A layered oxide material, a preparation method, an electrode, a secondary battery and use are disclosed. The layered oxide material has a general chemical formula Na.sub.xCu.sub.iFe.sub.jMn.sub.kM.sub.yO.sub.2+β, in which M is an element that is doped for replacing the transition metals; x, y, i, j, k, and β are respectively the molar ratios of respective elements, provided that x, y, i, j, k, and β satisfy the relations: y+i++j+k=1, and x+my+2i+3j+4k=2(2+β), where 0.8≦x≦1, 0<i≦0.3, 0<j≦0.5, 0<k≦0.5, 0.02≦β≦0.02, and m is the valence of M. The layered oxide material has a space group of R3m.

A positive electrode for a sodium ion secondary battery includes a positive electrode active material that intercalates and deintercalates sodium ions, a conductive assistant, a binder, and a carboxylic acid, the binder containing a vinylidene fluoride-based polymer, the carboxylic acid having at least one of a boiling point and a thermal decomposition point, and whichever of the boiling point and the thermal decomposition point is lower being higher than 150° C. The carboxylic acid is preferably at least one selected from the group consisting of hydroxy acids and polycarboxylic acids.

The present invention relates to cellulose nanofibrils decorated with magnetic nanoparticles as well as a method for the preparation thereof and a material comprising the nanofibrils.

A positive electrode active material for a sodium secondary battery includes a sodium composite transition metal oxide represented by Formula 1 and having a P3 crystal structure, and a positive electrode and a sodium secondary battery which include the positive electrode active material.
Na.sub.x[Li.sub.aM.sub.1-a]O.sub.2  [Formula 1]
wherein M is at least one transition metal, 0.64≤x≤0.7, and 0.01≤a≤0.1.

A sintered MnZn ferrite body containing main components comprising 53.30-53.80% by mol of Fe calculated as Fe.sub.2O.sub.3, 6.90-9.50% by mol Zn calculated as ZnO, and the balance of Mn calculated as MnO, and sub-components comprising 0.003-0.020 parts by mass of Si calculated as SiO.sub.2, more than 0 parts and 0.35 parts or less by mass of Ca calculated as CaCO.sub.3, 0.30-0.50 parts by mass of Co calculated as Co.sub.3O.sub.4, 0.03-0.10 parts by mass of Zr calculated as ZrO.sub.2, and 0-0.05 parts by mass of Ta calculated as Ta.sub.2O.sub.5, pre 100 parts by mass in total of the main components (calculated as the oxides), and having an average crystal grain size of 3 μm or more and less than 8 μm and a density of 4.65 g/cm.sup.3 or more.

Described herein is a method for producing ferrite nanocrystals. The method includes providing a solution including a fatty acid, an aliphatic amine and an alcoholic solvent, adding at least one organometallic precursor compound including a metal selected from the group consisting of Fe, Mn, Co and Zn and an aromatic organic molecule to the solution thereby obtaining a reaction mixture, transferring the reaction mixture to a sealed reactor, thereby obtaining a filling percentage of the sealed reactor between 20 and 70 vol. %, and heating the sealed reactor to a temperature between 160° C. and 240° C. for at least 3 hours.

Electrode materials comprising an electrochemically active material, wherein said electrochemically active material comprises a layered potassium metal oxide. The layered potassium metal oxide may be of formula K.sub.xMO.sub.2. The invention also relates to electrodes, electrochemical cells and batteries comprising said electrode material. For example, said battery may be a lithium or lithium-ion battery, a sodium or sodium-ion battery, or a potassium or potassium-ion battery.

An improved method of forming a transition metal layered oxide material for alkali-ion battery cathodes include combining an alkali-containing precursor and at least one transition metal precursor or other metal precursor at a low temperature of less than 100° C. to form a liquid eutectic alloy mixture. The mixture is then heated at a temperature between 300° C. to 500° C. to pre-calcinate the mixture, and subsequently the pre-calcinated mixture is subjected to a final calcination at a temperature of 500° C. to 1000° C. to obtain a crystalline oxide material. A P2-type or O3-type cathode may be formed with the layered oxide material, and a sodium-ion battery cell may include the so-formed P2-type or O3-type cathode.

Thermochemical storage materials having the general formula A.sub.xA′.sub.1-xB.sub.yB′.sub.1-yO.sub.3-δ, where A=La, Sr, K, Ca, Ba, Y and B=Mn, Fe, Co, Ti, Ni, Cu, Zr, Al, Y, Cr, V, Nb, Mo, are disclosed. These materials have improved thermal storage energy density and reaction kinetics compared to previous materials. Concentrating solar power thermochemical systems and methods capable of storing heat energy by using these thermochemical storage materials are also disclosed.

The present invention relates to a ferrite particle, containing a crystal phase component containing a perovskite crystal represented by the compositional formula:

RZrO.sub.3 (provided that R represents an alkaline earth metal element), and having an apparent density in a range represented by the following formula:

1.90≤Y≤2.45

provided that Y in the formula is the apparent density (g/cm.sup.3) of the ferrite particle.