▎ 摘　　要

NOVELTY - A graphite nanofiber having cylindrical structure comprises graphene sheets (12), each having truncated conical shape, arranged sequentially through catalytic metal particles. Alternatively, small pieces of graphene sheets having a shape adapted for a surface shape of catalytic metal particle, are arranged one over the other in layers, through catalytic metal particles. USE - For electron emitting source and cathode material of lithium ion secondary battery (all claimed). ADVANTAGE - The graphite nanofibers have excellent electron emission characteristics such as high electron emission density and electron emitting ability at low electrical field and high quality as active material for cathodes. The nanofiber provides excellent charging and discharging capacities, to cathode and long life cycle, fast charging ability and high service or discharge capacity, to batteries. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) an electron emitting source which has carbon layer comprising graphite nanofibers, deposited on electrode substrate (11) or its patterned surface; (2) preparation of electron emitting source which involves growing a graphene sheet on an electrode substrate or its patterned surface comprising iron, cobalt or their alloy, using carbon containing gas and hydrogen gas, by thermal CVD method, or the method involves dispersing graphite nanofiber powder in a solvent to form a paste and applying the paste on a electrode substrate or immersing electrode substrate into a dispersion of graphite nanofiber powder in solvent and depositing graphite nanofibers on the substrate by electro-deposition; (3) a display element having several transparent conductive films with desired pattern, an electron emitting source and a luminous body opposed to carbon layer, and designed so that if selecting the carbon layer and the transparent conductive film and applying electric voltage, electrons are emitted from the carbon layers, so that only a specific portions on luminous body emit light; (4) a negative electrode carbonaceous material comprising graphite nanofibers; and (5) a lithium ion secondary battery which has anode including lithium transition metal oxide as anode active material, cathode including carbonaceous material comprising graphite nanofibers as cathode active material and organic solvent-based electrolyte. DESCRIPTION OF DRAWING(S) - The figure shows sectional view structure of graphite nanofibers. Electrode substrate (11) Graphene sheet (12) Through-hole (13)