High-temperature thermochemical energy storage materials using doped magnesium-transition metal spinel oxides are provided. transition metal spinel oxides, such as magnesium manganese oxide (MgMn).sub.3O.sub.4, are promising candidates for high-temperature thermochemical energy storage applications. However, the use of these materials has been constrained by the limited extent of their endothermic reaction. Embodiments described herein provide for doping magnesium-transition metal spinel oxides to produce a material of low material costs and with high energy densities, creating an avenue for plausibly sized modules with high energy storing capacities.

Provided is a new method for producing a positive electrode active material for lithium secondary batteries, by which even in the case of washing a spinel type lithium transition metal oxide with water or the like, the service life characteristics can be further enhanced, and the concentration of magnetic substances can be effectively reduced. Suggested is a method for producing a positive electrode active material for lithium secondary batteries, the method including a water washing step of bringing a powder of a spinel type lithium transition metal oxide into contact with a polar solvent and thereby washing the powder; and a drying step of subsequently drying the powder by heating the powder to 300 C. to 700 C. in an atmosphere containing oxygen.

A method of producing an oxide of manganese including reacting, in a first aqueous solution, a manganese salt and an alkali agent to form manganese hydroxide; separating the manganese hydroxide from the first solution; mixing the manganese hydroxide into an aqueous medium to form a manganese hydroxide suspension; mixing the manganese hydroxide suspension with alkali metal hydroxide to form a second aqueous solution; and oxidizing the manganese hydroxide in the second aqueous solution to form an oxide of manganese. The dried oxide of manganese includes birnessite, a maximum of 20% hausmannite, and a maximum of 10% feitknechtite, may further include a maximum of 400 ppm of anions, may have a specific surface area of at least 25 m.sup.2/g, and may have an average oxidation state of greater than 3.5.

A method for producing a nickel cobalt complex hydroxide includes first crystallization of supplying a solution containing Ni, Co and Mn, a complex ion forming agent and a basic solution separately and simultaneously to one reaction vessel to obtain nickel cobalt complex hydroxide particles, and a second crystallization of, after the first crystallization, further supplying a solution containing nickel, cobalt, and manganese, a solution of a complex ion forming agent, a basic solution, and a solution containing said element M separately and simultaneously to the reaction vessel to crystallize a complex hydroxide particles containing nickel, cobalt, manganese and said element M on the nickel cobalt complex hydroxide particles crystallizing a complex hydroxide particles comprising Ni, Co, Mn and the element M on the nickel cobalt complex hydroxide particles.

An inorganic sorbent for lithium extraction from lithium-containing natural and technological brines, which have low concentration of lithium. The sorbent has high selectivity for lithium in ion-exchange lithium-extraction processes and is expressed by the following general formula:

H.sub.xMnO.sub.y.Math.zAl.sub.2O.sub.3.Math.nH.sub.2O;

wherein: x is a number ranging from 0.5 to 2.0, y is a number ranging from 2.0 to 3.0, z is a number ranging from 0.01 to 0.1, and n is a number ranging from 1.0 to 2.0.

An electro-active material, including a mixture of a first component including at least a first compound of formula (I) Li.sub.xMnO.sub.y and a second component including at least a second compound of formula (II) Li.sub.xH.sub.yV.sub.3O.sub.8, wherein in formula (I): 0x2, 1y3, and 22yx5, and wherein in formula (II): 0x4.5, 0.01y2, and 0.01x+y6.5. The first compound is in the form of particles having a certain particle size and the second compound is in the form of nanoparticles having a certain particle size or nanofibers having certain dimensions. The first and second components are present in amounts of 1:99% to 99:1% by weight, and the mixture, upon being mechanically pressed in a range of 20 to 70 KN with a die, has a synergic effect of pressed density (SEPD) greater than 100%.

A method for producing a nickel cobalt complex hydroxide includes first crystallization of supplying a solution containing Ni, Co and Mn, a complex ion forming agent and a basic solution separately and simultaneously to one reaction vessel to obtain nickel cobalt complex hydroxide particles, and a second crystallization of, after the first crystallization, further supplying a solution containing nickel, cobalt, and manganese, a solution of a complex ion forming agent, a basic solution, and a solution containing said element M separately and simultaneously to the reaction vessel to crystallize a complex hydroxide particles containing nickel, cobalt, manganese and said element M on the nickel cobalt complex hydroxide particles crystallizing a complex hydroxide particles comprising Ni, Co, Mn and the element Mon the nickel cobalt complex hydroxide particles.

The invention is concerned with a method for combined production of nanomaterials and heat. The method comprises feeding at least one precursor material and a fuel into a combustion unit for the generation of heat and nanoparticles, whereby the precursor material is combusted to be decomposed and oxidized in a sufficient temperature. The heat generated in the combustion of the fuel and the precursor material is recovered by using at least one heat exchanger. The combusted fuel is cooled down and the nanoparticles generated in the form of oxides in the combustion are collected. The system of the invention for combined production of nanomaterials and heat comprises a combustion unit, means for feeding at least one precursor material, fuel and oxidizer into the combustion unit for combustion, a heat exchanger for recovering heat from the combustion unit, and for cooling the combusted fuel, and means for collecting nanomaterials in the form of oxides from the combustion of the precursor material(s).

According to one embodiment, there is provided an active material. The active material includes a composite oxide. The composite oxide has a monoclinic crystal structure. The composite oxide is represented by a general formula of Li.sub.wNa.sub.4-xM1.sub.yTi.sub.6-zM2.sub.zO.sub.14+. In the general formula, the M1 is at least one element selected from the group consisting of Rb, Cs, K and H; the M2 is at least one metallic element selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Fe, Co, Mn and Al; w is within a range of 0w<12; x is within a range of 0<x<4; y is within a range of 0y<2; z is within a range of 0<z<6; and is within a range of 0.30.3.

A method of forming a high energy density composite cathode material is disclosed. The method includes providing a lithium-rich manganese layered oxide (LRMO), coating the LRMO with a TiO.sub.2 precursor, and ball-milling the TiO.sub.2 coated LRMO with LiH to form a Li.sub.xTiO.sub.2 coated LRMO composite, wherein x is less than or equal to 1 and greater than zero.