A random mat includes a chopped fiber bundle [A] obtained by obliquely cutting a partially separated fiber bundle [B] prepared by alternately forming separation-processed sections, each of which is separated into a plurality of bundles, and not-separation-processed sections, along the lengthwise direction of a fiber bundle, wherein the total cross-sectional area of reinforcing fibers exhibits a specific change amount between both tips of the chopped fiber bundle [A]; a production method produces the random mat; and a fiber-reinforced resin molding material uses the random mat.

In order to provide a gas diffusion electrode medium having high thermal conductivity despite having low density and excellent both in handleability and cell performance, provided is a gas diffusion electrode medium including carbon fiber felt including carbon fibers having an average fiber diameter of 5 to 20 μm, wherein at least a part of the carbon fibers that constitute the carbon fiber felt have a flat part in which, in a plane view of a surface of the carbon fiber felt, a maximum value of a fiber diameter is observed to be 10 to 50% larger than the average fiber diameter, and a frequency of the flat parts at the surface of the carbon fiber felt is 50 to 200/mm.sup.2.

In order to provide a gas diffusion electrode medium having high thermal conductivity despite having low density and excellent both in handleability and cell performance, provided is a gas diffusion electrode medium including carbon fiber felt including carbon fibers having an average fiber diameter of 5 to 20 μm, wherein at least a part of the carbon fibers that constitute the carbon fiber felt have a flat part in which, in a plane view of a surface of the carbon fiber felt, a maximum value of a fiber diameter is observed to be 10 to 50% larger than the average fiber diameter, and a frequency of the flat parts at the surface of the carbon fiber felt is 50 to 200/mm.sup.2.

A method for reducing the resistivity of a carbon nanotube nonwoven sheet includes providing a carbon nanotube nonwoven sheet comprising a plurality of carbon nanotubes and applying pressure to the carbon nanotube nonwoven sheet to reduce air voids between carbon nanotubes within the carbon nanotube nonwoven sheet.

A method for reducing the resistivity of a carbon nanotube nonwoven sheet includes providing a carbon nanotube nonwoven sheet comprising a plurality of carbon nanotubes and applying pressure to the carbon nanotube nonwoven sheet to reduce air voids between carbon nanotubes within the carbon nanotube nonwoven sheet.

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, in one embodiment, a nanostructured article. In an embodiment, the nanostructured article includes a first material made from a plurality of intermingled nanotubes placed on top of one another to form a continuous structure with sufficient structural integrity to be handled. The nanostructured article can also include a second material made from a plurality of nanotubes forming a layer situated on a surface of the first material. The second material, in an embodiment, has a nanotube density lower than the nanotube density of the first material. The nanostructured article further a layer of ordered pyrolytic carbon between the first material and the second material to enhance the bond and structural integrity between the first material and the second material, as well as enhancing the electrical and thermal conductivity between the first and second materials. A process for forming the nanostructured article is also provided.

The present invention provides, in one embodiment, a nanostructured article. In an embodiment, the nanostructured article includes a first material made from a plurality of intermingled nanotubes placed on top of one another to form a continuous structure with sufficient structural integrity to be handled. The nanostructured article can also include a second material made from a plurality of nanotubes forming a layer situated on a surface of the first material. The second material, in an embodiment, has a nanotube density lower than the nanotube density of the first material. The nanostructured article further a layer of ordered pyrolytic carbon between the first material and the second material to enhance the bond and structural integrity between the first material and the second material, as well as enhancing the electrical and thermal conductivity between the first and second materials. A process for forming the nanostructured article is also provided.

A system that receives nanomaterials, forms nanofibrous materials therefrom, and collects these nanofibrous materials for subsequent applications. The system is coupled to a chamber that generates nanomaterials, typically carbon nanotubes produced from chemical vapor deposition, and includes a mechanism for spinning the nanotubes into yarns or tows. Alternatively, the system includes a mechanism for forming non-woven sheets from the nanotubes. The system also includes components for collecting the formed nanofibrous materials. Methods for forming and collecting the nanofibrous materials are also provided.