The present invention relates to a cathode active material for a secondary battery and a preparation method thereof, and more particularly, to a lithium composite oxide including a secondary particle formed as primary particles cohere, in which a manganese (Mn) oxide is present in the periphery of the primary particles, a concentration of an Mn oxide in the primary particle has a concentration gradient from the center of the primary particle to a surface of the particle, a concentration of an Mn oxide in the secondary particle has a concentration gradient from a surface of the secondary particle to the center thereof, and a lithium ion migration path is formed in the primary particle, and a preparation method thereof. A secondary battery including the cathode active material for a secondary battery may have high safety, while exhibiting high capacity and high output.

By using a potassium ion secondary battery positive electrode active material comprising a potassium compound represented by general formula (1): K.sub.nMO.sub.m, wherein M is copper or iron, n is 0.5 to 3.5, and m is 1.5 to 2.5, provided is a potassium ion secondary battery positive electrode active material having higher theoretical discharge capacity and higher effective capacity than a potassium secondary battery using Prussian blue as a positive electrode active material.

A positive electrode material for lithium secondary batteries capable of easily doping vanadium oxide with molybdenum, and a method of manufacturing the same are disclosed. The method of manufacturing a positive electrode material for lithium secondary batteries includes (a) reacting vanadium oxide with a water-soluble molybdenum-based compound in the presence of a solvent; and (b) thermally treating the reaction product of (a).

A lithium cobalt composite oxide for a lithium secondary battery and a lithium secondary battery, the lithium cobalt composite oxide including a magnesium (Mg)-doped lithium cobalt composite oxide having an atomic ratio of Mg to cobalt (Co) of about 0.0035:1 to about 0.01:1, wherein the Mg-doped lithium cobalt composite oxide further includes fluorine (F).

The present invention relates to a method of producing metal nanoparticles and metal sulfide nanoparticles using a recombinant microorganism co-expressing metallothionein and phytochelatin synthase, which are heavy metal-adsorbing proteins, and to the use of metal nanoparticles and metal sulfide nanoparticles synthesized by the method. The present invention provides a method for synthesizing metal nanoparticles which have been difficult to synthesize by conventional biological methods. The present invention makes it possible to synthesize metal nanoparticles in an environmentally friendly and cost-effective manner, and also makes it possible to synthesize metal sulfide nanoparticles. In addition, even metal nanoparticles which could have been produced by conventional chemical or biological methods are produced in a significantly increased yield by use of the method of the present invention.

According to one embodiment, an active material is provided. This active material includes active material particles containing orthorhombic Na-containing niobium titanium composite oxide, and satisfies the following formula (1):
1A5/A0(1) where A5 is a mole content ratio of a Li mole content L5 to a total of a Ti mole content T5 and a Nb mole content N5, and A0 is a mole content ratio of a Li mole content L0 to a total of a Ti mole content T0 and a Nb mole content N0.

According to one embodiment, an active material is provided. This active material includes active material particles containing orthorhombic Na-containing niobium titanium composite oxide, and satisfies the following formula (1):
1A5/A0(1) where A5 is a mole content ratio of a Li mole content L5 to a total of a Ti mole content T5 and a Nb mole content N5, and A0 is a mole content ratio of a Li mole content L0 to a total of a Ti mole content T0 and a Nb mole content N0.

Process for manufacturing a lithiated transition metal oxide, said process comprising the steps of (a) mixing at least one lithium salt and a precursor selected from transition metal oxides, transition metal oxyhydroxides, transition metal hydroxides, and transition metal carbonates, (b) pre-calcining the mixture obtained in step (a) at a temperature in the range of from 300 to 700 C., and (c) calcining the pre-calcined mixture according to step (b) in a multi-stage fluidized bed reactor at a temperature in the range of from 550 C. to 950 C.,
wherein the temperatures in step (b) and (c) are selected in a way that step (c) is being performed at a temperature higher than that of step (b).

Process for manufacturing a lithiated transition metal oxide, said process comprising the steps of (a) mixing at least one lithium salt and a precursor selected from transition metal oxides, transition metal oxyhydroxides, transition metal hydroxides, and transition metal carbonates, (b) pre-calcining the mixture obtained in step (a) at a temperature in the range of from 300 to 700 C., and (c) calcining the pre-calcined mixture according to step (b) in a multi-stage fluidized bed reactor at a temperature in the range of from 550 C. to 950 C.,
wherein the temperatures in step (b) and (c) are selected in a way that step (c) is being performed at a temperature higher than that of step (b).

A positive electrode active material comprising: a compound which has a crystal structure belonging to space group Fm-3m and which is represented by the following composition formula: Li.sub.xMe.sub.yO.sub.X.sub.. In the formula, the Me represents one or more elements selected from the group consisting of Mn, Ni, Co, Fe, Al, Sn, Cu, Nb, Mo, Bi, Ti, V, Cr, Y, Zr, Zn, Na, K, Ca, Mg, Pt, Au, Ag, Ru, Ta, W, La, Ce, Pr, Sm, Eu, Dy, and Er. The X represents one element selected from the group consisting of Cl, Br, I, N, and S. The following conditions are satisfied: 0.5x1.5; 0.5y1.0; 1<2; and 0<1.