A method of preparing a positive active material involves mixing a nickel compound, a cobalt compound, and optionally a metal compound to obtain a first mixture, subjecting the first mixture to a co-precipitation reaction to obtain a first resulting product, washing with water, filtering and drying the first resulting product to prepare a transition metal hydroxide precursor, subjecting the transition metal hydroxide precursor to a primary heat treatment to prepare a transition metal composite oxide precursor, mixing the transition metal composite oxide precursor and a dehydrated lithium salt to obtain a second mixture, and performing a secondary heat treatment on the second mixture to prepare a nickel-based lithium transition metal oxide. The dehydrated lithium salt is prepared by drying a hydrated lithium salt having an average particle diameter (D.sub.50) of about 400-600 m and then pulverizing the resultant to have a D.sub.50 of about 3-30 m.

A positive active material for a rechargeable lithium battery includes a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2, the second compound having a smaller particle size than that of the first compound, wherein cation mixing in the surface portion of the positive active material is less than or equal to about 7.5%, cation mixing in the bulk of the positive active material is less than or equal to about 3%, a residual lithium content on the surface of the positive active material is less than or equal to about 3,000 ppm, and the first compound and the second compound each independently include 90 at % to about 98 at % of Ni with respect to the metals excluding Li.

Li.sub.a1Ni.sub.x1Co.sub.y1M.sup.1.sub.1x1y1O.sub.2,Chemical Formula 1

Li.sub.a2Ni.sub.x2Co.sub.y2M.sup.2.sub.1x2y2O.sub.2.Chemical Formula 2

A metal composite hydroxide represented by a general formula (1): Ni.sub.1xyCo.sub.xMn.sub.yM.sub.z(OH).sub.2+ (where 0.02x0.3, 0.02y0.3, 0z0.05, and 0.50.5 are satisfied and M is at least one element selected from the group consisting of Mg, Ca, Al, Si, Fe, Cr, V, Mo, W, Nb, Ti, and Zr), in which the metal composite hydroxide contains a first particle having a core portion inside the particle and a shell portion formed around the core portion and [(D90D10)/MV] is less than 0.80.

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, 0.0x0.5; 0.0y0.5; 0.1z0.5; 0.0t0.3; 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.

The present disclosure relates to a positive active material for a lithium rechargeable battery and a lithium rechargeable battery including the same, which include a first compound represented by Chemical Formula 1 and a second compound represented by Chemical Formula 2, and a content of the first compound is 65 wt % or more based of the positive active material of 100 wt %.

Li.sub.a1Ni.sub.b1Co.sub.c1Mn.sub.d1M1.sub.e1M2.sub.f1O.sub.2-f1[Chemical Formula 1]

Li.sub.a2Ni.sub.b2CO.sub.c2Mn.sub.d2M3.sub.e2M4.sub.f2O.sub.2-f2[Chemical Formula 2] Chemical Composition 1 and 2 of each composition and molar ratio is as defined in the specification. Each composition and molar ratio of Chemical Formula 1 and 2 is as defined in the specification.

The present invention provides a method of preparing a positive electrode active material for a secondary battery including preparing a first transition metal-containing solution including a nickel raw material, a cobalt raw material, and a manganese raw material and a second transition metal-containing solution including a nickel raw material, a cobalt raw material, and a manganese raw material in a concentration different from that of the first transition metal-containing solution; preparing a reaction solution, in which nickel manganese cobalt-based composite metal hydroxide particles are formed, by adding an ammonium cation-containing complexing agent and a basic compound as well as the second transition metal-containing solution to the first transition metal-containing solution and performing a co-precipitation reaction in a pH range of 11 to 13.

Provided are a positive electrode active material for nonagueous secondary batteries, the material having a narrow particle-size distribution and a monodisperse property and being capable of increasing a battery capacity; an industrial production method thereof; and a nonaqueous secondary battery using the positive electrode active material and having excellent electrical characteristics. The positive electrode active material is represented by a general formula: Li.sub.1+uNi.sub.xCo.sub.yMn.sub.zM.sub.tO.sub.2+ (wherein, 0.05u0.95, x+y+z+t=1, 0x0.5, 0y0.5, 0.5z<0.8, 0t0.1, and M is an additive element and at least one element selected from Mg, Ca, Al, Ti, V, Cr, Zr, Nb, Mo, and W), has an average particle diameter of 3 to 12 um, and has [(d.sub.90d.sub.10)/average particle diameter], an index indicating a scale of particle-size distribution, of 0.60 or less.

An anode active material for a sodium ion secondary battery, a sodium ion secondary battery including an anode active material, and an electric device including the sodium ion secondary battery are disclosed. The anode active material for a sodium ion secondary battery includes a cobalt tin spinel oxide represented by Co.sub.2.4Sn.sub.0.6O.sub.4. The sodium ion secondary battery includes an anode made of an anode active material composed of a cobalt tin spinel oxide represented by Chemical Formula 1 below:
Co.sub.2+xSn.sub.1-xO.sub.4,Chemical Formula 1 where x is a real number satisfying 0x0.9; an electrolyte; and a cathode. The sodium ion secondary battery has high capacity characteristics. The electric device including the sodium ion secondary battery includes an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, and an electric power storage system.

Scalable pseudocapacitive cathode materials are provided that can be effectively paired with pseudocapacitive anode materials and used to produce fast charging, long cycle lifetime lithium ion batteries. A sol-gel templating method which forms materials with dissolution resistant surfaces that can avoid capacity loss due to dissolution in high surface area nanostructured LiMn.sub.2O.sub.4 powders, is also provided. The materials have a long needle-like morphology with dominant <111> surface sites and demonstrate higher capacity and less dissolution than similarly sized materials synthesized with a different structure.

The present invention relates to a method for removing radioactive element thorium in a rare earth mineral, comprising: mixing the rare earth mineral with selenium dioxide in water, reacting radioactive element thorium with selenium dioxide by hydrothermal method, cooling to form a crystal, and separating the crystal to remove the radioactive element thorium. In the invention, tetravalent element thorium is selectively bound to inorganic ligand selenium dioxide in a hydrothermal environment to form a crystal, thereby achieving removal of radioactive element thorium. The method has high crystallization rate and high decontamination efficiency, and removes thorium from trivalent lanthanide element by crystallization solidification under a uniform reaction condition. Compared to a conventional industrial method for thorium separation, the method has low energy consumption and high separation ratio, enables one-step solidification separation, and effectively avoids the disadvantages of redundant separation operations and a large amount of organic and radioactive liquid wastes.