A positive electrode active material has a small difference in a crystal structure between the charged state and the discharged state. For example, the crystal structure and volume of the positive electrode active material, which has a layered rock-salt crystal structure in the discharged state and a pseudo-spinel crystal structure in the charged state at a high voltage of approximately 4.6 V, are less likely to be changed by charging and discharging as compared with those of a known positive electrode active material. In order to form the positive electrode active material having the pseudo-spinel crystal structure in the charged state, it is preferable that a halogen source such as a fluorine and a magnesium source be mixed with particles of a composite oxide containing lithium, a transition metal, and oxygen, which is synthesized in advance, and then the mixture be heated at an appropriate temperature for an appropriate time.

The present invention relates to a method for synthesizing dysprosium-doped cobalt-chromate for supercapacitor applications and a composition for the same, wherein an efficient and cost-effective Solution Combustion synthesis method is utilized for the preparation of Dy-doped CoCr.sub.2O.sub.4 (CCD). The stoichiometric dissolution of metal and rare earth nitrates, along with fuels, in distilled water forms a green-colored solution, subsequently heated to 450 degrees Celsius. The resulting ash undergoes grinding to yield a fine green pigment with a controlled size of 25 nm. Electrochemical properties of CCD are thoroughly examined through cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. Capacitive behavior, evaluated via various techniques, demonstrates an increase in capacitance with Dy.sup.3+ concentration. Density of states calculations reveal improved electronic features after Dy.sup.3+ doping, emphasizing enhanced charge storage capabilities. This invention provides insights into an advanced synthesis approach and the electrochemical potential of Dy-doped CoCr.sub.2O.sub.4 for energy storage applications.

Homogeneous water oxidation catalysts (WOCs) for the oxidation of water to produce hydrogen ions and oxygen, and methods of making and using thereof are described herein. In a preferred embodiment, the WOC is a polyoxometalate WOC which is hydrolytically stable, oxidatively stable, and thermally stable. The WOC oxidized waters in the presence of an oxidant. The oxidant can be generated photochemically, using light, such as sunlight, or electrochemically using a positively biased electrode. The hydrogen ions are subsequently reduced to form hydrogen gas, for example, using a hydrogen evolution catalyst (HEC). The hydrogen gas can be used as a fuel in combustion reactions and/or in hydrogen fuel cells. The catalysts described herein exhibit higher turn over numbers, faster turn over frequencies, and/or higher oxygen yields than prior art catalysts.

The disclosed embodiments relate to the manufacture of a precursor co-precipitate material for a cathode active material composition. During manufacture of the precursor co-precipitate material, an aqueous solution containing at least one of a manganese sulfate and a cobalt sulfate is formed. Next, a NH.sub.4OH solution is added to the aqueous solution to form a particulate solution comprising irregular secondary particles of the precursor co-precipitate material. A constant pH in the range of 10-12 is also maintained in the particulate solution by adding a basic solution to the particulate solution.

A ferrite composition is provided containing Ba, Co, and Ir and having a Z-type hexaferrite phase and a Y-type hexaferrite phase. The ferrite composition has the formula Ba.sub.3Co.sub.(2-x)Ir.sub.xFe.sub.(24-2x)O.sub.41 where x=0.05-0.20. The composition has equal or substantially equal values of permeability and permittivity while retaining low magnetic and dielectric loss factors. The composition is suitable for ultrahigh frequency applications such as high frequency and microwave antennas.

The disclosed embodiments relate to the manufacture of a precursor co-precipitate material for a cathode active material composition. During manufacture of the precursor co-precipitate material, an aqueous solution containing at least one of a manganese sulfate and a cobalt sulfate is formed. Next, a NH.sub.4OH solution is added to the aqueous solution to form a particulate solution comprising irregular secondary particles of the precursor co-precipitate material. A constant pH in the range of 10-12 is also maintained in the particulate solution by adding a basic solution to the particulate solution.

Ferrite films, antennas including ferrite films, and methods of making thereof are provided. The methods can include tape casting of a slurry to produce a green film, wherein the slurry includes a ferrite powder, a dispersant, and a binder in a suitable solvent; and densifying the green film to produce the ferrite film having a thickness of 50 m to 5 mm. The methods can be used to make large area films, for example the films can have a lateral area of about 1000 cm.sup.2 to 3000 cm.sup.2. VHF/UHF antennas are including the ferrite films are also provided.

A method for delithiating a lithium and transition metal nitride. The method involves mixing an oxidising agent with the lithium and transition metal nitride and recovering the material obtained. The transition metal may be Mn, Fe, Co, Ni, Cu, or a mixture thereof. The material obtained by the method may be used as a negative electrode material for a lithium-ion battery.

Provided are methods for preparing and using reaction vessels obtained or obtainable by 3D-printing methods, including a method for preparing a product compound, the method comprising the steps of: (i) providing a reaction vessel that is obtained by a 3-D printing method, wherein the reaction vessel has a reaction space; (ii) providing one or more reagents, optionally together with a catalyst or a solvent, for use in the synthesis of the product compound; and (iii) permitting the one or more reagents to react in the reaction space, optionally in the presence of the catalyst and the solvent, in the reaction vessel, thereby to form the product compound.

[Summary] A positive electrode active material is provided to contain: a solid solution lithium-containing transition metal oxide (A) represented by Li.sub.1.5[Ni.sub.aCo.sub.bMn.sub.c[Li].sub.d]O.sub.3 (where a, b, c and d satisfy the relations of a+b+c+d=1.5, 0.1<d0.4, 1.1a+b+c<1.4, 0.2a0.7 and 0<b/a<1); and a lithium-containing transition metal oxide (B) represented by LiM.sub.XMn.sub.2XO.sub.4 (where M represents Cr or Al, and x satisfies the relation of 0x<2).