A porous membrane comprising stacked layers of nanosheets, each nanosheet comprising one to three atomic layers of a 2D material comprising or consisting of one or more transition metal dichalcogenides is provided. The nanosheets have pores and the membrane comprises a network of water permeation pathways including through-pathways formed by the pores, horizontal pathways formed by gaps between the layers, and vertical pathways formed by gaps between adjacent nanosheets and stacking defects between the layers. Also provided is a method for making the membrane.

Provided is ITO particles satisfying a relationship expressed in Expression (1) given below. 16×S/P.sup.2≤0.330 . . . (1) (In the expression, S indicates a particle area in a TEM photographed image, and P indicates a perimeter of the particle).

A method of manufacturing a gas sensor for detecting xylene is provided. A method of manufacturing a gas sensor includes reacting a mixed material including a first material containing a cobalt (Co) element and a second material containing a chromium (Cr) element to form a CoCr.sub.2O.sub.4 hollow structure having a hollow shape.

The present invention relates to a positive electrode active material which has the structural stability of a lithium composite oxide constituting a positive electrode active material and a lithium secondary battery including the same. The lithium composite oxide constituting the positive electrode active material according to the present invention is able to reduce the surface area and grain boundary of secondary particles having a side reaction with an electrolyte solution, thereby improving high-temperature stability and reducing gas generation caused by the positive electrode active material, and the structural stability of the lithium composite oxide may be improved using a cation-mixing layer covering the surface of a primary particle.

Proposed are a layered Group III-V compound having ferroelectric properties, a Group III-V compound nanosheet that may be prepared using the same, and an electrical device including the materials. Proposed is a layered compound represented by [Formula 1] M.sub.x−mA.sub.yB.sub.z (M is at least one of Group I or Group II elements, A is at least one of Group III elements, B is at least one of Group V elements, x, y, and z are positive numbers which are determined according to stoichiometric ratios to ensure charge balance when m is 0, and 0<m<x), and having ferroelectric-like properties.

In an aspect, a Co.sub.2Z ferrite has the formula: (Ba.sub.1-xSr.sub.x).sub.3Co.sub.2+yM.sub.yFe.sub.24-2y-zO.sub.41. M is at least one of Mo, Ir, or Ru. The variable x can be 0 to 0.8, or 0.1 to 0.8. The variable y can be 0 to 0.8, or 0.01 to 0.8. The variable z can be −2 to 2. The Co.sub.2Z ferrite can have an average grain size of 5 to 100 nanometers, or 30 to 80, or 10 to 40 nanometers as measured using at least one of transmission electron microscopy, field emission scanning electron microscopy, or x-ray diffraction.

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.

An object of the present invention is to provide ferrite particles having a high magnetic permeability in a frequency band of 1 MHz to 1 GHz. Another object is to provide a resin composition containing the ferrite particles and an electromagnetic wave shielding material composed of the resin composition. The ferrite particles are composed of a single crystalline body having an average particle size of 1 to 2000 nm and has a spherical particle shape, wherein the ferrite particles contain substantially no Zn, 3 to 25 wt % of Mn, and 43 to 65 wt % of Fe, and a real part μ′ of a complex magnetic permeability measured using a molding composed of the ferrite particles and a binder resin has a maximal value in a frequency band of 100 MHz to 1 GHz.

An electrode material, its manufacturing method, and its use as a cathode material in batteries are provided. The electrode material comprises a plurality of nanoparticles, each having a diameter of approximately 100-400 nm and comprising a core and a shell encapsulating the core. The shell comprises carbon and nitrogen, respectively having a mass fraction of approximately 70-90% and approximately 5-20% relative to a total mass of the shell. The core comprises sulfur, having a mass fraction of approximately 40-97% relative to a total mass of the core. The core has a mass fraction of approximately 50-90% relative to a total mass of each nanoparticle. The electrode material can be used in a cathode of a Li—S battery, which has a good energy storage capacity, a high electrochemical stability, and a low capacity decay.

The present disclosure relates to a positive electrode active material, a method of preparing the same, and a lithium secondary battery having a positive electrode including the same. The positive electrode active material includes: a lithium transition metal oxide particle in which a portion of Li is substituted with Na, and which includes Ni and Co atoms, wherein the lithium transition metal oxide particle includes a concentration gradient region in which the concentration of Co atoms decreases from the surface toward the center of the particle.