Disclosed herein is a preparation method of graphene, capable of preparing graphene having a smaller thickness and a large area, and with reduced defect generation, by a simplified process. The preparation method of graphene includes forming dispersion including a carbon-based material including unoxidized graphite, and a dispersant; and continuously passing the dispersion through a high pressure homogenizer including an inlet, an outlet, and a micro-channel for connection between the inlet and the outlet, having a diameter in a micrometer scale, wherein the carbon-based material is exfoliated, as the material is passed through the micro-channel under application of a shear force, thereby forming graphene having a thickness in nanoscale.

Favorable electrical characteristics are given to a semiconductor device. Furthermore, a semiconductor device having high reliability is provided. One embodiment of the present invention is an oxide semiconductor film having a plurality of electron diffraction patterns which are observed in such a manner that a surface where the oxide semiconductor film is formed is irradiated with an electron beam having a probe diameter whose half-width is 1 nm. The plurality of electron diffraction patterns include 50 or more electron diffraction patterns which are observed in different areas, the sum of the percentage of first electron diffraction patterns and the percentage of second electron diffraction patterns accounts for 100%, the first electron diffraction patterns account for 90% or more, the first electron diffraction pattern includes observed points which indicates that a c-axis is oriented in a direction substantially perpendicular to the surface where the oxide semiconductor film is formed.

A positive electrode active material for a lithium secondary battery, a method of preparing the same, and a lithium secondary battery, the positive electrode active material including nickel, cobalt, and manganese, wherein the positive electrode active material has a core part and a surface part, an amount of manganese in the core part and the surface part is higher than 25 mol %, and amounts of nickel and cobalt in the positive electrode active material vary such that a concentration gradient of the nickel and the cobalt in a direction from the core part to the surface part is present in the positive electrode active material.

A conductive porous material includes a skeleton structure containing a fibrous carbonaceous material of biological origin, and graphene held by the skeleton structure. A volume resistivity of the conductive porous material measured under pressure of less than or equal to 10 MPa is 1.010.sup.3 to 1.010.sup.0 .Math.cm. A biomass degree of the conductive porous material, as measured by accelerator mass spectrometry (AMS) method, is in a range of 5 to 55 pMC. An electrode includes the conductive porous material.

A mercury-based compound is in powder form and has the general chemical formula: M1.sub.aX.sub.b, where M1 is Hg, MxcMyd or a combination thereof, with Mx being Hg and My being an arbitrary element; wherein X is chloride, bromide, fluoride, iodide, sulphate nitrate or a combination thereof, wherein a, b, c and d are numbers between 0.1 and 10, wherein particles of the powder have a minimum average dimension of width of at least 50 nm and a maximum average dimension of width of at most 20 m, and wherein the mercury-based compound is paramagnetic and is present in an excited state.

A method for removing an organic ligand from a surface of a particle including: obtaining a particle having an organic ligand disposed on a surface thereof; contacting the particle with an alkylammonium salt represented by Chemical Formula 1:

NR.sub.4.sup.+A.sup.Chemical Formula 1 wherein groups R are the same or different and are each independently hydrogen or a C1 to C20 alkyl group, provided that at least one group R is an alkyl group, and A is a hydroxide anion, a halide anion, a borohydride anion, a nitrate anion, a phosphate anion, or a sulfate anion; and heat-treating the particle to carry out a reaction between the alkylammonium salt and the organic ligand.

Favorable electrical characteristics are given to a semiconductor device. Furthermore, a semiconductor device having high reliability is provided. One embodiment of the present invention is an oxide semiconductor film having a plurality of electron diffraction patterns which are observed in such a manner that a surface where the oxide semiconductor film is formed is irradiated with an electron beam having a probe diameter whose half-width is 1 nm. The plurality of electron diffraction patterns include 50 or more electron diffraction patterns which are observed in different areas, the sum of the percentage of first electron diffraction patterns and the percentage of second electron diffraction patterns accounts for 100%, the first electron diffraction patterns account for 90% or more, the first electron diffraction pattern includes observed points which indicates that a c-axis is oriented in a direction substantially perpendicular to the surface where the oxide semiconductor film is formed.

A silicon carbon composite, a negative electrode active material, a negative electrode composition, a negative electrode, a lithium secondary battery, a battery module, and a battery pack are provided. The silicon carbon composite satisfies a condition of 1.3((B+C)/A)<4, wherein A is an intensity of a peak having a chemical shift value in the range of 20 ppm to 15 ppm in a .sup.29Si-MAS-NMR spectrum, B is an intensity of a peak having a chemical shift value in the range of 20 ppm to 100 ppm in the .sup.29Si-MAS-NMR spectrum; and C is an intensity of a peak having a chemical shift value in the range of 110 ppm to 140 ppm in the .sup.29Si-MAS-NMR spectrum.

A composition may include an engineered synthetic carbonate comprising a structure, morphology, or combination thereof differing relative to a reference carbonate, wherein. A composition may include a thermal decomposition threshold of the engineered synthetic carbonate is in a range of from about 5% to about 30% less than the reference carbonate.

Disclosed is a method of: providing a hydrogenated sp.sup.2 carbon allotrope, and releasing hydrogen gas from the carbon allotrope. The method may use an apparatus having: a vessel for containing the hydrogenated sp.sup.2 carbon allotrope, a fuel cell capable of using hydrogen gas a fuel, and a tube for transporting hydrogen gas from the vessel to the fuel cell. The carbon allotrope may be made by: providing a mixture of an sp.sup.2 carbon allotrope and liquid ammonia, adding an alkali metal to the mixture, and sonicating the mixture to form a hydrogenated form of the carbon allotrope. The hydrogenated carbon can be at least 3.5 wt % hydrogen covalently bound to the carbon.