Lithium ion batteries, electrodes, nanofibers, and methods for producing same are disclosed herein. Provided herein are batteries having (a) increased energy density; (b) decreased pulverization (structural disruption due to volume expansion during lithiation/de-lithiation processes); and/or (c) increased lifetime. In some embodiments described herein, using high throughput, water-based electrospinning process produces nanofibers of high energy capacity materials (e.g., ceramic) with nanostructures such as discrete crystal domains, mesopores, hollow cores, and the like; and such nanofibers providing reduced pulverization and increased charging rates when they are used in anodic or cathodic materials.

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.

A carbon fiber production method includes a carbon fiber production step including an oxidation step and a carbonization step; and an exhaust gas processing step including a heat exchange step; an external air mixing step; and a mixed external air supplying step in which the mixed external air is supplied to at least one step that uses heated gas in the steps in the carbon fiber production step; and among the exhaust gases, a high heating value exhaust gas having a heating value of 250 kcal/Nm.sup.3 or higher is supplied to an inlet side of an exhaust gas combustion apparatus and a low heating value exhaust gas having a heating value lower than 150 kcal/Nm.sup.3 is supplied to an outlet side of the exhaust gas combustion apparatus, respectively.

Described herein are porous carbon fibers, methods of making the porous carbon fibers, and methods of using the porous carbon fibers. In some aspects, the porous carbon fibers can have a hierarchical distribution of uniformly distributed meso- and micropores, wherein the micropores and mesopores can be interconnected. In aspects, the porous carbon fibers can have mesopores with a uniform pore size.

There is provided a method of making a hollow fiber. The method includes mixing, in a first solvent, a plurality of nanostructures, one or more first polymers, and a fugitive polymer which is dissociable from the nanostructures and the one or more first polymers, to form an inner-volume portion mixture. The method further includes mixing, in a second solvent, one or more second polymers to form an outer-volume portion mixture, and spinning the inner-volume portion mixture and the outer-volume portion mixture to form a precursor fiber. The method further includes heating the precursor fiber to oxidize the precursor fiber and to change a molecular-bond structure of the precursor fiber, and during heating, extracting the fugitive polymer from the inner-volume portion mixture. The method further includes obtaining the hollow fiber with the inner-volume portion having the nanostructures and the first polymers, and with the outer-volume portion having the second polymers.

Cord-yarn supercapacitors are disclosed herein. The cord-yarn supercapacitor can include two or more ply yarns twisted together and an electrolyte. The ply yarns can comprise an activated carbon fiber yarn and a non-activated carbon fiber yarn. The activated carbon fiber yarn can be derived from a staple yarn which has been carbonized and activated. The non-activated carbon fiber yarn can be derived from a multi filament yarn. The electrolyte can include a polymer gel. The cord-yarn supercapacitors disclosed herein provide a rope-format linear structure with great flexibility. This unique linear structure allows the supercapacitor to find use in applications such as apparel products, outdoor activity products, sports wears, and other industrial end uses. Methods of making cord-yarn supercapacitors are also disclosed.

Cord-yarn supercapacitors are disclosed herein. The cord-yarn supercapacitor can include two or more ply yarns twisted together and an electrolyte. The ply yarns can comprise an activated carbon fiber yarn and a non-activated carbon fiber yarn. The activated carbon fiber yarn can be derived from a staple yarn which has been carbonized and activated. The non-activated carbon fiber yarn can be derived from a multi filament yarn. The electrolyte can include a polymer gel. The cord-yarn supercapacitors disclosed herein provide a rope-format linear structure with great flexibility. This unique linear structure allows the supercapacitor to find use in applications such as apparel products, outdoor activity products, sports wears, and other industrial end uses. Methods of making cord-yarn supercapacitors are also disclosed.

Provided is a manufacturing method of a graphene-based liquid crystal fiber including: polymerizing a first aromatic monomer on a graphene-based compound to prepare a graphene composite in which a first aromatic polymer is surface-polymerized on the graphene-based compound; wet-spinning the graphene composite to manufacture a hydrogel fiber; and polymerizing a second aromatic monomer on the hydrogel fiber to fill pores of the hydrogel fiber with a second aromatic polymer.

Provided is a manufacturing method of a graphene-based liquid crystal fiber including: polymerizing a first aromatic monomer on a graphene-based compound to prepare a graphene composite in which a first aromatic polymer is surface-polymerized on the graphene-based compound; wet-spinning the graphene composite to manufacture a hydrogel fiber; and polymerizing a second aromatic monomer on the hydrogel fiber to fill pores of the hydrogel fiber with a second aromatic polymer.