The purpose of the present disclosure is to provide a CNT fiber that is constituted of aligned carbon nanotubes (CNTs), is thin, has little irregularity in thickness, has excellent winding properties when undergoing coiling processing, and has superior conductivity. Provided is a CNT fiber constituted of carbon nanotubes (CNTs) having a thickness of 0.01 μm-3 mm, having a coefficient of variation for irregularity in thickness of 0.2 or less, having a distribution rate a for deviation from roundness of 40% or greater, and a distribution rate b of 70% or greater. Also provided is a method for manufacturing the CNT fiber.

The present invention provides a method for producing a carbon nanotube sheet that is excellent in light transmittance and conductivity, and the carbon nanotube sheet. The method includes firstly modifying of modifying a free-standing unmodified carbon nanotube sheet in which a plurality of carbon nanotubes are aligned in a predetermined direction. The firstly modifying includes performing a densification process of bringing the unmodified carbon nanotube sheet into contact with either one of or both of vapor and liquid particles of a liquid substance to produce a modified carbon nanotube sheet that contains the carbon nanotubes which are mainly aligned in a predetermined direction, and that includes a high density portion where the carbon nanotubes are assembled together and a low density portion where density of the carbon nanotubes is relatively lower than density in the high density portion.

A silicone oil-treated silica particle according to the present invention includes a silica particle body and silicone oil. The silica particle body has a BET specific surface area of 70 m.sup.2/g to 120 m.sup.2/g. The silica particle body has been surface-treated with the silicone oil. The amount of free silicone oil liberated from the surface of the silica particle body in the silicone oil accounts for 2.0 mass % to 5.0 mass % with respect to the silica particle body. A surface-treated styrene acrylic resin particle, in which 2 parts by mass of the silicone oil-treated silica particle has been added to 100 parts by mass of a styrene acrylic resin particle having a particle size median of 5 μm to 8 μm, has a degree of agglomeration of 18 % or less.

An amorphous silicon-carbon composite, a method for preparing the amorphous silicon-carbon composite using a pyrolysis method, a negative electrode for a lithium secondary battery, and a lithium secondary battery including the same.

A method of producing a positive electrode active material, the method includes: contacting first particles that contain a lithium transition metal composite oxide with a solution containing sodium ions to obtain second particles containing the lithium transition metal composite oxide and sodium element, wherein the lithium transition metal composite oxide has a layered structure and a composition ratio of a number of moles of nickel to a total number of moles of metals other than lithium in a range of from 0.7 to less than 1; mixing the second particles and a boron compound to obtain a mixture; and heat-treating the mixture at a temperature in a range of from 100° C. to 450° C.

A lithium complex oxide includes a mixture of first particles of n1 (n1>40) aggregated primary particles and second particles of n2 (n2≤20) aggregated primary particles, the lithium complex oxide represented by Chemical Formula 1 and having FWHM (deg., 2θ) of 104 peak in XRD, defined by a hexagonal lattice having R-3m space group, in a range of Formula 1:

Li.sub.aNi.sub.xCo.sub.yMn.sub.zM.sub.1-x-y-zO.sub.2,   [Chemical Formula 1]

where M is selected from: B, Ba, Ce, Cr, F, Mg, Al, Cr, V, Ti, Fe, Zr, Zn, Si, Y, Nb, Ga, Sn, Mo, W, P, Sr, and any combination thereof, 0.9≤a≤1.3, 0.6≤x≤1.0, 0.0≤y≤=0.4, 0.0≤z≤0.4, and 0.0≤1-x-y-z≤0.4,

−0.025≤FWHM.sub.(104)−{0.04+(x.sub.first particle−0.6)×0.25}≤0.025,   [Formula 1]

where FWHM.sub.(104) is represented by Formula 2,

FWHM.sub.(104)={(FWHM.sub.Chemical Formula 1 powder(104)−0.1×mass ratio of second particles)/mass ratio of first particles}−FWHM.sub.Si powder (220).   [Formula 2]

A negative active material includes a carbon material. The carbon material satisfies the following relationship: 6<Gr/K<16, Gr is a graphitization degree of the carbon material, measured by means of X-ray diffraction; and K is a ratio Id/Ig of a peak intensity Id of the carbon material at a wavenumber of 1250 cm.sup.−1 to 1650 cm.sup.−1 to a peak intensity Ig of the carbon material at a wavenumber of 1500 cm.sup.−1 to 1650 cm.sup.−1, and is measured by using Raman spectroscopy, and K is 0.06 to 0.15. The negative active material according to this application can significantly improve an energy density, cycle performance, and rate performance of the electrochemical device.

The method of producing a carbonaceous material for a negative electrode of a nonaqueous electrolyte secondary battery includes (1) an addition condensation step of subjecting a raw material mixture composed of phenols containing 50 mass% or greater of phenol and an aldehyde to addition condensation in the presence of a sodium-based basic catalyst at less than 5 mass% relative to the raw material mixture to produce a resol type phenol resin; (2) a heat treating step of subjecting the resol type phenol resin to a main heat treatment at a temperature of from 950° C. to 1500° C. in a non-oxidizing gas atmosphere to produce a heat-treated carbon; and (3) a coating step of coating the heat-treated carbon with pyrolytic carbon to produce a carbonaceous material.

Provided is a loss circulation material that may consist essentially of an acidic nanosilica dispersion and an activator. The acidic nanosilica dispersion may consist of acidic silica nanoparticles, stabilizer, and water, and may have a pH in a range of 3 to 6. The activator may be one or more from the group consisting of sodium bicarbonate, sodium chloride, or an amine salt. A method is provided for controlling lost circulation in a lost circulation zone in a wellbore comprising introducing the loss circulation material and forming a gelled solid from the loss circulation material in the lost circulation zone.

A super-flexible high thermal conductive graphene film and a preparation method thereof are provided. The graphene film is obtained from ultra large homogeneous graphene sheets through processes of solution film-forming, chemical reduction, high temperature reduction, high pressure suppression and so on. The graphene film has a density in a range of 1.93 to 2.11 g/cm.sup.3, is formed by overlapping planar oriented graphene sheets with an average size of more than 100 μm with each other through π-π conjugate action, and comprises 1 to 4 layers of graphene sheets which have few defects. The graphene film can be repeatedly bent for 1200 times or more, with elongation at break of 12-18%, electric conductivity of 8000-10600 S/cm, thermal conductivity of 1800-2600 W/mK, and can be used as a highly flexible thermal conductive device.