This positive electrode active material for nonaqueous electrolyte secondary batteries contains: a lithium transition metal composite oxide having secondary particles, each of which is formed of aggregated primary particles; and a surface modification compound which is present on at least the surfaces of the secondary particles, while containing at least one of Ca and Sr. The lithium transition metal composite oxide contains 70% by mole or more of Ni relative to the total number of moles of the metal elements excluding Li; and the total amount of Ca and Sr in the surface modification compound is 0.5% by mole or less relative to the total number of moles of the metal elements excluding Li in the lithium transition metal composite oxide.

The present invention pertains to: a positive electrode active material precursor containing first secondary particle composed of an aggregate of a plurality of first primary particles, the positive electrode active material precursor including a first center portion represented by chemical formula 1 and a first surface portion represented by chemical formula 2, wherein the thickness of the first surface portion is 2-20% of the average radius of the positive electrode active material precursor; and a positive electrode active material containing the positive electrode active material precursor.

The perovskite compound according to the invention has a cubic perovskite structure, has high catalytic activity in oxygen reduction and evolution reactions, and has excellent durability, and thus, can be used as a catalyst of electrochemical devices, particularly as a fuel cell catalyst.

A method of preparing bismuth vanadate particles is described. The bismuth vanadate particles prepared via ultrasonication and hydrothermal treatment exhibit controlled morphology (e.g., octahedral shape) and crystallinity (e.g., tetragonal crystal symmetry). A photoelectrode containing bismuth vanadate particles and a method of using the photoelectrode in a photoelectrochemical cell for water splitting is also provided.

A lithium-ion battery anode material containing surface-coated disordered rocksalt lithium vanadium oxide is disclosed. The surface coating contains a species selected from the group consisting of carbon, a metal oxide, a metalloid oxide, a metal fluoride, a metalloid fluoride, a metal phosphate, a metalloid phosphate, and combinations thereof. Materials, designs, synthesis methods, and devices related to fast-charging lithium-ion batteries are provided. This invention fills a technology gap by providing anode materials with disordered rocksalt lithium vanadium oxides to achieve fast charging in 10 minutes or less, greater than 200 W.Math.h/kg energy density, a lifetime of at least 10,000 cycles, and improved battery safety. Methods of making and using the optionally surface-coated disordered rocksalt lithium vanadium oxide are disclosed. Many experimental examples are included, demonstrating several remarkable attributes of this battery technology.

A solid electrolyte includes an ion conductor represented by at least one of Formulae 1 to 3,
Li.sub.1+3xM1.sub.1−xO.sub.2  Formula 1
wherein, in Formula 1, M1 is a trivalent element, and 0<x<1,
L.sub.1−yM2O.sub.2−yX.sub.y  Formula 2
wherein, in Formula 2, M2 is a trivalent element, X is at least one of a halogen atom or a pseudohalogen, and 0<y<1,
Li.sub.1−z(a−3)M3.sub.1−zD.sub.zO.sub.2  Formula 3
wherein, in Formula 3, M3 is a trivalent element, D is at least one of a monovalent element to a hexavalent element, and 0<z<1.

To provide a ferrite sintered magnet having a high residual magnetic flux density (Br), a high coercive force (HcJ), a good production stability, 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. 0.14≤x≤0.22, 11.60≤(12-y)z≤11.99, and 0.13≤yz≤0.17 are satisfied. 0.30≤Mc≤0.63 is satisfied in which Mc is CaO content (mass %) converted from a content of Ca included in the ferrite sintered magnet.

The present invention relates to single crystalline RbUO.sub.3, hydrothermal growth processes of making such single crystals and methods of using such single crystals. In particular, Applicants disclose single crystalline RbUO.sub.3 single crystalline RbUO.sub.3 in the Pm-3m space group. Unlike other powdered RbUO.sub.3, Applicants' single crystalline RbUO.sub.3 has a sufficient crystal size to be characterized and used in the fields of neutron detection, radiation-hardened electronics, nuclear forensics, nuclear engineering photovoltaics, lasers, light-emitting diodes, photoelectrolysis and magnetic applications.

The invention relates to Chevrel-phase materials and methods of preparing these materials utilizing a precursor approach. The Chevrel-phase materials are useful in assembling electrodes, e.g., cathodes, for use in electrochemical cells, such as rechargeable batteries. The Chevrel-phase materials have a general formula of Mo.sub.6Z.sub.8 (Z=sulfur) or Mo.sub.6Z.sup.1.sub.8-yZ.sup.2.sub.y (Z.sup.1=sulfur; Z.sup.2=selenium), and partially cuprated Cu.sub.1Mo.sub.6S.sub.8 as well as partially de-cuprated Cu.sub.1-xMg.sub.xMo.sub.6S.sub.8 and the precursors have a general formula of M.sub.xMo.sub.6Z.sub.8 or M.sub.xMo.sub.6Z.sup.1.sub.8-yZ.sup.2.sub.y, M=Cu. The cathode containing the Chevrel-phase material in accordance with the invention can be combined with a magnesium-containing anode and an electrolyte.

A positive electrode active material precursor for a lithium secondary battery containing at least Ni, in which S/D.sub.50 that is a ratio of a BET specific surface area S to a 50% cumulative volume particle size D.sub.50 is 2×10 to 20×10.sup.6 m/g, and, in powder X-ray diffraction measurement using a CuKα ray, A/B that is a ratio of an integrated intensity A of a diffraction peak within a range of 2θ=37.5±1° to an integrated intensity B of a diffraction peak within a range of 2θ=62.8±1° is more than 0.80 and 1.33 or less.