A lithium ion conductive solid electrolyte contains a lithium ion conductive powder having a garnet-type crystal structure including at least Li, La, Zr, and O, and a lithium ion conductive polymer. The lithium ion conductive solid electrolyte can maintain its shape without use of an additional polymer different from the lithium ion conductive polymer. The lithium ion conductive solid electrolyte exhibits an activation energy of 30 kJ/mol or less at 20° C. to 80° C.

A positive electrode active material that has high capacity and excellent charge and discharge cycle performance for a secondary battery is provided. The positive electrode active material includes a group of particles including a first group of particles and a second group of particles. The group of particles includes lithium, cobalt, nickel, aluminum, magnesium, oxygen, and fluorine. When the number of cobalt atoms included in the group of particles is taken as 100, the number of nickel atoms is greater than or equal to 0.05 and less than or equal to 2, the number of aluminum atoms is greater than or equal to 0.05 and less than or equal to 2, and the number of magnesium atoms is greater than or equal to 0.1 and less than or equal to 6. When particle size distribution in the group of particles is measured by a laser diffraction and scattering method, the first group of particles has a first peak and the second group of particles has a second peak; the first peak has a local maximum value at longer than or equal to 2 μm and shorter than or equal to 4 μm, and the second peak has a local maximum value at longer than or equal to 9 μm and shorter than or equal to 25 μm.

Regeneration of degraded cathode particles in lithium-ion batteries is achieved using a combination of hydrothermal treatment of cycled electrode particles followed by short thermal annealing. The methods provide for direct regeneration of Li-ion cathode materials including LiCoO.sub.2, LiMn.sub.2O.sub.4, LiFePO.sub.4, and Li.sub.xNi.sub.y Mn.sub.z Co.sub.1−y−zO.sub.2, in an economical and environmentally-friendly process.

An iron-containing Chevrel phase material, contains iron and Mo.sub.6S.sub.8 clusters, in particular an iron-containing Chevrel phase material having a formula Fe.sub.xMo.sub.6S.sub.8, wherein 2≤x≤4. The iron-containing Chevrel phase provides an efficient catalyst for the electrochemical production of ammonia from water and nitrogen gas.

A ceramic membrane for oxidative coupling of methane can include a perovskite oxide and catalyst material on a surface of the membrane.

High photoluminescence, high stability, inorganic perovskite compounds comprising an alkali metal selected from potassium (K), rubidium (Rb), and cesium (Cs); copper (Cu); and at least one halogen selected from chlorine (Cl), bromine (Br), and iodine (I). The perovskites may be free of lead (Pb). The inorganic perovskite compound may be used in an optoelectronic device. The optoelectronic device optionally contains a phosphor such as a blue-emitting phosphor. The inorganic perovskite compound may be used as an anti-counterfeiting nanotaggant applied on or within an object that susceptible to counterfeiting to enable confirmation of an authentic object.

Ferromagnetic materials are disclosed that comprise at least one Dirac half metal material. In addition, Dirac half metal materials are disclosed, wherein the material comprises a plurality of massless Dirac electrons. In addition, ferromagnetic materials are disclosed that includes at least one Dirac half metal material, wherein the material comprises a plurality of massless Dirac electrons, wherein the material exhibits 100% spin polarization, and wherein the plurality of electrons exhibit ultrahigh mobility. Spintronic devices and heterostructures are also disclosed that include a Dirac half metal material.

A positive electrode active material with little deterioration is provided. Positive electrode active material particles with little deterioration are provided. A power storage device with little deterioration is provided. A highly safe power storage device is provided. A novel power storage device is provided. A secondary battery includes a positive electrode and a negative electrode. In the secondary battery, the positive electrode includes a positive electrode active material; the positive electrode active material includes a crystal exhibiting a layered rock-salt crystal structure; the crystal is represented by the space group R-3m; the positive electrode active material is a particle containing lithium, cobalt, titanium, magnesium, and oxygen; the concentration of the magnesium in a surface portion of the particle is higher than the concentration of the magnesium in an inner portion of the particle; and in the positive electrode active material, the concentration of the titanium in the surface portion of the particle is higher than the concentration of the titanium in the inner portion of the particle.

The breakage or cracking of a positive electrode active material due to pressure application, repeated charging and discharging, or the like is likely to cause dissolution of a transition metal, an excessive side reaction, and the like. With a crack, unevenness, a step, roughness, or the like on the surface of a positive electrode active material, stress tends to be concentrated on part, which easily causes breakage. By contrast, with a smooth surface and a nearly spherical shape, stress concentration is alleviated; thus, breakage is unlikely to occur. Therefore, a positive electrode active material with a smooth surface and little unevenness is formed. For example, when the positive electrode active material is subjected to image analysis using a microscope image, the median value of the solidity is larger than or equal to 0.96. Alternatively, the median value of the fractal dimension of the positive electrode active material is smaller than or equal to 1.143. Alternatively, the median value of the circularity of the positive electrode active material is larger than or equal to 0.7.

The present invention discloses a quaternary cathode material, an cathode and a battery. Particularly, the present invention provides the quaternary cathode material with a chemical structural formula: Li.sub.xNi.sub.a′Co.sub.bMn.sub.c′Al.sub.dM.sub.yO.sub.2, wherein 1x1.05,0<y0.025.0.3a′0.95,0.03b01.0.01c′0.05,0.01d0.005 and a′+b+c′+d=1; M is a dopant selecting from at least one of Zr, Al, B, Ti, Mg, Nb, Ba, Si, P, W, Sr and F. The quaternary cathode material has an α-NaFeO.sub.2 ty