Disclosed is a carbon-based fiber sheet and a lithium-sulfur battery including the same. The carbon-based fiber sheet for the lithium-sulfur battery is doped with a high concentration of nitrogen and thus plays a role of preventing diffusion by adsorbing lithium polysulfide eluted from a positive electrode during charging and discharging, thereby suppressing a shuttle reaction and thus improving capacity and lifecycle properties of the lithium-sulfur battery.

Disclosed is a carbon-based fiber sheet and a lithium-sulfur battery including the same. The carbon-based fiber sheet for the lithium-sulfur battery is doped with a high concentration of nitrogen and thus plays a role of preventing diffusion by adsorbing lithium polysulfide eluted from a positive electrode during charging and discharging, thereby suppressing a shuttle reaction and thus improving capacity and lifecycle properties of the lithium-sulfur battery.

The present invention provides a carbon fiber aggregate that is characterized by comprising carbon fibers in which crystallite interplanar spacing (d002) measured using X-ray diffraction is 0.3400 nm or more, the average liber diameter being 10-900 nm, and the powder volume resistivity being 4.00×10.sup.−2 Ω.Math.cm or less when the packing density is 0.8 g/cm.sup.3.

The present invention provides a carbon fiber aggregate that is characterized by comprising carbon fibers in which crystallite interplanar spacing (d002) measured using X-ray diffraction is 0.3400 nm or more, the average liber diameter being 10-900 nm, and the powder volume resistivity being 4.00×10.sup.−2 Ω.Math.cm or less when the packing density is 0.8 g/cm.sup.3.

With the present invention a carbon fiber aggregate is provided that has an average fiber diameter of 100-1000 nm, and a fiber diameter variation coefficient (CV value) greater than 0.5 and less than or equal to 1.0.

The present invention provides pitch-based ultrafine carbon fibers that have an average fiber diameter of at least 100 nm and less than 700 nm, and an average fiber length of 10 μm or more, wherein C—O bonds >C═O bonds in terms of the abundance ratio (molar ratio) of C—O bonds and C═O bonds derived from the O1s orbital as measured by X-ray photoelectron spectroscopy.

The present invention provides pitch-based ultrafine carbon fibers that have an average fiber diameter of at least 100 nm and less than 700 nm, and an average fiber length of 10 μm or more, wherein C—O bonds >C═O bonds in terms of the abundance ratio (molar ratio) of C—O bonds and C═O bonds derived from the O1s orbital as measured by X-ray photoelectron spectroscopy.

The present disclosure relates to a process for preparing carbon fibers. The process involves blending a carbon nano-material with a carbon material to obtain a homogenous blend, heating the homogenous blend to obtain mesophase pitch having particles with reduced mesophase sphere size followed by spinning the mesophase pitch to obtain the pitch fibers. The pitch fibers are then carbonized to obtain the carbon fibers. The carbon fibers prepared by the process of the present disclosure have improved tensile properties as compared to the conventional pitch based carbon fibers.

The present invention provides a carbon fiber aggregate that is characterized by comprising carbon fibers in which crystallite interplanar spacing (d002) measured using X-ray diffraction is 0.3400 nm or more, the average liber diameter being 10-900 nm, and the powder volume resistivity being 4.00×10.sup.−2 Ω.Math.cm or less when the packing density is 0.8 g/cm.sup.3.

The present invention provides a carbon fiber aggregate that is characterized by comprising carbon fibers in which crystallite interplanar spacing (d002) measured using X-ray diffraction is 0.3400 nm or more, the average liber diameter being 10-900 nm, and the powder volume resistivity being 4.00×10.sup.−2 Ω.Math.cm or less when the packing density is 0.8 g/cm.sup.3.