The present invention discloses a method for preparing graphene nanofibers and non-woven fabrics using a fluid with a ultra-high draw ratio by means of a high-voltage electrospinning method. Compared with other methods for preparing graphene fibers (such as wet spinning, air-assisted spinning, etc.), the graphene fibers obtained by the present method have smaller diameters (about 100 nm to 500 nm) and a higher yield. The fibers themselves have better mechanical and electrical properties. The invention discloses a method for preparing ultra-fine graphene nanofibers and non-woven fabrics by electrospinning a mixed spinning liquid system of polymer and graphene oxide (the polymer is sodium polyacrylate). This method is highly efficient and environmentally friendly, and the resulted graphene nanofibers are the thinnest graphene fibers as currently known.

A method of producing a sulfonated polymer. The method includes providing a source for a quantity of a polymer containing polymer fibers. The quantity of the polymer is heated while immersed in sulfuric acid to 100-200° C. for a period time in a closed reactor containing an atmosphere and capable of holding pressure generated by a reaction between the quantity of the polymer and the sulfuric acid resulting in a sulfonated polymer, wherein substantially all the quantity of the polymer from the source is converted into sulfonated polymer. The sulfonated polymer is then removed from the reactor and dried. An electrode suitable for use as an electrode in an electrochemical energy storage cell is disclosed. The electrode contains amorphous porous carbon fibers made from a sulfonated polymer with a morphology wherein the amorphous porous carbon fibers have the morphology of the sulfonated polymer from which they are made.

A carbon fiber wherein an average fiber diameter of a single fiber is in a range of 3 to 10 μm, and an average value of an intensity ratio (D/G) of a D peak to a G peak in a Raman spectrum in a cross section perpendicular to a fiber axis direction of the single fiber is 0.90 or less in a region inside a circle having a diameter of 1 μm and centered at a center of gravity of the cross section of the single fiber, and is 0.90 or less in a region up to 1 μm inside from an outer periphery of the cross section of the single fiber, wherein the D peak is observed at around 1360 cm.sup.−1 and derived from a defect in a graphite structure and the G peak is observed at around 1590 cm.sup.−1 and derived from the graphite structure.

A carbon fiber wherein an average fiber diameter of a single fiber is in a range of 3 to 10 μm, and an average value of an intensity ratio (D/G) of a D peak to a G peak in a Raman spectrum in a cross section perpendicular to a fiber axis direction of the single fiber is 0.90 or less in a region inside a circle having a diameter of 1 μm and centered at a center of gravity of the cross section of the single fiber, and is 0.90 or less in a region up to 1 μm inside from an outer periphery of the cross section of the single fiber, wherein the D peak is observed at around 1360 cm.sup.−1 and derived from a defect in a graphite structure and the G peak is observed at around 1590 cm.sup.−1 and derived from the graphite structure.

A carbon material precursor comprises an acrylamide-based polymer having a weight-average molecular weight of 10,000 to 2,000,000 and a polydispersity of the molecular weight (weight-average molecular weight/number-average molecular weight) of 5.0 or less.

A carbon material precursor comprises an acrylamide-based polymer having a weight-average molecular weight of 10,000 to 2,000,000 and a polydispersity of the molecular weight (weight-average molecular weight/number-average molecular weight) of 5.0 or less.

A method for producing a carbon material, the method including a step of performing a carbonization treatment by heating an organic polymer material to a temperature higher than 400° C. in a non-oxidizing atmosphere containing a gaseous substance (A) composed of at least one of acetylene and an acetylene derivative.

A method for producing a carbon material, the method including a step of performing a carbonization treatment by heating an organic polymer material to a temperature higher than 400° C. in a non-oxidizing atmosphere containing a gaseous substance (A) composed of at least one of acetylene and an acetylene derivative.

A carbon fiber manufacturing method includes joining first and second target fiber bundles with a joining fiber bundle, and carbonizing the joined bundles by feeding them through one or more carbonization furnaces. The joining includes forming an overlap between a first end of the joining fiber bundle and a second end of the first target fiber bundle and jetting a fluid to the overlap to form a first entangled portion, and forming an overlap between a second end of the joining fiber bundle and a first end of the second target fiber bundle and jetting a fluid to the overlap to form a second entangled portion. When the first and second entangled portions each have two or more entangling points with a tensile strength not less than 400 N, the relationship defined by the inequality is satisfied: 40>{L2/(L2−A)}×(S+13), where L2 is a length (mm) of an elongation section inside a first carbonization furnace upstream in a feeding direction of the fiber bundles, A is a maximum distance (mm) between an entangling point in the first entangled portion and an entangling point in the second entangled portion, and S is an elongation (%) of the joined fiber bundles fed through the carbonization furnace.

A carbon fiber manufacturing method includes joining first and second target fiber bundles with a joining fiber bundle, and carbonizing the joined bundles by feeding them through one or more carbonization furnaces. The joining includes forming an overlap between a first end of the joining fiber bundle and a second end of the first target fiber bundle and jetting a fluid to the overlap to form a first entangled portion, and forming an overlap between a second end of the joining fiber bundle and a first end of the second target fiber bundle and jetting a fluid to the overlap to form a second entangled portion. When the first and second entangled portions each have two or more entangling points with a tensile strength not less than 400 N, the relationship defined by the inequality is satisfied: 40>{L2/(L2−A)}×(S+13), where L2 is a length (mm) of an elongation section inside a first carbonization furnace upstream in a feeding direction of the fiber bundles, A is a maximum distance (mm) between an entangling point in the first entangled portion and an entangling point in the second entangled portion, and S is an elongation (%) of the joined fiber bundles fed through the carbonization furnace.