Disclosed herein are embodiments of composite hexagonal ferrite materials formed from a combination of Y phase and Z phase hexagonal ferrite materials. Advantageously, embodiments of the material can have a high resonant frequency as well as a high permeability. In some embodiments, the materials can be useful for magnetodielectric antennas.

The disclosure discloses a method for preparing a high-voltage cathode material by body modification and regeneration of a waste lithium cobaltate material. The waste lithium cobaltate cathode material is calcined, and then measured; a lithium source, a magnesium source, nano-scale TiO.sub.2 and the waste lithium cobaltate cathode material powder are mixed to obtain a mixture, placed in a ball milling tank containing absolute ethanol, and the resulting mixture is ball milled, and then dried to obtain a mixed powder; the mixed powder is calcined to obtain a magnesium-titanium co-doped regenerated lithium cobaltate cathode material; the magnesium-titanium co-doped regenerated lithium cobaltate cathode material is added into a mixed solution obtained by ultrasonically mixing absolute ethanol with the aluminum source, and then heated and stirred continually until the solvent evaporates to obtain a residue; the residue is calcined to obtain an aluminum-coated magnesium-titanium co-doped regenerated lithium cobaltate cathode material.

The disclosure discloses a method for preparing a high-voltage cathode material by body modification and regeneration of a waste lithium cobaltate material. The waste lithium cobaltate cathode material is calcined, and then measured; a lithium source, a magnesium source, nano-scale TiO.sub.2 and the waste lithium cobaltate cathode material powder are mixed to obtain a mixture, placed in a ball milling tank containing absolute ethanol, and the resulting mixture is ball milled, and then dried to obtain a mixed powder; the mixed powder is calcined to obtain a magnesium-titanium co-doped regenerated lithium cobaltate cathode material; the magnesium-titanium co-doped regenerated lithium cobaltate cathode material is added into a mixed solution obtained by ultrasonically mixing absolute ethanol with the aluminum source, and then heated and stirred continually until the solvent evaporates to obtain a residue; the residue is calcined to obtain an aluminum-coated magnesium-titanium co-doped regenerated lithium cobaltate cathode material.

A method for making an iron-based oxide magnetic powder includes adding raw material solution containing trivalent iron ions, or trivalent iron ions and ions of a metal element that partially substitutes Fe sites, and an alkaline aqueous solution for neutralizing the raw material solution to a reaction system to adjust the pH of the reaction system to 1.0 or higher and 3.0 or lower. Hydroxycarboxylic acid is added to the obtained reaction solution and thereafter the pH of the reaction system is neutralized to 7.0 or higher and 10.0 or lower. The obtained precipitate of a substituent metal element-containing iron oxyhydroxide is coated with silicon oxide and then heated, whereby an iron-based oxide magnetic powder is obtained with a reduced content of fine and coarse particles, a particle shape close to a perfect sphere, and particles of ε-iron oxide in which Fe sites are partially substituted by other metal elements.

The present invention provides a positive active material for a rechargeable lithium battery, the active material including a dopant and having a crystalline structure in which metal oxide layers (MO layers) including metals and oxygen and reversible lithium layers are repeatedly stacked, wherein in a lattice configured by oxygen atoms of the MO layers adjacent to each other, the dopant time of charge, thereby forming a lithium trap and/or lithium dumbbell structure.

The present invention provides a positive active material for a rechargeable lithium battery, the active material including a dopant and having a crystalline structure in which metal oxide layers (MO layers) including metals and oxygen and reversible lithium layers are repeatedly stacked, wherein in a lattice configured by oxygen atoms of the MO layers adjacent to each other, the dopant time of charge, thereby forming a lithium trap and/or lithium dumbbell structure.

A positive electrode active material for a secondary battery is provided. The positive electrode active material being a lithium cobalt-based oxide includes a doping element M. A lithium cobalt-based oxide particle containing the doping element M in an amount of 3,000 ppm or more, wherein in a bulk portion corresponding to 90% of a core side among the radius from a core of the particle to a surface thereof, the doping element M in the lithium cobalt-based oxide particle is contained at a constant concentration, and in a surface portion from the surface of the particle to 100 nm in a core direction, the doping element M is contained at a concentration equal to or higher than that in the bulk portion and has a concentration in which the concentration thereof is gradient gradually decreased in the core direction from the surface of the particle.

The present invention provides a positive electrode active material precursor for a secondary battery which includes primary particles of Co.sub.3O.sub.4 or CoOOH, wherein the primary particle contains a doping element in an amount of 3,000 ppm or more, and has an average particle diameter (D.sub.50) of 15 μm or more, and a positive electrode active material for a secondary battery which includes particles of a lithium cobalt-based oxide, wherein the primary particle contains a doping element in an amount of 2,500 ppm or more, and has an average particle diameter (D.sub.50) of 15 μm or more.

The present invention provides a positive electrode active material precursor for a secondary battery which includes primary particles of Co.sub.3O.sub.4 or CoOOH, wherein the primary particle contains a doping element in an amount of 3,000 ppm or more, and has an average particle diameter (D.sub.50) of 15 μm or more, and a positive electrode active material for a secondary battery which includes particles of a lithium cobalt-based oxide, wherein the primary particle contains a doping element in an amount of 2,500 ppm or more, and has an average particle diameter (D.sub.50) of 15 μm or more.

A CoVO.sub.x composite electrode and method of making is described. The composite electrode comprises a substrate with an average 0.5-5 μm thick layer of CoVO.sub.x having pores with average diameters of 2-200 nm. The method of making the composite electrode involves contacting the substrate with an aerosol comprising a solvent, a cobalt complex, and a vanadium complex. The CoVO.sub.x composite electrode is capable of being used in an electrochemical cell for water oxidation.