of preparing the same, and a lithium secondary battery including a positive electrode including the nickel-based active material are provided.

A positive electrode active material for a lithium secondary cell, having a layered structure and comprising at least nickel, cobalt and manganese, the positive electrode active material satisfying requirements (1), (2) and (3) below: (1) a composition represented by a composition formula: Li[Li.sub.x(Ni.sub.Co.sub.Mn.sub.M.sub.).sub.1-x]O.sub.2, wherein 0x0.10, 0.30<0.34, 0.30<0.34, 0.32<0.40, 00.10, <, +++=1, M represents at least one metal selected from the group consisting of Fe, Cu, Ti, Mg, Al, W, Zn, Sn, Zr, Ga and V; (2) a secondary particle diameter of 2 m or more and 10 m or less; and (3) a maximum peak value in a pore diameter range of 90 nm to 150 nm in a pore diameter distribution determined by mercury porosimetry.

A positive electrode active material for non-aqueous electrolyte secondary battery with improved cycle characteristics and high temperature storage characteristics, without impairing an advantage of high capacity which lithium nickel composite oxide inherently possesses. The positive electrode active material for non-aqueous electrolyte secondary battery includes lithium nickel composite oxide represented by a general formula (1): Li.sub.1+uNi.sub.1xyzCo.sub.xMn.sub.yMg.sub.zO.sub.2 (However, u, x, y and z in the formula satisfies 0.015u0.030, 0.05x0.20, 0.01y0.10, 0.01z0.05, 0.10x+y+z0.25.), and wherein crystallite diameter is 100 nm to 130 nm. In addition, the positive electrode active material for non-aqueous electrolyte secondary battery is produced at least by an oxidation roasting step, a mixing step, and a calcining step.

A composite oxide which includes lithium, at least one of calcium and magnesium, and nickel and manganese, and has a lithium-excess layered rock-salt structure, and a cathode active material and a lithium secondary battery which contain the composite oxide.

A two-step thermochemical gas reduction process based on poly-cation oxides includes repeatedly cycling a thermal reduction step and a gas reduction step. In the thermal reduction the poly-cation oxide is heated to produce a reduced poly-cation oxide and oxygen. In the gas reduction step, the reduced poly-cation oxide is reacted with a gas to reduce the gas, while reoxidizing the poly-cation oxide. The poly-cation oxide has at least two distinct crystal structures at two distinct temperatures and is capable of undergoing a reversible phase transformation between the two distinct crystal structures. For example, the poly-cation oxide may be an entropy tuned mixed metal oxide, such as an entropy stabilized mixed metal oxide, where the entropy-tuning is achieved via change in crystal structure of one of more of the compounds involved. The gas reduction process may be used for water splitting, CO.sub.2 splitting, NO.sub.x reduction, and other gas reduction processes.

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.

The invention relates to novel electrodes containing one or more active materials comprising: A.sub.aM.sup.1.sub.vM.sup.2.sub.wM.sup.3.sub.xM.sup.4.sub.YM.sup.5.sub.zO.sub.2C(Formula 1) wherein A comprises either sodium or a mixed alkali metal in which sodium is the constituent; M.sup.1 is nickel in oxidation state less than or equal to 4+, M.sup.2 comprises a metal in oxidation state less than or equal to 4+, M.sup.3 comprises a metal in oxidation state 2+, M.sup.4 comprises a metal in oxidation state less than or equal to 4+, and M.sup.5 comprises a metal in oxidation state 3+ wherein 0a1 v>0 at least one of w and y is >0 x0 z0 c>0.1 where (a, v, w, x, y, z and c) are chosen to maintain electroneutrality. Such materials are useful, for example, as electrode materials in sodium-ion battery applications.
A.sub.aM.sup.1.sub.VM.sup.2.sub.WM.sup.3.sub.XM.sup.4.sub.YM.sup.5.sub.ZO.sub.2c(Formula 1)