The present invention features a new way of doping layered cathode materials in lithium ion batteries. Using a .sup.“high entropy” doping strategy, more than four impurity elements can be introduced to the host materials. The present invention applies this high entropy doping strategy to a high nickel content layered oxide material and a lithium-manganese rich material. This new high entropy doping strategy allows the layered oxide materials used in the positive electrode of lithium ion battery to achieve high energy density, long life cycle and reduced reliance on the expensive and toxic cobalt, all of which are desired attributes for improving the performance of lithium ion batteries and reducing their cost.

A positive electrode active material with high charge and discharge capacity is provided. A positive electrode active material with high charge and discharge voltage is provided. A power storage device that hardly deteriorates is provided. A highly safe power storage device is provided. A novel power storage device is provided. A positive electrode active material containing lithium, a plurality of transition metals, oxygen, and an impurity element. The positive electrode active material includes a first region including a surface portion and a second region provided inward from the first region, and the concentration of a transition metal is higher in the first region than in the second region. An impurity region is included between the first region and the second region.

A coated particle having excellent thermal expansion control and electrical insulation properties includes a core of a first inorganic compound containing a metal or semimetal element P; and a shell of a second inorganic compound containing a metal or semimetal element Q. The first inorganic compound satisfies 1, and the coated particles satisfy 2 and 3. 1: |dA(T)/dT| is ≥10 ppm/°C at T1 of -200° C. to 1,200° C. A is (an a-axis lattice constant of a crystal in the first inorganic compound)/(a c-axis lattice constant of a crystal in the first inorganic compound). 2: in XPS of a surface of each of the coated particles, a ratio of a number of atoms of Q contained in the shell to a number of atoms of P contained in the core t is 45 to 300. 3: an average particle diameter of each coated particle is 0.1 to 100 .Math.m.

A method for producing mesoporous magnesium hydroxide nanoplates involving solvothermal treatment of a solution of a magnesium salt, a base, a glycol, and water is disclosed. The method does not use a surfactant or template in the solvothermal treatment. The method yields mesoporous nanoparticles of magnesium hydroxide having a plate-like morphology with a diameter of 20 nm to 100 nm, a mean pore diameter of 2 to 10 nm, a surface area of 50 to 70 m.sup.2/g, and a type-III nitrogen adsorption-desorption BET isotherm with a H3 hysteresis loop. An antibacterial composition containing the mesoporous magnesium hydroxide nanoplates is also disclosed. A method for reducing nitroaromatic compounds with a reducing agent and the mesoporous magnesium hydroxide nanoplates as a catalyst is also disclosed.

A composition consisting essentially of a perovskite crystalline structure includes ions of a first metal M1 which occupies an A-site of the perovskite crystalline structure and ions of a second metal M2 which occupies a B-site of the perovskite crystalline structure. M2 has two oxidation states capable of forming a redox couple suitable for reversibly catalyzing an oxygen reduction reaction (ORR) and an oxygen evolution reaction (OER). The composition also includes ions of a third metal M3 at least a portion of which substitutes for M1 in the A-site of the perovskite crystalline structure, and at least a portion of which optionally also substitutes for M2 in the B-site of the perovskite crystalline structure. At least some of the ions of M3 have a different oxidation state to the ions of M1. The composition also includes atoms of an element X, which is a chalcogen.

A positive-electrode active material containing a compound that has a crystal structure belonging to the space group FM-3M and is represented by the composition formula (1):
Li.sub.xMe.sub.yO.sub.αF.sub.β  (1) wherein Me denotes one or two or more elements selected from the group consisting of Mn, Co, Ni, Fe, and Al, and the following conditions are satisfied. 1.3≤x≤2.2, 0.8≤y≤1.3, 1≤α≤2.93, 0.07≤β≤2.

Nanosized cubic lithium lanthanum zirconate is synthesized by forming a solution including an organic compound and compounds of lithium, lanthanum, and zirconium; drying the solution to yield a solid; and heating the solid in the presence of oxygen to pyrolyze the organic compound to yield a product comprising nanosized cubic lithium lanthanum zirconate.

To provide a ferrite sintered magnet having a high residual magnetic flux density (Br) and a high coercive force (HcJ), and also able to produce at a low cost. The ferrite sintered magnet includes a hexagonal M-type ferrite including A, R, Fe, and Co in an atomic ratio of A.sub.1-xR.sub.x(Fe.sub.12-yCo.sub.y).sub.zO.sub.19. A is at least one selected from Sr, Ba, and Pb. R is La only or La and at least one selected from rare earth elements. 0.13≤x≤0.23, 10.80≤(12−y)z≤12.10, and 0.13≤yz≤0.20 are satisfied.

A ferrite sintered magnet including ferrite grains having a hexagonal crystal structure. The ferrite grains satisfy 0.56≤W≤0.68 where W is an average value of circularities of the ferrite grains in a cross section parallel to an axis of easy magnetization.

A cubic boron nitride particle population having highly-etched surfaces and a high toughness index is produced by blending a reactive metal powder with a plurality of cubic boron nitride particles to form a blended mixture. The blended mixture is compressed to form a compressed mixture. The compressed mixture is subjected to a temperature and a pressure, where the temperature is controlled to cause etching of the plurality of cubic boron nitride particles by reaction of cubic boron nitride with the reactive metal powder, thereby forming a plurality of etched cubic boron nitride particles. Also, the temperature and pressure are controlled to cause boron nitride to remain in a cubic boron nitride phase. Afterwards, the plurality of etched cubic boron nitride particles is recovered from the compressed mixture to form the particle population. Preferably, the particle population contains no hexagonal boron nitride.